That's the good news heading into Cancun global warming talks
Nov. 29. The bad news is that the carbon dioxide emissions aren't
likely to stay down for long.
Industrial carbon-dioxide emissions, the driver behind a new
round of global climate talks set to begin in Cancun, Mexico, Nov.
29, eased in 2009, according to a group of scientists monitoring
Emissions from burning coal, oil, and natural gas fell 1.3
percent compared with emissions in 2008, notes in the team from the
Global Carbon Project, set up in 2001 to keep track of CO2 emissions
as well as conduct research on Earth's carbon cycle.
Even so, concentrations of CO2 rose last year to a level where,
for every 1 million molecules of gases in the atmosphere, 387 of
them were carbon dioxide. By contrast, the average level for 2008
was 385 ppm.
Concentrations continued to rise even as emissions slipped
because even at the reduced pace, humans are pumping CO2 into the
atmosphere faster than natural processes can scrub the gas, meaning
that human emissions can stay in the atmosphere for centuries, if
"More CO2 is staying in the atmosphere instead of being absorbed
by the ocean and land sinks, like trees and other vegetation," said
Richard Feely, an oceanographer at the National Oceanic and
Atmospheric Administration's Marine Environmental Laboratory in
Seattle and a member of the team producing the report.
"We're concerned that if the natural sinks can't keep pace with
the increased CO2 emissions, then the physical and biological
impacts of global warming will accelerate over the next century."
The rising concentration highlights the challenge negotiators
headed to Cancun face in confronting global warming.
Many countries have agreed in principle to try to stabilize
emissions at 350 parts-per-million by century's end. That would
result in a 50 percent chance of holding the increase in global
average temperatures to about 2 degrees C over preindustrial levels.
Yet stabilizing concentrations at any level essentially means
ceasing emissions once the desired level is achieved. Global CO2
concentrations already have passed the 350 mark.
Among the factors the team cites for lower emissions last year:
the global economic downturn and an increase in carbon-dioxide
uptake by the oceans and by plants on land, encouraged by La Nina.
La Nina is one-half of a natural seesaw shift in climate that takes
place across the tropical Pacific every three to seven years.
This swing "has a very clear impact on global carbon cycle," says
Pierre Friedlingstein, an atmospheric scientist at the University of
Exeter in Britain and the lead author of a summary of the reports
findings that appears in the current issue of the journal Nature