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Arctic sea ice melting ever faster
Arctic sea ice is melting faster than any year on record (though we only have about 30 years of accurate records as people weren't compiling data before then. However, older records of sea ice from sailors are being studied to give some ideas of past conditions and the general picture is of more sea ice historically, not less. The existence of species like polar bears that have evolved to live on sea ice also shows that there has always been at least enough sea ice to support a top predator.)
The problem is that it's part of the positive feedback mechanism that is heating up the planet. Greenhouse gas emissions cause temperature rises which heat the planet (for complex climatological reasons, the Arctic gets a higher proportion of the temperature rise than other areas - so rises are greater here).
The temperature rise melts ice. This changes the Earth's albedo and makes us absorb more heat, melting more ice, lowering the albedo still further.
Incidentally, here's a rather nice graph showing the contribution of different factors to climate variation. If you combine the effects of solar variation, CO2 emissions, atmospheric dust, sulphate pollution, etc, here's what you get. (For a discussion of how the graph has been derived, see here) This graph only goes upto the early 90s, so the effect of albedo changes not shown - I suspect predictive graphs for the next decade would show an impact.
The problem is that it's part of the positive feedback mechanism that is heating up the planet. Greenhouse gas emissions cause temperature rises which heat the planet (for complex climatological reasons, the Arctic gets a higher proportion of the temperature rise than other areas - so rises are greater here).
The temperature rise melts ice. This changes the Earth's albedo and makes us absorb more heat, melting more ice, lowering the albedo still further.
Incidentally, here's a rather nice graph showing the contribution of different factors to climate variation. If you combine the effects of solar variation, CO2 emissions, atmospheric dust, sulphate pollution, etc, here's what you get. (For a discussion of how the graph has been derived, see here) This graph only goes upto the early 90s, so the effect of albedo changes not shown - I suspect predictive graphs for the next decade would show an impact.
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