[graffis-l] POLAR ICE CAP GONE BY 2030?

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At 08:13 AM 9/8/07, you wrote:

>Polar ice cap gone by 2030?

>Posted by: " Mark Graffis " mgraffis mgraffis

>Fri Sep 7, 2007 10:50 am (PST)

>http://www.wunderground.com/blog/JeffMasters/show.html

>

>Polar ice cap gone by 2030?

>July's huge drop in Arctic sea ice extent continued into August 2007,

>according to figures released this week by the National Snow and Ice Data

>Center. August 2007 sea ice extent plunged 31% compared to the average

>from 1979-2000. As of September 4, 2007, the sea ice extent was a full 17%

>below the record minimum that occurred on September 20-21, 2005. Although

>the rate of melting is starting to slow down as the days grow shorter,

>more melting is expected this month.

>

>The difference in sea ice extent between August 1979 (the beginning of the

>data record) and August 2007 was a startling 37%. University of Illinois

>Polar Research Group presented similar estimates this week. They measure

>sea ice area--not extent. Sea ice area does not include all the long,

>narrow cracks in the ice, and so the numbers for sea ice area are

>different (lower) than for sea ice extent. Their sea ice area estimate for

>September 5, 2007 (Figure 1) was 42% less than for the same date 28 years ago.

>

>Figure 1. Comparison of sea ice area on September 5, 1979 and September 5,

>2007. Sea ice area in early September has declined 42% in the 28 years

>since 1979. Image credit: University of Illinois Polar Research Group.

>

>An ice-free Arctic in just 23 years?

>None of our computer climate models predicted that such a huge loss in

>Arctic ice would occur so soon. Up until this year, the prevailing view

>among climate scientists was that an ice-free Arctic ocean would occur in

>the 2070-2100 time frame. The official word on climate change, the

>February 2007 report from the U.N.-sponsored Intergovernmental Panel on

>Climate Change (IPCC), warned that without drastic changes in greenhouse

>gas emissions, Arctic sea ice will " almost entirely " disappear by the end

>of the century. This projection is now being radically revised. Earlier

>this year, I blogged about a new study that predicted abrupt losses of

>Arctic sea ice were possible as early as 2015, and that we could see an

>ice-free Arctic Ocean as early as 2040. Well, the Arctic Ocean has

>suffered one of the abrupt losses this study warned about--eight years

>earlier than this most radical study suggested. It is highly probable that

>a complete loss of summer Arctic sea ice will occur far earlier than any

>scientist or computer model predicted. In an interview published yesterday

>in The Guardian Dr. Mark Serreze, and Arctic ice expert with the National

>Snow and Ice Data Center, said: " If you asked me a couple of years ago

>when the Arctic could lose all of its ice, then I would have said 2100, or

>2070 maybe. But now I think that 2030 is a reasonable estimate. It seems

>that the Arctic is going to be a very different place within our

>lifetimes, and certainly within our children's lifetimes. " While natural

>fluctuations in wind and ocean circulation are partly to blame for this

>loss of sea ice, human-caused global warming is primarily to blame. In the

>words of Dr. Serreze: " The rules are starting to change and what's

>changing the rules is the input of greenhouse gases. This year puts the

>exclamation mark on a series of record lows that tell us something is

>happening. "

>

>The implications

>

>The melting of the Arctic sea ice will not raise ocean levels appreciably,

>since the ice is made up of frozen sea water that is floating in the

>ocean. Sea ice melt does contribute slightly to sea level rise, since the

>fresh melt water is less dense than the salty ocean water it displaces.

>According to Robert Grumbine's sea level FAQ, if all the world's sea ice

>melted, it would contribute to about 4 millimeters of global sea level

>rise. This is a tiny figure compared to the 20 feet of sea level rise

>locked up in the ice of the Greenland ice sheet, which is on land.

>

>The biggest concern about Arctic sea ice loss is the warmer average

>temperatures it will bring to the Arctic in coming years. Instead of

>white, reflective ice, we will now have dark, sunlight-absorbing water at

>the pole, leading to a large increase in average temperature. Warmer

>temperatures will accelerate the melting of the Greenland ice sheet, which

>holds enough water to raise sea level 20 feet. The official word on

>climate, the 2007 IPCC report, predicted only a 0.6-1.9 foot sea level

>rise by 2100, due to melting of the Greenland ice sheet and other factors.

>I believe these estimates will need to be revised sharply upwards in light

>of the unexpectedly high Arctic sea ice loss this summer.

>

>One more point--global warming skeptics often criticize using computer

>model climate predictions as a basis for policy decisions. These models

>are too uncertain, they say. Well, the uncertainty goes both

>way--sometimes the models will underestimate climate change. We should

>have learned this lesson when the ozone hole opened up--another case where

>the models failed to predict a major climate change. The atmosphere is not

>the well-behaved, predictable entity the models try to approximate it as.

>The atmosphere is wild, chaotic, incredibly complex, and prone to sudden

>unexpected shifts. By pumping large amounts of greenhouse gases into the

>air, we have destabilized the climate and pushed the atmosphere into a new

>state it has never been in before. We can expect many more surprises that

>the models will not predict. Some of these may be pleasant surprises, but

>I am expecting mostly nasty surprises.

>

>I'll have an update on 99L when it becomes a tropical depression.

>

>Jeff Masters

 

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