No Stopping
Global Warming
By Maggie Fox
18 March, 2005
Planet
Ark
Even if people stopped pumping out carbon
dioxide and other pollutants tomorrow, global warming would still get
worse, two teams of researchers reported on Thursday.
Sea levels will rise more than they have already risen, worsening the
damage caused by extreme high tides and storm surges, and droughts,
heat waves and storms will become more severe, the climate experts predicted.
That makes immediate
action to slow global warming even more vital, the teams at the National
Center for Atmospheric Research in Colorado report in the journal Science.
"Even if we
stabilize greenhouse gas concentrations, the climate will continue to
warm, and there will be proportionately even more sea level rise,"
said the NCAR's Gerald Meehl, who led one of the two studies.
"The longer
we wait, the more climate change we are committed to in the future."
Virtually no one
disagrees human activity is fueling global warming, and a global treaty
signed in Kyoto, Japan, aims to reduce polluting emissions. But the
world's biggest polluter, the United States, has withdrawn from the
1997 treaty, saying its provisions would hurt the US economy.
Meehl's team ran
two computer simulations of climate change -- complex programs, he said,
that took months to run on supercomputers.
Those models included
as many variables as the researchers could think of, such as human carbon
emissions, other pollution, current temperatures and their rate of change,
emissions from volcanoes, changes in solar radiation and shifts in the
ozone layer.
"Then we ran
for the 21st century three different scenarios," Meehl said in
a telephone interview.
One scenario assumed
human production of carbon dioxide and other so-called greenhouse gases
stabilized in 2000 and ran the model to the year 2100.
"We found that
just based on the ingredients that have already been put into the atmosphere
in the 20th century, we already are committed to another half a degree
(0.5 degree C or 0.9 degree F) of global warming," Meehl said.
"That's about
what we saw in the 20th century. We are already committed to as much
climate change in the 21st century as we saw in the 20th century."
That would mean
more extreme weather and a rise in sea levels, not even accounting for
melting ice, Meehl said.
Experts say sea
levels have risen 4 inches (9 cm) already over the past century and
could rise between 4 and 40 inches (9 to 88 cm) more in the next century.
If completely melted,
the Greenland ice sheet would add 25 feet (7 metres) to overall sea
level and the West Antarctic Ice Sheet would raise it by 16 feet (5
metres) -- enough to swamp most of Florida, Bangladesh and New York
City's Manhattan island.
In a second study
in Science, the NCAR's Tom Wigley said he used a much simpler climate
model to make a similar prediction.
He found it may
not be possible to reduce emissions enough to stop the sea from rising.
Even if all emissions stopped now, he calculated, changes were under
way that would lead to a rise in sea levels of 4 inches (10 cm) per
century.