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Updated: 3 min 9 sec ago

Human Activity Increasing Rate of Record-Breaking Hot Years

Wed, 11/22/2017 - 02:48

American Geophysical Union (AGU) Press Release

A new study finds human-caused global warming is significantly increasing the rate at which hot temperature records are being broken around the world.

Global annual temperature records show there were 17 record hot years from 1861 to 2005. The new study examines whether these temperature records are being broken more often and if so, whether human-caused global warming is to blame.

The results show human influence has greatly increased the likelihood of record-breaking hot years occurring on a global scale. Without human-caused climate change, there should only have been an average of seven record hot years from 1861 to 2005, not 17. Further, human-caused climate change at least doubled the odds of having a record-breaking hot year from 1926 to 1945 and from 1967 onwards, according to the new study.

The study also projects that if greenhouse gas emissions remain high, the chance of seeing new global temperature records will continue to increase. By 2100, every other year will be a record breaker, on average, according to the new study accepted for publication in Earth’s Future, a journal of the American Geophysical Union.

The new findings show how climate change is visibly influencing Earth’s temperature, said Andrew King, a climate extremes research fellow at the University of Melbourne in Australia and lead author of the new study.

“We can now specifically say climate change is increasing the chance of observing a new temperature record each year,” he said. “It’s important to point out we shouldn’t be seeing these records if human activity weren’t contributing to global warming.”

The study strengthens the link between human activity and recent temperature trends, according to Michael Mann, a climatologist and director of the Earth System Science Center at Pennsylvania State University, who was not involved with the new research.

“This work builds on previous research establishing that, without a doubt, the record warmth we are seeing cannot be explained without accounting for the impact of human activity on the warming of the planet,” Mann said.

Record-Breaking Heat

Record hot years have been occurring more frequently in recent decades. 2014 was the hottest year on record since 1880, but that record was quickly broken in 2015 and again in 2016. Research published earlier this year in Geophysical Research Letters found these three consecutive records in global temperatures were very likely due to anthropogenic warming.

Record-breaking temperatures tend to attract attention because they are one of the most visible signs of global warming. As a result, understanding how and why the rate of record-breaking is changing is critical for communicating the effects of climate change to the public, King said.

Previous research examined changes in rates of record-breaking temperatures in specific countries or regions. However, these studies couldn’t analyze global temperature trends because they relied on gathering large numbers of daily temperature records from different sources, according to King. Additionally, they didn’t directly attribute changes in record-breaking to human activity.

In the new study, King developed a method to isolate the human role in changing rates of record-breaking temperatures globally. Unlike previous studies, the method uses a single source of temperature data, in this case global annual temperatures, allowing King to study temperature records on a global scale.

King first looked at global temperature data from 1861 to 2005 and identified which years were hot record breakers. He then used a wide array of climate models to simulate global temperatures in this period. Some of the models included only natural influences on the climate such as volcanic eruptions, while other models featured both natural influences and human influences such as greenhouse gas emissions and the release of aerosols into the atmosphere.

King found only the climate models that included human influences had the same number of record-breaking hot years as historical temperature records—15 to 21, on average. The models without human influences only had an average of seven record-breaking hot years from 1861 to 2005.

He also determined human-caused climate change at least doubled the odds of having a record-breaking hot year from 1926 to 1945 and from 1967 onwards. The odds didn’t increase from 1945 to 1967 because man-made aerosol emissions generated a cooling effect, which counteracted warming due to anthropogenic greenhouse gases.

King’s research can also be applied to quantify the influence of human activities on a specific record-setting event. He applied his method to record-setting hot global temperatures in 2016 and record-setting hot local temperatures in central England in 2014. He found human influence led to a 29-fold increase in the likelihood of seeing both new records compared to a situation with no human influence on climate.

Categories: Ecological News

Fears of Radiation Leak Soar After North Korea Nuclear Site Collapse Kills 200

Wed, 11/01/2017 - 05:43

By Jake Johnson
Common Dreams

The disaster is believed to have resulted from Pyongyang’s hydrogen bomb test, which sparked earthquakes and landslides

Experts are issuing urgent warnings of a possible radiation leak following the collapse of a tunnel at North Korea’s Punggye-ri nuclear test site, an accident that reportedly killed at least 200 people.

“Should [the Punggye-ri site] sink, there is a possibility” that hazardous radioactive gas could be released into the atmosphere, warned South Korea weather agency chief Nam Jae-cheol during a parliamentary meeting on Monday, ahead of reports of the incident.

The tunnel’s collapse, first reported by the Japanese outlet TV Asahi on Tuesday, is presumed to have occurred as a result of the destabilization caused by Pyongyang’s powerful hydrogen bomb test last month.

The Telegraph, citing South Korean news agency Yonhap, reported that the original incident took place on Oct. 10 though it remains unclear exactly when the secondary collapse may have occurred.

Business Insider‘s Alex Lockie reports that according to North Korean sources, the tunnel initially “collapsed on 100 workers, and an additional 100 went in to rescue them, only to die themselves under the unstable mountain.”

Lockie continued:

The tunnels in and out of the test site had been damaged previously, and the workers may have been clearing or repairing the tunnels to resume nuclear testing. Additionally, with the test site compromised, hazardous radioactive material left over from the blast may seep out, which could possibly cause an international incident.

If the debris from the test reaches China, Beijing would see that as an attack on its country, Jenny Town, the assistant director of the U.S.-Korea Institute and a managing editor at 38 North, previously told Business Insider.

Reports of the deadly accident come on the heels of an analysis by the Washington Post suggesting that North Korea’s nuclear tests may have become “so big that they have altered the geological structure of the land.”

“Some analysts now see signs that Mount Mantap, the 7,200-foot-high peak under which North Korea detonates its nuclear bombs, is suffering from ‘tired mountain syndrome,'” the Post noted. “The mountain visibly shifted during the last nuclear test, an enormous detonation that was recorded as a 6.3-magnitude earthquake in North Korea’s northeast. Since then, the area, which is not known for natural seismic activity, has had three more quakes.”

This work is licensed under a Creative Commons Attribution-Share Alike 3.0 License

Categories: Ecological News

Record-Low 2016 Antarctic Sea Ice Due to ‘Perfect Storm’ of Tropical, Polar Conditions

Fri, 09/08/2017 - 00:46

By Hannah Hickey
UWNEWS

While winter sea ice in the Arctic is declining so dramatically that ships can now navigate those waters without any icebreaker escort, the scene in the Southern Hemisphere is very different. Sea ice area around Antarctica has actually increased slightly in winter — that is, until last year.

A dramatic drop in Antarctic sea ice almost a year ago, during the Southern Hemisphere spring, brought its maximum area down to its lowest level in 40 years of record keeping. Ocean temperatures were also unusually warm. This exceptional, sudden nosedive in Antarctica differs from the long-term decline in the Northern Hemisphere. A new University of Washington study shows that the lack of Antarctic sea ice in 2016 was in part due to a unique one-two punch from atmospheric conditions both in the tropical Pacific Ocean and around the South Pole.

The study was published Aug. 24 in Geophysical Research Letters.

“This combination of factors, all these things coming together in a single year, was basically the ‘perfect storm,’ for Antarctic sea ice,” said corresponding author Malte Stuecker, a UW postdoctoral researcher in atmospheric sciences. “While we expect a slow decline in the future from global warming, we don’t expect such a rapid decline in a single year to happen very often.”

The area of sea ice around Antarctica at its peak in late 2016 was 2 million square kilometers (about 800,000 square miles) less than the average from the satellite record. Statistically, this is three standard deviations away from the average — an event that would be expected to occur randomly just once every 300 years.

The record low was not predicted by climate scientists, so UW researchers looked at the bigger picture in ocean and atmospheric data to explain why it happened.

The previous year, 2015-16, had a very strong El Niño in the tropical Pacific Ocean. Nicknamed the “Godzilla El Nino,” the event was similar to other monster El Niños in 1982-83 and 1997-98. Unlike the 1997-98 event, however, it was only followed by a relatively weak La Niña in 2016.

Far away from the tropics, the tropical El Niño pattern creates a series of high- and low-pressure zones that cause unusually warm ocean temperatures in Antarctica’s eastern Ross, Amundsen and Bellingshausen seas. But in 2016, when no strong La Niña materialized, researchers found that these unusually warm surface pools lingered longer than usual and affected freeze-up of seawater the following season.

“I’ve spent many years working on tropical climate and El Niño, and it amazes me to see its far-reaching impacts,” Stuecker said.

Meanwhile, observations show that the winds circling Antarctica were unusually weak in 2016, meaning they did not push sea ice away from the Antarctic coast to make room for the formation of new ice. This affected ice formation around much of the Southern Ocean.

“This was a really rare combination of events, something that we have never seen before in the observations,” Stuecker said.

The researchers analyzed 13,000 years of climate model simulations to study how these unique conditions would affect the sea ice. Taken together, the El Niño pattern and Southern Ocean winds explain about two-thirds of the 2016 decline. The rest may be due to unusually big storms, which a previous paper suggested had broken up ice floes.

Scientists predict Antarctica’s ocean will be one of the last places on Earth to experience global warming. Eventually the Southern Ocean’s surface will begin to warm, however, and then sea ice there will begin its more long-term decline.

“Our best estimate of the Antarctic sea ice turnaround point is sometime in the next decade, but with high uncertainty because the climate signal is small compared to the large variations that can occur from one year to the next,” said co-author Cecilia Bitz, a UW professor of atmospheric sciences.

Stuecker noted that this type of big, rare weather event is useful to help understand the physics behind sea ice formation, and to learn how best to explain the observations.

“For understanding the climate system we must combine the atmosphere, ocean and ice, but we must focus on more than a specific region,” Stuecker said. “If we want to understand sea ice in Antarctica, we cannot just zoom in locally — we really have to take a global perspective.”

The other co-author is Kyle Armour, a UW assistant professor of atmospheric sciences and oceanography. The research was funded by the National Science Foundation and a National Oceanographic and Atmospheric Administration’s Climate and Global Change Postdoctoral Fellowship Program, administered by the University Corporation for Atmospheric Research’s Cooperative Programs for the Advancement of Earth System Science.

For more information, contact Stuecker at stuecker@atmos.washington.edu or Bitz at bitz@uw.edu and reach either scientist at 206-543-1339.

Categories: Ecological News