Rise in atmospheric CO2 accelerates as economy grows, natural carbon sinks weaken

October 22, 2007

Human activities are releasing carbon dioxide faster than ever, while the natural processes that normally slow its build up in the atmosphere appear to be weakening. These conclusions are drawn in a new study in the early online edition of the Proceedings of the National Academy of Sciences, October 22-26. The report states that “together, these effects characterize a carbon cycle that is generating stronger-than-expected climate forcing sooner than expected.”

Between 2000 to 2006, human activities such as burning fossil fuels, manufacturing cement, and tropical deforestation contributed an average of 4.1 billion metric tons of carbon to the atmosphere each year, yielding an annual growth rate for atmospheric carbon dioxide of 1.93 parts per million (ppm).

“This is the highest since the beginning of continuous monitoring in 1959,” states the report. The growth rate of atmospheric carbon dioxide is significantly larger than those for the 1980s and 1990s, which were 1.58 and 1.49 ppm per year, respectively. The present atmospheric concentration of carbon dioxide is 381 ppm, the largest concentration in the last 650,000 years, and probably in the last 20 million years.

While the worldwide acceleration in carbon dioxide emissions had been previously noted, the current analysis provides insights into its causes. “The new twist here is the demonstration that weakening land and ocean sinks are contributing to the accelerating growth of atmospheric CO2,” says co-author Chris Field, director of the Carnegie Institution’s Department of Global Ecology.

Changes in wind patterns over the Southern Ocean resulting from human-induced global warming have brought carbon-rich water toward the surface, reducing the ocean’s ability to absorb excess carbon dioxide from the atmosphere. On land, where plant growth is the major mechanism for drawing carbon dioxide out of the atmosphere, large droughts have reduced the uptake of carbon.

Emissions from the burning of fossil fuels constituted the largest source of anthropogenic carbon, releasing an average of 7.6 billion metric tons each year between 2000 and 2006, a significant jump from 6.5 billion tons in the 1990s. Emissions generated by land-use changes such as deforestation have remained constant, but shifted in geographic focus.

Source: Carnegie Institution

Explore further: Curbing climate change—why it's so hard to act in time

Related Stories

Curbing climate change—why it's so hard to act in time

August 18, 2017

This summer I worked on the Greenland ice sheet, part of a scientific experiment to study surface melting and its contribution to Greenland's accelerating ice losses. By virtue of its size, elevation and currently frozen ...

NASA studies CubeSat mission to solve Venusian mystery

August 15, 2017

Venus looks bland and featureless in visible light, but change the filter to ultraviolet, and Earth's twin suddenly looks like a different planet. Dark and light areas stripe the sphere, indicating that something is absorbing ...

The time window for the 1.5-degree target is closing

August 14, 2017

Earth's climate is out of balance: the planet has been warming since industrialization began, because CO2 increasingly collects in the atmosphere. Even an immediate stop of all emissions would not bring global warming to ...

Video: Developing carbon management solutions

July 20, 2017

Global consumption of fossil fuels is causing atmospheric carbon dioxide and other greenhouse gases to rise to levels that threaten human and environmental sustainability. These gases warm the planet and negatively impact ...

Recommended for you

Hot spot at Hawaii? Not so fast

August 18, 2017

Through analysis of volcanic tracks, Rice University geophysicists have concluded that hot spots like those that formed the Hawaiian Islands aren't moving as fast as recently thought.

Supervolcanoes: A key to America's electric future?

August 16, 2017

Most of the lithium used to make the lithium-ion batteries that power modern electronics comes from Australia and Chile. But Stanford scientists say there are large deposits in sources right here in America: supervolcanoes.

Greenland ice flow likely to speed up

August 16, 2017

Flow of the Greenland Ice Sheet is likely to speed up in the future, despite a recent slowdown, because its outlet glaciers slide over wet sediment, not hard rock, new research based on seismic surveys has confirmed. This ...

Climate change will cut crop yields: study

August 15, 2017

Climate change will have a negative effect on key crops such as wheat, rice, and maize, according to a major scientific report out Tuesday that reviewed 70 prior studies on global warming and agriculture.

5 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

NotParker
3.7 / 5 (3) Oct 23, 2007
Facts:

1) The Southern Hempisphere is cooling and has been for 5 years
2) More sunshine is reaching the earth
3) CO2 is released by oceans when they warm up
Elenneth
4 / 5 (2) Oct 23, 2007
The capacity for a liquid to hold a dissolved gas (i.e. dissolved carbon dioxide in ocean water) decreases as the temperature of the liquid increases. For example, an opened can of soda at room temperature will loose its carbonation much faster than an opened can of soda in the refrigerator.

Therefore, the warmer the temperature of the ocean, the less of an ability it has to hold carbon dioxide and the greater its rate of dissolved carbon dioxide release. In this case, carbon-rich water, as it moves from a lower depth (read: cooler temperature) to a shallower depth (read: warmer temperature), it would make sense that it would release stored carbon dioxide.

I am not certain that I have heard of that statement that more sunshine is reaching the earth. From where do you draw this?
mikiwud
3.5 / 5 (2) Oct 25, 2007
If there are less clouds more heat reaches the Earth thus warming the oceans.The heating could be caused by thermal action from the Earth's core.As the greenhouse effect signature predicted by the computer models is not visible in the recorded data,this is more likley than AGW.
Elenneth
5 / 5 (1) Oct 25, 2007
Cloud coverage also serves as insulation to keep the heat in. That is why deserts, which are often devoid of cloud cover, can reach extreme daytime temperatures, while at night experience a drastic plummet in the temperature because of a lack of cloud cover to insulate against lost heat.
mikiwud
4 / 5 (2) Oct 26, 2007
Elenneth,
That is the local effect felt anywere it happens.
Globaly the effect is more cloud,less heat reaches the earth also more is reflected back into space and vice versa.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.