Fossil Fuels May Decrease Earth's Natural Capacity to Store Carbon

Aug 02, 2005

Rising fossil fuel emissions may actually decrease the Earth's natural capacity to absorb carbon dioxide from the atmosphere, according to a newly published study--which means that the warming of Earth's climate could accelerate even faster than scientists have anticipated.

The study, which was posted on-line this week by the journal Proceedings of the National Academy of Sciences, is based on a new computer simulation of the global carbon cycle developed by Inez Fung of the University of California at Berkeley and her colleagues, with support from the National Science Foundation (NSF)'s climate dynamics program.

Fung and her coworkers put particular emphasis on modeling how carbon dioxide emissions affect the strength and capacity of the environment's natural carbon repositories, including plants, soil, rain, clouds, bacteria, phytoplankton and oceans. The researchers also used observations from the past two centuries to project the coming century.

Their major finding was an inverse relationship between the rate at which carbon dioxide is emitted from the burning of fossil fuels like coal, oil and gas, and the capacity of land and ocean to absorb that carbon dioxide: the faster the emissions, the less effective were the carbon sinks.

There are a number of reasons for this, Fung explains. In the ocean, for example, carbon dioxide from the atmosphere mixes fairly rapidly into the upper layers, down to about 100 meters or so. Then from there it slowly leaks into the deep ocean, where it will stay sequestered for centuries. But rising global temperatures warm the upper layers and make the ocean more stratified, so that the carbon dioxide has a tougher time mixing further downward.

On land, meanwhile, climate warming tends to dry out the tropics and reduce plant growth there, which in turn reduces the rate of photosynthesis and carbon uptake.

Taking all the effects together, says Fung, "our finding implies that carbon storage by the oceans and land will lag farther and farther behind as climate change accelerates with growing carbon dioxide emissions, creating an amplifying loop between the carbon and climate systems."

The team's model used the low range of temperature increases for the 21st century, predicting a rise of 1.4 degrees Centigrade for a "business-as-usual" fossil fuel emission scenario. Overall, said Fung, the model agrees with others predicting large ecosystem changes, especially in the tropics.

"Carbon exchange among Earth's atmosphere, oceans and land, and its relationship to climate, is one of the most challenging issues in environmental sciences today," said Jay Fein, director of NSF's climate dynamics program. "Fung's results have important implications for future potential climate changes: climate warming would increase the airborne part of carbon dioxide derived from human activities, and would in effect amplify climate change."

Source: National Academy of Sciences

Explore further: NASA image: Sunrise from the International Space Station

add to favorites email to friend print save as pdf

Related Stories

Coming up for air

Oct 29, 2014

Sometimes you've got to hit bottom to battle your way back up. In 1992, the United Nations cited Mexico City as having the worst air quality in the world, with so much pollution that birds sometimes dropped ...

NIST 'combs' the atmosphere to measure greenhouse gases

19 hours ago

By remotely "combing" the atmosphere with a custom laser-based instrument, researchers from the National Institute of Standards and Technology (NIST), in collaboration with researchers from the National Oceanic ...

Recommended for you

Hubble sees 'ghost light' from dead galaxies

12 hours ago

(Phys.org) —NASA's Hubble Space Telescope has picked up the faint, ghostly glow of stars ejected from ancient galaxies that were gravitationally ripped apart several billion years ago. The mayhem happened ...

Cassini sees sunny seas on Titan

12 hours ago

(Phys.org) —As it soared past Saturn's large moon Titan recently, NASA's Cassini spacecraft caught a glimpse of bright sunlight reflecting off hydrocarbon seas.

Is space tourism safe or do civilians risk health effects?

15 hours ago

Several companies are developing spacecraft designed to take ordinary citizens, not astronauts, on short trips into space. "Space tourism" and short periods of weightlessness appear to be safe for most individuals ...

An unmanned rocket exploded. So what?

18 hours ago

Sputnik was launched more than 50 years ago. Since then we have seen missions launched to Mercury, Mars and to all the planets within the solar system. We have sent a dozen men to the moon and many more to ...

When did galaxies settle down?

18 hours ago

Astronomers have long sought to understand exactly how the universe evolved from its earliest history to the cosmos we see around us in the present day. In particular, the way that galaxies form and develop ...

User comments : 0

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.