Unparalleled warmth changing Arctic
Washington: The Arctic is experiencing a multi-year stretch of unparalleled warmth "that is unlike any period on record", according to the 2018 Arctic Report Card by the US National Oceanic and Atmospheric Administration.
The report released on Tuesday stated that human-caused climate change is transforming the Arctic, both physically through the reduction of sea ice and biologically through reductions in wildlife populations and introduction of marine toxins and algae, CNN reported.
Temperatures in the Arctic were warming more than twice as fast as the overall planet's average temperature, with temperatures this year in the highest latitudes (above 60 degrees north) coming in 1.7 degrees Celsius above the 1981-2010 average, it said.
These were the second warmest (behind 2016) air temperatures ever recorded during the Arctic year, which runs from October through September to avoid splitting the winter season.
The five years since 2014 have been warmer than any other years in the historical record, which goes back to 1900.
Although Arctic temperatures have been subject to wild swings back and forth through the decades due to natural variability, they have been consistently warmer than average since 2000 and at or near record since 2014, the report said.
"The changes we are witnessing in the Arctic are sufficiently rapid that they cannot be explained without considering our impacts on the chemistry of the atmosphere," Thomas Mote, a research scientist at the University of Georgia who authored part of the report, told CNN.
Mote expressed than any natural cycle or mechanism that would lead to the amount of warming and ice loss that has been observed would take much longer than the few years over which we have seen these drastic changes.
The rapid warming of the Arctic is known as "Arctic amplification", which is due to multiple feedback loops that the report describes.
Warmer temperatures lead to less ice and snow, which means less sunlight is reflected and more is absorbed by the darker oceans.
This warms the ocean further, which in turn decreases the sea ice even more. The lack of sea ice and more ocean surface leads to additional cloudiness later in the fall season, which keeps the Arctic region warmer even later into the winter.