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

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.