Global Warming--Earth is Tougher Than We Thought
13-Nov-2001 

Researchers may have been overestimating
the degree of warming that the Earth will
experience in the future. This has been
revealed by studies of the release of carbon
dioxide back into the atmosphere from the
soil, a process known as soil respiration. A
team at the University of Oklahoma spent a
year artificially warming areas of the prairie
at a fixed level above the air temperature
and comparing the results with unheated
areas. 

Over the course of the year, the rate at
which CO2 was released through the activity
of fungi, such as mushrooms, was no
greater in the warmed areas than in the
unheated soils. This is the opposite of the
current theory that says the hotter it gets,
the faster soil pumps out CO2. For every 10
degrees that temperatures rise, CO2
emissions from soils were thought to
double. But the team concluded that the
soils’ organisms quickly adjusted to higher
temperatures. 

Additional data suggests that the prairie
grasses in the heated areas thrived under
the additional warmth, meaning that that
the world’s grasslands may soak up more
CO2 than they give off, according to Linda
Wallace, a plant ecologist at the University
of Oklahoma. “This is good news on a
global basis,” she says. “Grasslands cover a
such a huge proportion of the terrestrial
portion of globe. We’d been kind of
discounting them, saying that as things
warm up, they would become carbon
sources. But in reality, these grasslands
could become carbon sinks,” meaning that
they would soak up carbon, removing it from
the atmosphere and lessening the
greenhouse effect. 

Long-term experiments have already shown
that, faced with increased concentrations of
CO2, trees go through a relatively short
“growth spurt,” then their growth rate slows
as they become acclimatized to higher CO2
levels, according to Lindsey Rustad, a soil
ecologist with the U.S. Forest Service. 

These studies show that the Earth may be
more resilient that we thought, and better
able to cope with the increasing
temperatures brought on by excessive
carbon dioxide emissions.