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: New water balance calculation for the Dead Sea

add to favorites email to friend print save as pdf

Related Stories

What geology has to say about global warming

Jul 14, 2014

Last month I gave a public lecture entitled, "When Maine was California," to an audience in a small town in Maine. It drew parallels between California, today, and Maine, 400 million years ago, when similar ...

Recommended for you

EU sets new energy savings target at 30%

4 hours ago

After months of tough negotiations, the European Commission recommended Wednesday a new energy savings target of 30 percent so as to combat climate change and ensure self-sufficiency.

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.