One of the major TV news networks reported recently that fewer people these days believe in global warmer, perhaps because in these economic times they aren't willing to accept restrictions on green house gas emissions (mostly CO2) that might burden them with increased energy costs. That's too bad, because the evidence for a warming planet is growing, and there are dire consequences awaiting an unsuspecting public. I read a post on one of the blogs I follow, Bad Mom, Good Mom, that, while decrying the lack of awareness of global warming dynamics, provided a very nice example of the albedo effect and why polar ice melt is something to be concerned about. Read the post here.
You can get an idea of polar ice shinkage by playing with this widget on the NYT Science page.
The problem with sea ice melt is that it creates a positive feedback loop, like eating potato chips -- the more you eat the more you want. With sea ice, the more it melts, the more of the sun's heat the water absorbs, and the warmer the water, the more the sea ice melts, and so on. Basically, sea ice is like your house air conditioner, only for the planet. The dramatic downward trend in sea ice coverage portends dire consequences for efforts to halt global warming. Because of positive feedback, many scientists believe we may already have passed the tipping point. We'd better hope not.