Government bid to delay air pollution plan fails

Image copyright Getty Images

Image caption Air pollution has been described as a "public health emergency"

The UK Government has lost a court bid to delay publication of its air pollution strategy, and must now release it before the June election.

Courts had given the government until Monday 24 April to set out draft guidelines to tackle illegal levels of nitrogen dioxide (NO2) pollution.

But late last week, ministers lodged an application to delay their release until after the general election.

They argued __that publication would fall foul of election "purdah" rules.

These limit government announcements with political implications during the election period.

But on Thursday, the High Court ordered the draft plans to be published on 9 May, five days after the local elections, but long before the general election on 8 June.

The date for publication of the final document remains unchanged on 31 July.

Reality Check: Does pollution cut short 40,000 lives a year?

Green group wins air pollution court battle

During the hearing, government barrister James Eadie QC told Mr Justice Garnham __that publication would drop a "controversial bomb" into the mix of local and national elections.

The new strategy was requested last year, after a court ruled that existing measures to tackle air pollution proposed by the government did not meet the requirements of law.

But the High Court decided that purdah was a convention only and did not override legal obligations to clean up the air. Additionally, the impact on public health would exempt it from the purdah rules anyway.

Legal battle

Thursday's decision is the latest development in a long-running legal action brought against the government by a group of environmental lawyers, ClientEarth. The campaigners began proceedings after the UK breached EU limits for nitrogen dioxide (NO2) in the air.

These limits were introduced by EU law in 1999 and were to have been achieved by 2010. Some 37 out of 43 regions in the UK have been in breach over levels of NO2, one of several nitrogen oxide (NOx) pollutants.

Diesel vehicles are a key source of NOx emissions, and NO2 has been linked to a range of respiratory illnesses. Around 40,000 people are estimated to die prematurely every year in the UK because of poor air quality.

Reacting to the ruling on Thursday, James Thornton, ClientEarth's chief executive, said: "ClientEarth is delighted with Justice Garnham's decision.

"The judge listened to the government's claims that it needed to delay taking care of public health, but he rejected them vigorously and is keeping the government to the deadline of releasing the final plan on 31 July."

The government could yet appeal the ruling, which might effectively delay the process anyway.

Mr Thornton said: "I would urge them not to appeal. I would say: 'get to work'. Enough dither, enough delay, clean up the air."

Reluctant decision

Representing the government, Mr Eadie QC said the application had been brought with considerable reluctance and was not "some sort of guise or demonstration of lack of commitment to improving air quality".

In April 2015, ClientEarth won a Supreme Court ruling against the government over air pollution levels.

That judgment ordered ministers to come up with a plan to bring down air pollution to within legal limits as soon as possible.

But ClientEarth was dissatisfied with those proposals, and took the government to the High Court in a judicial review, which it won.

London's Labour Mayor, Sadiq Khan, said: "I am pleased that the government will now have to face its responsibilities sooner rather than later.

"Ministers were dragged kicking and screaming to face the huge scale of this health crisis, but rather than take immediate action to protect the public they deliberately used the election as a smokescreen to hold back their plan."

He added: "I hope that after this appalling delay, this Government delivers a strong plan to finally get a grip on this issue and urgently introduces a diesel scrappage fund to rid our streets of the dirtiest cars."

Follow Paul on Twitter.

Read More

Most scientific studies only use male subjects. Here's why that's a terrible idea.

“Pigeons, or rock doves as people call them to be fancy, are fascinating creatures,” said Rebecca Calisi, a professor of neurobiology, physiology, and behavior at the University of California, Davis. “An average person might view them as common or boring or as pests, but pigeons have been unlocking secrets about biology and reproduction for centuries. Charles Darwin even kept pigeons and was, in part, inspired by them.”

Calisi is a co-author on a recent study in the journal Scientific Reports which looked at differences in the genetic expressions of the hypothalamic-pituitary-gonadal—basically the systems __that drive us to make babies—of both female and male pigeons. Gene expression is the process by which certain genes are activated or turned on so __that they express certain traits. The classic example is eye color: a person may carry the trait for blue eyes, but depending on the other genes they carry, that trait might be expressed as blue, hazel, or even brown. This study is unique not just because of its results, which create sort of foundational framework that others can use to study gene expression in the future, but also because the research actually acknowledges something often ignored in science: that females exist.

Women are woefully underrepresented in science, not just as researchers but also as subjects. Even in animal studies, as many as eighty percent of subjects are male (despite the fact that there are roughly as many women in the world as men). Less than a quarter of the subjects in clinical trials are women. And when trials do enroll women, they're generally studied only at their most biologically “male-like” (when neither ovulating nor menstruating). It’s a bit like trying to study rainfall on a sunny day. Researchers say that they do this because the ovarian cycle makes studying women “complex.” But, noted Calisi, “This in fact is representational of what the female experience is, so we need to come up with a way to study this.”

In fact, because we don’t study women, we often make them sick. Women are far more likely than men to experience negative outcomes from medication, in part because women metabolize drugs differently. Even your typical flu vaccine, which is calibrated for men, includes twice the dosage your average woman needs. And the female focus hurts men too: women, for example, are more likely to suffer from the disease multiple sclerosis, but their symptoms tend to be milder. What is it about women that both puts them at an increased risk for the disease, but also ameliorates its symptoms? And can it be used to help treat the disease in men?

“There’s sexism at many different levels, and this definitely affects the rigor of the science that is conducted,” said Calisi.

It was the similarities, not the differences, between the sexes that drew Calisi to pigeons. To begin with, male and female pigeons look exactly the same. Pigeons lack sex-specific markings, like the flamboyant feathers that separate peacocks from peahens, or the size differential of male and female bald eagles (the females are bigger). And pigeons, like most birds, have internal genitalia, or testes and ovaries, so you can’t tell a male pigeon from a female pigeon just by looking at it. Finally, like humans, both male and female pigeons care for the young—although unlike human males, pigeon dads also lactate.

“Pigeons produce specialized cells in their crop sacs. When chicks are born, the cells slough off to produce this milky, cottage cheese-like substance that is high in milk, protein, fat, antibodies—lots of good stuff, like human breast milk,” said Calisi. “Hormones like prolactin that help to control lactation in birds are the same ones that human mothers use to stimulate milk production.”

So pigeons seemed like a good place to start. Calisi and a team of researchers including Matthew D. MacManes, a geneticist at the University of New Hampshire, looked at pigeons to ask how genes behave differently in males versus in females. Specifically, they looked at the hypothalamus, which is basically the reproduction control center in the brain; the pituitary gland, which is attached directly below the hypothalamus and produces and secretes many of the hormones; and the gonads, which manifest as the ovaries in women but in males become testes. And all of these systems are present in humans, too.

What they found was that the gene activity differed between males and females in all of these tissues. “Of course, one would expect that males and females would be different when it comes to these tissues involved with reproduction, especially when you compare testes to ovaries,” said Calisi. What was interesting is that the genes differed in the hypothalamus and pituitary too, even when the birds were not actively engaged in reproduction—courting, mating, or caregiving.

In the pituitary, which in a pigeon is roughly the size of a grain of rice, about 200 genes were more active in males than in females, while about 150 genes were more active in females than in males. In other words, male and females had similar genes, but different ones were turned on.

“This makes us wonder: does the pituitary contribute to a male being a male and a female being a female?” said Calisi, “What are all of these genes doing? For most of them we don't know.”

It’s a foundational study—Calisi and her team will continue down this line of inquiry. But it’s the kind of question that can only be raised—and eventually answered—by studying both sexes. Which is why Calisi says that by mainly studying males, “We’re missing out on opportunities to use diversity to broaden the way we ask questions and solve problems.”

"This work was not done to combat sexism," Calisi added. "We included both sexes because that's what one should do.”

Read More

New research on eyeballs just might lead to a jet lag cure

Your biological clock is probably the most reliable machinery in your body: it runs 24-7 to regulate vital functions from sleep to metabolism and remains stubbornly steadfast when you fly across time zones. Scientists still don’t know exactly how this this internal clock works. But now researchers have identified a missing gear __that could offer a cure for jet lag.

A recent study published in the Journal of Physiology discovered a new group of cells in the retina __that send signals about light changes from the eye to the brain. These cells produce and release a molecule called vasopressin to help regulate the biological clock or the circadian rhythm of rats.

Scientists already knew that vasopressin plays a role in hypothalamus’ suprachiasmatic nucleus (SCN), the center for circadian rhythm in the brain, but this is the first research to show a retinal input of vasopressin. In theory, one could tweak the behavior of these cells within the eye to reduce vasopressin signaling—which could help regulate your internal clock and kick jet lag to the curb.

“In humans, you can't inject anything into the brain. But you could think about [applying] eye drops into the eye and then help to reset your biological clock,” says the leading author Mike Ludwig, a professor of neurophysiology at the University of Edinburgh in Scotland. “But that is very futuristic. We are far from that at the moment,” Ludwig says.

Hugh Piggins, an expert in circadian rhythm at the University of Manchester who was not involved in the study, agrees that “this is very basic research, but it raises some exciting possibilities.”

“We've known for a long time that you can combat things like jet lag by controlling how much light you're exposed to, what times of the day you get up... That's just dealing with light,” Piggins says. “This [study] would say that maybe there's another way.”

Animals have already been cured of jet lag through the inhibition of vasopressin—a 2013 study published in Science tested such a method. “If you interfere with the signaling of vasopressin [in the SCN]… these animals don’t seem to have jet lag,” says Ludwig. When researchers changed light-night cycles in their experiment, the animals reset their biological clocks immediately.

Regarding the current study, Piggins says one can speculate that these retinal vasopressin cells could be involved in jet lag, “but the complication is that some of the brain clock cells themselves also make vasopressin.”

“So it's going to be very complicated to determine what vasopressin made by the clock cells does versus what vasopressin coming from the eye does,” he says.

In addition, one must remember that vasopressin also plays important roles in regulating blood pressure and fluid balance in the body, says Piggins. “It's involved in many other processes other than how light is communicated to the brain,” so a drug that acts on vasopressin signaling might have other effects.

Study author Ludwig is also cautious. “We still need to understand what the mechanism of the signaling in the SCN is,” he says. “[The eye drop] may never work, because still you have to get things into the eye [and] it has to act on the cells. It's a very long way to go.”

Currently, the only thing available to treat jet lag is melatonin, says Michael Iuvone, a professor of ophthalmology at Emory University who was not involved in the study. “It also acts on the SCN and has some effects there. But it's not all that effective. It does work in some people, but not everybody.”

“I think the major significance of the study is that it creates a new avenue of research that may allow us to ultimately regulate circadian biology,” Iuvone says. “And there's potential there for treating sleep disorders and other types of circadian disorders that are related to the circadian clock.”

Read More

Language is training artificial intelligence to replicate human bias

Language is all about repetition. Every word you’re reading was created by humans, and then used by other humans, creating and reinforcing context, meaning, the very nature of language. As humans train machines to understand language, they’re teaching machines to replicate human bias.

“The main scientific findings __that we’re able to show and prove are __that language reflects biases,” said Aylin Caliskan of Princeton University’s Center for Information Technology Policy. “If AI is trained on human language, then it’s going to necessarily imbibe these biases, because it represents cultural facts and statistics about the world.”

Caliskan’s work, together with coauthors Joanna Bryson and Arvind Narayanan, was published last week in Science. Essentially, they found that if someone trains a machine to understand human language, then it’s going to pick up those inherent biases as well.

In humans, one of the best ways to test for bias is the implicit association test, which asks people to associate a word like “insect” with a word like “pleasant” or “unpleasant” and then measures the latency, or the time it takes to make that connection. People are quick to label insects as unpleasant and slower to label them as pleasant, so it’s a good metric for associations.

Testing hesitation in a computer doesn’t really work, so the researchers found a different way to see what words computers are more willing to associate with others. Like students guessing at the meaning of an unfamiliar word based only on the words that appear near it, the researchers trained an AI to associate words that appear close to each other online, and to not associate words that don’t.

Imagine each word as a vector in three dimensional space. Words commonly used in the same sentences are closer to it, and words rarely used in sentences with it are vectors farther away. The closer two words are, the more likely the machine associates them. If people say "programmer" close to "he" and "computer" but say "nurse" close to "she" and "costume," that illustrates the implicit bias in language.

Feeding computers this kind of language data in order to teach them isn't a new concept. Tools like Stanford’s Global Vectors for Word Representation—which existed before this paper—plot vectors between related words based on their use. GloVe’s wordsets include 27 billion words pulled from 2 billion Tweets, 6 billion words pulled from Wikipedia in 2014, and 840 billion words pulled from a random trawl through the internet.

“You could say “how many times does ‘leash’ occur near ‘cat?’” and “how many times does ‘leash’ occur near ‘dog?’” and “how many times does ‘leash’ occur near ‘justice?’”, and that would be part of the characterization of the word,” Bryson said. “And then these vectors, you can compare them with cosines. How close is cat to dog? How close is cat to justice?”

Just as an implicit association test shows what concepts a human unconsciously thinks of as being good or bad, the calculation of the average distance between different groups of words showed researchers what biases a computer had started to show in its understanding of language. It’s remarkable that machines trained to understand language picked up on human biases about flowers (they’re pleasant) and insects (they’re unpleasant), and Bryson said it would be a significant study if that was all it showed. But it went deeper than that.

“There’s a second test, which is measuring the quantity between our findings and statistics that are made public,” said Caliskan. “I went to 2015’s Bureau of Labor Statistics, and every year they publish occupation names along with percentage of women and percentage of, for example, black Americans in that occupation. By looking at the makeup of 50 occupation names and calculating their association with being male or female, I got 90 percent correlation with Bureau of Labor data, which was very very surprising, because I wasn’t expecting to be able to find such a correlation from such noisy data.”

So computers are picking up on racism and sexism by associating job-related words with a particular gender or ethnic group. One example emphasized in the paper is “programmer,” which is not a gendered word in English, yet through its use now has connotations of being a male profession.

“We hadn’t thought, when you're saying programmer are you saying male or are you saying female,” said Bryson, “but it turns out it’s there in the context in which the word normally occurs.”

Machines trained on datasets of language as it’s used (like GloVe) will pick up on this association, because that is the present context, but it means researchers in the future should be cautious about how they use that data, since the same human bias comes baked-in. When Caliskan trained the tool on the Wikipedia wordset, which is held to a neutral language editorial standard, she found that it contained the same bias she found in the larger set of words pulled from the internet.

“In order to be aware of bias, in order to unbias, we need to quantify it,” Caliskan said, “How does bias get in language, do people start making biased associations from the way they are exposed to language? Knowing that will also help us find answers to maybe less biased future.”

One answer may be looking to other languages. The study focused on English-language words on the internet, so the biases it found in word use are the biases, generally, of English-speaking people with access to the internet.

“We are looking at different types of languages and based on the syntax of the language we are trying to understand if it affects gender stereotypes or sexism, just because of the syntax of the language,” said Caliskan. “Some are genderless, some are little more gendered. In English there are gendered pronouns, but things get more gendered [in languages] such as German where the nouns are gendered, and it can go further. Slavic languages have gendered adjectives or even verbs, and we wonder, how does this affect gender bias in society?”

Understanding how bias gets into a language is also a way of understanding what other, implicit meanings people add to words besides their explicit definitions.

“In a way this is helping me think about consciousness,” said Joanna Bryson, one of the authors on the study. “What is the utility of consciousness? You want to to have memory of the world, you want to know what kind of things normally happen. That’s your semantic memory.”

The mutability of language, the way semantic context is formed through use, means this doesn’t have to be the only way we understand this world.

“You want to be able to create a new reality,” continued Bryson. “Humans have decided that we’ve got our stuff together well enough now that we could have women working and developing careers and that’s a perfectly plausible thing to do. And now we can negotiate a new agreement, like, “we’re not going to say ‘the programmer he’, we’re gonna say ‘the programmer they’, even if we’re talking about singular, because we don’t want to make people feel like they can’t be programmers.”

And unless people account for these existing biases when programming machines on human language, they’ll create not an unbiased machine, but a machine that replicates human bias.

“Many people think machines are neutral,” said Caliskan. “Machines are not neutral. If you have a sequential algorithm that’s making decisions sequentially, like machine learning, you know that it is trained on a set of human data, and as a result it has to present and reflect that data, since historical data includes biases, the trained models will have to include those biases as well, if it’s a good training algorithm. If it’s accurate enough, it will be able to understand all those associations. The machine learning system learns what it sees.”

Read More

Warning: Do NOT get into a breath-holding contest with a naked mole rat

“We had hints __that naked mole rats might be rock stars at surviving oxygen deprivation,” said Thomas Park, a biologist at the University of Illinois, Chicago. That's why he stuck a bunch of naked mole rats in a chamber with only five percent oxygen. As a point of comparison, the atmosphere at sea level is about 21 percent oxygen. The atmosphere at the top of Mount Everest is around six percent. The results of his experiment were published today in the journal Science, and they're pretty wild.

“There's nothing special about five percent except __that we knew it would be fatal to humans, and fatal to laboratory mice, and probably to everybody else,” said Park. "We were at the ready to abort the experiment and pull the animals out of the chamber if they started to look like they were having problems.”

Park and his colleagues expected the naked mole rats to start running out of oxygen within 15 to 20 minutes. After all, the literal lab rats they exposed to the same conditions all died within that timespan.

“An hour into the experiment [the naked mole rats] looked perfectly fine,” said Park. “After five hours, we were convinced that five percent oxygen is not a problem for these guys, so we decided to call it a night, go home, and have dinner.”

To understand why Park and his colleagues at the Max Delbrück Institute in Berlin and the University of Pretoria in South Africa suspected that naked mole rats might do well in a low oxygen environments, it helps to know a bit about the critters.

Naked mole rats are cold blooded. It’s a trait that they share with reptiles, but not with other mammals. The fact that they don't really regulate their own body temperature means they don't expend any energy staying warm, so they need less oxygen compared to more common rats and mice. And their hemoglobin, or red blood cells, are unusually sticky. They can pull oxygen out of air that would leave most mammals gasping for breath. Then, of course, there’s the way naked mole rats live: in complex burrow systems with upwards of 200-300 inhabitants, where CO₂ can easily accumulate.

“In their burrow system,” said Park, “the oxygen levels are very low and the carbon dioxide levels are very high.”

What do you do after learning that naked mole rats can survive with very little oxygen? See if they can survive with no oxygen.

Park and his colleagues put naked mole rats in a container with no oxygen at all. Like any rational mammal, the naked mole rats passed out within 30 seconds. But unlike mice (or you and I, ostensibly) they continued making breath-like movements for up to four minutes. Park and his colleagues kept them in the containers for an additional minute after their last visible attempt at breathing. But the naked mole rats took the licking and kept on ticking: they were just playing possum.

Upon being released from their containers, they began breathing within seconds. When they rejoined the colony, they behaved normally—suggesting no ill effects.

The secret to their rebound? Fructose.

Humans—and our brains—use glucose, a very simple sugar, for energy. Glucose is great in that it’s incredibly efficient. The downside, however, is that it only works in the presence of oxygen. So, when we’re deprived of oxygen, our brain starves and begins to die pretty quickly.

Humans can't really use fructose as an alternative: when we consume fructose from a piece of fruit (or, perhaps more likely these days, a high fructose corn syrup sweetened beverage) it has to be processed through our liver in order for our body to use it. That isn’t the case for the naked mole rat. While we have some fructose transporters, mole rats have many more on key organs—their brains and hearts. And they have more of the enzyme that allows them to process fructose directly.

So when a naked mole rat finds herself in an environment with no oxygen, she may not have enough energy to get up and run around—but her body will still produce enough nutrition for her hey organs to keep her alive.

Like most things that naked mole rats do, this is basically unheard of in the mammal world. But it's just another day at the office for a plant.

“One thing we've been horsing around with is the idea that the naked mole rat has an insect-like social structure like ants and bees," said Park, “and it has a thermoregulation system like a reptile, and they metabolize fructose like a plant.”

Park thinks that because naked mole rats are leveraging systems that humans already have, this knowledge could potentially be converted into a kind of treatment to help prevent brain damage when people have a heart attack or a stroke, or as a form of preventative medication for high altitude travelers. Because of their facility with low-oxygen environments, naked mole rats also don’t get pulmonary edema, the fluid in the lungs associated with combining low oxygen levels with high elevations. Perhaps in the future, Everest climbers could take a naked-mole-rat-inspired shot to help them summit the mountain instead of lugging up supplementary oxygen.

In the meantime, naked mole rats will continue to be their delightfully strange selves.

Read More

A river in Canada just turned to piracy because of global warming

A river in Canada just became a victim of piracy. River piracy.

Yes, one river straight-up stole another river’s water, with a swashbuckling assist from a melting glacier and the unique landscape of the area deep in the Yukon.

In a paper published in Nature Geoscience geomorphologists describe how the Slims river—which normally flows north—was abruptly cut off from its water supply. Now all __that water feeds a totally different river—the Kaskawulsh—which flows south.

The researchers didn’t expect to observe a case of river piracy when they went to investigate the area.

“Our goal was to look at how this glacial river [the Slims] adjusts over the course of a year,” says study co-author Dan Shugar. “We certainly didn’t expect it to be totally gone.”

But when Shugar and his colleagues went into the field, that’s exactly what they found. Where the Slims river once flowed, only a shallow lake remained.

Shugar and his co-authors decided to figure out why, so they headed to the river’s source, the Kaskawulsh glacier. As the massive sheet melts, it feeds huge rivers like the Slims and the Kaskawulsh, which join up with even longer rivers. But it wasn’t feeding the Slims anymore.

River piracy—which ranks among the coolest technical terms in the world—happens when water from one river or stream gets co-opted by another river. Usually, it’s seen in the geologic record, as a river carves a different path through soil and stones, but not in real-time. This particular instance of river piracy is fairly unique. It only happened because the glacier which fed the rivers was located in just the right place.

The glacier sits directly on the border between the two drainage basins, which is why it was able to supply water to both rivers for so long. But now, the glacier had retreated, melting in the face of climate change. In it’s smaller shape, it occupies a slightly different footprint in the mountains, and meltwater __that was once divided equitably is now primarily diverted to the Kaskawulsh river instead.

Specifically, a lake right at the toe of the glacier, Slims lake, was able to melt its way through the ice of the glacier towards the Kaskawulsh river basin. That issued a death sentence for the Sims river. “It was beheaded, if you will” Shugar says.

And there's no coming back from a beheading.

“For the Slims lake to re-establish a hydrologic connection with the Slims river would require the glacier to advance, and that’s unlikely to happen in the current climate,” Shugar says.

Now the Slims river will have to cope with much-reduced flows, while the white waters of the Kaskawulsh river will be stronger as both river systems try to adjust to the new normal.

Shugar says that this sudden change in river flows can be directly linked to human-caused climate change. The melting of these glaciers, Shugar says, is happening much faster than can be explained by natural causes.

“Climate change is happening. And it's not just happening over there, in some other place. It's happening here in North America, and some of the consequences can be very rapid and might not always be what we were expecting,” Shugar says.

Read More

Unknown ancient reptile roamed the Pyrenees mountains

Image copyright Óscar Sanisidro / Institut Català de Paleontologia

Image caption Artistic reconstruction of an archosauromorph

The footprints of a mysterious reptile __that lived about 250 million years ago have been identified in fossils from the Pyrenees mountains.

Scientists say the new species is a member of the group __that gave rise to crocodiles and dinosaurs.

The reptile lived at a time when the Earth was recovering from a mass extinction that wiped out most animals.

The discovery may shed light on how the group of animals evolved and spread.

About 252 million years ago, a mass extinction devastated life on land and in the oceans. Some 90% of species disappeared.

At the time, the Earth was very different from today, with continents grouped into the supercontinent, Pangaea.

Researchers led by Eudald Mujal of Universitat Autònoma de Barcelona, Spain, examined fossilised footprints from about 247 to 248 million years ago found in the Pyrenees mountains in Catalonia.

They found most tracks were made by the ancestors of crocodiles and dinosaurs, a group known as archosauromorphs.

Most footprints were small, about half a metre in length, although a few were longer than three metres.

Among them was a new footprint that is thought to be a new species of reptile, Prorotodactylus mesaxonichnus.

Image copyright Eudald Mujal

Image caption Tracks are visible in the rock

The makers of the footprints could belong to the Euparkeria, a group of dinosaur relatives known from the same time period in Poland, Russia, China and South Africa.

Co-researcher Josep Fortuny of the Institut Català de Paleontologia Miquel Crusafont said the footprints suggest the animals, measuring around half a metre, used all four limbs to walk and often also left marks with their tails.

"Some footprints point to the possibility of bipedal locomotion in specific moments with the aim of moving faster," he said.

The researchers think archosauromorphs dominated the river beds of the ancient Pyrenees.

The group may have been key to the recovery of ecosystems after the extinction, going on to spread across the supercontinent.

"These tracks represent the first evidence of the vertebrate recovery of the End-Permian extinction," Eudald Mujal told BBC News.

He said the search was underway for fossilised bones of the animals that made the tracks.

The research is published in the journal, PLOS ONE.

Follow Helen on Twitter.

Read More

Hundreds of icebergs are suddenly invading shipping lanes

There is a swarm of about 481 icebergs parked in the shipping lanes of the North Atlantic right now, creating a hazardous area so treacherous __that ships are having to detour 400 nautical miles out of their way to avoid the Titanic’s infamous fate.

The number of icebergs is unusual not only because of the large number but also because of the speed at which the icebergs gathered, and strange timing, early in the year.

“As of March 27 we had only tracked 37 icebergs into the transatlantic shipping lanes in the 2017 ice season. One week later, on April 3 we had 455,” says Coast Guard Commander Gabrielle McGrath, the head of the International Ice Patrol. “We’re now at 481 at this point.”

The International Ice Patrol (IIP) has records __that stretch back to the early 1900s. McGrath says the average number of icebergs that have encroached into this area at the end of March is about 83. By the end of April that rises to 212—high, but not as high as we’re seeing now. Usually, this number of icebergs isn’t seen until the end of August, which averages a count of about 485.

The IIP monitors 500,000 square miles of ocean, keeping track of icebergs in the North Atlantic. The Patrol was set up in the aftermath of the Titanic disaster. In its 104 year history, no ship that has heeded one of the Patrol’s daily charts and warnings has collided with an iceberg. “We have had some issues with iceberg collisions, but that happened to ships that did not heed our warnings, and went inside the iceberg limit,” McGrath says.

“I have about a decade of experience with the Ice Patrol, and in my time here, and talking with people who have been here longer, I’ve never seen anything like this or heard of anything like this before,” McGrath says. A perfect combination of weather patterns set up the unusual iceberg influx that shipping companies are contending with today.

The icebergs we’re seeing actually started their journey years ago. It usually takes between one to three years for an iceberg to make its way from breaking off of a glacier in Greenland—a process called calving—to floating in the transatlantic shipping lanes at a latitude of about 48 degrees North. It takes so long because the icebergs don’t head straight south. Instead, McGrath says, they go north first—in the West Greenland current—then make a u-turn and head south again in the Labrador current.

Changes in the annual number of icebergs in shipping lanes are attributed to winter wind behavior off the coast of Greenland. In 2013, winds blew mostly towards the shore, keeping the icebergs away from the currents and close to the island. The onshore winds also compacted the sea ice, keeping it closer to shore as well. That year, only 13 icebergs made it to the shipping lanes. The next year, offshore winds dominated, creating a very different situation.

“Typically if you have offshore winds throughout the winter months, that will allow the sea ice to grow far off the coast,” McGrath says. “That sea ice will form around the icebergs and will protect them from deterioration by the waves. That allows them to drift much further south and east.” In 2014, 1,546 icebergs made it into the shipping lanes.

While winter weather can play a huge role in dictating the annual supply of icebergs for a year, it’s spring that really provides the extra push that sends the icebergs on their way. Storms and warmer weather break up the sea ice, freeing the icebergs from their chilly cocoon.

In this case, a storm off Newfoundland in mid-to-late March broke up the sea ice. Then, a massive storm with sustained hurricane force winds moved through the area near Newfoundland between March 27 and 29. “Those counterclockwise winds really pulled the icebergs to the south and into the shipping lanes,” McGrath says.

Eventually, the icebergs will meet their end. They’ll keep moving with the winds and the currents, slowly breaking down. A storm with high waves (like the one that released them in the first place) would destroy the icebergs even faster. “The waves are the highest deteriorating factor in an iceberg,” McGrath explains. Waves hit icebergs right at the water line, battering them until they break down into smaller pieces. But until then, ships will need to keep their distance.

Icebergs are a problem for shipping companies, because this area is the main shipping route between Europe and North America. It’s currently the fastest route to ship goods by sea between the two areas, but the icebergs mean that shipping companies have to go 400 nautical miles and at least a day or two out of their way in order to stay safe. That takes up valuable time—and valuable fuel. But in the end, there’s really no other choice.

No one wants a sequel to Titanic.

Read More

As mountains grow, they drive the evolution of new species

Mountains aren't just beautiful: these locales also tend to host some of the richest diversity of species on the planet. We’ve known this for a long time—ever since Alexander von Humboldt, the Prussian geographer and naturalist, first climbed up the Andes in the 18th century. But nobody has really figured out why.

One popular hypothesis goes like this: the reason why mountains have so many different species is that, as mountains are uplifted by colliding tectonic plates, the process creates more environments, and therefore more opportunities for new species to adapt to them. However, this hypothesis never had any explicit quantitative testing until now, according to a recent study published in the Proceedings of the National Academy of Sciences.

Many other studies have looked at the diversity of one single plant group or another, and results seemed to support the popular hypothesis. “That claim is often made. The hypothesis often incorporates the narratives of these studies, but it's never been explicitly tested” across time and space, through quantitative comparison, says study co-author Richard Ree, Associate Curator of Botany at Chicago’s Field Museum.

Ree and colleagues found __that as China’s Hengduan mountains formed eight million years ago, the rate of diversification there was more than twice as fast as __that found in the Himalayas—which are quite close by, but much older—during the same stretch of time.

The Hengduan Mountains are pretty young, geologically speaking—the Himalayas are more than twice as old, having formed around 20 million years ago. But the spot is bursting with biodiversity: the younger mountains play host to more than one third of the 30,000 species of vascular plants (basically everything except mosses) found across China, says Ree.

Colin Hughes, an assistant professor at the Department of Systematic and Evolutionary Botany at the University of Zurich who was not involved in the study, says the researchers “have made a significant step forward."

“We’ve known that part of the world is very diverse since the 19th century," Hughes says. "But nobody understood the evolutionary history of this hotspot in any general way until now, so this is a landmark study.”

To test the hypothesis that uplifting of the mountains brings up more species at a faster rate, Ree and his colleague Yaowu Xing compared the evolutionary histories of 19 groups of plants in the Hengduan Mountains, the Himalayas, and the connected Qinghai-Tibetan plateau.

“The fact that these mountains have different ages and they are right next to each other gives us a natural experiment," says Ree.

Using evolutionary trees generated from DNA sequences and ancient fossil data, Ree and Wu were able to confirm that the tremendous tectonic uplift of the Hengduan mountains over the last eight million years indeed coincided with a rapid diversification.

That pattern revealed itself only as the researchers considered all 19 plant groups as a whole. “People [in the field] tend to focus on one group of a plant at a time and tell their story,” says Ree. “In this case, you wouldn't necessarily see the bigger picture [in that way], because each individual group doesn't have the statistical power of the signal to tell you this pattern.”

Ree thinks the next step is to study the results of uplift that may have more direct effects on evolution. Diversification might be more likely to occur in certain habitats or elevations, for example. Hughes thinks that future studies could separate the plants by their habitats, like Himalayan blue poppies in high elevation alpine zones and conifers and maples in lower elevation forest zones, to see how diversity might vary in different zones. “I think it's likely that the diversification history of those different habitats might be different,” he says.

And just as Hengduan's diversity was assessed by comparing it to the Himalayas, this new data might provide insight into the evolution of another mountain's species. Mountains are often so isolated from the lowland around them that they're referred to as "sky islands," says Hughes. This isolation makes comparative study of one mountain to the next intriguing, as subtle variables may make one drastically different from another in the same region.

“Those of us who study the diversity of life are interested ultimately in explaining the origin of every species,” says Ree. “Across the world, some places have a lot of species, some have fewer species, so a basic question is: why is it the case? How is there this disparity of species richness?”

"If we ever hope to have any kind of basic understanding of life," says Ree, that's something we need to figure out. And mountains may be the perfect laboratory.

Read More

How to make the best protest sign

On April 22, scientists, science-lovers, and at least one official Science Guy will be gathering in Washington, D.C. for the March for Science. A week later, on April 29, the People's Climate Movement will march in favor of action against climate change. If you plan to attend either event, you’ll want to voice your support for science. And __that means designing the perfect sign.

Bigger is better, of course. Bold letters and ample surface area are key. Then there's carrying it. At marches in DC, sticks are forbidden for safety reasons, which means science fans will need to get creative with their poster grips.

To help you plan, Popular Science spoke with Michele Demsky, an exec at poster company ArtSkills, about how to stock up on materials and plan out the perfect sign—and what to do with it when your arms (inevitably) get tired.

Choose your board wisely

Most people make their signs from either poster board or foamcore. Each option has its pros and cons, so your choice will really depend on personal preferences.

Poster board is cheaper, and you can roll it up to transport it more easily, although this may give the board a curve so it’s less likely to stay flat when you want it to. That roll-ability also means it's more prone to flopping over. To bolster the less sturdy material, you can glue or tape flat wooden paint stirrers to the corners.

Foamcore is more expensive, but it’s also sturdier and more weather-resistant. “Foam board is stiff,” Demsky says, “and it’s so light you can hold it with your pinky.” A foam sign will stay upright more easily, and you can even add a three-dimensional attachment—say, a Styrofoam model of the Earth—without the edges flopping over. Because of this stiffness, however, it can be awkward to transport from place to place.

Can you handle this?

Once you’ve picked a material, you’ve got to figure out a way to carry it. “If you have a type of handle, it’s easier to hold onto,” says Demsky.

One solution is a product called an easel back, a self-sticking cardboard attachment you can press to poster boards to make them stand up on a surface. For our purposes, you can attach two easel backs to the back of your sign where you’ll want to hold it, fold them open, and trim the cardboard to make it comfortably fit your hands.

You can also attach two small, light rods to the bottom of your poster and hold them. Paint stirrers, for example, are available for free at hardware stores, and even a pair of cardboard paper towel tubes can support the weight of poster board or foamcore.

If you’d prefer to avoid attaching objects to your sign, then you should probably choose a foamcore base. It’s sturdy enough __that you can cut out your own handles in the sides, the bottom, or both.

No matter which handles you use, holding up even the lightest sign for hours will tire out your arms. So you’ll want a plan B.

“Get some string, cut two holes in the top of your posterboard, and hang it around your neck,” Demsky says. “It’s the easiest way of taking a break.” You can even create a sandwich board by hanging one sign from your front and another from your back.

Get spacey

Your message won’t do much good if people can’t see it. “In order to get noticed, you have to plan,” Demsky says.

First, sketch out your words in pencil, using a ruler to keep your lines straight and ensure even spacing. Make sure that everything fits and is centered before you follow up with marker or paint. You can also play around with size and framing.

“What is it you want to say?” Demsky asks. “Make sure that word speaks loudly; it’s got to be the biggest. Framing something helps your eye land in the center.”

To make your words visible from a distance, letters should be large and boldly marked. If you’re working up close to the sign, say at a kitchen table, visibility can be difficult to determine. You may want to stand back some distance and see if your message will still be easily readable.

For maximum effect, Demsky recommends using stencils, or drawing bubble letters and then filling them in. For the less artistically inclined, there are stick-on poster letters, demonstrated below.

Color me visible

When you choose your materials, make sure to take color into consideration. “White and black is good contrast,” says Demsky, “but if you can get a rainbow or hot pink poster board, when you have a bright color, the eye normally will go to that.”

Bright colors, shimmering or glittering materials, even poster lights can draw more attention to your sign. But if the colors of your letters don’t contrast with the color of your board, your words will be harder to see. For example, using rainbow colors for your letters might be eye-catching, but if one of those colors is yellow, it will disappear against a white poster.

If the words are your biggest priority, go with black letters on a white poster (or white letters on a black poster). This combination will create the most legible message. To spruce up your sign, try black letters on a bright backdrop, or bright letters on a white background.

“If you’re using a rainbow board or a bright neon, black is your best bet for letters,” says Demsky. “Holographic neon letters look great on a white poster.” These options maintain a contrast between letters and board, which should make them legible—even if they’re not as stark as black-on-white.

But what to write? We'll leave that up to you.

Read More

Frankenviruses may have gobbled up host cells in order to grow

From the German-ish setting of Mel Brook’s 1974 cult classic Young Frankenstein to the discovery site of four new supersized viruses in an Austrian wastewater treatment facility, Eastern Europe seems to be positively teeming with entities __that push the boundary of what it means to be aliiiiiveeeee!

Viruses are kind of a biological black box. We can’t agree on whether or not they’re alive. We aren’t super certain how they evolved. And we can’t even see them under a light microscope, let alone with our unaided eyes. In fact, you’d have to corral about 300 viruses into a line to get them to amount to the width of a human hair, according to NPR.

Or so we thought. In 2003, scientists discovered a giant virus, closer to the size of a cell and totally visible under a microscope. They named these critters “mimiviruses” (but we all know they meant “frankenviruses”) and promptly started to ponder the implications of this discovery on our entire understanding of life on Earth.

Was it, many asked, a “fourth domain”? Should we teach children not just about eukaryotes, bacteria, and archaea, from which all life springs, but also about viruses?

The new Austrian frankenviruses—which many insist on calling “klosneuviruses,” a sub-family of the so-called mimiviruses—are beginning to provide some answers.

New genetic sequencing revealed the viruses have an outsized number of genes dedicated to making proteins, according to a study out this week in the journal Science. That’s unusual for viruses, which typically have to infect a host and drain its cells of resources in order to replicate. Why this is remains unknown.

But comparing __that genetic data to other frankenviruses and to cells allowed the researchers to piece together a very sinister family tree. Their data suggests frankenviruses started out small and contained like any other virus and grew bigger and bigger as they consumed more and more bits and bobs from their hosts.

Like most origin stories, however, this explanation is hard for everyone to agree on. Perhaps the most stark disagreement comes from researchers who continue to think the exact opposite: that the world used to be covered in frankenviruses that have been slowly whittled away into the simpler, smaller, but no less vicious viruses we know and fear today.

All that’s certain is that scientists are determined to nail down the origins of the frankenvirus family—and that the family seems to be growing.

Giant viruses have now been found not just in wastewater in Austria, but around the world, from the coast of Chile to ponds in Australia. There may even be one living near you that you haven't noticed… although the bolts in its little virus neck should be a pretty dead giveaway.

Read More

There’s a treasure trove on the seafloor—and that could be a bad thing

Rare minerals might not sound as exciting as sunken treasure to you, but to the mining industry those materials could be literally more valuable than gold. And there are few regulations in place yet to stop deep sea mining from destroying the seafloor.

Right now the bottom of the ocean's first line of defense is the International Seabed Authority (not to be confused with the International Waterbed Authority, which dissolved back in the late ‘90s). They’ve been working on the issue since they were first formed by the 1982 United Nations Convention on the Law of the Sea, and they’ve been fighting an uphill (upstream?) battle ever since. It’s not for lack of action—they’ve enacted regulations and proposed recommendations—it’s for lack of knowledge. We’ve only explored a tiny percentage of the ocean and mapped little of the seafloor, so it’s difficult to know where mining is likely to take place or how it will affect the surrounding waters.

But goodness knows that’s not stopping anyone from exploring what’s down there. Recently a team of British scientists found a plethora of valuable minerals atop an underwater mountain called Tropic Seamount. It’s basically a huge flat-topped mound of some of the scarcest materials on Earth. This particular group was part of a research mission—and while they were expecting to find rare minerals, they didn’t anticipate quite so much of them. There’s the equivalent of one twelfth the world’s supply of tellurium down there, which is used in advanced solar panels, plus rare earth elements __that go into electronics.

That makes deep sea deposits valuable, and the fact __that it’s currently very expensive and time-consuming to mine them isn’t likely to stop everyone. And you know what they say: if you can’t stop ‘em, regulate ‘em. The million—or maybe billion—dollar question is: how?

Even people who have spent their lives exploring the ocean depths are unsure. Cindy Van Dover, who has ventured down in the submersible Alvin both as a pilot and as a lead scientist for the last several decades, explains that it’s hard to apply limited knowledge of certain sections of the seafloor to the entire thing.

“We know if they mine in some places they’re just going to rip up the seafloor, so to some extent we know that there’s some habitat destruction going on,” but she says, “There’s lots of unknowns. There are organisms that have very long lives. There are organisms that have very rapid reproduction that might seem resilient, but they live at hydrothermal vents so they’re really only endemic to small patch, and they’ll have to go find another patch.”

Without knowledge of how mining effects will accumulate over time, it’s challenging to create effective legislation.

We know what happens when we mine on land, so when authorities create terrestrial mining regulations they know exactly what to guard against. It’s not so easy in the ocean. But it's vital that we act now. “Once they begin, it’s going to be like deep sea fishing, where it’s really difficult to manage,” says Van Dover. “I feel like we have this opportunity right now to get the regulations right.”

On the seafloor there are no disgruntled residents to complain about mining impacts. Fish and microscopic organisms can’t tell us they’re dying—they just do. Those living at deep sea vents and other major geological hubs—which are likely to be more enriched in precious minerals—might be especially vulnerable, since they don’t have large habitats. Plus, they’re out in international waters, where no country has the economic motivation to keep others in check. It’ll be up to the International Seabed Authority to keep everyone in line—that, and our innate desire to preserve nature. And that’s always worked well in the past...right?

Read More

A forensic stabbing machine, a trio of solar flares, and other amazing images of the week

Read More

Saturn moon 'able to support life'

Image copyright NASA/JPL-Caltech/SSI

Image caption Easy to sample: Jets of water spew from the south pole of Enceladus.

Saturn's ice-crusted moon Enceladus may now be the single best place to go to look for life beyond Earth.

The assessment comes on the heels of new observations at the 500km-wide world made by the Cassini probe.

It has flown through and sampled the waters from a subsurface ocean __that is being jetted into space.

Cassini’s chemistry analysis strongly suggests the Enceladean seafloor has hot fluid vents - places __that on Earth are known to teem with life.

To be clear: the existence of such hydrothermal systems is not a guarantee that organisms are present on the little moon; its environment may still be sterile. But the new results make a compelling case to return to this world with more sophisticated instrumentation - technologies that can re-sample the ejected water for clear evidence that biology is also at play.

"We're pretty darn sure that the internal ocean of Enceladus is habitable and we need to go back and investigate it further," said Cassini scientist Dr Hunter Waite from the Southwest Research Institute in San Antonio, Texas.

"If there is no life there, why not? And if there is, all the better. But you certainly want to ask the question because it's almost as equally as interesting if there is no life there, given the conditions," he told BBC News.

• Saturn mission approaches tour finale
• Enceladus: A second genesis of life?
• Europa: Our best shot at finding alien life?
• Saturn: To see finally the face of Peggy

Image copyright WHOI/NSF/NASA

Image caption On Earth, the microbes at vents support a range of more complex organisms

The sub-surface ocean on Enceladus is thought to be many kilometres deep, kept liquid by the heat generated from the constant gravitational squeezing the moon receives from the mighty Saturn.

Cassini has already established that this voluminous liquid is in contact with the rock bed from the types of salts and silica that have also been detected in the jets.

But what scientists really wanted to know is if a particular interactive process seen at Earth was taking place in the distant abyss - something called serpentinisation.

At the mid-ocean ridges on our planet, seawater is drawn through, and reacts with, hot upwelling rocks that are rich in iron and magnesium. As the minerals in these rocks incorporate H2O molecules into their crystal structure, they release hydrogen - a byproduct that can be used by some microbes as an energy source to drive their metabolism.

It is the definitive signal for molecular hydrogen in the plumes of Enceladus that Cassini has now confirmed.

"If you were a micro-organism, hydrogen would be like candy - it's your favourite food," explained Dr Chris McKay, an astrobiologist with the US space agency (Nasa).

"It's very good energetically; it can support micro-organisms in grand style. Finding hydrogen is certainly a big plus; icing on the cake for the habitability argument, and a very tasty one at that."

The type of microbes described by Dr McKay are called methanogens because they make methane as they react the hydrogen with carbon dioxide.

Image copyright Source: NASA

Nasa, which leads the Cassini mission, was due to make the hydrogen announcement a couple of months after the probe's last fly-through of the moon's jets in October 2015. But the agency held off.

One of the concerns was that the Ion and Neutral Mass Spectrometer on the satellite can actually make molecular hydrogen inside itself if water enters the instrument in a particular way.

Dr Waite's group has spent a year analysing the data to make sure the hydrogen signal is intrinsic to the jets and not merely some artefact of the INMS's operation. And although serpentinisation is arguably the best explanation for the signal, it is possible to produce the gas also from the heating of very primitive (meteoritic) rock.

The Cassini mission is coming to a close. Having spent 12 years circling Saturn, it is now running low on fuel and will be dumped in the atmosphere of the ringed planet in September - to ensure it cannot collide with Enceladus at some future date and contaminate it.

Image copyright NASA/JPL-Caltech/SETI Institute

Image caption Europa holds a vast, salty ocean beneath its fractured ice shell

As brilliant as the probe's instruments are, they were never designed to make a direct life detection at the bright white moon. This would need a whole new class of spectrometers. A proposal is being put together to fly them in 2026.

Nasa has already green-lit a mission to Europa, an ocean moon of Jupiter. It very likely has serpentinisation going on as well. But its ice shell is very much thicker and it could be that very little of the water escapes to space.

The appeal of Enceladus is the ease with which its subsurface can be studied because of the material carried into space by its network of geysers. A probe only needs fly through the emission to make the investigation.

"The Cassini mission has really brought Enceladus to the fore in terms of the search for life elsewhere in the Solar System," commented British Cassini scientist Dr Andrew Coates.

“The top three now I would say are about equal. There's Mars, which may have had life 3.8 billion years ago when conditions were very different to what they are now. There's Europa, which has a subsurface ocean; and now Enceladus. Those three may have, or had, the right conditions for life."

Dr Waite added: “For life, you need liquid water, organics, and the CHNOPS elements (carbon, hydrogen, nitrogen, oxygen, phosphorus, sulphur). OK, we haven't yet measured phosphorus and sulphur at Enceladus. But you also need some kind of metabolic energy source, and the new Cassini results are an important contribution in that regard."

A paper describing the work of Dr Waite's group is published in the journal Science.

Image copyright Cassini Imaging Team/SSI/JPL/ESA/NASA

Image caption The Cassini probe will end its mission by dumping itself in Saturn's atmosphere

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

Read More

Violent end as young stars dramatically collide

Image copyright ALMA (ESO/NAOJ/NRAO), J. Bally/H. Drass et al.

Image caption These dramatic images show the remains of a 500-year-old explosion from the birth of a group of massive stars

Scientists have captured a dramatic and violent image of the collision between two young stars __that tore apart their stellar nursery.

Located in the constellation of Orion, the explosive event happened some 500 years ago sending giant streamers of dust and gas across interstellar space.

Researchers say the clash produced as much energy as our Sun would over 10 million years.

Details of the event have been published in the Astrophysical Journal.

Image copyright ALMA (ESO/NAOJ/NRAO), J. Bally/H. Drass et al.

Image caption The blue colour in the Alma data represents gas approaching at the highest speeds; the red colour is from gas moving more slowly.

Huge explosions in space are mostly associated with supernovas, which can take place in the dying moments of giant, ancient stars.

This new image though shows an explosion taking place at the other end of the stellar lifecycle.

Stars are born when a massive cloud of gas starts to collapse under its own gravity. At a distance of 1,500 light years from Earth, a number of very young stars began to form in a region called the Orion Molecular Cloud 1, (OMC-1).

Gravity pulled these proto-stars closer at increasing speed until about 500 years ago, two of them either grazed or collided head-on, triggering a powerful explosion __that hurled gas and dust debris out into space at more than 150km per second.

Back in 2009, researchers first saw hints of the scale of the explosion. Now using the Atacama Large Millimeter/submillimetre Array (Alma), based in northern Chile, astronomers have been able to see the violent event in high resolution.

Image copyright ESO/C.Malin

Image caption Antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), on the Chajnantor Plateau in the Chilean Andes seen at night

"What we see in this once calm stellar nursery is a cosmic version of a 4 July fireworks display, with giant streamers rocketing off in all directions," said lead author Prof John Bally from the University of Colorado.

The team has discovered new details about the structure of the streamers that extend past the explosion for almost a light year. The team members are learning about the distribution and high-velocity motion of the carbon monoxide gas inside the huge gas trails. It may also help their understanding of the star birth process.

"Though fleeting, proto-stellar explosions may be relatively common, by destroying their parent cloud, as we see in OMC-1, such explosions may also help to regulate the pace of star formation in these giant molecular clouds," said Prof Bally.

Scientists expect that explosions such as this one are most likely short-lived, with the remnants of the debris seen by Alma lasting only for centuries.

"People most often associate stellar explosions with ancient stars, like a nova eruption on the surface of a decaying star or the even more spectacular supernova death of an extremely massive star," Prof Bally said.

"Alma has given us new insights into explosions on the other end of the stellar life-cycle, star birth."

Follow Matt on Twitter and on Facebook.

Read More

The 10 best science images, videos, and visualizations of the year

We are all too aware of how hard it can be to explain science. Describing concepts, theories, processes, and phenomena use up a lot of words—and even after careful consideration those words can fall short. That's why for the last three years Popular Science has teamed up with the National Science Foundation to honor the best science visualizations out there.

As part of this year's Vizzies, we're highlighting an intricate illustration of brain neurons and a visual explainer of humming bird tongues. We're celebrating a lexicon of American Sign Language and a photo of how hungry starfish larva move the water around them.

How did we select the best of the best? Experts selected by the National Science Foundation judged hundreds of entries on their impact, ability to make a complex subject easier to understand, and originality. This panel of experts pared down the list to 50 finalists—10 illustrations, 10 interactive designs, 10 photographs, 10 posters and graphics, and 10 videos. Those 50 visualizations were put up for public review. The final result: One experts' choice winner and one people's choice winner per category.

These are our winners:

The "Hungry Starfish" is a fundamentally Californian product. William Gilpin, a PhD candidate in physics at Stanford University, found out the school was offering classes at its marine village on the Pacific Ocean. So he and his fellow researchers headed out, ready for a break from the lab. What they ended up finding surprised them: starfish move using hundreds of elaborate, tube-like feet, and they also seem to control the waters around them.

When they headed back to the lab, they found very little research had been done on the way starfish move the water around them, so they set about finding—and illustrating—the answer themselves. "Hungry Starfish" is essentially an elaborate time lapse photo, created when all of the vortices the starfish makes were imaged and combined into one surprisingly delicate image of the starfish's superpower. Those vortices aren't just for fun: they're for softly pulling algae into a starfish larva's tiny mouth.

Soft robots—ones made entirely out of squishy materials—are about to take over. They're theoretically safer and more resilient than metallic mechanoids, but scientists haven't quite figured out practical ways to make every part of a robot mushy. Octobot is a step (or eight) in the right direction: it's entirely soft, powered by chemical reactions __that push fluid and gas into its limbs.

As Harvard researchers worked to design the bot, they frequently used fluorescent dyes to better visualize its intricate inner-workings. "To us, these dyes always made the 3D printed Octobots so beautiful, and we thought __that they would make for an awesome photograph," says study co-lead Ryan Truby, a PhD candidate in applied physics. "We hope our photograph will appeal to the imaginations of both academic and broader audiences interested in robots and inspire a vision of future entirely soft robots like the Octobot."

It took data from “essentially dozens if not hundreds” of scientific sources to create this intricate image of the brain, says team lead Greg Dunn, a neuroscientist at the University of Pennsylvania.

Combining hand drawings, optical engineering, gilding (the process of etching into gold), and other artistic and technical processes, they created this depiction of about 500,000 neurons hard at work. It’s “a reminder that the most incredible machine in the universe” is inside each of us, the team wrote.

Self Reflected was featured at the Franklin Institute in Philadelphia, with the goal of prompting viewers to consider what looking at an elaborate representation of the brain looks like from inside the brain. In addition to this image of the full brain viewed from the side, Dunn’s team generated a variety of other works with different focuses and resolutions.

Every month, the RCSB Protein Data Bank shares a “Molecule of the Month.” This zika virus had the honor of being the featured image for May 2016.

The zoomed-in illustration reveals something of a topographic map of the infecting agent. It shows not just the envelope that encircles the virus, but also the RNA (in yellow) that lives inside it and allows it to replicate. When the image was first published, scientists had been aware of the virus for almost 70 years, but understanding of the disease was limited. “Study of Zika virus has gained new importance because of the recent spread of the virus in many countries around the globe and its connection to birth defects and a rare neurological disease,” the illustrator wrote at the time.

Shane Loeffler started working on his app, Flyover Country, when he realized his undergraduate studies in geoscience at the University of Minnesota provided him with a unique—and entertaining—view on flying.

“I was flying over the San Rafael Swell,” he says, “and I could look down and I had been down there hitting those rocks with hammers, and now I’m above, reading a Wikipedia article [about the features below].” The app uses GPS signals to show people the topography of the land beneath them, as well as special features, like sites where dinosaur fossils are embedded in the soil. Loeffler, who is working with a small team to further develop the app, says it can also be used to enhance hiking and camping, road trips, and other more earth-bound activities.

American Sign Language is a language like any other—but it can’t be easily organized like a traditional English dictionary. This and other barriers make it hard for parents of deaf children to aid them in language acquisition, says Naomi Caselli, a lecturer on Deaf Studies at Boston University's School of Education.

Caselli and her team decided to take all of the ASL data available to them and organize it in a new way. ASL-LEX organizes 1,000 signs into groups based on things like similar hand shape or movement. What’s more, these little nodes are sized according to their common usage, so words like “book” are a little easier to find than a word like “castle.” It’s already helping hearing teachers and parents communicate with deaf children, and Caselli says the researchers are working hard to ensure that trend continues.

Eleanor Lutz isn't an astronomer—she's pursuing a PhD in biology at the University of Washington—but she loves sifting through the data that NASA makes public. That's how she got the idea to map Mars—with a Victorian twist. "Unlike other planetary maps, this map uses a Victorian style inspired by medieval cartographers," Lutz says. "Victorian-style maps are from a time when most of the world remained a mystery, and travelers only knew about nearby lands. Now that people have mapped the entire globe, I think that Mars has taken over our collective imagination as the next mystery to explore. I wanted to make the geography of Mars more tangible to the general public."

The hardest part? Fact-checking the name of each feature. "Since everything on the map is a proper noun, I had to go through and manually make sure every single landmark name and the name origin were spelled correctly."

When Esther Ng set out to visualize a hummingbird’s tongue, she had no idea where her work would take her. At the time, no one was really sure what a hummingbird tongue looked like, though new discoveries about the little bird’s micro-pumping abilities were all the rage.

“It's so tiny,” says Esther, a student at the University of Illinois focusing on scientific and medical illustrations. “Even with a video, it's very hard to catch.” To fix this, she headed to the Field Museum in Chicago. “They let me borrow [the bird] to look under a microscope, to pull the tongue out and draw how it is,” she says. It was nothing like she imagined, but those surprises are what make her work so enjoyable.

Video: Expert's Choice

Network Earth

"The situation is very tragic," data visualizer Mauro Martino says of climate change. It's so sad, in fact, that on many researchers "you can smell the sadness," Martino adds. It makes sense: they've dedicated decades of their life and career to researching disasters and impending doom. But Martino, the creator and director of IBM's Cognitive Visualization Lab, strives to turn their data into more upbeat, visual stories that people want to watch and share with their friends.

In "Network Earth," Martino and his team created a film that shows the interconnections between all life on Earth. It was created to accompany a research paper on Earth's resilience published in Nature. While the paper was theoretical, Martino says, the video aims to show that "math can be poetically expressed visually" and made to feel real and tangible to viewers around the world.

Video: People's Choice

The hunt for Planet Nine

When astronomers Michael Brown and Konstantin Batygin published the best-ever evidence for the existence of a ninth planet—a massive world orbiting in the farthest reaches of our solar system—the hunt for the mysterious celestial body captured the public's imagination. This video for Chicago's Adler Planetarium uses that fascinating research to show visitors how such scientific explorations unfold.

"Our goal with this show was not to teach people about Planet Nine, and it certainly wasn’t to convince them that Planet Nine exists," says Patrick McPike, a visual engineer at the planetarium. "The show is really about the excitement and process of scientific discovery. We hope that the show gets people more involved in science, whether that is by following science news more closely or by studying it themselves."

Read More

Fertilizer has saved billions of lives, but it also has a dark side

The following is an excerpt from "Pandora’s Lab: Seven Stories of Science Gone Wrong" by Paul A. Offit.

We’re not __that complicated. Although we come in different shapes and sizes, heights and weights, and backgrounds and temperaments, and although we have different genes __that make different proteins and different enzymes, we all boil down to four essential elements: hydrogen, oxygen, carbon, and nitrogen. If any one of these elements becomes unavailable, our time on earth will end. Three of the four elements are easily obtained.

Hydrogen comes from the water we drink, which consists of two hydrogen atoms and one oxygen atom (H 2 O). Oxygen, not surprisingly, comes from the air we breathe (O 2 ). (Only fish, through their gills, can extract oxygen from water.) Carbon also comes from the air. Green plants, in the presence of sunlight, take carbon dioxide (CO₂) from the air and capture it in the form of complex sugars that contain carbon (i.e., photosynthesis). We get our carbon from eating plants or from eating animals that ate the plants. Either way, because air and water are abundant, hydrogen, oxygen, and carbon are also abundant.

The weakest link in the cycle of life is nitrogen, which comes only from soil. When farmers grow crops like corn, wheat, barley, potatoes or rice, they deplete nitrogen from the soil. If they don’t replace it, the soil won’t be rich enough to grow more crops. Farmers replenish nitrogen in three ways. They use natural fertilizers made from decaying plants or animal manure. They rotate their crops with legumes like chickpeas, alfalfa, peas, soybeans, or clover, which harbor bacteria in their roots that take nitrogen from the air and convert it into a usable form in the soil—a process called “nitrogen fixation.” Or they wait for thunderstorms; lightning, as it turns out, can also fix nitrogen from the air.

If every farmer in every country on every continent in the world used every inch of fertile land, sprinkled their fields with natural fertilizers, meticulously rotated their crops, and convinced everyone to eat a vegetarian diet, they could feed about four billion people. But, as of 2016, more than seven billion people roamed the earth. And although pockets of people are starving, the problem isn’t that there isn’t enough food. There’s plenty of food. The problem is that the food isn’t distributed efficiently to those who need it.

So how are farmers able to do this? How are they able to feed so many people? The answer lies in an event that occurred on July 2, 1909. Because of this singular moment, 50 percent of the nitrogen in our bodies comes from natural sources and 50 percent comes from the work of one man—a man who at once saved our lives and sowed the seeds of our destruction. Fritz Haber was born on December 9, 1868, in Breslau, Germany. At the age of twenty-six, Haber attended the University of Karlsruhe, which had an excellent relationship with Badische Anilin & Soda-Fabik (BASF): a large chemical company just a stone’s throw down the Rhine River.

Haber’s task, taking nitrogen from the air and creating a chemical compound that could nourish crops, wasn’t easy. Although air is 79 percent nitrogen, it doesn’t exist as a single atom (N). It exists as two atoms coupled together (N₂) in a triple bond that is essentially unbreakable: the strongest chemical bond in nature. While N₂ in the air can be used to inflate a million balloons, it can’t be used to grow a single stalk of corn.

Because N₂ isn’t commonly broken down by nature, it took an unnatural process to do it: in a sense, an act against nature. The formula is simple:

N₂ + 3H₂ <—> 2NH₃

Reading from left to right, two paired nitrogen atoms combine with three paired hydrogen atoms to form two molecules of ammonia. Ammonia, Haber knew, would be perfect as a synthetic fertilizer.

A series of fortuitous events allowed Fritz Haber to succeed where many before him had failed. First, a young physicist from England named Robert Le Rossignol came to his laboratory. Le Rossignol was a skilled and inventive experimenter, eventually designing a small tabletop apparatus made of quartz and iron capable of withstanding temperatures as high as 1,832 o F, hot enough to melt copper; and pressures as high as 3,000 pounds per square inch, strong enough to crush a submarine. Second, Haber found a catalyst to speed up the reaction: osmium, a rare metal used as a filament in light bulbs. Third, Haber found a way to cool down ammonia quickly so that it didn’t burn up in the high heat. Finally, and most important, Haber’s mentor at Karlsruhe, Carl Engler, persuaded BASF to fund Haber’s experiments; if they worked, BASF would own the patents and Haber would have a commercial partner.

Haber and Le Rossignol tinkered with the fittings and tried different temperatures and pressures. Finally, in March 1909, they had a glimpse of success. Haber was ecstatic. “Come down, you have to see how the liquid ammonia is running out!” he shouted to a colleague, who remembered, “I can still see it. There was about a cubic centimeter of ammonia. It was fantastic.” It wasn’t much—about a fifth of a teaspoon—but it was a start. Within a few months, Haber and Le Rossignol’s apparatus was producing ammonia round the clock.

Ten months after Haber’s demonstration, scientists at BASF built a small prototypic unit in Ludwigshafen, a village not far from Karlsruhe. The plant officially opened on May 18, 1910. Haber’s 2-foot high tabletop apparatus had become a 26-foot high mega-machine. Within two months, the unit had produced more than 2,000 pounds of ammonia. By the beginning of January 1911, it was producing more than 8,000 pounds a day.

Other countries mimicked Haber’s process. By 1963, about 300 ammonia plants were in operation and more than 40 were under construction. Today, about 130 million tons of nitrogen are removed from the air and spread across the earth as fertilizer. More than three billion people alive today—and billions more in the future—owe their existence to Fritz Haber. Never before have so many people enjoyed so much food.

But there’s a dark side.

The largest nitrogen producing plant in the United States is located in Donaldsonville, Louisiana. Every day the plant consumes a million dollars worth of natural gas, boils 30,000 tons of water from a local river into steam, and produces 5,000 tons of ammonia (2 million tons a year). Every day these 5,000 tons of ammonia are loaded onto railcars, placed onto barges, floated down the Mississippi River, and sprinkled onto corn and wheat fields across the land. Not all of the nitrogen contained in ammonia ends up in crops. Only about a third of the nitrogen layered onto a cornfield, for instance, ends up in a kernel of corn. The rest washes into streams and leeches into groundwater.

The Gulf of Mexico, located next to the Louisiana ammonia plant, is a perfect example of what can happen when no one is watching. Every year about 1.5 million tons of nitrogen are dumped into the Gulf. This excess nitrogen has caused an overgrowth of algae that clouds the water and chokes off oxygen and sunlight to other species, like fish and mollusks. Algal overgrowth has killed streams, lakes, and coastal ecosystems across the northern hemisphere. And it’s not just the fish that are dying. The birds that eat the fish are dying, too. Synthetic nitrogen pollution isn’t limited to the waters; it’s also entered the air and come back to earth as acid rain, further damaging lakes, streams, and forests as well as the animals that depend on them. These problems will only worsen.

In the Deutsches Museum in Munich, separated from onlookers by a small barrier, stands the tabletop device built by Fritz Haber and Robert Le Rossignol to fix nitrogen from the air. Onlookers occasionally stop, stare for a few seconds, and walk past, thinking little of this machine that launched the worldwide manufacture of synthetic fertilizer, a process that has given so many people their lives and—due to ongoing contamination of the environment with excess nitrogen—a process that has probably started the clock on their eventual destruction.

Excerpted from the book Pandora's Lab by Paul Offit, published by National Geographic Partners on April 4, 2017.

Paul A. Offit, MD is a professor of pediatrics and director of the Vaccine Education Center at the Children’s Hospital of Philadelphia.

Popular Science is delighted to bring you selections from new and noteworthy science-related books. If you are an author or publisher and have a new and exciting book that you think would be a great fit for our website, please get in touch! Send an email to books@popsci.com.

Read More

Bill Nye is going to march on Washington

Bill Nye, star of the megahit "Science Guy" television show of the 90s, announced his public support of the March for Science in a blog post on Thursday. The April 22 march is billed as a call for the world to support and safeguard science in light of recent policy changes disrupting research at the Environmental Protection Agency, National Institutes of Health, NASA, and more. The event will include a teach-in and rally on the National Mall followed by a march through the streets of D.C.

Nye, whose new Netflix series will drop the day before (an air date set long before the march was planned, but presumably also intended to coincide with Earth Day, which is on April 22), will be at the event as a speaker and honorary co-chair. He explained his support for the march in a blog post for The Planetary Society, a science nonprofit of which he is currently the CEO.

The March for Science aligns with The Planetary Society's values, he said, and evokes the wishes of its late founder Carl Sagan. Nye studied under the legendary science communicator at Cornell, and believes __that marching in April is the right thing to do to uphold Sagan's legacy.

"He was a space science champion, advocate and communicator," Nye wrote. "He inspired the world to experience space science and delight in discoveries: achieved and within reach. His legacy lives on, through us: through you.” Science, Nye added, is universal—and space exploration, which is experiencing a bold new renaissance, brings out the very best in humanity.

“We march to inspire unity," Nye wrote. "When we explore the cosmos, we come together and accomplish extraordinary things. Space science brings people of all walks of life together to solve problems and experience the unparalleled awe of exploration. Everyone—regardless of race, gender, nationality, creed or ability—is welcome in our journey to advance space science.”

Read More

This graphene filter could make it cheaper to drink seawater

A new study released earlier this week in the journal Nature Nanotechnology may be a major step towards making desalinated water—water in which salt is removed to make it safe for drinking—a viable option for more of the world. Researchers from the University of Manchester modified graphene oxide membranes, a type of selectively permeable membrane __that allows some molecules to pass while keeping others behind, to let water through while trapping salt ions. It's essentially a molecular sieve.

Finding new sources of fresh water is important, because roughly 20 percent of the world's population—1.2 billion people—lack access to clean drinking water, according to the United Nations. It’s a number that’s expected to grow as populations increase and existing water supplies dwindle, in part due to climate change. This reality has led some to suggest __that the world’s next “gold rush” will be for water. Others have a less sanguine approach, worrying that the wars of the future will be fought over water. And this concern is not without merit: the war currently raging in Yemen is linked, at least in part, to water conflicts.

But while fresh water is scarce (a scant three percent of the world’s water is fresh) water itself is not. The Earth is more than 70 percent water, but 97 percent is undrinkable because it’s either salt or brackish (a mix of salt and fresh water). The occasional gulp of seawater while swimming aside, drinking saltwater is dangerous for humans—it leads to dehydration and eventually death. Hence the famous lined from the Rhyme of the Ancient Mariner: “water, water everywhere, nor any drop to drink.”

Desalination could be a solution. After all, the technique is already employed in parts of the Middle East and the Cayman Islands. However, the two techniques currently employed—multi-stage flash distillation, which flash heats a portion of the water into steam through a series of heat exchanges, and reverse osmosis, which uses a high-pressure pump to push sea water through reverse osmosis membranes to remove ions and particles from drinking water—have several key drawbacks.

“Current desalination methods are energy intensive and produce adverse environmental impact,” wrote Ram Devanathan a researcher at the Energy and Environment Directorate at Pacific Northwest National Laboratory, in an op-ed that accompanied the study. “Furthermore, energy production consumes large quantities of water and creates wastewater that needs to be treated with further energy input.”

Graphene oxide membranes show promise as a relatively inexpensive alternative, because they can be cheaply produced in a lab—and though water easily passes through them, salts do not. However, when immersed in water on a large-scale, graphene oxide membranes tend to quickly swell. Once swollen, the membranes not only allow water to pass through, but also sodium and magnesium ions, i.e. salt, defeating the purpose of the filtration.

Study author Rahul Nair and his colleagues discovered that by placing walls made of epoxy resin on either side of the graphene oxide, they could stop the expansion. And by restricting the membranes with resin, they were able to fine tune their capillary size to prevent any errant salts from hitching a ride on water molecules.

The next step will be testing it on an industrial scale to see if the method holds up. If it works, many people might just be drinking (a glass of water) to it.

Read More

Even our ancient ancestors had to deal with bed bugs

For about as long as humans have been living in places, bed bugs have been infesting them. In a new study in Journal of Medical Entomology, researchers present evidence of the oldest bed bug ancestors ever uncovered: tiny fragments of insidious insects from some 5,000 to 11,000 years ago.

Cimex lectularius and Cimex hemipterus, the species __that haunt our nightmares (and sometimes, if we're really unlucky, our apartments) are thought to have split from their close relatives at least 98,000 years ago—perhaps even before modern humans hit the scene 200,000 years ago. But we only know __that by turning back the evolutionary clock in their DNA.

"Cimicidae is almost unknown in the fossil record," the researchers wrote in the study. One fossilized bug from a mid-Cretaceous amber deposit in Myanmar is considered a member of the same broader family as Climex, but it's not a close relative—Quasicimex eilapinastes is what's called a stem-group member, which means it descended from an ancestor shared with the bed bug but has no living descendants. Cimex lectularius has been spotted in the remains of wells and latrines from colonial Jamestown and settlements of similar time periods, and once even in 3,500-year-old fossils in Egypt, but the rest of the insect's history is without record.

The newly described ancient insects aren't of the sort that would suck human blood, but they represent the oldest-ever fossilized records of the genus Cimex. Until these bits of Cimex pilosellus, Cimex latipennis, and Cimex antennatus were found, the oldest known bed bugs of any sort were the Climex lectularius specimens found in Egypt in the 1990s.

The fragments described in this new paper belonged to species that feed on bats. But, study author and zooarchaeologist Martin Adams told Live Science, they likely "would have fed on humans if the opportunity presented itself." There are many recorded instances of this in the modern day, the researchers noted.

The insects' location—Paisley Caves in Oregon—played host to humans during the same time period, so it would have been difficult for those settlers to avoid playing host to some bat-loving bed bugs. So why didn't the ancient blood suckers adapt to these convenient sources of nutrition? It seems likely that species such as lectularius branched off from their relatives in the midst of a similar set-up—with humans and bats living alongside one another in caves—tens of thousands of years earlier. Why didn't it happen again, creating new lineages of bed bugs that preferred, well, beds? Not that we're complaining. But it's a puzzle Adams and his colleagues are trying to work out.

"Were the cimicid populations too small to establish themselves outside the caves, or were the host populations too small?" Adams pondered in a statement. "Given that Paisley Caves was only a seasonal occupation area for human hunter-gatherers, did the humans move around too much, or were the bugs not able to withstand the environment outside the caves for very long? Or, were there other constraints involved?"

These questions might sound like an itch not worth scratching if you're not an entomologist. But the more we understand about the common bed bug's lineage, the better equipped we are to keep them from creeping into our modern homes.

Read More

What is climate change?

Media playback is unsupported on your device

Media captionMatt McGrath explains why we should care about climate change

BBC News looks at what we know and don't know about the Earth's changing climate.

What is climate change?

The planet's climate has constantly been changing over geological time. The global average temperature today is about 15C, though geological evidence suggests it has been much higher and lower in the past.

However, the current period of warming is occurring more rapidly than many past events. Scientists are concerned __that the natural fluctuation, or variability, is being overtaken by a rapid human-induced warming __that has serious implications for the stability of the planet's climate.

What is the "greenhouse effect"?

The greenhouse effect refers to the way the Earth's atmosphere traps some of the energy from the Sun. Solar energy radiating back out to space from the Earth's surface is absorbed by atmospheric greenhouse gases and re-emitted in all directions.

The energy that radiates back down to the planet heats both the lower atmosphere and the surface. Without this effect, the Earth would be about 30C colder, making our planet hostile to life.

Scientists believe we are adding to the natural greenhouse effect with gases released from industry and agriculture (known as emissions), trapping more energy and increasing the temperature. This is commonly referred to as global warming or climate change.

The most important of these greenhouse gases in terms of its contribution to warming is water vapour, but concentrations show little change and it persists in the atmosphere for only a few days.

On the other hand, carbon dioxide (CO2) persists for much longer (it would take hundreds of years for it to return to pre-industrial levels). In addition, there is only so much CO2 that can be soaked up by natural reservoirs such as the oceans.

Most man-made emissions of CO2 are through the burning of fossil fuels, as well as through cutting down carbon-absorbing forests. Other greenhouse gases such as methane and nitrous oxide are also released through human activities, but their overall abundance is small compared with carbon dioxide.

Since the industrial revolution began in 1750, CO2 levels have risen by more than 30% and methane levels have risen more than 140%. The concentration of CO2 in the atmosphere is now higher than at any time in at least 800,000 years.

Image caption Source: Nasa GISS

What is the evidence for warming?

Temperature records going back to the late 19th Century show that the average temperature of the Earth's surface has increased by about 0.8C (1.4F) in the last 100 years. About 0.6C (1.0F) of this warming occurred in the last three decades.

Satellite data shows an average increase in global sea levels of some 3mm per year in recent decades. A large proportion of the change in sea level is accounted for by the thermal expansion of seawater. As seawater warms up, the molecules become less densely packed, causing an increase in the volume of the ocean.

But the melting of mountain glaciers and the retreat of polar ice sheets are also important contributors. Most glaciers in temperate regions of the world and along the Antarctic Peninsula are in retreat. Since 1979, satellite records show a dramatic decline in Arctic sea-ice extent, at an annual rate of 4% per decade. In 2012, the ice extent reached a record minimum that was 50% lower than the 1979-2000 average.

The Greenland Ice Sheet has experienced record melting in recent years; if the entire 2.8 million cu km sheet were to melt, it would raise sea levels by 6m.

Satellite data shows the West Antarctic Ice Sheet is also losing mass, and a recent study indicated that East Antarctica, which had displayed no clear warming or cooling trend, may also have started to lose mass in the last few years. But scientists are not expecting dramatic changes. In some places, mass may actually increase as warming temperatures drive the production of more snows.

The effects of a changing climate can also be seen in vegetation and land animals. These include earlier flowering and fruiting times for plants and changes in the territories (or ranges) occupied by animals.

Image copyright AFP

Image caption Climate change could cause more extremes of weather

What about the pause?

In the last few years, there has been a lot of talk about a pause in global warming. Commentators argued that since 1998, there had been no significant global warming despite ever increasing amounts of carbon dioxide being emitted. Scientists have tried to explain this in a number of ways.

These include:

• variations in the Sun's energy output
• a decline in atmospheric water vapour
• greater storage of heat by the oceans.

But so far, there is no general consensus on the precise mechanism behind the pause.

Sceptics highlight the pause as an example of the fallibility of predictions based on computer climate models. On the other hand, climate scientists point out that the hiatus occurs in just one component of the climate system - the global mean surface temperature - and that other indicators, such as melting ice and changes to plant and animal life, demonstrate that the Earth has continued to warm.

In fact, a study published in Science journal in June 2015 doubted there had been a warming hiatus in the first place.

How much will temperatures rise in future?

In its 2013 assessment, the Intergovernmental Panel on Climate Change (IPCC) forecast a range of possible scenarios based on computer modelling. But most simulations indicate that global surface temperature change by the end of the 21st Century is likely to exceed 1.5C, relative to 1850.

A threshold of 2C is generally regarded as the gateway to dangerous warming.

Even if we cut greenhouse gas emissions dramatically now, scientists say the effects will continue because parts of the climate system, particularly large bodies of water and ice, can take hundreds of years to respond to changes in temperature. It also takes greenhouse gases decades to be removed from the atmosphere.

Media playback is unsupported on your device

Media captionHow temperatures have risen since 1884

How will climate change affect us?

The scale of potential impacts is uncertain. The changes could drive freshwater shortages, bring sweeping changes in food production conditions, and increase the number of deaths from floods, storms, heat waves and droughts. This is because climate change is expected to increase the frequency of extreme weather events - though linking any single event to global warming is complicated.

Scientists forecast more rainfall overall, but say the risk of drought in inland areas during hot summers will increase. More flooding is expected from storms and rising sea levels. There are, however, likely to be very strong regional variations in these patterns.

Poorer countries, which are least equipped to deal with rapid change, could suffer the most.

Plant and animal extinctions are predicted as habitats change faster than species can adapt, and the World Health Organization (WHO) has warned that the health of millions could be threatened by increases in malaria, water-borne disease and malnutrition.

As an increased amount of CO2 is released into the atmosphere, there is increased uptake of CO2 by the oceans, and this leads to them becoming more acidic. This ongoing process of acidification could pose major problems for the world's coral reefs, as the changes in chemistry prevent corals from forming a calcified skeleton, which is essential for their survival.

Computer models are used to study the dynamics of the Earth's climate and make projections about future temperature change. But these climate models differ on "climate sensitivity" - the amount of warming or cooling that occurs as a particular factor, such as CO2. goes up or down.

Models also differ in the way that they express "climate feedbacks".

Global warming will cause some changes that look likely to create further heating, such as the release of large quantities of the greenhouse gas methane as permafrost (permanently frozen soil found mainly in the Arctic) melts. This is known as a positive climate feedback.

But negative feedbacks exist that could offset warming. Various "reservoirs" on Earth absorb CO2 as part of the carbon cycle - the process through which carbon is exchanged between, for example, the oceans and the land.

The question is: how will these balance out?

More: BBC News climate change special report

Read More