—————————-
“This trend will continue into the future.”
” … poleward shifts of westerly winds in the
Southern Ocean reduced the region’s ability to
suck up CO2 as have mid-latitude droughts, which
slowed the growth rate of forests and plants that
capture carbon.”
“… this research shows that CO2 emissions over
the past decade were higher than those considered
in the most dire scenarios for future climate
change, which means that even more drastic
actions will be needed to stem global warming.”
——————————————————————-
Scientific American
October 22, 2007
Climate Change Pollution Rising-Thanks to Overwhelmed Oceans and Plants
Carbon dioxide levels in the atmosphere continue
to rise thanks to dirtier economies and a
weakening in natural systems’ ability to remove
the greenhouse gas
The world may finally acknowledge that global
warming is a major environmental hazard. But new
research shows that reducing the main greenhouse
gas behind it may be even more difficult than
previously believed. The reason: the world’s
oceans and forests, which scientists were
counting on to help hold off catastrophic rises
in carbon dioxide, are already so full of CO2
that they are losing their ability to absorb this
climate change culprit.
“For every ton of CO2 emitted [into] the
atmosphere, the natural sinks are removing less
carbon than before,” says biologist Josep “Pep”
Canadell, executive director of the Global Carbon
Project-an Australia-based research consortium
devoted to analyzing the pollution behind global
warming. “This trend will continue into the
future.”
Specifically, oceans and plant growth absorbed
only around 540 kilograms per metric ton (1,190
pounds per short ton) of the CO2 produced in
2006, compared with 600 kilograms per metric ton
(1,322 pounds per short ton) in 2000. Coupled
with an emissions growth rate of 3.3
percent-triple the growth rate of the 1990s-the
atmospheric burden is now rising by nearly two
parts per million of CO2 a year, the fastest
growth rate since 1850, the international team of
researchers reports in Proceedings of the
National Academy of Sciences USA.
“We have yet to make real progress in turning the
world toward decreasing CO2 emissions,” says the
study’s co-author Chris Field, director of the
Carnegie Institution of Washington’s Department
of Global Ecology in Stanford, Calif. “A greater
buildup of CO2 means more warming.”
Atmospheric concentrations of the most ubiquitous
greenhouse gas reached 381 parts-per-million in
2006 after emissions of CO2 from burning fossil
fuels rose to 8.4 billion metric tons (1.85 X
1013 pounds) per year, according to figures from
the United Nations, British Petroleum and the
U.S. Geological Survey.
All told, human activity released 9.9 billion
metric tons (2.18 X 1013 pounds) of carbon in
2006, up from just 8.4 billion metric tons (1.85
X 1013 pounds) in 2000. At the same time,
poleward shifts of westerly winds in the Southern
Ocean reduced the region’s ability to suck up CO2
as have mid-latitude droughts, which slowed the
growth rate of forests and plants that capture
carbon.
New maritime measurements over the past decade
also show that the North Atlantic’s ability to
absorb CO2 has been cut in half, according to
researchers from the University of East Anglia
who were not affiliated with the study by
Canadell and his colleagues. “Until now, we
thought that the decline in the efficiency of
natural sinks was going to happen during the 21st
century and more strongly during [its] second
half,” Canadell says. “If we didn’t [include in
the assumptions] that this was going to happen
[so soon], have we underestimated the decline in
the efficiency into the future?”
In addition, this research shows that CO2
emissions over the past decade were higher than
those considered in the most dire scenarios for
future climate change, which means that even more
drastic actions will be needed to stem global
warming. “The longer we wait to reduce
emissions,” Canadell says, “the harder the cuts
that will be required to stabilize atmospheric
CO2 emissions.”
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