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: Life on Mars? Implications of a newly discovered mineral-rich structure

add to favorites email to friend print save as pdf

Related Stories

Researchers reveal how ocean bacteria use light to grow

9 hours ago

Sunlight stimulates common ocean bacteria to use carbon dioxide for growth when high-quality organic carbon food sources are scarce, according to surprising research by an international team that includes ...

Exporting US coal to Asia could drop emissions 21 percent

7 hours ago

Under the right scenario, exporting U.S. coal to power plants in South Korea could lead to a 21 percent drop in greenhouse gas emissions compared to burning the fossil fuel at plants in the United States, according to a new ...

New analysis links tree height to climate

Aug 14, 2014

What limits the height of trees? Is it the fraction of their photosynthetic energy they devote to productive new leaves? Or is it their ability to hoist water hundreds of feet into the air, supplying the ...

Recommended for you

A spectacular landscape of star formation

1 hour ago

This image, captured by the Wide Field Imager at ESO's La Silla Observatory in Chile, shows two dramatic star formation regions in the Milky Way. The first, on the left, is dominated by the star cluster NGC ...

Students see world from station crew's point of view

Aug 19, 2014

NASA is helping students examine their home planet from space without ever leaving the ground, giving them a global perspective by going beyond a map attached to a sphere on a pedestal. The Sally Ride Earth ...

Exoplanet measured with remarkable precision

Aug 19, 2014

Barely 30 years ago, the only planets astronomers had found were located right here in our own solar system. The Milky Way is chock-full of stars, millions of them similar to our own sun. Yet the tally ...

New star catalog reveals unexpected 'solar salad'

Aug 19, 2014

(Phys.org) —An Arizona State University alumnus has devised the largest catalog ever produced for stellar compositions. Called the Hypatia Catalog, after one of the first female astronomers who lived in ...

User comments : 0