Steve writes:
> It is pretty hard to get worked up when you find out that in
> percentage terms we are talking someting on the order of say 2%.
There has been a considerable increase in the concentrations of CO2, much
more than 2 %. The increase in other green house gases is also much higher
than 2 % over the last century. We have not even begun to estimate yet the
effect of new greenhouse gases such as the ozone depleting chemicals
containing chlorine and bromine. Again the real magnitude of the greenhouse
gases is not their volumes or their molecular weights but their 'infrared
absorption' capacities. Nitrogenous compounds like nitrous oxide and
nitrogen dioxide for instance are thousands of times more potent green house
gases than CO2.
35) ARCTIC WARMING SIGNALS DIRE STRAITS FOR BIRDS
CNN
April 5, 2000
Internet:
http://www.cnn.com/2000/NATURE/04/05/arctic.birds.enn/index.html
Climate change could cut rare Arctic bird populations in half,
according to a study released Monday by the Worldwide Fund for
Nature. Using climate models, scientists from the World
Conservation Monitoring Centre assessed the effects of temperature
and shrinking habitat on water birds in the Arctic region. During
the past century, global mean temperature increased by .9 degrees
Fahrenheit. Nowhere on the planet has the warming been more
striking than in the Arctic, where average temperatures have risen
as much as 2.7 F per decade since the 1960s, the researchers note.
In the next 70 to 100 years, scientists predict that the
concentration of carbon dioxide in the environment could double.
Arctic habitats are expected to be among the first biomes to show
the direct impact of climate change. The report warns that higher
temperatures will cause wooded forests to advance northward,
replacing the Arctic tundra, an essential breeding area for
millions of birds. Arctic water birds most threatened by the
global warming include the critically endangered red-breasted
goose, tundra bean goose, spoon-billed sandpiper and emperor
goose.
With a global temperature increase of only 1.7 degrees by 2070,
all of these birds would lose more than 50 percent of their
habitat, the report notes. More than two-thirds of all geese and
nearly 95 percent of all calidrid waders breed in the Arctic. The
study forecasts that a 40 percent to 57 percent loss of tundra in
the next 100 years may mean a loss of habitat for 5 million geese
and 7.5 million calidrid waders. While some scientists argue that
the birds might adjust to their changing surroundings, others
argue that many species such as waders, cannot physically adapt to
brushy or tree-like habitats.
"This study once more underlines the urgent need to reduce the
emissions of global warming gases to slow the rate of climate
change," the researchers write. "In order to facilitate adaptation
to a changed climate, we need to seriously consider changes in
habitat management." One possible strategy is the introduction of
more grazing animals such as reindeer to the area to keep
encroaching forests at bay and preserve the tundra. The authors
will present their findings at the Arctic Science Summit Week in
Cambridge, England, which ends April 7.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|