Posted by
InchDeep on Saturday, May 10, 2008 9:52:28 PM
From The Austrailian.
Amazon 'at threat' from cleaner air
CLEANER air due to reduced coal burning could help destroy the Amazon this century, according to a study in the journal Nature.
The
research identifies a link between reduced sulfur dioxide emissions
from coal burning and increased sea surface temperatures in the
tropical North Atlantic that boosts the drought risk in the Amazon
rainforest.
With the rainforest already threatened by development, higher global temperatures could tip the balance, it says.
"Generally, pollution is a bad thing, but in this case improving the
air may have ironically led to a drying of the Amazon," said Peter Cox,
a researcher at the University of Exeter in Britain, who led the study.
“It shows you have to deal with greenhouse gases.”
The
Amazon - the world's largest tropical rainforest - plays a critical
role in the global climate system because it contains about one 10th of
the total carbon stored in land ecosystems.
The researchers
used a climate-carbon model to simulate the impacts of future climate
change on the Amazon and compared it to data from a 2005 drought that
devastated a large chunk of the rainforest.
They estimated
that by 2025 a drought on the same scale could happen every other year
and by 2060 such a crisis could hit nine out of every 10 years - enough
to turn the rainforest into savannah grassland, Cox said.
In
the pre-industrial age, the Amazon was less vulnerable. But higher
temperatures and destruction of the forest make droughts far more
likely than in the past, the researchers said.
“The Amazon is said to be the lungs of the planet,” Cox said. “You don't want to damage it.”
The
researchers believe that efforts to clean up sulphate aerosol particles
from coal burning at power stations in the 1970s and 1980s helps to
explain the threat.
The pollution predominately in the
northern hemisphere had limited warming in the tropical north Atlantic,
keeping the Amazon wetter than it normally would have been.
But
with that protection evaporating due to cleaner air and as greenhouse
gases fuel global warming, the rainforest now faces a deadly drought
risk, the researchers said.
“Reduced sulphur emissions in
North America and Europe will see tropical rain bands move northwards
as the north Atlantic warms, resulting in a sharp increase in the risk
of Amazonian drought,” Chris Huntingford, a researcher at Britain's
Centre for Hydrology and Ecology said.
The findings highlight
the need to deal not only with greenhouse gas emissions but also with
the direct destruction of the rainforests as well, the researchers
said.
They said 20 per cent of global carbon dioxide emissions
stem from burning of trees to build new homes and roads as development
pushes farther into the delicate region, they added.
“You can argue there is a greater urgency to deal with the deforestation issue in our model,” he said.