April should be prime walrus hunting season for the native villages that dot Alaska’s remote western coast. In years past the winter sea ice where the animals rest would still be abundant, providing prime targets for subsistence hunters. But this year sea-ice coverage as of late April was more like what would be expected for mid-June, well into the melt season. These conditions are the continuation of a winter-long scarcity of sea ice in the Bering Sea—a decline so stark it has stunned researchers who have spent years watching Arctic sea ice dwindle due to climate change.
Winter sea ice cover in the Bering Sea did not just hit a record low in 2018; it was half that of the previous lowest winter on record (2001), says John Walsh, chief scientist of the International Arctic Research Center at the University of Alaska Fairbanks. “There’s never ever been anything remotely like this for sea ice” in the Bering Sea going back more than 160 years, says Rick Thoman, an Alaska-based climatologist with the National Oceanic and Atmospheric Administration….
…The unusual warmth continued throughout this winter, in part because of an atmospheric pattern that kept warm air and storms periodically sweeping up from the south. One such event in February helped push the monthly temperature over the Bering and Chukchi seas some 18 to 21.5 degrees Fahrenheit (10 to 12 degrees Celsius) above normal. Consequently, the Bering Sea lost half its ice extent at a time when ice should still have been growing. The storms also pushed back against the normal southward flow of ice from the Chukchi Sea into the Bering. Accompanying winds stirred up waves that kept new ice from forming, and broke up what thin ice there was….
…“Next year will almost certainly not be this low.” But as temperatures continue to rise, he says, “odds are very strong that we will not go another 160 years before we see something like this” happen again.
When Arctic temperatures spike, extreme winter weather is 2 to 4 times more likely in Boston and New York, while the West tends to be warmer, a new study shows.
Heavy snowfalls are generally more frequent since 1990, and in many cities the most extreme snowfalls have occurred primarily during recent decades.
Declining temperature contrast between the Arctic and the mid-latitudes leads to a wavier jet stream that disrupts normal weather patterns.
By Bob Berwyn Mar 13 2018 Read full InsideClimate News story
The warmer the Arctic, the more likely the Northeast will be clobbered by blizzards, says a team of researchers who analyzed winter weather patterns going back to 1950.
Citing disruptive storms like Snowzilla (2016), Snowmaggedon (2010) and Snowpocalypse (2009), the climate scientists wrote that “heavy snowfalls are generally more frequent since 1990, and in many cities the most extreme snowfalls have occurred primarily during recent decades.”
Their study, published in the journal Nature Communications, links the increased frequency of extreme winter storms with the rapid and persistent warming of the Arctic since around 1990. When temperatures over the Arctic spike, especially high in the atmosphere, extreme winter weather is two to four times more likely in Boston and New York, while the U.S. West tends to see warmer and drier conditions, they conclude.
Jennifer Francis, a Rutgers University climate researcher and co-author of the study, said that while the study doesn’t show causation, the pattern they found reinforces other studies showing that the declining temperature contrast between the Arctic and the mid-latitudes leads to a wavier jet stream that disrupts normal weather patterns….
Judah Cohen, Karl Pfeiffer, Jennifer A. Francis. Warm Arctic episodes linked with increased frequency of extreme winter weather in the United States. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-02992-9
A study published in 2017 found that these types of warming events have been increasing in frequency and duration during winter as the Arctic continues to warm at more than twice the rate of the rest of the globe.
The Arctic was 5.1 degrees Celsius warmer than normal on February 27, following several days of unusually hot weather. Climate Reanalyzer
“What’s exactly driving these changes is not clear, but having storm tracks move further north (i.e. the North Atlantic storm track) may be tied to the northward retreat of the ice edge,” said Julienne Stroeve, a senior research scientist at the National Snow and Ice Data Center in Boulder, Colorado, in an email.
“Thus, while having temperatures exceed freezing during winter is not uncommon, but it may be becoming more common as the climate changes and the ice edge continues to retreat.”
Stroeve said that it’s not just summer and fall sea ice showing steep declines, but that this is occurring year round now. “What it shows us too is that the winter sea ice is now also starting to respond as every winter now for the past 4 winters has been more extreme than the year before in terms of record low sea ice,” she said….
Long absent, cold temperatures finally return to California
2018 brought the warmest first half of winter on record to most of the American Southwest, including Southern California. (NOAA/NCDC)
The 2017-2018 “rainy season” has been a pretty unusual one over much of California. The season to date has been nearly the driest on record to date over much of Southern California, and conditions have also become increasingly dry across the north as the season has progressed. Until mid-February, California had suffered through one of its warmest starts to the winter on record (in Southern California, and across most of the interior American Southwest, it was the warmest first half of winter on record)….
the dipole pattern – abnormally high temperatures over much of the West along with chilly conditions in the East – has dominated North American weather in four of the past five winters
When ocean temperatures off the West Coast of North America are warmer than normal, as they have been most of the time since winter 2013, the jet stream tends to form a ridge of high pressure along the West Coast, causing storms to be diverted away from California and leaving much of the West high and dry…
Damage from extreme weather events during 2017 racked up the biggest-ever bills for the U.S. Most of these events involved conditions that align intuitively with global warming: heat records, drought, wildfires, coastal flooding, hurricane damage and heavy rainfall.
Paradoxical, though, are possible ties between climate change and the recent spate of frigid weeks in eastern North America. A very new and “hot topic” in climate change research is the notion that rapid warming and wholesale melting of the Arctic may be playing a role in causing persistent cold spells.
Weird and destructive weather was in the news almost constantly during 2017, and 2018 seems to be following the same script. Most U.S. Easterners shivered their way through the end of 2017 into the New Year, while Westerners longed for rain to dampen parched soils and extinguish wildfires. Blizzards have plagued the Eastern Seaboard – notably the “bomb cyclone” storm on Jan. 4, 2018 – while California’s Sierra Nevada stand nearly bare of snow….
….Regardless what it’s called, this dipole pattern – abnormally high temperatures over much of the West along with chilly conditions in the East – has dominated North American weather in four of the past five winters. January 2017 was a stark exception, when a strong El Niño flipped the ridge-trough pattern, dumping record-breaking rain and snowpack on California while the east enjoyed a mild month.
Two other important features are conspicuous in the dipole temperature pattern: extremely warm temperatures in the Arctic near Alaska and warm ocean temperatures in the eastern Pacific. Several new studies point to these “ingredients” as key to the recent years with a persistent dipole.
The new twist in this story is that the Arctic has been warming at at least double the pace of the rest of the globe, meaning that the difference in temperature between the Arctic and areas farther south has been shrinking. This matters because the north/south temperature difference is one of the main drivers of the jet stream. The jet stream creates the high- and low-pressure systems that dictate our blue skies and storminess while also steering them. Anything that affects the jet stream will also affect our weather.
When ocean temperatures off the West Coast of North America are warmer than normal, as they have been most of the time since winter 2013, the jet stream tends to form a ridge of high pressure along the West Coast, causing storms to be diverted away from California and leaving much of the West high and dry.
If these warm ocean temperatures occur in combination with abnormally warm conditions near Alaska, the extra heat from the Arctic can intensify the ridge, causing it to reach farther northward, become more persistent, and pump even more heat into the region near Alaska. And in recent years, Alaska has experienced periods of record warm temperatures, owing in part to reduced sea ice…
….It is widely expected that global warming will produce fewer low-temperature records, a tendency already observed. But it may also be true that cold spells will become more persistent as dipole patterns intensify, a tendency that also seems to be occurring.
It’s hard to nail down whether this weather pattern – overall warmer winters in North America but longer cold snaps – will persist. Understanding the mechanisms behind these complex interactions between natural influences and human-caused changes is challenging.
Scientists have found surprising evidence of rapid climate change in the Arctic: In the middle of the Arctic Ocean near the North Pole, they discovered that the levels of radium-228 have almost doubled over the last decade.
The finding indicates that large-scale changes are happening along the coast — because the source of the radium is the land and shallow continental shelves surrounding the ocean. These coastal changes, in turn, could also be delivering more nutrients, carbon, and other chemicals into the Arctic Ocean and lead to dramatic impacts on Arctic food webs and animal populations….
Lauren E. Kipp, Matthew A. Charette, Willard S. Moore, Paul B. Henderson, Ignatius G. Rigor. Increased fluxes of shelf-derived materials to the central Arctic Ocean. Science Advances, 2018; 4 (1): eaao1302 DOI: 10.1126/sciadv.aao1302
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