Arctic sea ice is melting much, much faster than even the best climate models had projected (actual observations in red). The reason is most likely unmodeled amplifying feedbacks. The image (from Climate Crocks via Arctic Sea Ice Blog) comes from a 2007 GRL research paper by Stroeve et al.
Everyone should indeed be scared by what we are doing to the Arctic because it will accelerate global warming, speed up sea level rise, and make deadly superstorms like Sandy more frequent and more destructive (see “NOAA Bombshell: Warming-Driven Arctic Ice Loss Is Boosting Chance of Extreme U.S. Weather“).
This is what’s new up north in 2012:
New records set for snow extent, sea ice extent and ice sheet surface melting, despite air temperatures — a key cause of melting — being unremarkable relative to the last decade.
Multiple observations provide strong evidence of widespread, sustained change driving Arctic environmental system into new state.
Here’s a video summary from NOAA:
Two of the most worrisome highlights are:
- Below the tundra, record high permafrost temperatures occurred in northernmost Alaska.
- Duration of melting was the longest observed yet on the Greenland ice sheet, and a rare, nearly ice sheet-wide melt event occurred in July.
The record Greenland melt is scary because if the Greenland ice sheet disintegrates, sea levels would rise 20 feet — and the process appears to be accelerating to a critical “tipping point” (see also “Science Stunner: Greenland Ice Melt Up Nearly Five-Fold Since Mid-1990s”). Indeed, polar researcher Jason Box, lead author of the Greenland section of the report, told the annual meeting of the American Geophysical Union in San Francisco:
“In 2012 Greenland crossed a threshold where for the first time we saw complete surface melting at the highest elevations in what we used to call the dry snow zone,” he told reporters at the AGU. “As Greenland crosses the threshold and starts really melting in the upper elevations it really won’t recover from that unless the climate cools significantly for an extended period of time which doesn’t seem very likely.”
The tundra warming is scary because it is a frozen locker of carbon whose defrosting will further accelerate warming (see “Carbon Feedback From Thawing Permafrost Will Likely Add 0.4°F – 1.5°F To Total Global Warming By 2100).”
Here is more detail on what’s happening in the tundra:
- In 2012, new record high temperatures at 20 [meters, 65 feet] depth were measured at most permafrost observatories on the North Slope of Alaska and in the Brooks Range, where measurements began in the late 1970s. Only two coastal sites show exactly the same temperatures as in 2011.
- A common feature at Alaskan, Canadian and Russian sites is greater warming in relatively cold permafrost than in warm permafrost in the same geographical area.
- During the last fifteen years, active-layer thickness [ALT] has increased in the Russian European North, the region north of East Siberia, Chukotka, Svalbard and Greenland.
The “ALT is the top layer of soil and/or rock that thaws during the summer and freez[es] again during the fall, i.e., it is not permafrost.”
The report makes painfully clear why all of these Arctic trends are going to continue — global warming and amplifying feedbacks:
Large changes in multiple indicators are affecting climate and ecosystems, and, combined, these changes provide strong evidence of the momentum that has developed in the Arctic environmental system due to the impacts of a persistent warming trend that began over 30 years ago. A major source of this momentum is the fact that changes in the sea ice cover, snow cover, glaciers and Greenland ice sheet all conspire to reduce the overall surface reflectivity of the region in the summer, when the sun is ever-present. In other words, bright, white surfaces that reflect summer sunlight are being replaced by darker surfaces, e.g., ocean and land, which absorb sunlight. These conditions increase the capacity to store heat within the Arctic system, which enables more melting – a positive feedback. Thus, we arrive at the conclusion that it is very likely that major changes will continue to occur in the Arctic in years to come, particularly in the face of projections that indicate continued global warming.
Anyone who thinks we can delay aggressive deployment of carbon-free technology simply has shut their eyes and ears to the growing scientific evidence.
- Death Spiral Watch: Experts Warn “Near Ice-Free Arctic In Summer” In A Decade If Volume Trends Continue