by Craig Dillon
craigdillon@ameritech.net 773-349-3059 3646 S. Winchester, Chicago, IL USA
Over a year ago, I read that the Arctic ice thickness declined from 16 ft in 1988 to 9 ft by 2003. Doing a simple arithmetic extrapolation, I came up with the year 2020 when the ice would have zero thickness. In other words, it would not exist in the summertime.
I was mystified by the climatologists reporting 2100 as the time for an ice free arctic summer. Then they predicted 2080, then 2060, and now 2040. Out of curiosity I talked to several climatologists around the world on this. One said that they use ice coverage data instead of ice thickness data because there are more measurements. He admitted it led to poor conclusions.
I found several noted climatologists who agreed with my assessment that the year 2020 is closer to the mark. But, they did defend the published numbers, saying that scientists are by nature and training conservative. And so, one way of interpreting the published predicted dates is that they represent the "best" case, not the most probable.
Going with the 2020 date, you will find many people who say "So what, the ice is already in the water and wont add to sea level rise."
They are right and wrong. The melting of the Arctic Ocean summer ice does not directly raise sea levels. What it does do is warm all air going to greenland from the north and west to above freezing.
Greenland ice stays ice during summers because the air coming to it has been refrigerated to below freezing by the Arctic Ocean ice pack. When that pack is gone, the air is not cooled, but warmed.
With warm air coming to Greenland every summer, the melting of the Greenlands ice must increase immensely. Unfortunately, no one has modeled this situation, so we do not have any quantified estimates of how MUCH ice will melt each year in that situation.
My rough estimate is that the increased melting will be at least ten times, and maybe much more than the present summer melt rate. The big question is "How long can Greenland have an ice cap, if the Arctic Ocean has no summer ice?"
The estimates for sea level rise assume the Arctic ice will be there until 2100, and that Greenland does not melt very much. These estimates may need to be revised.
As for the methane and CO2 being released by the melting permafrost in Siberia and Canada....thats for another article.
