Arctic
The crew of the U.S. Coast Guard Cutter Healy, in the midst of their ICESCAPE mission, retrieves supplies for some mid-mission fixes dropped by parachute from a C-130 in the Arctic Ocean in this July 12, 2011 NASA handout photo obtained by Reuters June 11, 2011. Scientists punched through the sea ice to find waters richer in phytoplankton than any other region on earth. Phytoplankton, the base component of the marine food chain, were thought to grow in the Arctic Ocean only after sea ice had retreated for the summer. Scientists now think that the thinning Arctic ice is allowing sunlight to reach the waters under the sea ice, catalyzing the plant blooms where they had never been observed. REUTERS/Kathryn Hansen

The amount of greenhouse gases in Earth's atmosphere hit a record high in 2012, continuing an upward trend driving climate change, according to a report released Wednesday by the World Meteorological Organization (WMO).

The atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased to levels unprecedented in the last 800,000 years, the WMO's 5th Annual Assessment Report stated.

Since the start of the industrial era in 1750, global average CO2 has increased by 41 percent, methane by 160 percent and nitrous oxide by 20 percent, the U.N. agency stated.

“As a result of this, our climate is changing, our weather is more extreme, ice sheets and glaciers are melting, and sea levels are rising,” Michael Jarraud, the head of the WMO, said.

CO2, the single-most-important greenhouse gas on a global scale, reached 393.1 parts per million last year, or 141 percent of pre-industrial levels before 1750. The amount in the atmosphere increased 2.2 parts per million from 2011 to 2012, which is above the average (2.02ppm) of the past 10 years.

“Limiting climate change will require large and sustained reductions of greenhouse gas emissions. We need to act now, otherwise we will jeopardize the future of our children, grandchildren and many future generations,” Jarraud said. “Time is not on our side.”