- Greenland Reels: Climate Disrupting Feedbacks Have Begun
Thursday, 05 March 2015 11:10By Bruce Melton, Truthout
The author waves from a point about a mile onto the ice sheet near what is called Point 660, about 25 miles from Kangerlussuaq, on the west coast of Greenland, 100 miles north of the Arctic Circle. Dust accumulates on the ice from as far away as Siberia. As the ice melts, most of the dust is left behind to absorb more sunlight and melt more ice in a climate change feedback that has already begun. (Photo: Bruce Melton)
Greenland is warmer than it has been in more than 100,000 years and climate disrupting feedback loops have begun. Since 2000, ice loss has increased over 600 percent, and liquid water now exists inside the ice sheet year-round, no longer refreezing during winter.
Melt and ice loss dynamics from Greenland are far more complicated than we understood just a few years ago. New discoveries have been made that add large uncertainties as to exactly how fast ice melt and iceberg discharge will increase in the future. Over the last decade, continued research into the rate of ice loss in Greenland has downplayed any rapid acceleration of current melt rates. New discoveries could be changing our understanding of this last decade’s work.
Greenland: Warmer Than in 100,000 Years
About 5,000 years ago, Greenland reached its warmest period in over 100,000 years. Since this time, Greenland had been cooling and the ice sheet was stable or growing. Beginning 30 to 40 years ago, however, a rapid reversal of cooling and ice sheet growth began.
The last 18 years have seen more melt than average across the ice sheet every year with an increasing trend that peaked in 2012 when the entire ice sheet surface temperature went above freezing for four days. (1)The melt line, or the elevation on the 11,000-foot-high ice sheet where the temperature does not rise above freezing in any given year, has steadily been increasing since the 1970s. (2) All of this melt is exposing areas beneath the ice sheet that have not been exposed in a very long time.
Across Baffin Bay to the west of Greenland is Baffin Island. This is the largest of the islands in the Canadian Arctic Archipelago, and ranked the fifth largest in the world; it is almost as big as Texas (Greenland is the largest). Baffin Island has its own ice cap as well as satellite ice caps to the main body of ice. It is these satellite ice caps that attracted the attention of researchers.
Collecting samples, Baffin Island, Professor Gifford H. Miller, University of Colorado, Institute of Arctic and Alpine Research (INSTAAR)
Led by the Institute of Arctic and Alpine Research, University of Colorado, Boulder, these researchers found dead plants and mosses still rooted in the ground immediately adjacent to the melting ice. The plants were dated with carbon-14 dating techniques to a time period 44,000 years ago that was in the depths of the last 100,000-year-long ice age. (3) At that time, the ice was growing and temperatures in the Arctic were 25 to 35 degrees Fahrenheit colder than the warmest time of our current interglacial era – the time between ice ages. The average temperature across the globe was 9 to 14 degrees colder than today. (4)
To find temperatures similar to today’s, we would have to go back nearly 120,000 years ago to the previous warmup between glacial periods, so it is virtually certain from these findings that the plants that these researchers found have not seen daylight in over 100,000 years. One of the amazing things this work reports is that some of the mosses at the 145 sites surveyed began to regrow once the ice melted away. (5)
Since the global thermal maximum temperature that occurred after the end of the last ice age about 5,000 years ago, Baffin Island cooled nearly 5 degrees Fahrenheit, but since the 1960s, this area has warmed nearly 7 degrees Fahrenheit, and the snow line has increased in altitude over 2,700 feet (half a mile). (6) This research definitively puts to rest the talking point that Greenland was warmer than today at any time in the past 100,000 years. The warming has also taken place entirely in the last 50 years, and during this entire 5,000-year-long period the natural cycles have been cooling, not warming.
The Dust Feedback
As the ice sheet melts around its edges, dust captured in eons of snow becomes exposed. Most of this dust does not get washed away by melt, (please click the link below to read this article on Truthout- http://www.truth-out.org/news/item/29462-greenland-reels-climate-disrupting-feedbacks-have-begun)