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Sea Ice Extent Sinks To Record Lows At Both Poles (sciencedaily.com) 211

According to NASA, Arctic sea ice appears to have reached on March 7 a record low wintertime maximum extent. On the opposite side of the planet, Antartica ice hit its lowest extent ever recorded by satellites (since satellites began measuring sea ice in 1979) on March 3 at the end of summer in the Southern Hemisphere. Science Daily reports: Total polar sea ice covered 6.26 million square miles (16.21 million square kilometers), which is 790,000 square miles (2 million square kilometers) less than the average global minimum extent for 1981-2010 -- the equivalent of having lost a chunk of sea ice larger than Mexico. The ice floating on top of the Arctic Ocean and surrounding seas shrinks in a seasonal cycle from mid-March until mid-September. As the Arctic temperatures drop in the autumn and winter, the ice cover grows again until it reaches its yearly maximum extent, typically in March. The ring of sea ice around the Antarctic continent behaves in a similar manner, with the calendar flipped: it usually reaches its maximum in September and its minimum in February. This winter, a combination of warmer-than-average temperatures, winds unfavorable to ice expansion, and a series of storms halted sea ice growth in the Arctic. This year's maximum extent, reached on March 7 at 5.57 million square miles (14.42 million square kilometers), is 37,000 square miles (97,00 square kilometers) below the previous record low, which occurred in 2015, and 471,000 square miles (1.22 million square kilometers) smaller than the average maximum extent for 1981-2010.

Earth Hit Record Hot Year in 2016: NASA (news.com.au) 267

Earth sizzled to a third-straight record hot year in 2016, government scientists have said. They mostly blame man-made global warming with help from a natural El Nino, which has since disappeared. From a report: Measuring global temperatures in slightly different ways, NASA and the National Oceanic and Atmospheric Administration announced that last year passed 2015 as the hottest year on record. NOAA calculated that the average 2016 global temperature was 14.84 degrees Celsius (58.69 degrees Fahrenheit) -- beating the previous year by 0.04 Celsius (0.07 degrees F). NASA's figures, which include more of the Arctic, are higher at 0.22 degrees (0.12 Celsius) warmer than 2015. The Arctic "was enormously warm, like totally off the charts compared to everything else," said Gavin Schmidt, director of NASA's Goddard Institute of Space Studies in New York, where the space agency monitors global temperatures. Records go back to 1880. This is the fifth time in a dozen years that the globe has set a new annual heat record. Records have been set in 2016, 2015, 2014, 2010 and 2005.

2016 Was Second Hottest Year For US In More Than 120 Years of Record Keeping (climatecentral.org) 436

Last year was the second hottest year for the United States in more than 120 years of record keeping, according to the National Climatic Data Center, marking 20 above-average years in a row. While Georgia and Alaska recorded their hottest year, every state had a temperature ranking at least in the top seven. Climate Central reports: The announcement comes a week before the National Oceanic and Atmospheric Administration, which released the U.S. data, and NASA are expected to announce that 2016 set the record for the hottest year globally. Both the global record and the U.S. near-record are largely attributable to greenhouse gas-driven warming of the planet. In addition to the pervasive warmth over the last year, the U.S. also had to deal with 15 weather and climate disasters that each caused more than $1 billion in damage. Together, they totaled more than $46 billion in losses and included several disastrous rain-driven flooding events. These events, along with continued drought, lay bare the challenge for the country to learn how to cope with and prepare for a changing climate, said Deke Arndt, the climate monitoring chief of NOAA's National Centers for Environmental Information. The temperature for the contiguous U.S. was 2.9 degrees Fahrenheit above the 20th century average for 2016, displacing 2015 and ranking only behind 2012, when searing heat waves hit the middle of the country. More notable than the back-to-back second place years, Arndt said, was that 2016 was the 20th consecutive warmer-than-normal year for the U.S. and that the five hottest years for the country have all happened since 1998. Those streaks mirror global trends, with 15 of the 16 hottest years on record occurring in the 21st century and no record cold year globally since 1911.

New Analysis Shows Lamar Smith's Accusations On Climate Data Are Wrong (arstechnica.com) 502

Layzej writes from a report via Ars Technica: In 2015, NOAA released version 4 of their marine temperature dataset called ERSST. The new dataset accounted for a known cooling bias introduced when ocean temperature measurements transitioned from being taken in ship engine intake valves to buoy-based measurements. The warming of the last couple decades increased ever so slightly in NOAA's new analysis. This was a red flag for U.S. House Science Committee Chair Lamar Smith (R-TX), who rejects the conclusions of climate science -- like the fact that the Earth's climate is warming. Suddenly he wanted to see the researchers' e-mails and echoed the accusations of contrarian blogs about scientists' supposedly nefarious adjustments to sea surface temperature measurements. Rather than invoking scientific conspiracies, issues like this should be settled by analyzing the data. A new study, led by University of California Berkeley's Zeke Hausfather, does just that -- and Rep. Smith won't like these results, either. To test the NOAA dataset, Zeke's team created instrumentally homogeneous temperature records from sensors available only over the last couple decades. As it happens, the Argo float data, the buoy data, and the satellite data each hew closer to the updated dataset that NOAA used. The older version (3b) gives a global average that is too cool in recent years, growing to an offset of about 0.06 degrees Celsius. The researchers repeat this same analysis for two more major sea surface datasets that are used by the UK Met Office and the Japanese Meteorological Agency for their global temperature records. Both of those datasets also drift cooler than the comparison data, but less so than NOAA's old dataset.

Sea Ice In Arctic and Antarctic Is At Record Low Levels This Year (cnn.com) 313

dryriver quotes a report from CNN: For what appears to be the first time since scientists began keeping track, sea ice in the Arctic and the Antarctic are at record lows this time of year. "It looks like, since the beginning of October, that for the first time we are seeing both the Arctic and Antarctic sea ice running at record low levels," said Walt Meier, a research scientist with the Cryospheric Sciences Laboratory at NASA's Goddard Space Flight Center, who has tracked sea ice data going back to 1979. While it is too early to know if the recent, rapid decline in Antarctic sea ice is going to be a regular occurrence like in the Arctic, it "certainly puts the kibosh on everyone saying that Antarctica's ice is just going up and up," Meier said. The decline of sea ice has been a key indicator that climate change is happening, but its loss, especially in the Arctic, can mean major changes for your weather, too. The report notes that air temperatures in the Arctic have been exceeding 35 degrees Fahrenheit (20 degrees Celsius) above average, while "sea ice in the northern latitudes is at a lower level than ever observed for this time of the year." October and November is when the Arctic region typically gains ice. This year, air temperatures are staying much warmer and closer to the freezing mark of 32 degrees Fahrenheit. What's more is that water temperatures in the Arctic Ocean are several degrees above average, as a result of having less sea ice.

China Tells Trump Climate Change Isn't a Hoax it Invented (bloomberg.com) 302

China couldn't have invented global warming as a hoax to harm U.S. competitiveness because it was Donald Trump's Republican predecessors who started climate negotiations in the 1980s, China's Vice Foreign Minister Liu Zhenmin said, according to a Bloomberg report. From the article:U.S. Presidents Ronald Reagan and George H.W. Bush supported the Intergovernmental Panel on Climate Change in initiating global warming talks even before China knew that negotiations to cut pollution were starting, Liu told reporters at United Nations talks on Wednesday in Marrakech, Morocco. Ministers and government officials from almost 200 countries gathered in Marrakech this week are awaiting a decision by President-elect Trump on whether he'll pull the U.S. out of the Paris Agreement to tackle climate change. The tycoon tweeted in 2012 that the concept of global warming "was created by and for the Chinese in order to make U.S. manufacturing non-competitive." China's envoy rejected that view. "If you look at the history of climate change negotiations, actually it was initiated by the IPCC with the support of the Republicans during the Reagan and senior Bush administration during the late 1980s," Liu told reporters during an hour-long briefing.

Study Links Human Actions To Specific Arctic Ice Melt (sciencemag.org) 234

sciencehabit writes from a report via Science Magazine: Since at least the 1960s, the shrinkage of the ice cap over the Arctic Ocean has advanced in lockstep with the amount of greenhouse gases humans have sent into the atmosphere, according to a study published this week in Science. Every additional metric ton of carbon dioxide (CO2) puffed into the atmosphere appears to cost the Arctic another 3 square meters of summer sea ice -- a simple and direct observational link that has been sitting under scientists' noses. If current emission trends hold, the study suggests the Arctic will be ice free by 2045 -- far sooner than some climate models predict. The study suggests that those models are underestimating how warm the Arctic has already become and how fast that melting will proceed. And it gives the public and policymakers a concrete illustration of the consequences of burning fossil fuels. For instance, a U.S. family of four would claim nearly 200 square meters of sea ice, based on U.S. emissions in 2013. Over 3 decades, that family would be responsible for destroying more than an American football field's worth of ice.

Global CO2 Concentration Passes Threshold of 400 ppm -- and That's Bad for the Climate (time.com) 376

The average concentration of CO2 in the atmosphere hit the symbolic level of 400 parts per million (ppm) for the first time in 2015 and has continued to surge in 2016, according to the World Meteorological Organization. From a report on Time:Scientists say humans may need to take some carbon dioxide out of the atmosphere to stop global warming. The carbon dioxide concentration is unlikely to dip below the 400 ppm mark for at least several decades, even with aggressive efforts to reduce global carbon emissions, according to the WMO report, which confirms similar findings reported last month. Carbon dioxide can last in the atmosphere for thousands of years without efforts to remove it. "The year 2015 ushered in a new era of optimism and climate action," said WMO Secretary-General Petteri Taalas, referring to the landmark Paris Agreement to address climate change. "The real elephant in the room is carbon dioxide, which remains in the atmosphere for thousands of years and in the oceans for even longer."

Climate Change Doubled the Size of Forest Fires In Western US, Says Study (time.com) 191

An anonymous reader quotes a report from TIME: Man-made climate change has doubled the total area burned by forest fires in the Western U.S. in the past three decades, according to new research. Damage from forest fires has risen dramatically in recent decades, with the total acres burned in the U.S. rising from 2.9 million in 1985 to 10.1 million in 2015, according to National Interagency Fire Center data. Suppression costs paid by the federal government now top $2 billion. Now a new study, published in the journal Proceedings of the National Academy of Sciences, has found that a significant portion of the increase in land burned by forest fires can be attributed to man-made climate change. Other factors are also at play, including natural climate shifts and a change in how humans use land, but man-made climate change has had the biggest impact. That trend will likely continue as temperatures keep rising, researchers said. Climate change contributes to forest fires in a number of ways. Fires kill off trees and other plants that eventually dry and act as the fuel to feed massive wildfires. Global warming also increases the likelihood of the dry, warm weather in which wildfires can thrive. Average temperatures in the Western U.S. rose by 2.5 degree Fahrenheit since 1970, outpacing temperature rise elsewhere on the globe, according to the research.

Study: Earth Is At Its Warmest In 120,000 Years (washingtonpost.com) 221

An anonymous reader quotes a report from Washington Post: As part of her doctoral dissertation at Stanford University, Carolyn Snyder, now a climate policy official at the U.S. Environmental Protection Agency, created a continuous 2 million year temperature record, much longer than a previous 22,000 year record. Snyder's temperature reconstruction, published Monday in the journal Nature, doesn't estimate temperature for a single year, but averages 5,000-year time periods going back a couple million years. Snyder based her reconstruction on 61 different sea surface temperature proxies from across the globe, such as ratios between magnesium and calcium, species makeup and acidity. But the further the study goes back in time, especially after half a million years, the fewer of those proxies are available, making the estimates less certain, she said. These are rough estimates with large margins of errors, she said. But she also found that the temperature changes correlated well to carbon dioxide levels. Temperatures averaged out over the most recent 5,000 years -- which includes the last 125 years or so of industrial emissions of heat-trapping gases -- are generally warmer than they have been since about 120,000 years ago or so, Snyder found. And two interglacial time periods, the one 120,000 years ago and another just about 2 million years ago, were the warmest Snyder tracked. They were about 3.6 degrees (2 degrees Celsius) warmer than the current 5,000-year average. Snyder said if climate factors are the same as in the past -- and that's a big if -- Earth is already committed to another 7 degrees or so (about 4 degrees Celsius) of warming over the next few thousand years. "This is based on what happened in the past, Snyder noted. "In the past it wasn't humans messing with the atmosphere."

NASA: Arctic Sea Ice 2nd-Lowest On Record (earthsky.org) 206

An anonymous reader quotes a report from EarthSky: NASA and the National Snow and Ice Data Center (NSIDC) said on September 15, 2016 that summertime Arctic sea ice appears to have reached its annual minimum on September 10. With fall approaching and temperatures in the Arctic dropping, it's unlikely more ice will melt, and so the 2016 Arctic sea ice minimum extent will likely be tied with 2007 for the second-lowest yearly minimum in the satellite record. Satellite data showed this year's minimum at 1.60 million square miles (4.14 million square km). NASA said in a statement: "Since satellites began monitoring sea ice in 1978, researchers have observed a steep decline in the average extent of Arctic sea ice for every month of the year [...] The sea ice cover of the Arctic Ocean and surrounding seas helps regulate the planet's temperature, influences the circulation of the atmosphere and ocean, and impacts Arctic communities and ecosystems. Arctic sea ice shrinks every year during the spring and summer until it reaches its minimum yearly extent. Sea ice regrows during the frigid fall and winter months, when the sun is below the horizon in the Arctic." The NASA/NSIDC statement explained why the melt of Arctic sea ice surprised scientists in 2016. For one thing, it changed pace several times: "The melt season began with a record low yearly maximum extent in March and a rapid ice loss through May. But in June and July, low atmospheric pressures and cloudy skies slowed down the melt. Then, after two large storms went across the Arctic basin in August, sea ice melt picked up speed through early September." NASA posted an animation on YouTube that "shows the evolution of the Arctic sea ice cover from its wintertime maximum extent, which was reached on Mar. 24, 2016, and was the lowest on record for the second year in a row, to its apparent yearly minimum, which occurred on Sept. 10, 2016, and is the second lowest in the satellite era."

Climate Change Contrarians Lose Big Betting Against Global Warming (theguardian.com) 303

Layzej writes: Two members of the Global Warming Policy Foundation academic advisory board have each lost [roughly $1,320 (1,000 British Pound)] betting that 2015 would not be warmer than 2008. The Guardian reports: "Between 2008 and 2015 there would be more than 0.1C of human-caused global warming, so for 2015 to be cooler would have required a huge La Nina event, or big volcanic eruption, or perhaps the contrarians were banking on human-caused global warming being wrong. Whatever their reasoning, it was a foolish bet to make. 2015 was a record-breaking hot year, about 0.32C hotter than 2008. It wasn't even close." The winner of the bet, economist Chris Hope, also discussed the possibility of implementing climate betting markets, and noted: "they could offer a financial incentive for people who disagree about the likelihood of climate change to carefully assess the risks, instead of just shouting their disagreement across the void. If we do nothing, all the signs are that dangerous climate change is one of the safest bets around."

India Records Its Hottest Day Ever As Temperature Hits 51C (123.8F) (theguardian.com) 217

An anonymous reader writes: A city in northern India has shattered the national heat record, registering a searing 51C -- the highest since records began -- amid a nationwide heatwave. The new record was set in Phalodi, a city in the desert state of Rajasthan, and is the equivalent of 123.8F. It tops a previous record of 50.6C set in 1956."Yesterday (Thursday) was the hottest temperature ever recorded in the country... 51C in Phalodi," said BP Yadav, a director of India's meteorological department, on Friday.

Earth Day: 175 Nations Sign Historic Paris Climate Deal (usatoday.com) 138

An anonymous reader quotes a report from USA Today: World leaders from 175 countries signed the historic Paris climate accord Friday, using Earth Day as a backdrop for the ceremonial inking of a long-fought deal that aims to slow the rise of harmful greenhouse gases. The deal sets a target of limiting global warming by 2100 to "well below" 2 degrees Celsius (3.6 degrees F), as compared to pre-industrial levels. To accomplish that, each nation sets its own target for reducing emissions and updates that mark each year. Friday's signing sets a record for the number of countries signing an agreement on the first available day, the Associated Press reported. The old record goes back to the Law of the Sea in Montego Bay, which was signed by 119 countries in 1982, according to AccuWeather. Signing the accord is only one step in the process. The leaders must now go back to their home countries' governments to ratify and approve the agreement, which could take months or years. The deal goes into effect once 55 countries representing at least 55% of global emissions formally join.

Consensus On Consensus: Climate Experts Agree On Human-Caused Global Warming (theguardian.com) 795

mspohr quotes a report from The Guardian written by Dana Nuccitelli, environmental scientist and contributor to SkepticalScience.com: There is an overwhelming expert scientific consensus on human-caused global warming. Authors of seven previous climate consensus studies -- including Naomi Oreskes, Peter Doran, William Anderegg, Bart Verheggen, Ed Maibach, J. Stuart Carlton, John Cook, [Dana Nuccitelli] and six of her colleagues -- have co-authored a new paper that should settle this question once and for all. The two key conclusions from the paper are: 1) Depending on exactly how you measure the expert consensus, it's somewhere between 90% and 100% that agree humans are responsible for climate change, with most of our studies finding 97% consensus among publishing climate scientists. 2) The greater the climate expertise among those surveyed, the higher the consensus on human-caused global warming.

Quoted from IOPscience: Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. The consensus that humans are causing recent global warming is shared by 90%-100% of publishing climate scientists according to six independent studies by co-authors of this paper. Those results are consistent with the 97% consensus reported by Cook et al based on 11 944 abstracts of research papers, of which 4014 took a position on the cause of recent global warming. A survey of authors of those papers also supported a 97% consensus. Tol comes to a different conclusion using results from surveys of non-experts such as economic geologists and a self-selected group of those who reject the consensus. We demonstrate that this outcome is not unexpected because the level of consensus correlates with expertise in climate science. At one point, Tol also reduces the apparent consensus by assuming that abstracts that do not explicitly state the cause of global warming ('no position') represent non-endorsement, an approach that if applied elsewhere would reject consensus on well-established theories such as plate tectonics. We examine the available studies and conclude that the finding of 97% consensus in published climate research is robust and consistent with other surveys of climate scientists and peer-reviewed studies.

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