Satellites Give False Estimates of Multiyear Arctic Sea Ice Extent
30.11.2009 - Atmosphere & Space, Water & Oceans, Ice & Snow, Other, Arctic
In 2008 and 2009, satellites that surveyed the Arctic sea ice extent provided data showing the multiyear sea ice extent recovering. However while sailing an icebreaker research vessel, the NGCC Amundsen, in the southern Beaufort Sea, University of Manitoba researcher Dr. David Barber found thin, "rotten" ice instead of thick multiyear ice satellites had picked up.
The findings of the study, which have now been accepted for publication in the Geophysical Research Letters, have shown that contrary to what both the public and scientists have believed until now, sea ice in the Arctic has not been recovering since the 2007 all time low. During his trip on the NGCC Amundsen, much of the multiyear ice in the Beaufort Sea was so decayed that the icebreaker hardly had to slow down to break it.
Why were the satellites duped into thinking the sea ice was recovering? Barber explains that when assessing sea ice thickness, satellites shoot microwaves at the icescape and then record how they scatter. Each kind of ice was thought to have its own unique signature, which in fact is not the case as it turns out. The new study shows that not only has the thin, "rotten" sea ice have similar near-surface temperatures, but it also has similar near-surface salinities, as well as similar open water and new sea ice fractions at the surface, which makes it easy for satellites to mistake thin, "rotten" ice for multiyear sea ice.
The results, while consistent with estimates that show the amount of multiyear ice in the Northern Hemisphere was the lowest on record in 2009, implying that multiyear sea ice continues to diminish rapidly in the Canada Basin despite aerial extent was larger in 2009 than in 2007.
Dr. Barber says his findings have "significant implications for assessment of the speed of global climate change impacts in the Arctic and for increased shipping and industrial development in the Arctic."
