Tuesday, September 16, 2008

Arctic Ice

WASHINGTON (AP) — Crucial Arctic sea ice this summer shrank to its second lowest level on record, continuing an alarming trend, scientists said Tuesday.

The ice covered 1.74 million square miles on Friday, marking a low point for this summer, according to NASA and the National Snow and Ice Data Center in Boulder, Colo. Last summer, the sea ice covered only 1.59 million square miles, the lowest since record-keeping began in 1979.

Arctic sea ice, which floats on the ocean, expands in winter and retreats in summer. In recent years it hasn't been as thick in winter.

Sea ice is crucial to worldwide weather patterns, both serving as a kind of refrigerator and reflecting the sun's heat. Given recent trends, triggered by man-made global warming, scientists warn that within five to 10 years the Arctic could be free of sea ice in the summer.

Even though the sea ice didn't retreat this year as much as last summer, "there was no real sign of recovery," said Walt Meier of the snow and ice data center. This year was cooler and other weather conditions weren't as bad, he said.

"We're kind of in a new state of the Arctic basically, and it's not a good one," Meier said. "We're definitely sliding towards a point where the summer sea ice will be gone."

Correct me if I'm wrong, but isn't 1.74 million square miles larger than 1.59 million square miles? And if that's the case, isn't "trend" a bit misleading at this point?

Could it be that the "trend" has ended and the ice melt is starting to slow? You'll remember we were told the ice would completely melt this summer. Didn't happen. We were told the polar bears are in decline as a result of the ice melt. In fact, their numbers have grown.

Speaking of the polar bears, I found this article to dispute the "growing population" claim (emphasis, mine):

Answer from Dr. Derocher: The various presentations of biased reporting ignore, or are ignorant of, the different reasons for changes in populations. If I thought that there were more bears now than 50 years ago and a reasonable basis to assume this would not change, then no worries. This is not the case.

The bottom line here is that it is an apples and oranges issue. The early estimates of polar bear abundance are a guess. There is no data at all for the 1950-60s. Nothing but guesses. We are sure the populations were being negatively affected by excess harvest (e.g., aircraft hunting, ship hunting,self-killing guns, traps, and no harvest limits). The harvest levels were huge and growing. The resulting low numbers of bears were due only to excess harvest but, again, it was simply a guess as to the number of bears.

After the signing of the International Agreement on Polar Bears in the 1970s, harvests were controlled and the numbers increased. There is no argument from anyone on this point. Some populations recovered very slowly (e.g., Barents Sea took almost 30 years) but some recovered faster. Some likely never were depressed by hunting that much, but the harvest levels remained too high and the populations subsequently declined. M'Clintock Channel is a good example. The population is currently down by over 60% of historic levels due only to overharvesting. Some populations recovered as harvests were controlled, but have since declined due to climate-related effects (e.g., Western Hudson Bay). In Western Hudson Bay, previously sustainable harvests cannot be maintained as the reproductive and survival rates have declined due to changes in the sea ice.

At this point, we lack quantitative data for an overall assessment of trend in Canada or Nunavut as a whole. There is, however, very strong evidence for a decline in Western Hudson Bay and the Southern Beaufort Sea based on quantitative studies. More recently, scientists working in the Southern Hudson Bay have reported a major decline in the condition of polar bears. A decline in condition was the precursor to the population decline in Western Hudson Bay. There is clear suggestion of a population decline due to over-harvest in Baffin Bay, Kane Basin and possibly Norwegian Bay.

The point is that you cannot simply summarize the status of polar bears—the information lies in the individual populations. You cannot put the various time periods together into a simplistic overview. Sea ice is declining but again, it is not declining the same everywhere. Some small areas of multi-year ice may improve habitat for polar bears. This latter point, however, does not mean that the habitat in all areas will improve and the predictions are very clear that the primary habitat of polar bears is at risk.

So, there is no data from early on so we assume the worst case scenario.

Typical envirocrat double talk.

1 comment:

Silent E said...

WOW... They've been keeping these records since 1979. 30 years..... Yeah, that's a GREAT snap shot of data. How old is the Earth again?