Diane9247
Humanitarian
Reged: 01/15/07
Posts: 1917
Loc: Californian in Oregon
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Hi Carly -
I know what you mean - I've been terribly frustrated by those who are convinced that the "story" of global warming is some sort of leftist political conspiracy. They are the same people who do not read any of the scientific evidence, or I should say, don't know any science at all. And, they're proud of it. This kind of militant ignorance is taking us all down.
Anyway, thanks for listening, I'm finished with my tirade!
D.
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blt
Cartographer
Reged: 01/25/03
Posts: 638
Loc: Santa Cruz, Ca
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Cold Winter in 2008?
The winter of2007/8 has spawned news stories about it's severe cold and has been touted as proof that 'global warming' movement has been fabricated for political gain. However the science indicates that while this last winter has been colder than usual (in parts of N America and over the Pacific), it's still quite a bit warmer than the historic means.
Winter 2008
One indication of this is the latest assessment of the extent of the Arctic sea ice from NASA .
Quote:
Arctic sea ice grows and declines seasonally, ranging from an average minimum extent in September of 2.5 million square miles to an average winter maximum extent of 5.9 million square miles in March. This March, instruments on NASA’s Aqua satellite and NOAA and U.S. Defense Department satellites showed the maximum sea ice extent slightly increased by 3.9 percent over that of the previous three years, but it is still below the long-term average by 2.2 percent. Increases in ice extent occurred in areas where surface temperatures were colder than the historical averages. At the same time, as a result of the export of ice from the Arctic, the area of perennial ice decreased to an all-time minimum.
While this was the fifth least February sea ice extent on record, the story is more interesting when the age of the ice is plotted
Quote:
The ice in the Arctic is much younger than normal, with vast regions now covered by first-year ice and much less area covered by multiyear ice. Left: February distribution of ice by its age during normal Arctic conditions (1985-2000 average). Right: February 2008 Arctic ice age distribution
El Nina
The current drop in temp is in line a the effects expected from an El Nina event. Here is a rollup of the 2008 winter temperatures from NYT article. The El Nina : Nino oscillation is manifested by a decade long oscillation of sea-surface temperatures in the Pacific
Edited by blt (03/22/08 03:36 PM)
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Kempster
Master Guide
Reged: 05/29/04
Posts: 1524
Loc: Eden Prairie, MN, USA
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Your continued attention to this topic and frequent updates to these posts make this thread especially useful and informative! Thank you, blt for your hard work!
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blt
Cartographer
Reged: 01/25/03
Posts: 638
Loc: Santa Cruz, Ca
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This season, the Arctic sea ice appears to be headed to another record low. The NSIDC continues to monitor the sea ice and has an excellent summary web page on the current state of the Arctic and scientific commentary on the current retreat. Most interesting is the real time chart showing the extent of the sea ice compared to 2007's record low
 .
As you can see we are on track for another record low. Last year the Arctic sea ice broke up at a record rate during the last few weeks of June and July. This year, the sea ice is exceptionally new and thin and if the same percentage of one year old ice melts as previous years, we can expect another historical low.
Quote:
This bar plot shows estimates of sea ice extent at the 2008 September minimum based on known ice survival rates. The blue dotted line indicates the record-breaking minimum extent of 2007; the red dotted line shows the mean estimate based on all years between 1983 and 2007.
(From the May NSIDC summary )
Edited by blt (06/15/08 03:21 PM)
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Groovy23
Environmentalist
Reged: 09/08/06
Posts: 1228
Loc: Central London, UK.
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Arctic sea ice is melting even faster than last year, despite a cold winter.
A widespread Arctic melt would have major impacts on wildlife
Data from the US National Snow and Ice Data Center (NSIDC) shows that the year began with ice covering a larger area than at the beginning of 2007.
But now it is down to levels seen last June, at the beginning of a summer that broke records for sea ice loss.
Scientists on the project say that much of the ice is so thin that it melts easily, and the Arctic may be ice-free in summer within five to 10 years.
"We had a bit more ice in the winter, although we were still way below the long-term average," said Julienne Stroeve from NSIDC in Boulder, Colorado.
"So we had a partial recovery; but the real issue is that most of the pack ice has become really thin, and if we have a regular summer now, it can just melt away," she told BBC News.
In March, Nasa reported that the area covered by sea ice was slightly larger than in 2007, but much of it consisted of thin floes that had formed during the previous winter. These are much less robust than thicker, less saline floes that have already survived for several years.
After a colder winter, ice has been melting even faster than last year
A few years ago, scientists were predicting ice-free Arctic summers by about 2080. Then computer models started projecting earlier dates, around 2030 to 2050.
Then came the 2007 summer that saw Arctic sea ice shrink to the smallest extent ever recorded, down to 4.2 million sq km from 7.8 million sq km in 1980.
By the end of last year, one research group was forecasting ice-free summers by 2013.
"I think we're going to beat last year's record melt, though I'd love to be wrong," said Dr Stroeve.
"If we do, then I don't think 2013 is far off any more. If what we think is going to happen does happen, then it'll be within a decade anyway."
Rising tide
Countries surrounding the Arctic are eyeing the economic opportunities that melting ice might bring.
Canada and Russia are exploring sovereignty claims over tracts of Arctic seafloor, while just this week US President George Bush has urged more oil exploration in US waters - which could point the way to exploitation of reserves off the Alaskan coast.
But from a climate point of view, the melt could bring global impacts accelerating the rate of warming and of sea level rise.
"This is a positive feedback process," commented Dr Ian Willis, from the Scott Polar Research Institute in Cambridge.
"Sea ice has a higher albedo (reflectivity) than ocean water; so as the ice melts, the water absorbs more of the Sun's energy and warms up more, and that in turn warms the atmosphere more - including the atmosphere over the Greenland ice sheet."
Greenland is already losing ice to the oceans, contributing to the gradual rise in sea levels. The ice cap holds enough water to lift sea levels globally by about seven metres (22ft) if it all melted.
Natural climatic cycles such as the Arctic Oscillation play a role in year-to-year variations in ice cover. But Julienne Stroeve believes the sea ice is now so thin that there is little chance of the melting trend turning round.
"If the ice were as thin as it was in the 1970s, last year's conditions would have brought a dip in cover, but nothing exceptional.
"But now it's so thin that you would have to have an exceptional sequence of cold winters and cold summers in order for it to rebuild."
Source: BBC
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Edited by Groovy23 (06/19/08 01:44 PM)
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blt
Cartographer
Reged: 01/25/03
Posts: 638
Loc: Santa Cruz, Ca
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Will the North Pole be ice free this year? It's story that's been making some news. Here is the basic argument:. Take a look at the image below
The Image shows the age of the sea ice. Unlike 2007, in 2008 year the sea ice over the pole is only a year old. This means that it is thinner than normal and has a very good chance of melting this summer. Compare the image this year to the record from 1984-2007 in the animation below:
You can see that one-year old ice over the pole is unprecedented, and the perfect setup to an ice-free pole this year
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blt
Cartographer
Reged: 01/25/03
Posts: 638
Loc: Santa Cruz, Ca
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The NSIDC has posted new data (July 3,2008). It doesn't look good for the pole ice.
2008 has seen extensive early melting of record thin ice.
.
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Groovy23
Environmentalist
Reged: 09/08/06
Posts: 1228
Loc: Central London, UK.
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A large chunk of an Arctic ice shelf has broken free of the northern Canadian coast, scientists say.
Nearly 20 sq km (eight sq miles) of ice from the Ward Hunt shelf has split away from Ellesmere Island, according to satellite pictures.
It is thought to be the biggest piece of ice shed in the region since 60 sq km of the nearby Ayles ice shelf broke away in 2005.
Scientists say further splitting could occur during the Arctic summer melt.
The polar north is once again experiencing a rapid ice retreat this year, although many scientists doubt the record minimum extent of 4.13 million sq km (1.59 million sq miles) of sea-ice seen in 2007 will be beaten.
Nonetheless, dramatic changes are occurring in the region, affecting the ice both in the open ocean and the ice which is attached to the coast.
Researchers had predicted that the Ward Hunt Ice Shelf (WHIS) was likely to experience a major calving event of this nature.
Scientists travelling with the Canadian armed forces visited the area recently and found major new fractures in the ice that stretched for more 16km (10 miles).
Ellesmere Island was once bounded by one giant ice shelf that covered almost 10,000 sq km (3,500 sq miles).
Now this expanse of ice has retreated into a string of much smaller, individual shelves, which together cover just under 1,000 sq km (400 sq miles). At 440 sq km (170 sq miles) in size and 40m (130ft) thick, the WHIS is the largest of the remnant shelves. Scientists have been studying the Canadian feature because of what it can tell them about Arctic history.
Radiocarbon dating of drift wood trapped behind the shelf in Disraeli Fjord shows the shelf itself has been in place for at least 3,000 years.
However, an analysis of past records suggests that since the early 20th Century, the ice that makes up the WHIS has retreated by about 90%.
Researchers believe the mechanism which has maintained its stability - fresh water coming out of Disraeli Fjord and freezing under the shelf - may have been disturbed. If that is the case, the rest of the WHIS may disappear quite rapidly, researchers say.
Loss of sea-ice in the Arctic has global implications. The "white parasol" at the top of the planet reflects energy from the Sun straight back out into space, helping to cool the Earth.
Further loss of Arctic ice will see radiation absorbed by darker seawater and snow-free land, potentially warming the Earth's climate at an even faster rate than current observational data indicates.
As with the Ayles breakout in 2005, the authorities will have to track the Ward Hunt ice carefully. Its size means it could be a hazard to shipping and offshore development in the region.
Source: BBC
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satcom15
Tourist
Reged: 06/16/07
Posts: 169
Loc: Colorado, USA
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For those Naysayers hostile to or fearful of change, aggressive boasters of their ignorance, or doubters that choose to bury their head in the sand, the operative words are:
GLOBAL WARMING!
As blt shows in his discussions, regions can experience below normal temperatures. However, when viewed on the global scale and incorporating the oceans as huge heat sinks, the evidence is irrefutable. Since human industrialization begain in the last several hundred years, the planet as a whole has started warming at a rate unmatched in climate records that go back millions of years. The "rate" of change is of primary concern, not the absolute temperature (at least at the moment) - the planet has been hotter in the past, but never warmed as fast as it is now. The scientific evidence showing correlation between warming and human population growth/green house gas emmissions is clear and without question (despite a few "Nos" from those in the employ of organizations with a vested interest in the status quo intent on sowing false seeds of doubt to foment unecessary debate and postpone inevitable change).
Is the concept of Global Warming and its cause clear now? Good. Think in terms of embracing the urgent need to alter our behavior. And by the way, change does not mean we have to live with a single 40W light bulb, give up our beloved cars, or change lifestyle very much. Its really quite simple and minor efforts mean big savings. We humans have embarked on an experiment of climate change of our own making. What will its outcome be? Perhaps we should think in terms of conservation and alternative energy. Its good for the planet - and your wallet.
blt, Nice posts! Lots of excellent information. Incidentally, grew up in Cupertino and got my BS in Meteorology at San Jose State U. Know the Bay Area (SF and Monterey) very well.
Cheers!
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"So we arrived and were able to plant our flag at the geographical South Pole" R. Amundsen 1911
"The Pole. Yes, but under very different circumstances than expected" R. F. Scott 1912
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Groovy23
Environmentalist
Reged: 09/08/06
Posts: 1228
Loc: Central London, UK.
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The North Pole has become an island for the first time in human history as climate change has made it possible to circumnavigate the Arctic ice cap.
The historic development was revealed by satellite images taken last week showing that both the north-west and north-east passages have been opened by melting ice.
Prof Mark Serreze, a sea ice specialist at the National Snow and Ice Data Centre (NSIDC) in the US said the images suggested the Arctic may have entered a "death spiral" caused by global warming.
Shipping companies are already planning to exploit the first simultaneous opening of the routes since the beginning of the last Ice Age 125,000 years ago. The Beluga Group in Germany says it will send the first ship through the north-east passage, around Russia, next year, cutting 4,000 miles off the voyage from Germany to Japan.
Meanwhile, Stephen Harper, Canada's Prime Minister, has announced that ships entering the north-west passage should first report to his government. The routes have previously opened at different times, with the western route opening last year, and the eastern route opening in 2005.
The satellite images gathered by Nasa show that the north-west passage opened last weekend and the final blockage on the east side of the ice cap, an area of sea ice stretching to Siberia, dissolved a few days later.
Last year the extent of sea ice in the Arctic reached a record low that could be surpassed in the next few weeks, with some scientists warning that the ice cap could soon vanish altogether during summer.
Four weeks ago tourists had to be evacuated from a park on Baffin Island because of flooding caused by melting glaciers, and polar bears have been spotted off Alaska trying to swim hundreds of miles to the retreating ice cap.
Measurements on August 26 showed an ice cap of just over two million square miles, confirming the second biggest ice cap melt since records began. New of the opening of the passages emerged as the British explorer and adventurer Lewis Gordon Pugh began a kayak expedition to the North Pole aimed at drawing attention to the dramatic impact of melting polar ice.
"I want to bring home to world leaders, on this expedition, the reality of what is now happening here in the Arctic," said the 38-year-old environmentalist in his blog.
"The rate of change is clearly faster than nearly all the models predict, which has huge implications for climate change and how to tackle it."
Meanwhile Prof James Lovelock, of the University of Oxford, has claimed "planet-scale engineering of the climate" may have to be attempted to counter global warming.
Source: Telegraph
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