Naked Science Forum
Life Sciences => The Environment => Topic started by: paul.fr on 21/01/2009 19:28:47
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The continent of Antarctica is warming up in step with the rest of the world, according to a new analysis.
Scientists say data from satellites and weather stations indicate a warming of about 0.6C over the last 50 years.
Writing in the journal Nature, they say the trend is "difficult to explain" without the effect of rising greenhouse gas levels in the atmosphere.
Meanwhile, scientists in Antarctica say a major ice shelf is about to break away from the continent.
The Wilkins Ice Shelf is said to be "hanging by a thread" from the Antarctic Peninsula, the strip of land pointing from the white continent towards the southern tip of South America.
In isolation
Most of Antarctica's scientific stations are located along the peninsula, and scientists have known for many years that this portion of the continent is getting warmer.
But trends across the bulk of the continent have been much harder to discern, mainly because data from land stations is scarce.
It is somewhat insulated from the rest of the world's weather systems by winds and ocean currents that circulate around the perimeter.
In the new analysis, a team of US scientists combined data from land stations with satellite readings
"We have at least 25 years of data from satellites, and satellites have the huge advantage that they can see the whole continent," said Eric Steig from the University of Washington in Seattle.
"But the [land] stations have the advantage that they go back much further in time.
"So we combined the two; and what we found, in a nutshell, is that there is warming across the whole continent, it's stronger in winter and spring but it is there in all seasons."
They conclude that the eastern region of the continent, which is larger and colder than the western portion, is warming at 0.1C per decade, and the west at 0.17C per decade - faster than the global average.
The 2007 assessment of the global climate by the Intergovernmental Panel on Climate Change (IPCC) concluded: "It is likely that there has been significant anthropogenic (human-induced) warming over the past 50 years averaged over each continent except Antarctica", with the word "likely" in this context meaning "at least 66% probability".
The scientists said this study did not change that picture, with natural climatic cycles probably involved as well as elevated greenhouse gas concentrations.
"It's hard to think of any situation where increased greenhouse gases would not lead to warming in Antarctica," said Drew Shindell from Nasa's Goddard Institute for Space Studies (Giss) in New York.
"We're almost certain that greenhouse gas increases are contributing to this warming, but what's difficult is to attribute this warming and so say how much is down to natural warming and how much down to anthropogenic causes."
Last year, scientists from the UK Met Office used climate models to attribute trends at the poles, and concluded that human emissions of greenhouse gases were largely responsible for the observed warming.
Gareth Marshall from the British Antarctic Survey (BAS), who was not involved in the analysis, commented: "This study shows that, similar to the other six continents, Antarctica has undergone a significant warming over the past 50 years.
"The magnitude of this warming is similar to the rest of the southern hemisphere, where we believe it is likely that human activity has played some role in the temperature increase, and therefore it is also likely that this is the case regarding an Antarctic warming."
Cool analysis
Over the last 30 years, satellites have also shown that sea ice is slowly growing in extent around Antarctica, which some observers say indicates a cooling across the continent or at least in the surrounding seas.
Map
But Walt Meier from the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado, which follows ice trends at the poles, said wind patterns were probably the main reason.
"Around Antarctica, the winds play a much bigger role than they do in the Arctic," he said.
"If they're blowing northwards you can grow ice quite quickly and in contrast if they blow southwards the ice can contract quickly, whereas in the Arctic it's much more constrained (by land masses).
"So this positive trend in the Antarctic is certainly not an indication of any cooling trend."
One region that has seen spectacular losses of ice in recent years is the peninsula.
A BAS team currently on site is reporting that the Wilkins shelf, about 15,000 sq km in area, is probably about to break free.
"It really could go at any minute, and I wouldn't be at all surprised if the final cracks started to appear very soon," said BAS's David Vaughan.
Flyover of the Wilkins ice shelf: BAS researcher David Vaughan says it is hanging on by a thread
If it does, it will follow the course of other shelves that have made breakaways in recent years, such as the Larsen B in 2002.
Although spectacular, such events are not necessarily due to man-made climate change.
A much bigger question is whether the new analysis of Antarctic warming heralds any major melting in the West Antarctic ice sheet, which could led to big changes in sea level and global impacts.
"The vulnerability is higher than we thought, but still we face uncertainties in understanding these processes that make it very difficult to forecast when these changes would occur," said Drew Shindell.
http://news.bbc.co.uk/1/hi/sci/tech/7843186.stm
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0.6oC in 50 years? It's that sort of statistic that makes the average person wonder if there actually is anything to worry about.
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Here is a link to a Climate Change ppt (http://nature.berkeley.edu/biometlab/espm111/espm%20111%20Climate%20Change.pdf) from a Prof. in Berkely, California. Oh, just for information. You know.
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Try this one too:)
http://www.nepjol.info/index.php/AEJ/article/view/739/759
It may seem that 0.6 Centigrades is negligible but if you read the pdf you will find that there is a difference between a 'statistic' and specified regions.
Earth is a non-linear system, and will exhibit a great variety of exposure to this 'statistic' heat.
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You should really read this one.
If you're just are planning to read one:)
http://www.nepjol.info/index.php/AEJ/article/view/739/759
I highly recommend it.
I think that India, Pakistan, Nepal, Tibet, in fact all mountainous regions, will see the fastest changes in their environment.
But we're all in the same boat here.
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It may seem that 0.6 Centigrades is negligible but if you read the pdf you will find that there is a difference between a 'statistic' and specified regions.
But even so... over 50 years? Not exactly racing away, is it.
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From the Journal of AGRICULTURE AND ENVIRONMENT Vol. 8, 2007, pp. 133-144
Nepal.
"In Mongolia a 1,738-year tree-ring record from remote alpine forests in the Tarvagatay Mountains indicated that 20th century temperatures in this region were the warmest of the last millennium.
Tree growth during 1980-1999 was the highest of any 20-year period on record, and 8 of the 10 highest growth years occurred since 1950. The 20th century warming was observed in tree-ring reconstructions of temperature from widespread regions of Eurasia, including sites in the Polar Urals, Yakutia, and the Taymir Peninsula, Russia (D.Arrigo, 2001)......
In Southeast Europe and Middle East the temperatures reached as high as 43.8 oC in locations across Turkey, Greece, Romania, Italy, and Bulgaria. In Bulgaria, 100-year records for daily maximum temperature were broken at more than 75% of the observing stations on July. For Armenia, 2000 was the hottest summer of the century with widespread heat wave in July-August 2000.. Jordan reported the longest stretch of summer heat in its 77-year record (NCDC, 2000; WMO, 2000/, 2001).
Continental Europe warmed 0.8 oC during the past century, with the last decade being the warmest on record (IPCC, 2001b). In Germany temperatures were as much as 4 oC above average (WMO, 2002a) with warmest October on record, 2001.
The record-breaking temperatures occurred in the context of a warming trend of 0.8 oC over
continental Europe during the past century. Over the 20th century Central England
temperature warmed by about 0.5 oC with warmest October on record, 2001.
Four of the five warmest years in the 343-year record occurred in the last decade (Hulme, 1999)....
Experience with Kenya is of the worst drought in 60 years in 2001.
Over four million people were affected by a severely reduced harvest, weakened livestock, and poor sanitary conditions (USAID, 2001).....
Similarly Burning shores in South Africa in January 2000, as one of the driest Decembers on record and temperatures over 40 C recorded fueled extensive fires along the coast in the Western Cape Province. The fire intensity was exacerbated by the presence of invasive vegetation species, some of which give off 300% more heat when burned compared to natural vegetation (IFFN, 2000).
The case of a Disappearing lake is recorded recently for Lake Chad .
The surface area of the lake has decreased from 25,000 km in 1963 to 1,350 km today.
The examples of fire outbreak are recorded for Samos Island, Greece, Argentina and South
Africa. Fires due to dry conditions and record-breaking heat in July 2000 consumed one-fifth of
the island (Samos Island, Greece). Temperatures reached up to 40 C in some areas. "
DB, as I see it, first the third world and the 'undeveloped country's' will pay the price.
Then we won't have those 'cheap prices' at home any more.
And worse scenes on the telly than we ever have seen before.
And when country's will find themselves unable to feed their populations?
What do you think will happen?
How will they survive?
There are already strategic planning discussing what that might lead too.
Take a look at the situation in Africa for example.
No I think this is the most serious question you will meet in your life.
And it is very much an 'moral' one too.
As how we manage it will 'mark' us for later generations.
'Festung Europa' is a rather bad idea to me.
It stinks of bitter memories.
And Festung America is as bad.
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It may seem that 0.6 Centigrades is negligible but if you read the pdf you will find that there is a difference between a 'statistic' and specified regions.
But even so... over 50 years? Not exactly racing away, is it.
Look at it this way Eth. If it is truly only 0.6°C in the last 50 years (though it seems a little on the low side to me), and the amount of change that we've seen over the last 50 years is linked to that small change, consider the amount of change that is likely with the predicted rise in global temperatures of between 2°C and 6°C by 2100. And the change is not linear either.
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It may seem that 0.6 Centigrades is negligible but if you read the pdf you will find that there is a difference between a 'statistic' and specified regions.
But even so... over 50 years? Not exactly racing away, is it.
The latest I have heard is that the average global temperature rise will be 3 degrees c by 2100, so 0.6 deg.c. is a big number.
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Is this now a repository for all and any documents, or news articles, on climate change?
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It may seem that 0.6 Centigrades is negligible but if you read the pdf you will find that there is a difference between a 'statistic' and specified regions.
But even so... over 50 years? Not exactly racing away, is it.
The latest I have heard is that the average global temperature rise will be 3 degrees c by 2100, so 0.6 deg.c. is a big number.
Not forgetting that this is a GLOBAL AVERAGE. Since it is Climate Change, and there will be areas that get cooler, there will also be areas that get dramatically warmer. If this temperature range follows a normal distribution about the mean of 6°C and the range includes regions that cool, then there will be other regions that will experience temperature increases of more than 12°C.