TIME Environment

Heatwaves Caused By Climate Change 75% Of the Time, Study Finds

This picture shows two men attempting to push a car out of floodwaters after a storm swept Changsha, central China's Hunan province on taken on April 7, 2015
AFP/Getty Images This picture shows two men attempting to push a car out of floodwaters after a storm swept Changsha, central China's Hunan province on taken on April 7, 2015

Heavy precipitation is another result of climate change

Climate change is increasingly causing extreme weather like heavy rains, heat waves and severe storms, according to a new study.

Three-quarters of all hot spells occurring over land can be traced back to human activity, according to a study published Monday in Nature Climate Change. Global warming also causes 18% of heavy precipitation, the report finds, a figure that will increase to 40% if temperatures continue to rise.

“With every degree of warming it is the rarest and the most extreme events—and thereby the ones with typically the highest socio-economic impacts—for which the largest fraction is due to human-induced greenhouse gas emissions,” Swiss researchers Erich Fischer and Reto Knutti wrote.

The study looked at heat waves and heavy rains from 25 climate models over the period from 1901-2005 as well as projections for 2006-2100.

TIME Diet/Nutrition

How to Block the Hunger Pangs When You Diet

The hardest part of a diet are the cravings. That’s because dieting goes against the body’s developed-over-millions-of-years instinct to feed when energy levels drop. There’s a network of neurons that is exquisitely designed to sense when the body’s cells need more calories to fuel the metabolic, enzymatic, muscular, neurologic and sensory things they do. So when the body wants calories, we eat.

But what if it were possible to fool the body into thinking that it was full — without eating a bite?

Now scientists say you may be able to have your cake and not eat it — at least a little more easily. They worked with mice, but their findings could lead to new obesity treatments for people as well. In two papers published in Nature and Nature Neuroscience, researchers from different groups culminate a 15-year search for the specific nerve circuits in the brain responsible for hunger and satiety.

Scott Sternson, a researcher and group leader at the Howard Hughes Medical Institute’s Janelia Research Campus, investigated the signals that prompt us to eat. Do we eat to silence the negative sensations we get when we’re hungry? Or do we eat simply because we like the taste of food? Previous studies in animals suggests the latter, and the fact that we eat even when we’re not hungry also supports the idea.

But Sternson reports in Nature that his team found evidence it’s the desire to get rid of the unpleasant feelings associated with hunger that drives eating. Something called agouti-related peptide neurons (AgRP) are critical for regulating when animals eat. When calories dwindle and energy drops, AgRP are active, fueling appetite. “When we start to lose 5%, or 10% of body weight, that’s when these neurons are kicking in. And they are a big part of why most diets fail even though people do succeed in initially losing weight,” he says.

That may explain why diets go awry too. Sternson says AgRP nerves may not be active at the start of the diet, but as we lose weight, and the body senses that fewer calories are coming in, the neurons become more active, compelling us to fill up the missing calories and making us feel unpleasantly hungry all the time.

Sternson gave recently-fed mice mice different flavored capsules. Those flavors were associated each with either turning on or turning off the AgRP; when the mice were offered the flavored capsules again, they tended to favor the flavor they associated with when AgRP was turned on, and they felt hungry.

But when they did the same test on mice who hadn’t eaten in a while, the animals tended to favor the flavor linked to when AgRP was turned off — that’s when they didn’t feel the hunger pangs and the physical pain associated with hunger. Indeed, when they did more experiments that allowed them to peer inside the animals’ brains and see which nerves were active, the AgRP neurons started to quiet down as soon as the animals saw food, even before they began eating. But if the mice did not eat after seeing the food, the neurons would rev up again and remind the animals — painfully — that they hadn’t eaten.

But simply interrupting AgRP neurons wouldn’t be the safest way to support weight loss, says Dr. Bradford Lowell, professor of medicine at Harvard Medical School and Beth Israel Deaconess Medical Center and senior author of the other paper, published in Nature Neuroscience. Not only do AgRP neurons regulate appetite by driving animals to eat, but it also tries to conserve what energy remains by helping the body burn fewer calories. It signals the sympathetic nervous system, which controls things such as heart rate and blood pressure, to work less efficiently. And that could have negative effects on the heart.

The ideal situation would be to find something downstream of AgRP’s signaling that can be manipulated more safely. And that’s what Lowell spent the past 15 years doing. In his latest paper, he reports on a cluster of cells in the hypothalamus that might be just such a target. Unlike the neurons that trigger the heart-related symptoms when AgRP is activated, these nerves act as the hunger hub. Called melanocortin 4 receptor cells (MC4) hey are responsible, Lowell found, for feelings of satiety. Activating AgRP normally turns these cells off, so animals will feel the uncomfortable symptoms of hunger and start eating.

But one question that Lowell was keen on answering was whether animals eat to quiet down the hunger pangs of whether they simply eat because it activates reward and pleasure centers in the brain. By using the latest laser-technology that can activate specific neurons, they studied hungry mice and turned the MC4 cells on in one room and off when the mice wandered into another room, essentially tricking them into thinking they had just eaten, even if they hadn’t. Not surprisingly, the mice tended to spend more time in the room where the cells were turned on, and they felt “full.” “They were not eating any food but the mice chose to hang out in the room where their satiety signals were turned on. And they really liked it,” says Lowell.

But when they repeated the study with mice that had dined on chow, the results were different. This time, the mice didn’t show any preference and the satiety signals didn’t seem to affect them. That means that the animals ate mainly to get rid of the hunger pangs, and that given a choice, they would rather feel full.

That’s the same with people, and explains why diets are so hard to keep up. It’s a challenge to constantly fight the instinctive desire to quiet those hunger calls. But, says Lowell, it may be possible to manipulate the MC4 cells and fool the body into feeling the same satisfaction that comes with a full belly. “If we artificially turn on the downstream neurons of MC4, we are countering the adverse effect caused by AgRP being active. We are artificially removing the effect of the AgRP neurons on them,” he says.

And doing that, says Sternson, could help people who start a diet to stick with it. “We think it’s critical to understand all we can about these neurons, and how they control hunger when we start to loose weight. The more we understand the proteins that these neurons express, the more intelligently we can conceive potential treatment strategies,” he says. And those therapies might even make it possible to be hungry without feeling hungry, making them them the ultimate diet enabler.

TIME Natural Disasters

How Human Activity Is Causing Earthquakes Across the United States

Eight states in the South and Central U.S. are experiencing rapid earthquake growth partially as a result of oil and gas activity

The Rock may be about to star in the earthquake disaster movie San Andreas, but it turns out California is no longer the leading state for quakes. Oklahoma had more than 500 earthquakes of magnitude 3.0 or greater in 2014. Quakes in the Sooner State are now hundreds of times more common than less than a decade ago.

And Oklahoma is not alone. Eight states in the South and Central U.S. are experiencing rapid earthquake growth as a result human activity, according to a new report from the United States Geological Survey (USGS).

“These earthquakes are occurring at a higher rate than ever before and pose a much greater risk to people living nearby,” said Mark Petersen, a USGS official.

The man-made Oklahoma earthquakes are a relatively new phenomenon, the consequence of oil and gas drillers who have taken advantage of the fracking revolution injecting billions of gallons of wastewater underground. The increase in earthquake activity began in 2009, but the Oklahoma state government only acknowledged the role of oil and gas activity for the first time this week.

US Earthquake Map USGS
Courtesy of United States Geological SurveyA map of earthquake activity in the United States shows areas with suspected man-made earthquake activity marked with enclosed black lines.

Energy producers often need to dispose of polluted waste underground to prevent contamination of freshwater. Researchers have suggested that the disposal of drilling wastewater deep underground may increase the stress on fault lines as far as 6 miles away, and subsequently trigger earthquakes.

Thus far, most of the Oklahoma earthquakes have been relatively small. But recent research suggests that bigger quakes may be on the horizon as a result of the reactivation of a 300-million-year-old fault line in the middle of the country, according to a study published Thursday.

The damage caused by even a moderately-sized earthquake in Oklahoma would likely be greater than in a state like California–Oklahoma lacks the tougher building codes that are common in states accustomed to quakes. A 5.6 magnitude earthquake, considered moderate in most places that typically experience earthquakes, rocked the state in 2011. More than a dozen homes were destroyed, and two highways buckled.

The Oklahoma state government said this week that it will take action to prepare for more man-made earthquakes, and launched a website to explain the problem to residents.

Other states experiencing human-induced earthquakes include Alabama, Arkansas, Colorado, Kansas, New Mexico, Ohio, and Texas, according to the USGS.

Previous research has suggested that fracking, a controversial process of oil and gas extraction that involves opening up fractures in shale rock deep underground, may be in part directly responsible for some of these earthquakes, but the USGS says that the process is only “occasionally the direct cause of felt earthquakes.” Wastewater injection is a more common cause.

Read More: Earthquake Insurance Becomes Boom Industry in Oklahoma

TIME geology

Magma Under Yellowstone Supervolcano Could Fill Grand Canyon 14 Times

WYOMING, UNITED STATES - 1991/01/01: USA, Wyoming, Yellowstone National Park, Upper Geyser Basin, Chromatic Springs. (Photo by Wolfgang Kaehler/LightRocket via Getty Images)
Wolfgang Kaehler—Getty Images Yellowstone National Park, Upper Geyser Basin, Chromatic Springs.

Scientists have discovered a previously unknown reservoir

Researchers have discovered a previously unknown chamber of magma underneath Yellowstone’s supervolcano. That chamber contains 11,200 cubic miles of magma, which, in addition to the already-known 2,500 cubic miles in an upper chamber, means the combined amount could fill the Grand Canyon nearly 14 times.

The University of Utah has produced the first 3D image of the underground expanse, giving greater insight to how the hotspot works, Smithsonion reports. It has been erupting for 17 million years, most recently some 640,000 years ago. Most of the magma is hot, solid rock, not molten rock, and the risk of a new eruption has not increased with this discovery. Scientists say we would likely have fair warning before another eruption in the form of earthquakes, higher ground temperatures, or other indicators of volcanic activity.


Read next: The Problem with U.S. Wildlife Protection Efforts

Listen to the most important stories of the day.

TIME Research

Scientists Have Sequenced the Entire Genome of a Woolly Mammoth

Woolly Mammoth
Science Picture Co/Getty Images/Collection Mix: Subjects RM Woolly Mammoth

Genetic factors may have been responsible for their disappearance

An international team of scientists has sequenced the whole genome of the woolly mammoth, a breakthrough that could help our understanding of why these hairy cousins of the elephant went extinct.

The last surviving population died out on an Arctic island called Wrangel off the coast of Russia some 4,000 years ago, 6,000 years after their relatives disappeared from mainland Siberia, reports the Los Angeles Times.

The researchers, who published their findings in the journal Current Biology on Thursday, compared the DNA from two woolly mammoths that had been frozen in permafrost: a juvenile male that lived in northeastern Siberia 44,800 years ago and a male from Wrangel Island that lived some 4,300 years ago.

“From a single individual you can get information about the entire population,” said co-author of the study, Eleftheria Palkopoulou.

Using the stem cells of a modern African elephant as the test, the team found that the population of woolly mammoths marooned on Wrangel Island was so small that the beasts had become inbred.

Though climate change and human intervention are often touted as factors, scientists aren’t entirely sure what caused the mammoth to die out and researchers wanted to see whether genetic features could be responsible.

The genetic data also showed there were two major population declines, one some 300,000 years ago and another around 12,000 years ago, at the end of the last Ice Age.

But scientists warn the lack of diversity in DNA from the Wrangel population does not necessarily mean genetics caused the mammoth to die out, and a closer examination of the data could help them understand how these creatures evolved and what sets mammoths apart from modern elephants.

[L.A. Times]

TIME Research

‘A Moratorium on Human Gene Editing to Treat Disease Is Critical’

A leading scientist calls for caution on a promising new technology

Rudolf Jaenisch, MD, is a Founding Member, Whitehead Institute for Biomedical Research, and President, the International Society for Stem Cell Research

It has been just over a half-century since scientists solved the structure of DNA, and since that time, we have been fascinated by what the DNA encodes, how it is passed on from one generation to the next and what makes each of us unique. Technologies to introduce DNA changes have been used to study the function of genes and the proteins they encode, to identify genetic causes of disease and to develop better ways to treat them. Now, new research describes the editing of genes in human embryos—CRISPR-cas9—raising questions about the science, the implications and the ethics.

The research utilizes recent technologies that allow us to make precise, targeted changes to a DNA sequence. These technologies have proved remarkable in their ease-of-use and have become quickly adopted by researchers around the world to introduce or correct changes in gene sequences in a wide range of cell types.

These recent developments have piqued the imagination of scientists and the public alike, and there is much speculation about what comes next. Some have suggested the new technology will allow researchers to “fix” defective genes, so inheritable diseases are not passed to the next generation, while others have raised worries about the creation of “designer” babies.

In my role as president of the International Society for Stem Cell Research (ISSCR), a nonprofit group comprised of nearly 4,000 researchers, clinicians and ethicists from over 50 countries, I have been part of a diverse, global and ongoing dialogue about the complex scientific, societal and ethical issues surrounding germline modification technologies in humans. Following these broad discussions, the ISSCR recently issued a statement calling for a pause in attempts at gene editing technologies in early human embryos, or egg and sperm that are brought together with the intent to generate a baby, to allow for more extensive analysis of the potential risks of genome editing and for broad public discussion.

This statement is not intended to dampen excitement about the foundational research or clinical applications underway involving the modification of non-reproductive cells, rather to recognize the important scientific, as well as broad social and ethical considerations that arise when introducing genetic changes that are passed on to the next generation.

The scientific community has an obligation to think about the implications of their work and to engage the public and regulators in discussions around the science, its potential and limitations. We must ask ourselves and others tough questions: Even if we could safely modify the inheritable DNA in an embryo, egg or sperm, should we? In what scenarios might this be justified? How can we be assured that the technologies will not be abused? How do we maintain an openness with the public such that they understand and support the scientific community in their quest to improve public health?

Until we have addressed these complex questions, a moratorium on any clinical application of gene editing in human embryos is critical.

As we deliberate, we need continued laboratory research to enhance basic knowledge and to better understand the safety issues associated with human genome editing technologies. As in other areas of human stem cell research, the ISSCR and other groups advocate strongly for responsible and transparent practices, urging researchers worldwide to open their research to scrutiny.

The details of the most recently published research, which itself highlights serious technical challenges to editing the germline nuclear DNA for medical purposes, are less important than the dialogue it has generated. The scientific community appreciates the public’s interest in stem cell research and the opportunity to discuss openly the scientific, ethical and societal issues we consider each and every day.

TIME Television

Can Science Conquer Late-Night TV?

Smart talk: Tyson and guests in a season one episode
National Geographic Channels/Scott Gries Smart talk: Tyson and guests in a season one episode

A new talk show starring Neil deGrasse Tyson makes a play in an unlikely time slot

Carl Sagan had it easy. The famed astronomer, author and TV host, who died in 1996, may have mastered one of the most head-crackingly complex disciplines in all of the sciences, but when it came to explaining its mysteries to everyone else, he didn’t have to look hard for an audience. Space is intoxicating, Sagan was engaging and there just weren’t that many distractions that would keep people from tuning into his Cosmos series or reading his books.

Not so today. With 500 cable channels and an infinity of Internet options all vying for attention, customers are harder to come by. And too many of the ones who are left are being picked off by the forces of informational darkness—the anti-vaxxers and climate change deniers and moon-landing hoaxsters all peddling their chosen rubbish.

It’s those challenges that astronomer Neil deGrasse Tyson, director of the American Museum of Natural History’s Hayden Planetarium and host of the 21st-century reboot of Sagan’s Cosmos, must face every day. He’s done an impressive job so far, wooing science lovers with his books and TV appearances and Star Talk radio show. Now he’s stepping up his game, bringing Star Talk to TV in a frank bid for the minds and eyeballs of science’s non-lovers, non-believers and can’t-be-bothereds too.

Everything about the new Star Talk—which premiered on April 20 on the National Geographic Channel with a first-season, 10-episode run already in the can—breaks the science show rules. It ditches the familiar format of smart guy prowling a set with zillions of special effects to make the technical stuff go down easy in favor of a talk show recorded before a live audience in New York City’s Rose Center for Earth and Space, home to the Hayden. His co-host is a rotating cast of comedians, and his guest is typically a non scientist—Star Trek‘s George Takei, sex columnist Dan Savage, Interstellar director Christopher Nolan, President Jimmy Carter.

Much more daring—or much more reckless, depending on how you look at these things—is the show’s time slot: Monday nights at 11 p.m. EDT, when both basic cable and the broadcast networks bring their comedic sluggers to the plate. But the audience for the likes of Jon Stewart and Jimmy Fallon is exactly the demo Tyson is after, even if he’ll have to work hard to win them.

“We recognize candidly that a scientist alone would not have served as a draw for the audience to come to the show,” he says. “The icon or the celebrity is the excuse to talk about the science and we try to blend that with the pop culture and the comedy.”

It’s a mix that can work in both predictable and unpredictable ways. No surprise if you find Nolan talking wormholes and time dilation and the other cosmological puzzlers that made Interstellar go. No surprise either if Takei talks about the science of Star Trek and how much of it can—or already has—come true. But it’s refreshing if Carter does not have to talk about the Middle East peace process and instead can be allowed to show off the nuclear engineering cred he earned in the Navy. Something similar is true of Savage talking sex while constrained by the guardrails of an academic anthropologist who specializes in the neuroanatomy of love appearing with him.

The premiere episode, with Takei, also featured a scientist, astrophysicist Charles Liu of the State University of New York College of Staten Island. Judging by that first installment, the show could use a little tweaking—or perhaps relaxing—with everyone on the panel working a little less hard to fill their assigned roles and instead just allowing the conversation to go wherever it wants to go.

Future episodes could push the envelope of the new format further—perhaps even until it rips. Tyson speaks openly about the possibility of having both Charlie Sheen and, discomfitingly, Jenny McCarthy on the show. “Sheen was in the museum and asked some very deep philosophical questions about the universe,” he says. “Jenny McCarthy had me on her show and has a very curious mind about the universe. If she brings up vaccines I’d be all over her, but only if it goes there.”

Guests like that may just be a ratings play. Nothing could make Sheen’s gyros go haywire like talking cosmology—and you wouldn’t want to miss that. But there may be tactical genius behind bringing on someone like McCarthy. Scientific know-nothingism is a modern scourge, and an inquisitive but academically rigorous interlocutor like Tyson might be the kind of person who can school McCarthy in the difference between finding things out and making things up.

“Is science a satchel of facts that is poured into your head or is it an understanding of emergent truths?” he asks—clearly knowing his answer. “Science literacy is not just what you know but how your brain is wired for thought. If you can achieve that, you never have to ask if the moon landings are real again.”

Tyson is willing to take a flier on the possibility that viewers in the playtime slot of late-night TV might be willing to invest an hour in getting smarter. If he doesn’t succeed, it may say more about us than him.

Read next: Watch Neil deGrasse Tyson Explain the Meaning of Life

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TIME Healthcare

Inside the Hospital Room of the Future

Go inside the hospital room of the future with Andrew Quirk, a senior vice president at Skanska, to find out what inpatient care might look like by the year 2020

TIME astronomy

This Beautiful Photo Shows Why the Hubble Telescope Matters

NASA Hubble Space Westerlund 2
NASA/ESA/Hubble/AFP/Getty Images This Hubble Space Telescope image of the cluster Westerlund 2 and its surroundings has been released to celebrate Hubble's 25th year in orbit.

It's the 25th anniversary of the Hubble Space Telescope

The Hubble Space Telescope turns 25 on Friday, and in honor of its quarter-century anniversary, NASA unveiled a celebratory photo.

The Hubble photo captures the full spectrum of light emitted by new stars, showcasing more colors than the human eye can see on its own. The telescope reveals in magnificent detail the spawning of newborn stars and the gas and dust around them.

This particular image is of Gum 29, according to NASA, a region of the universe where many new stars are born 20,000 light years away from Earth. The intensely lit cluster is Westerlund 2, between 6 and 13 light years across and made up of 3,000 stars.

TIME Research

Chinese Researchers Modify Human Embryos in Study

Scientists and ethicists alike are expressing concern

This week, a team of Chinese researchers used a gene editing technique to try to modify several human embryos. The results have raised concern among many in the scientific community, including those who developed the technique.

The gene-editing technique, called CRISPR-Cas9, allows scientists to add or remove genetic material, which has significant implications for a variety of health problems. As TIME recently reported in the TIME 100 issue, CRISPR could, in theory, edit any human gene.

However, as science writer Carl Zimmer writes in National Geographic, scientists including those who developed the technology have publicly said it should not yet be used for any human engineering and that it’s not ready for clinical use. Researchers at Sun Yat-sen University recently tested the technique on human embryos (notably, embryos that would not have ever grown into a human). Zimmer writes:

All told, the researchers injected 86 embryos, 71 of which survived long enough for them to study. CRISPR only managed to cut DNA in a fraction of the embryos, and in only a fraction of those embryos did cells manage to take up the new version of the target gene (called beta-globin).

The experiment “came out poorly,” Zimmer says; in some cases, DNA was placed in the wrong spot and “off-target” mutations were discovered in the DNA. As Zimmer reports, scientists behind the CRISPR technique are arguing it was not ready for use. Jennifer Doudna, one of the creators of CRISPR, told Zimmer: “Although it has attracted a lot of attention, the study simply underscores the point that the technology is not ready for clinical application in the human germline. And that application of the technology needs to be on hold pending a broader societal discussion of the scientific and ethical issues surrounding such use.”

Read more of Zimmer’s coverage of the new study at National Geographic.

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