Greenhouse Gas Levels Hit Record High in 2013: UN Report

With carbon dioxide rising in the atmosphere at its fastest rate in three decades, greenhouse gas levels reached a record high in 2013, according to a new UN report released Tuesday.

Based on the latest figures, published in the World Meteorological Organization's (WMO) annual Greenhouse Gas Bulletin, there was a 34 percent increase in radiative forcing - the rate at which the atmosphere warms up - between 1990 and 2013. This, the report says, was largely caused by a surge in levels of long-lasting greenhouse gases in the atmosphere such as carbon dioxide (CO2), methane and nitrous oxide.

"We are running out of time," WMO Secretary-General Michel Jarraud said in a statement. "Carbon dioxide remains in the atmosphere for many hundreds of years and in the ocean for even longer. Past, present and future CO2 emissions will have a cumulative impact on both global warming and ocean acidification. The laws of physics are non-negotiable."

While most people associate greenhouse gases with power plants and automobiles, the WMO's monitoring stations don't measure emissions from these sources. Instead, for the first time they recorded how much of the warming gases remain in the atmosphere after the complex interactions that take place between the air, land and oceans. About half of all emissions are taken up by the seas, trees and other living things, but scientists are growing increasingly worried that soon Mother Nature won't be able to keep up.

"We don't understand if this is temporary or if it is a permanent state, and we are a bit worried about that," Oksana Tarasova, a scientist and chief of the WMO's Global Atmospheric Watch program, told BBC News.

"If the oceans and the biosphere cannot absorb as much carbon, the effect on the atmosphere could be much worse," she added to The Washington Post.

The new figures for carbon dioxide were surprising, according to Tarasova, showing that concentrations last year grew at their fastest rate since 1984. Specifically, there was a jump of nearly three parts per million over 2012 levels, meaning the atmosphere reached 396 parts per million (ppm) in 2013. According to scientists, 400 ppm is a threshold that they fear crossing - for it means more drastic climatic impacts will become likely - but one that the Earth will likely surpass in the next two years, the report says.

"We have the knowledge and we have the tools for action to try keep temperature increases within 2 degrees Celsius to give our planet a chance and to give our children and grandchildren a future," Jarraud said in the statement. "Pleading ignorance can no longer be an excuse for not acting."