‘Rollercoaster’ temps prevailed as iceberg flotillas invaded North Atlantic
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”→
Melt season is 2 to 4 weeks ahead of 2012, which set record for low extent
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.
New study says impacts expected to show up in 20-30 years
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.
New study measures permafrost changes with impacts to carbon cycle
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.
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”→
The planet’s global warming streak continued in May, which marked the 13th month in a row that the average temperature over land and sea surfaces reached a new monthly record. According to the National Oceanic and Atmospheric Administration, it’s the longest such streak since record-keeping started in 1880.
Alaska makes up about 18 percent of the total U.S. land area but accounts for about 35 percent of the total carbon stock. The future of that carbon has big implications for global climate. If it’s released quickly, it could drive up global temperatures more than expected. And the carbon stored in high latitude ecosystems is considered to be vulnerable to climate change because of global warming. Continue reading “Climate: USGS measures Alaska land carbon stock”→