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http://news.independent.co.uk/low_res/story.jsp?story=607254&host=3&dir=507
 
Global warming: scientists reveal timetable
 
By Michael McCarthy, Environment Correspondent
 
03 February 2005
 
Global warming: scientists reveal timetable


Archbishop tells Church to help save the planet with green policies


A detailed timetable of the destruction and distress that global warming is likely to cause the world was unveiled yesterday.


It pulls together for the first time the projected impacts on ecosystems and wildlife, food production, water resources and economies across the earth, for given rises in global temperature expected during the next hundred years.


The resultant picture gives the most wide-ranging impression yet of the bewildering array of destructive effects that climate change is expected to exert on different regions, from the mountains of Europe and the rainforests of the Amazon to the coral reefs of the tropics.


Produced through a synthesis of a wide range of recent academic studies, it was presented as a paper yesterday to the international conference on climate change being held at the UK Met Office headquarters in Exeter by the author Bill Hare, of the Potsdam Institute for Climate Impact Research, Germany's leading global warming research institute.


The conference has been called personally by Tony Blair as part of Britain's attempts to move the climate change issue up the agenda during the current UK presidency of the G8 group of rich nations, and the European Union. It has already heard disturbing warnings from the latest climate research, including the revelation on Tuesday from the British Antarctic Survey that the massive West Antarctic ice sheet might be disintegrating - an event which, if it happened completely, would raise sea levels around the world by 16ft (4.9 metres).


Dr Hare's timetable shows the impacts of climate change multiplying rapidly as average global temperature goes up, towards 1C above levels before the industrial revolution, then to 2C, and then 3C.


As present world temperatures are already 0.7C above the pre-industrial level, the process is well under way. In the near future - the next 25 years - as the temperature climbs to the 1C mark, some specialised ecosystems will start to feel stress, such as the tropical highland forests of Queensland, which contain a large number of Australia's endemic plant species, and the succulent karoo plant region of South Africa. In some developing countries, food production will start to decline, water shortage problems will worsen and there will be net losses in GDP.



It is when the temperature moves up to 2C above the pre-industrial level, expected in the middle of this century - within the lifetime of many people alive today - that serious effects start to come thick and fast, studies suggest.


Substantial losses of Arctic sea ice will threaten species such as polar bears and walruses, while in tropical regions "bleaching" of coral reefs will become more frequent - when the animals that live in the coral are forced out by high temperatures and the reef may die. Mediterranean regions will be hit by more forest fires and insect pests, while in regions of the US such as the Rockies, rivers may become too warm for trout and salmon.


In South Africa, the Fynbos, the world's most remarkable floral kingdom which has more than 8,000 endemic wild flowers, will start to lose its species, as will alpine areas from Europe to Australia; the broad-leaved forests of China will start to die. The numbers at risk from hunger will increase and another billion and a half people will face water shortages, and GDP losses in some developing countries will become significant.



But when the temperature moves up to the 3C level, expected in the early part of the second half of the century, these effects will become critical. There is likely to be irreversible damage to the Amazon rainforest, leading to its collapse, and the complete destruction of coral reefs is likely to be widespread.


The alpine flora of Europe, Australia and New Zealand will probably disappear completely, with increasing numbers of extinctions of other plant species. There will be severe losses of China's broadleaved forests, and in South Africa the flora of the Succulent Karoo will be destroyed, and the flora of the Fynbos will be hugely damaged.


There will be a rapid increase in populations exposed to hunger, with up to 5.5 billion people living in regions with large losses in crop production, while another 3 billion people will have increased risk of water shortages.


Above the 3C raised level, which may be after 2070, the effects will be catastrophic: the Arctic sea ice will disappear, and species such as polar bears and walruses may disappear with it, while the main prey species of Arctic carnivores, such as wolves, Arctic foxes and the collared lemming, will have gone from 80 per cent of their range, critically endangering predators.


In human terms there is likely to be catastrophe too, with water stress becoming even worse, and whole regions becoming unsuitable for producing food, while there will be substantial impacts on global GDP.


                


Also in Environment


                Global warming: scientists reveal timetable
             Dramatic change in West Antarctic ice could produce 16ft rise in sea levels
             Coral reefs may start to dissolve in 30 years
           The whales' tale
                Global warming is 'twice as bad as previously thought'
                  





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Antarctic ice sheet is an 'awakened giant'

http://www.newscientist.com/article.ns?id=dn6962

February 2005
NewScientist.com news service
Jenny Hogan, Exeter

  The massive west Antarctic ice sheet, previously assumed to be stable, is 
starting to collapse, scientists warned on Tuesday.

Antarctica contains more than 90% of the world's ice, and the loss of any 
significant part of it would cause a substantial sea level rise. Scientists 
used to view Antarctica as a "slumbering giant", said Chris Rapley, from 
the British Antarctic Survey, but now he sees it as an "awakened giant".

  Rapley presented measurements of the ice sheet at a major climate 
conference in Exeter, UK. Glaciers on the Antarctic peninsula, which 
protrudes from the continent to the north, were already known to be 
retreating. But the data Rapley presented show that glaciers within the 
much larger west Antarctic Ice sheet are also starting to disappear.

If the ice on the peninsula melts entirely it will raise global sea levels 
by 0.3 metres, and the west Antarctic ice sheet contains enough water to 
contribute metres more. The last report of the Intergovernmental Panel on 
Climate Change, published in 2001, said that collapse of this ice sheet was 
unlikely during the 21st century. That may now need to be reassessed, 
Rapley warned.

Cork from a bottle

Changes on the peninsula, where 75% of the 400 mountain glaciers are in 
retreat, have provided new insights into the ways that ice sheets may 
disintegrate.

  In March 2002, a huge floating ice shelf known as Larsen B shattered into 
icebergs. This turned out to have an effect akin to pulling a cork from a 
bottle. With Larsen B no longer impeding movement, the ice floes that fed 
the shelf began moving faster towards the sea and started to thin. The 
finding took scientists by surprise when revealed in September 2004 and now 
modellers are now working to include such mechanisms in their predictions.

Climate records derived from the analysis of sediments show that ice 
shelves off the peninsula have been absent in several earlier eras, when 
natural variability warmed the world. But the break-up is affecting ice 
closer to the pole than ever recorded, said Rapley. "It's like the Heineken 
effect," he said, referring to the beer adverts that claim Heineken 
"reaches the parts other beers cannot reach".

  Indications that climate change may be affecting the west Antarctic ice 
sheet comes from three glaciers, including Pine Island and Thwaites. Data 
reveal they are losing more ice - mainly through the calving of icebergs - 
than is being replaced by snowfall. According to a preliminary analysis, 
the difference between the mass lost and mass replaced is about 60%.

Whether the loss of mass by the glaciers is due to natural variation or is 
caused by human-influenced warming of the oceans is not known for sure. 
Scientists are now making more field measurements to assess the causes, but 
warming is a likely culprit, said Rapley: "The fact that three of them are 
simultaneously accelerating suggests that is the case." The melting of 
these three glaciers alone is contributing an estimated 0.24 millimetres 
per year to sea level.

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