Ice Melt in the Northern Hemisphere Destabilized Antarctica

Nature, November 25 From 20,000 to 9,000 years ago, at the end of the last Ice Age, rapid melt of the Northern Hemisphere ice sheets raised sea levels around Antarctica by 80-130 meters, which in turn drove the rapid retreat of the Antarctica Ice Sheet. These rapid sea-level changes triggered ice shelf loss and retreat of […]

Accelerating Icelandic Glacier Melt in Past 25 Years

Frontiers in Earth Science, November 26 Over the past 130 years, glaciers in Iceland have lost about 20 percent of their total ice (540 gigatons of ice mass). Nearly half of this glacier loss has occurred in the past 25 years. Most projections (in other studies of Iceland’s glaciers) indicate accelerating loss as temperatures rise, […]

Threshold of Irreversible Loss of Greenland’s Ice Sheet in ~600 Years with High Emissions to 2100

The Cryosphere, December 1   Under emissions scenarios leading to 2°C of global warming and above, significant and rapid mass loss from the Greenland Ice Sheet would lock in several meters of unstoppable and irreversible global sea-level rise, persisting at least tens of thousands of years. The threshold of irreversibility could be reached in as […]

More Icebergs Might Lead to More Glacier Melt – and More Icebergs…

Nature Communications, November 25 Congestion of icebergs near an outlet glacier might lead to an increase in warmer water at the glacier’s base, causing greater calving of icebergs and even more ice loss, in a continuing feedback loop.  This modeling study found that underwater melting of icebergs in Greenland’s Sermilik fjord, at the end of the […]

Current Rates of Sea Level Rise Higher Than IPCC Estimates

Science, November 20 Over the past decade, sea levels have risen by an average of 4.8 millimeters per year, a rate much higher than the values estimated in the IPCC’s 2014 Fifth Assessment Report (AR5). This discrepancy suggests that the three main drivers of sea-level rise—thermal expansion of ocean water from global warming, melting glaciers […]

Increased Ocean Heat Flowing from the Tropics into the Arctic Ocean

Nature Climate Change, November 23   The flow of heat from subtropical waters into the Nordic Seas and Arctic Ocean has increased over the past three decades. Monthly measurements since 1990 have shown that since 2001, the amount of heat has increased from 305 to 326 terawatts per month. This increase in ocean heat transport […]

Increasing Glacier Melt Causes Higher Acidification Rates Around Svalbard

Journal of Geophysical Research – Biogeosciences, October 15 Glacier runoff during the peak of Svalbard’s meltwater season contains lower levels of most nutrients (nitrates, carbonates, organic carbons and phosphates) than in the waters surrounding the polar archipelago.  This nutrient-poor runoff increases the absorption of CO2 from the atmosphere in the surrounding ocean, raising acidification and […]

Possible 1000-km “River” Channel May Drain Greenland’s Northern Ice Sheet More Rapidly

The Cryosphere, November 12 Perhaps related to the above, a 1000-kilometer channel under the Petermann Glacier in northern Greenland may provide more rapid run-off from the ice sheet than previously appreciated.  Researchers realized that current maps of the bedrock under this portion of the ice sheet showed this channel as “blocked” at key points: due […]

Current Models Underestimate Ice Loss from Largest Greenland Glaciers

Nature Communications, November 17   From 1880 to 2012, Greenland’s three largest outlet glaciers lost enough ice to increase global sea levels by around 8 mm. These three glaciers currently drain 12% of the ice sheet, and together contain enough ice to raise sea levels by another 1.3 meters. However, climate projections under high emissions […]

Increasing River Temperatures Trigger Arctic Sea-Ice Decline and Atmospheric Warming

Science Advances, November 6 Warmer river discharge waters into the Arctic Ocean contributed up to 10% of regional sea-ice loss from Arctic continental shelves between 1980 and 2015. Particularly notable, this injection of warm freshwater also increased sea-ice breakup in late spring and early summer. The decline of Arctic sea-ice causes a warmer Arctic Ocean […]

Past Climate Conditions Anticipates Sea Level From Ice Sheets and CO2 Stabilization

Science, November 6 The Pliocene Epoch (3-4 million years ago) is our best analogue for current rates of climate change. During this period, CO2 concentrations peaked at 427 ppm; and sea-level was about 17 m higher than today, implying a near-to-complete loss of the Greenland and West Antarctic Ice Sheets, as well as substantial portions […]

Widespread Sea-Ice Decline in Nordic Seas Associated with Past Extreme Greenland Warming

Proceedings of the National Academy of Sciences, November 9   During the last Ice Age (about 110 000 to 10 000 years ago), a number of abrupt climate warming events increased temperatures up to 16.5°C over the Greenland Ice Sheet over just a few decades. New analysis of ice and sediment cores shows that such […]

High Arctic Temperatures and Low Sea-Ice Levels Cause Heatwaves at Mid-Latitudes

Environmental Research Letters, October 12 As the Arctic rapidly warms, the temperature difference between that region and warmer lower latitudes decreases, resulting in a weakened polar jet stream (the ribbon of very fast winds that greatly influences mid-latitude weather). Changes in the shape of the polar jet stream over the past decade have allowed for […]

Potential Climate Sensitivity Above 5°C from Cloud Feedback Mechanisms

Nature Geoscience, October 26 Updated CMIP6 climate models (produced for the next IPCC assessment AR6) consider the radiative effects of clouds and may show higher values of warming for a doubling of CO2 in the atmosphere.  If these new estimates are borne out, the upper limit of warming for a doubling of CO2 would rise […]

Additional Global Warming Feedbacks from Decay of the Earth’s Cryosphere

Nature Communications, October 27   New climate modelling shows that feedbacks from cryosphere melt dynamics including loss of Arctic summer sea-ice, melting of the Greenland and West Antarctic Ice Sheets, and retreat of mountain glaciers could result in an additional 0.4°C of global temperature rise under 1.5°C emissions scenarios. This warming response from melting ice […]