First-ever 'State of the Carbon Cycle Report' finds troubling imbalance

Nov 14, 2007

The first “State of the Carbon Cycle Report” for North America, released online this week by the U.S. Climate Change Science Program, finds the continent’s carbon budget increasingly overwhelmed by human-caused emissions. North American sources release nearly 2 billion tons of carbon into the atmosphere each year, mostly as carbon dioxide.

Carbon “sinks” such as growing forests may remove up to half this amount, but these current sinks may turn into new sources as climate changes.

“By burning fossil fuel and clearing forests human beings have significantly altered the global carbon cycle,” says Chris Field of the Carnegie Institution’s Department of Global Ecology, one of the report’s lead authors. A result has been the buildup of carbon dioxide in the atmosphere, but so far this has been partially offset by carbon uptake by the oceans and by plants and soils on land.

“In effect, we have been getting a huge subsidy from these unmanaged parts of the carbon cycle,” notes Field. Overall, this subsidy has sequestered, or hidden from the atmosphere, approximately 200 billion tons of carbon. In North America much of it has come from the regrowth of forests on former farmland and the uptake of carbon by agricultural soils.

But these carbon sinks may be reaching their limit as forests mature and climate conditions change. And some may literally go up in smoke if wildfires become more frequent, as some climate simulations predict. Planting forests and adopting carbon-conserving practices such as no-till agriculture may increase carbon sinks somewhat, but this would not come close to compensating for carbon emissions, which continue to accelerate.

“There are a lot of good reasons for replenishing our forests and encouraging better agricultural practices,” says Ken Caldeira, another author of the report, also at Carnegie’s Department of Global Ecology. “But if we want to mitigate our impact on the carbon cycle, there’s no escaping the fact that we need to drastically reduce carbon dioxide emissions.”

Source: Carnegie Institution

Explore further: Selective logging takes its toll on mammals, amphibians

add to favorites email to friend print save as pdf

Related Stories

Oso disaster had its roots in earlier landslides

Jul 23, 2014

The disastrous March 22 landslide that killed 43 people in the rural Washington state community of Oso involved the "remobilization" of a 2006 landslide on the same hillside, a new federally sponsored geological study concludes.

OCO-2 data to lead scientists forward into the past

Jul 21, 2014

(Phys.org) —NASA's Orbiting Carbon Observatory-2, which launched on July 2, will soon be providing about 100,000 high-quality measurements each day of carbon dioxide concentrations from around the globe. ...

Climate: Meat turns up the heat

Jul 21, 2014

Eating meat contributes to climate change, due to greenhouse gasses emitted by livestock. New research finds that livestock emissions are on the rise and that beef cattle are responsible for far more greenhouse gas emissions ...

Recommended for you

What's wiping out the Caribbean corals?

25 minutes ago

Here's what we know about white-band disease: It has already killed up to 95 percent of the Caribbean's reef-building elkhorn and staghorn corals, and it's caused by an infectious bacteria that seems to be ...

Selective logging takes its toll on mammals, amphibians

18 hours ago

The selective logging of trees in otherwise intact tropical forests can take a serious toll on the number of animal species living there. Mammals and amphibians are particularly sensitive to the effects of ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

southernwriter
3 / 5 (2) Nov 14, 2007
380 ppm in the atmosphere is only 38/100,000ths of 1%. It has increased only 80 ppm since the industrial revolution which means that after 100 years of co2 we have only increased by 8/100,000ths of 1%. CO2 has a specific gravity of 1.54 which means that it is 154% heavier than air and sinks to the ground when released. There is massive fraud being perpetrated in this movement/
Arkaleus
1 / 5 (1) Jun 08, 2009
Again the statistical context of human carbon emissions compared to natural carbon emissions is totally omitted. Human activity presents a single digit contribution to the total percentage of carbon released each year.

3-6% of the total emission is in no way a "key" contributor of carbon-caused climate change. It is at best a minor variable, most likely overshadowed by natural variations in the non-human sources. Perhaps they should seek to tax volcanoes and micro organisms, since they are the majority contributors to the world's carbon dioxide emissions.