Category: Arctic

Global warming started earlier than you think

New study suggests climate is very sensitive to greenhouse gases

Despite ups and downs from year to year, global average surface temperature is rising. By the beginning of the 21st century, Earth’s temperature was roughly 0.5 degrees Celsius above the long-term (1951–1980) average. (NASA figure adapted from Goddard Institute for Space Studies.
Despite ups and downs from year to year, global average surface temperature is rising. By the beginning of the 21st century, Earth’s temperature was roughly 0.5 degrees Celsius above the long-term (1951–1980) average. (NASA figure adapted from Goddard Institute for Space Studies).

Staff Report

Although the rate of global warming has increased dramatically in the last few decades, a new study suggests that human activities have been driving climate change for the past 180 years. The findings suggest that global warming is not just a  20th century phenomenon, and that the climate system is, indeed, quite sensitive to the buildup of heat-trapping pollution.

The study was led by Nerilie Abram, of  The Australian National University, who  warming began during the early stages of the Industrial Revolution and started leaving a fingerprint in  the Arctic and tropical oceans around the 1830s, much earlier than scientists had expected. Continue reading “Global warming started earlier than you think”

Climate: Arctic sea ice melt slows slightly in July

Experts say record low now unlikely

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Summer sea ice off the east coast of Greenland. @bberwyn photo.

Staff Report

Cool and stormy weather in the Arctic during July slowed the rate of sea ice loss to just below average for the month,  making it less likely sea ice extent will dwindle to a record low, according to the latest update from the National Ice and Snow Data Center. But it all depends on conditions the next few months.

For the month, sea ice extent averaged 2.14 million square miles, the third-lowest for July since satellite records started in 1979. It was only the second month of 2016 that didn’t end with a record-low extent, according to the NSIDC. The sea ice extent in July was 73,000 square miles above the previous record low 637,000 square miles below the 1981 to 2010 long-term average. Through 2016, the rate of decline for the month of July is 28,070 square miles per year, about 7.3 percent per decade. Continue reading “Climate: Arctic sea ice melt slows slightly in July”

Abrupt climate change linked with ocean current shutdown

‘Rollercoaster’ temps prevailed as iceberg flotillas invaded North Atlantic

iceberg
Can Arctic icemelt shut down crucial ocean currents? @bberwyn photo.

Staff Report

By studying chemical tracers in seafloor sediments, scientists have been able to show that periods of abrupt climate change during the last ice age are somehow linked with dramatic changes in key ocean currents, especially the Atlantic meridional overturning circulation, which carries heat from the tropics to the northern latitudes.

Specifically, the study looked at series of abrupt climate changes that occurred between 60,000 and 25,000 years ago, ending as the last ice age peaked. A press release on the study describes it as an era when “temperatures in the Northern Hemisphere went on a rollercoaster ride, plummeting and then rising again every 1,500 years or so.”

“People have long supposed this link between overturning circulation and these abrupt climate events. This evidence implicates the ocean,” said L. Gene Henry, the lead author of the study and a graduate student at Columbia University’s Lamont-Doherty Earth Observatory. The findings, published in the journal Science, show for the first time that the ocean’s overturning circulation slowed during every one of those temperature plunges — at times almost stopping. Continue reading “Abrupt climate change linked with ocean current shutdown”

Reaching Paris climate goals would help polar bears survive

New research suggests that capping global warming below 2 degrees Celsius would lower chances of big population decline by preserving critical sea ice

 Eric Regehr, U.S. Fish and Wildlife Service
Can these mighty Arctic predators survive the era of human-caused global warming?  Photo courtesy Eric Regehr, U.S. Fish and Wildlife Service.

Staff Report

Now that the world has a clear target for limiting global warming, scientists say they show how how achieving the goal would protect at least some ecosystems and vulnerable species from impacts.

One newly updated study found that aggressively cutting greenhouse gas emissions would help ensure the survival of polar bears, listed as threatened because of Arctic sea ice declines. Polar bears depend on the ice as platforms for feeding around the biologically rich continental shelves of the Arctic Ocean. Continue reading “Reaching Paris climate goals would help polar bears survive”

Climate: Arctic sea ice on pace for record meltdown

Arctic sea ice
The image above shows a May 21, 2016 view of Arctic sea ice in the Beaufort Sea from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Credit: Land Atmosphere Near-Real Time Capability for EOS (LANCE) System, NASA/GSFC.

Melt season is 2 to 4 weeks ahead of 2012, which set record for low extent

Staff Report

Arctic sea ice extent continues to track toward a record low, the National Snow and Ice Data Center reported last week, resuming regular updates of sea ice after switching to a new satellite for the measurements.

As of June 7, the sea ice meltdown was ahead of 2012 by two to four weeks. Sea ice extent hit a record low that year and has been near that level every year since. The past two years, it set new record-lows for winter extent.

There was extensive early ice melt in the Beaufort Sea and surging warm air from eastern Siberia and northern Europe are part of what is driving this year’s below-average ice conditions, according the June 7 bulletin from the NSIDC. Continue reading “Climate: Arctic sea ice on pace for record meltdown”

Greenland ice sheet meltdown not affecting Gulf Stream – yet

A pool of icy water twice the size of Lake Victoria could disrupt the Gulf Stream when it pours out of the Arctic Ocean into the Atlantic.
A pool of icy water twice the size of Lake Victoria could disrupt the Gulf Stream when it pours out of the Arctic Ocean into the Atlantic.

New study says impacts expected to show up in 20-30 years

Staff Report

Ocean researchers tracking currents in the North Atlantic say that, so far, the massive amounts of freshwater, pouring off the melting Greenland Ice Sheet haven’t yet had a major effect on the Gulf Stream.

That influx of fresh water has increased by 50 percent since 1990 from both enhanced summer melt and calving outlet glaciers that are adding about 5,000 cubic kilometers of water per year — equivalent to a quarter of the volume of the Baltic Sea. Continue reading “Greenland ice sheet meltdown not affecting Gulf Stream – yet”

Climate: Thawing Arctic lakes could boost greenhouse gases

Arctic lakes
Ice on Arctic lakes is thinning dramatically, leading to thawing permafrost beneath. @bberwyn photo.

New study measures permafrost changes with impacts to carbon cycle

Staff Report

Global warming is limiting the growth of seasonal ice on Arctic lakes, which could have implications for the global carbon cycle. new study accepted for publication in Geophysical Research Letters, permafrost beneath shallow Arctic lakes is starting to thaw — another sign of the widespread Arctic meltdown due to climate change.

Another recent study found that Arctic lakes in Canada’s northern archipelago are drying at an unprecedented rate. The findings also support previous University of Waterloo research on Arctic lake ice.

The changes stem from warmer winter temperatures and increased snowfall during the past 30 years. Lakebed temperatures of Arctic lakes less than 1 meter (3 feet) deep have warmed by 2.4 degrees Celsius (4.3 degrees Fahrenheit) during the past three decades, and during five of the last seven years, the mean annual lakebed temperature has been above freezing, the study found. Continue reading “Climate: Thawing Arctic lakes could boost greenhouse gases”