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Study: Global future bleak
Severe climate changes will create a very different Earth, scientists
By Ian Hoffman, STAFF WRITER
Inside Bay Area
If humanity taps all known oil, gas and coal reserves for energy,
plants and oceans will have trouble absorbing the growing carbon
dioxide in the atmosphere, and temperatures will soar beyond current
projections, virtually eliminating tundra, sea ice and cold climate
forests, according to a study by Lawrence Livermore Lab researchers.
Scientists there asked supercomputers to simulate the complete
burnout of all fossil fuels and the resulting changes in climate
through 2300, two centuries longer than almost any other climate
What they found was a dramatically changed world, with temperatures
rising an average of 14.5 degrees worldwide and 68 degrees or more in
Bala Govindasamy, a Livermore atmospheric scientist and lead author
of the study, said the simulation is highly conservative: It probably
overestimates the ability of plants to absorb carbon dioxide and so
underestimates the climate change.
"So the reality may be worse," he said. "We may not have seen the
climate change today, but if we continue to emit fossil fuels as
usual, I think we are headed for real severe climate consequences,
and the sooner we take action, the better."
The greatest warming occurs in the next century, beyond the time
frame for most climate projections, when carbon dioxide levels in the
atmosphere reach 1,000 parts per million, or nearly four times pre-
industrial concentrations, in about 2140, then peak in 2300 at
1,438 parts per million.
Scientists are uncertain how well societies can adapt to a doubling
or tripling of carbon dioxide, but there is growing consensus that a
quadrupling would pose major challenges.
"We don't even want to get close to 1,000," said physicist Steven
Chu, director of Lawrence Berkeley National Laboratory. "That's a
Such a scenario could come sooner than Livermore's simulation
indicates. The model is highly sophisticated, a product of one of
only about a half-dozen research teams worldwide that have built a
full representation of the Earth's climate, soils, vegetation and
"The ecosystems actually move," Govindasamy said. "The land ice in
the arctic completely disappears, and the tundra basically
What takes its place are trees, not boreal forests, which retreat to
only northern Siberia and Greenland, but expanding tropical and
temperate forests that are fertilized by all the extra carbon dioxide
in the air. Later this century especially, the model says trees are
growing wildly and absorbing a large amount of carbon dioxide, as are
But the model assumes unlimited nutrients in the soil to feed all
"At some point, the plants tend to run out of something else they
need, either nitrogen or water," said Scott Doney, an atmospheric
scientist at Woods Hole Oceanographic Institute who is developing a
similar full, Earth system model with Inez Fung, a leading climate
researcher at the University of California, Berkeley.
If plant growth is limited as temperatures rise and the tropics
become drier, then large tropical forests could die off and release
their stored carbon dioxide to the atmosphere. The same could happen
if peat deposits in tundra get both warm and dry, or if vegetation
worldwide becomes dry enough for fires to release their carbon.
If any of those occur, climate change will occur faster. If not, the
absorption of carbon dioxide by the land and the oceans drops off
anyway. Doney said the Livermore study "gives a sense of how bad the
climate change could be" if humanity doesn't find new, cleaner energy
"The Earth is not going to clean up the carbon mess for us," he
said. "We're going to have to do it or live with the consequences."
Contact Ian Hoffman at ihoffman@...
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