Thursday, March 20, 2008

The Big Melt Continues

Living in the American Upper Midwest it's easy to discount climate change given the past winter however all indications point towards more global warming. Another example cited by New Scientist shows that Arctic sea ice is even more transient than before, the above images showing that Arctic sea ice is now more likely than ever to melt away during the coming summer.

"You're looking down on the North pole. The figure to the left shows the average winter ice extent between 1985 and 2000; that to the right is the situation now, in February 2008. The colours are the big thing - they show how old the ice is, from six years and older in purple to less than one year in red.

The take-home message is that more than 70% of the ice in the Arctic has "grown" since last summer. That's a scarily low number - usually only half is "new growth".

"Ice can stay around for up to 10 years," says Walter Meier of the National Snow and Ice Data Center at the University of Colorado, US. "Old ice is really thick, tough as nails, and very resistant to short term melting." New ice, that red stuff in the figure above, is not thick, not tough - and not resistant to melting."

The Independent has further info on the seasonal changes in Britain that point towards climate disruption:

"In fact, the blurring of the seasons in Britain is now as serious a piece of evidence of climate change as the rapidly increasing melting of ice across the globe, in glaciers and in the land-based and marine ice sheets of the Arctic and the Antarctic.

The phenomenon shows that a whole range of organisms is already responding actively to the greatest environmental change in human history, in a way that people – and especially politicians – are not.

Last month, that shift produced its most remarkable image yet – a photograph, taken in Dorset, of a red admiral, an archetypal British summer butterfly, feeding on a snowdrop, an archetypal British winter flower.

Although that is not an event likely to cause alarm among the public, it was quite inconceivable until very recently. It is undeniable confirmation that a profound alteration in the environment, the consequences of which are likely to prove catastrophic, is already under way.

It is happening so quickly, and without people realising its true significance, because, in Britain, the major effects of climate change are initially being felt as less cold winters, rather than as hotter summers.

That has produced a startling rise in winter temperatures in recent years, clearly visible when current monthly means are compared to the average for 1961 to 1990.

To take the figures for last winter from the Central England Temperature Record, the world's oldest, which dates back to 1659: January 2007 was 3.2C warmer than the 1961-90 average, February was 2.0C warmer, March was 1.5C warmer, and April was 3.3C warmer. So far this year, January has been 2.8C above the 1961-90 average for the month, and February, 1.6C

Those are substantial rises. Although there is always natural variation in temperatures, recent winters taken together show a remarkable warming trend.

It has meant that many of what used to be thought of as the traditional signs of spring are happening very much earlier, causing primroses, for example, spring flowers par excellence, to bloom in some parts of the country as early as November. Other traditional spring plants, such as dog's mercury and the lesser celandine (a favourite of Wordsworth's) can be seen in January rather than March.

And in what is perhaps an even more vivid change, dandelions and daisies, which used to come into flower in spring on lawns (where they were permitted), now flower in many places all winter long.

Insects are responding similarly. A number of butterflies that overwinter as hibernating adults can now be seen in January rather than March or April, including the peacock and the comma, and especially the red admiral.

This last species used to be a spring migrant from the Continent but, in the recent warmer winters, it has begun to overwinter here.

Bumblebees have similarly become visible in mid-winter, and frogspawn, usually laid about March, can be seen in December in the South-west and south Wales."

Frogspawn, sea ice, and Red Admirals all seem to be saying the same thing.

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