When the strong winds that circle the Arctic slacken, cold polar air can escape and cause extreme winter chills in parts of the Northern hemisphere. A new study finds that these weak states have become more persistent over the past four decades and can be linked to cold winters in Russia and Europe.
…[This study is the] first to show that changes in winds high up in the stratosphere substantially contributed to the observed winter cooling trend in northern Eurasia. While it is still a subject of research how the Arctic under climate change impacts the rest of the world, this study lends further support that a changing Arctic impacts the weather across large swaths of the Northern Hemisphere population centers….
…Despite global warming, recent winters in the Northeastern US, Europe and especially Asia were anomalously cold — some regions like Western Siberia even show a downward temperature trend in winter. In stark contrast, the Arctic has been warming rapidly. Paradoxically, both phenomena are likely linked: When sea-ice North of Scandinavia and Russia melts, the uncovered ocean releases more warmth into the atmosphere and this can impact the atmosphere up to about 30 kilometers height in the stratosphere disturbing the polar vortex. Weak states of the high-altitude wind circling the Arctic then favors the occurrence of cold spells in the mid-latitudes.
….”Jet Stream changes can lead to more abrupt and surprising disturbances to which society has to adapt. The uncertainties are quite large, but global warming provides a clear risk given its potential to disturb circulation patterns driving our weather — including potentially disastrous extremes.”
Marlene Kretschmer, Dim Coumou, Laurie Agel, Mathew Barlow, Eli Tziperman, Judah Cohen. More-Persistent Weak Stratospheric Polar Vortex States Linked to Cold Extremes. Bulletin of the American Meteorological Society, 2017; DOI: 10.1175/BAMS-D-16-0259.1
Arctic and Antarctic sea ice extents remain near-record lows
September 18, 2017
The globally averaged temperature over land and ocean surfaces for August 2017 was the third highest for the month of August in the NOAA global temperature dataset record, which dates back to 1880. The June-August seasonal global temperature was also third highest on record, while the year-to-date global temperature was second warmest in the 138-year record….
In a new analysis of climate models, researchers reveal the significant global effects that seemingly anomalous polynyas, or openings in sea ice, can have. Their findings indicate that heat escaping from the ocean through these openings impacts sea and atmospheric temperatures and wind patterns around the globe and even rainfall around the tropics.…Though this process is part of a natural pattern of climate variability, it has implications for how the global climate will respond to future anthropogenic warming.
…The work raises many new questions, such as how a decreasing sea ice extent, including the recent breaking off of a massive chunk of the Antarctic peninsula, will affect the frequency of polynyas and how the presence or absence of polynyas will affect how much atmospheric temperatures warm in response to anthropogenic climate change.
….Their model indicated that polynyas and accompanying open-ocean convection occur roughly every 75 years. When they occur, the researchers observed, they act as a release valve for the ocean’s heat. Not only does the immediate area warm, but there are also increases in overall sea-surface and atmospheric temperatures of the entire Southern Hemisphere and, to a lesser extent, the Northern Hemisphere, as well….
Anna Cabré, Irina Marinov, Anand Gnanadesikan. Global Atmospheric Teleconnections and Multidecadal Climate Oscillations Driven by Southern Ocean Convection. Journal of Climate, 2017; 30 (20): 8107 DOI: 10.1175/JCLI-D-16-0741.1
Measurements over Canada’s Mackenzie River Basin suggest that thawing permafrost is starting to free greenhouse gases long trapped in oil and gas deposits.
The conclusion of the authors: The warming climate triggers not only the natural production of biogenic methane, it can also lead to stronger emissions of fossil gas. This contributes significantly to the permafrost-carbon-climate feedback
Global warming may be unleashing new sources of heat-trapping methane from layers of oil and gas that have been buried deep beneath Arctic permafrost for millennia.As the Earth’s frozen crust thaws, some of that gas appears to be finding new paths to the surface through permafrost that’s starting to resemble Swiss cheese in some areas, scientists said.
In a study [see below] released today, the scientists used aerial sampling of the atmosphere to locate methane sources from permafrost along a 10,000 square-kilometer swath of the Mackenzie River Delta in northwestern Canada, an area known to have oil and gas desposits.
Deeply thawed pockets of permafrost, the research suggests, are releasing 17 percent of all the methane measured in the region, even though the emissions hotspots only make up 1 percent of the surface area, the scientists found.
In those areas, the peak concentrations of methane emissions were found to be 13 times higher than levels usually caused by bacterial decomposition—a well-known source of methane emissions from permafrost—which suggests the methane is likely also coming from geological sources, seeping up along faults and cracks in the permafrost, and from beneath lakes.
…A 2012 study made similar findings near the edge of permafrost areas and around melting glaciers. Now, there is more evidence that “the loss of permafrost and glaciers opens conduits for the release of geologic methane to the atmosphere, constituting a newly identified, powerful feedback to climate warming,” said the 2012 study’s author, Katey Walter Anthony, a permafrost researcher at the University of Alaska Fairbanks.
“Together, these studies suggest that the geologic methane sources will likely increase in the future as permafrost warms and becomes more permeable,” she said…. Since the study only covered two years, it doesn’t show long-term trends, but it makes a strong argument that there is significant methane escaping from trapped layers of oil and gas, Schuur said
Study in the Mackenzie Delta in Canada shows high amount of geological methane emission
The thawing permafrost soils in the Arctic regions might contribute to the greenhouse effect in two respects: on the one hand rising temperatures lead to higher microbial methane production close to the surface. On the other hand thawing subsurface opens increasingly pathways for old, geologic methane…
Katrin Kohnert, Andrei Serafimovich, Stefan Metzger, Jörg Hartmann, Torsten Sachs. Strong geologic methane emissions from discontinuous terrestrial permafrost in the Mackenzie Delta, Canada. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-05783-2
The warmer Arctic has triggered cooler winters and springs in North America, which has in turn weakened vegetation growth and lowered carbon uptake capacity in its ecosystems, research shows.
The team analyzed an index of sea surface temperatures from the Bering Sea and found that in years with higher than average Arctic temperatures, changes in atmospheric circulation resulted in the aforementioned anomalous climates throughout North America. In those years of intense cold and low precipitation, the team found that the unfavorable conditions adversely affected vegetation growth — including crop yields — which in turn decreased carbon uptake capacity by about 14%. In other words, although Arctic warming has increased carbon uptake in the Northern Hemisphere, this research has shown that the resulting interannual variability in Arctic temperatures can affect regions further away in North America and may counteract the initially observed increases in carbon uptake…
Jin-Soo Kim, Jong-Seong Kug, Su-Jong Jeong, Deborah N. Huntzinger, Anna M. Michalak, Christopher R. Schwalm, Yaxing Wei, Kevin Schaefer. Reduced North American terrestrial primary productivity linked to anomalous Arctic warming. Nature Geoscience, 2017; DOI: 10.1038/ngeo2986
..in the latest sign of how quickly changes are happening, new research published this week shows that the Arctic has seen more frequent bouts of warm air and longer stretches of mild weather. The new findings show that while warm snaps have occurred even as far as back as the 1890s, a massive shift is afoot in the region, which is warming twice as fast as the rest of the world…
Background temperatures have also been rising faster there. The North Pole region has warmed 2.3°F (1.3°C) per decade since 1979, a trend largely driven by climate change. Though the new study doesn’t tease out whether the increase in warm days is due directly to climate change, it’s part of a hugepileofevidence of how rising carbon pollution is altering the Arctic faster than the rest of the world….
….The winter of 2015-2016, for example, saw temperatures nearly 3.6 degrees Fahrenheit (2 degrees Celsius) warmer than the previous record high monthly winter temperature. At the end of December 2015, scientists recorded a temperature of 36 degrees Fahrenheit (2.2 degrees Celsius) in the Central Arctic, the warmest temperature ever recorded in this region from December through March.
…On average, the Atlantic side of the North Pole now has ten warming events each winter, while the Pacific Central Arctic has five such events, according to the study. More storms come in to the Arctic from the Atlantic Ocean during winter, which results in more warming events on the Atlantic side of the North Pole….
Robert M. Graham, Lana Cohen, Alek A. Petty, Linette N. Boisvert, Annette Rinke, Stephen R. Hudson, Marcel Nicolaus, Mats A. Granskog. Increasing frequency and duration of Arctic winter warming events. Geophysical Research Letters, 2017; DOI: 10.1002/2017GL073395
“It’s another sign that the Arctic is unraveling. We had heat waves in the central Arctic last winter, record-low winter sea ice coverage, and even periods of ice retreat when it should be growing,” said Mark Serreze, director of the National Snow and Ice Data Center.
The Arctic’s record-warm winter has allowed thousands of square miles of sea ice off Alaska to melt more than a month early, leaving the shoreline vulnerable to waves and exposing dark ocean water to absorb more heat from the sun…As of May 24, the ice cover on the Chukchi Sea had melted away from the shore along a 300 mile stretch, from Point Hope all the way to Barrow, the northernmost town in the United States. Satellite and radar data show the ice-free area totaled about 54,000 square miles.
The huge area of open water off the coast is something you would normally see in early July, said Mark Serreze, director of the National Snow and Ice Data Center. The rapid disintegration of the Chukchi Sea ice is an “exclamation point” on a remarkable series of rapid fire Arctic changes, he said.
“It’s another sign that the Arctic is unraveling. We had heat waves in the central Arctic last winter, record-low winter sea ice coverage, and even periods of ice retreat when it should be growing. These extremes are moving from place to place,” Serreze said. The Arcticclimate change underway is caused by the buildup of heat-trapping greenhouse gases.
…The rapid recent decline in ice coverage and thickness has led researchers to believe that most of the Arctic Ocean will be free of ice in the summers as soon as the mid-2020s.
NSIDC researcher Julienne Stroeve, currently based at University College, London, said at a recent science conference that each of the last 10 years saw record-low sea ice coverage, and that there were seven months of record-low sea ice conditions during 2016, setting the stage for a Chukchi Sea meltdown.
Sea ice conditions were so unusual in late 2016 that NSIDC lead scientist Ted Scambos called it a black swan event in December, after reporting record low ice extent in the Arctic and Antarctica, far below natural historic variations. In mid-November 2016, much of the Arctic—spanning an area as large as the lower 48 states—was 30 to 35 degrees above average.
…a large part of the world’s coast is Arctic, and that erosion, on average, is taking a 1.5-foot bite out of that coastline each year, said Michael Fritz, a polar and ocean researcher with the Alfred Wegener Institute in Potsdam, Germany.
Continued freak warmth in the Arctic helped propel global average temperatures to the second-warmest level on record for the month of April, NASA reported on Monday.
The new findings illustrate how the planet is still setting climate milestones even in the absence of other factors that tend to elevate global air and sea temperatures, such as an El Niño event.
This makes clear the growing influence of human-caused global warming on the planet’s climate, month after month, year after year, as the amounts of planet-warming greenhouse gases in the atmosphere continue to rise to levels unseen during all of human history. …The top 3 hottest months of April to occur since instrument records began in 1880 have all taken place since 2010.
…For April of 2017, the story is dominated by unusual warmth in parts of the Arctic, including across Siberia, parts of China, Alaska and the northwest portions of the Arctic Ocean. Greenland, however, had below average temperatures for the month, though that weather pattern reversed itself in early May.
Arctic sea ice tied for for the lowest level on record during the month of April, after setting record lows throughout the fall and winter. The sea ice cover, which has been declining since satellites first began keeping tabs on it in 1979, is now far thinner and younger than average as it enters the summer melt season. (Older, thicker ice has a higher chance of surviving the summer melt.) …
This April merely tied April 2016 for the lowest extent on record, but it’s hardly reason to celebrate. The Arctic was missing 394,000 square miles of ice, with each day setting a record low or within 36,000 square miles of setting one…
….One of the biggest issues for sea ice is its increasingly youthful appearance. Young ice is more susceptible to the vagaries of weather, whether it be warm air or water or storms that knock it around and break it up.
Ice older than five years in age now only comprises 5 percent of the Arctic’s ice pack. It accounted for 30 percent of all Arctic sea ice in 1984, but relentless warmth driven by rising carbon dioxide in the atmosphere has slowly squeezed it out of existence….
Arctic sea ice extent has trended in record low territory for months.Credit: Zack Labe
In the past, scientists typically avoided linking individual weather events to climate change, citing the challenges of teasing apart human influence from the natural variability of the weather. But that is changing.
…In a new study, published in this week’s issue of Proceedings of the National Academy of Sciences, Diffenbaugh and a group of current and former Stanford colleagues outline a four-step “framework” for testing whether global warming has contributed to record-setting weather events. The new paper is the latest in a burgeoning field of climate science called “extreme event attribution,” which combines statistical analyses of climate observations with increasingly powerful computer models to study the influence of climate change on individual extreme weather
….”Our results suggest that the world isn’t quite at the point where every record hot event has a detectable human fingerprint, but we are getting close,” Diffenbaugh said. For the driest and wettest events, the authors found that human influence on the atmosphere has increased the odds across approximately half of the area that has reliable observations.
….One high-profile test case was Arctic sea ice, which has declined by around 40 percent during the summer season over the past three decades. When the team members applied their framework to the record-low Arctic sea ice cover observed in September 2012, they found overwhelming statistical evidence that global warming contributed to the severity and probability of the 2012 sea ice measurements. “The trend in the Arctic has been really steep, and our results show that it would have been extremely unlikely to achieve the record-low sea ice extent without global warming,” Diffenbaugh said.
Noah S. Diffenbaugh, Deepti Singh, Justin S. Mankin, Daniel E. Horton, Daniel L. Swain, Danielle Touma, Allison Charland, Yunjie Liu, Matz Haugen, Michael Tsiang, Bala Rajaratnam. Quantifying the influence of global warming on unprecedented extreme climate events. Proceedings of the National Academy of Sciences, 2017; 201618082 DOI: 10.1073/pnas.1618082114