CO2 Levels Reach Record-Breaking Milestone in Northern Hemisphere

For the first time, carbon dioxide (CO2) levels have reached a record-breaking milestone, its monthly concentrations topping 400 parts per million (ppm) in April throughout the Northern Hemisphere, the World Meteorological Organization (WMO) reports.

This threshold reinforces the fact that human-caused greenhouse gas emissions are warming our planet to dangerous levels.

"Time is running out," warned WMO Secretary-General Michel Jarraud, according to a news release. "This should serve as yet another wakeup call about the constantly rising levels of greenhouse gases which are driving climate change. If we are to preserve our planet for future generations, we need urgent action to curb new emissions of these heat trapping gases."

The global annual average is set to exceed the 400 ppm level in 2015 or 2016, the agency added.

Measurements taken by meteorological stations from Canada to Germany, from France to Japan, from Barrow, Alaska to high atop Mauna Loa, Hawaii, contributed to this conclusion.

CO2 stays trapped in the atmosphere for hundreds of years, and even longer in oceans. It is by far the most significant greenhouse gas produced by humans, responsible for 85 percent of radiative forcing - the warming affect on our climate - from 2002-2012.

What's more, the amount of CO2 in the atmosphere has increased on average by two ppm per year for the past decade.

The northern hemisphere is home to more sources of fossil fuel burning and other carbon-dioxide producing activities, which take time to mix globally, which is why its CO2 levels are higher compared to other regions, Environment News Service reported.

The WMO Global Atmosphere Watch, a network than spans 50 countries, coordinates observations of CO2 and other heat-trapping gases like methane and nitrous oxide in the atmosphere to better compare such measurements worldwide.

The United Nations hopes to seal an international, legally binding climate agreement by the end of next year. One goal is to limit the average temperature increase to two degrees Celsius above pre-industrial times.

The Intergovernmental Panel on Climate Change noted that to achieve this goal, global greenhouse gas emissions must be lowered by 40 to 70 per cent compared with 2010 by mid-century, and to near-zero by the end of this century.