Polar Melting: Difference between revisions

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===== Newly discovered Greenland plume drives thermal activities in the Arctic =====

=====Warming Greenland ice sheet passes point of no return=====

AUGUST 13, 2020 by Laura Arenschield, The Ohio State University

  Nearly 40 years of satellite data from Greenland shows that glaciers on the island have shrunk so much that even if global warming were to stop today, the ice sheet would continue shrinking.

=====Past perspectives on the present era of abrupt Arctic climate change=====

Eystein Jansen, Jens Hesselbjerg Christensen, Trond Dokken, Kerim H. Nisancioglu, Bo M. Vinther, Emilie Capron, Chuncheng Guo, Mari F. Jensen, Peter L. Langen, Rasmus A. Pedersen, Shuting Yang, Mats Bentsen, Helle A. Kjær, Henrik Sadatzki, Evangeline Sessford & Martin Stendel  

  Abrupt climate change is a striking feature of many climate records, particularly the warming events in Greenland ice cores. These abrupt and high-amplitude events were tightly coupled to rapid sea-ice retreat in the North Atlantic and Nordic Seas, and observational evidence shows they had global repercussions. In the present-day Arctic, sea-ice loss is also key to ongoing warming. This Perspective uses observations and climate models to place contemporary Arctic change into the context of past abrupt Greenland warmings. We find that warming rates similar to or higher than modern trends have only occurred during past abrupt glacial episodes. We argue that the Arctic is currently experiencing an abrupt climate change event, and that climate models underestimate this ongoing warming.

=====A possible explanation for why West Antarctica is warming faster than East Antarctica=====

=====A massive waterfall formed on Greenland's ice sheet. Here's why it matters=====

  Scientists from the University of Cambridge in the UK recorded the extraordinary phenomenon through the use of aerial drones.

=====What’s Driving Antarctica's Meltdown?=====

  Now, new research is highlighting another threat: Since 2000, moist and warm tendrils of air known as atmospheric rivers have been swirling toward the coast more frequently, bringing more rain and surface melting. Antarctica has been losing about 250 billion tons of ice annually in recent years, and research shows the rate has increased sixfold since 1979. At this pace, researchers have suggested, West Antarctica's ice shelves may reach climate tipping points and crumble, sending sea level rise surging well beyond current projections.

=====Arctic Shifts to Carbon Source – Stunning Reversal After Capturing Carbon for Tens of Thousands of Years=====

  A NASA-funded study suggests winter carbon emissions in the Arctic may be adding more carbon into the atmosphere each year than is taken up by Arctic vegetation, marking a stark reversal for a region that has captured and stored carbon for tens of thousands of years.

  The study, published October 21, 2019, in Nature Climate Change, warns that winter carbon dioxide loss from the world’s permafrost regions could increase by 41% over the next century if human-caused greenhouse gas emissions continue at their current pace. Carbon emitted from thawing permafrost has not been included in the majority of models used to predict future climates.

=====Large loss of CO2 in winter observed across the northern permafrost region=====

  We estimate a contemporary loss of 1,662 TgC per year from the permafrost region during the winter season (October–April). This loss is greater than the average growing season carbon uptake for this region estimated from process models (−1,032 TgC per year). Extending model predictions to warmer conditions up to 2100 indicates that winter CO2 emissions will increase 17% under a moderate mitigation scenario—Representative Concentration Pathway 4.5—and 41% under business-as-usual emissions scenario—Representative Concentration Pathway 8.5. Our results provide a baseline for winter CO2 emissions from northern terrestrial regions and indicate that enhanced soil CO2 loss due to winter warming may offset growing season carbon uptake under future climatic conditions.

=====Alaska's Hottest Month on Record: Melting Sea Ice, Wildfires and Unexpected Die-Offs=====

  Arctic sea ice hit a record low in July after an early start to the melt season, according to the National Snow and Ice Data Center (NSIDC). The sea ice volume Arctic-wide was about 47 percent lower than the average from 1979-2018.

  In Alaska, the ice is now about 150 miles from shore—a phenomenon that has only occurred in recent years and never before September, according to Rick Thoman, a climate scientist with the Alaska Center for Climate Assessment and Policy.

=====Research Highlight: Loss of Arctic's Reflective Sea Ice Will Advance Global Warming by 25 Years=====

  Losing the remaining Arctic sea ice and its ability to reflect incoming solar energy back to space would be equivalent to adding one trillion tons of CO2 to the atmosphere, on top of the 2.4 trillion tons emitted since the Industrial Age, according to current and former researchers from Scripps Institution of Oceanography at the University of California San Diego.

=====Marine ice sheet instability amplifies and skews uncertainty in projections of future sea-level rise=====

  We have shown that model ensembles can be used to quantify a range of possible scenarios for future sea-level rise, including potentially catastrophic scenarios of rapid sea-level rise. However, large model ensembles can be prohibitively expensive when extended to the entire Antarctic Ice Sheet. To fully capture the complete range of possible Antarctic futures, we will need efficient methods for uncertainty quantification (32, 37) and model order reduction that captures the complexities of ice sheet dynamics (31, 34). Such sophisticated methods will ensure that we can make the most useful sea-level projections beyond 2100 for those stakeholders who depend on them.

=====Greenland Ice Melt Today=====

  Get daily satellite images and information about melting on the Greenland ice sheet. We post analysis periodically as conditions warrant.

=====Climate crisis: Alaska is melting and it’s likely to accelerate global heating=====

  The breakneck speed of Alaska’s rising heat is having cascading consequences, with vanishing sea ice exposing coastal communities to storms, altered wildlife and plant patterns that make it harder for people to find food. There is also a growing wildfire threat putting communities at risk.

=====Mass Die-Off of Puffins Raises More Fears About Arctic's Warming Climate=====

  The people of St. Paul Island, an Aleut community in the Bering Sea, are accustomed to seeing a lot of birds—millions stop there during their annual migrations. But they're not used to seeing them like this. What was happening in October 2016 was the beginning of a mass die-off. Thousands of tufted puffins were dying for no apparent reason, except for maybe one: changes in the ecosystem due to climate change.

=====‘Extraordinary thinning’ of ice sheets revealed deep inside Antarctica=====

  The warming of the Southern Ocean is resulting in glaciers sliding into the sea increasingly rapidly, with ice now being lost five times faster than in the 1990s. The West Antarctic ice sheet was stable in 1992 but up to a quarter of its expanse is now thinning. More than 100 metres of ice thickness has been lost in the worst-hit places.

=====Daily Kos Greenland Heat Dome=====

  Greenland’s Snow and Ice started melting in early April this year, weeks earlier than normal. Unprecedented early surface melting is well underway on the southeastern coastline now.

=====Arctic Sea Ice Minimum 2019=====

  The extent of Arctic sea ice at the end of this summer was effectively tied with 2007 and 2016 for second lowest since satellite monitoring began. An analysis of satellite data by NASA and the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder shows that the 2019 minimum extent, which was likely reached on Sept. 18, measured 1.60 million square miles (4.15 million square kilometers).

===== ‘Archived’ heat has reached deep into the Arctic interior, researchers say =====

  Arctic sea ice isn’t just threatened by the melting of ice around its edges, a new study has found: Warmer water that originated hundreds of miles away has penetrated deep into the interior of the Arctic.

  That “archived” heat, currently trapped below the surface, has the potential to melt the region’s entire sea-ice pack if it reaches the surface, researchers say.

=====Scientists are keeping a close eye on the Beaufort Gyre=====

  The Beaufort Gyre, an immense 60-mile-diameter pool of cold freshwater and sea ice, is “stuck” in a clockwise rotation that should have ended years ago. Its eventual reversal could send massive amounts of chilly water straight toward western Europe, plunging it into brutal winters and disrupting fisheries.

=====Warming of the interior Arctic Ocean linked to sea ice losses at the basin margins=====

  Arctic Ocean measurements reveal a near doubling of ocean heat content relative to the freezing temperature in the Beaufort Gyre halocline over the past three decades (1987–2017). This warming is linked to anomalous solar heating of surface waters in the northern Chukchi Sea, a main entryway for halocline waters to join the interior Beaufort Gyre.  

=====If We Lose the Ice we Lose the Entire Ecosystem=====

  The photographer has been documenting life at the poles for years. He is determined to safeguard these fragile habitats

====='We've never seen this': Massive Canadian Glaciers Shrinking Rapidly=====

  Scientists in Canada have warned that massive glaciers in the Yukon territory are shrinking even faster than would be expected from a warming climate – and bringing dramatic changes to the region.