The WMO's 2011 Greenhouse Gas Bulletin notes about 375 billion tons of carbon have been released into the atmosphere as CO2 since the start of the industrial era in 1750, mostly from the burning of fossil fuels.
About half of this CO2 remains in the atmosphere, with the rest being absorbed by the oceans and terrestrial biosphere, the WMO said.
"These billions of tons of additional carbon dioxide in our atmosphere will remain there for centuries, causing our planet to warm further and impacting on all aspects of life on earth," WMO Secretary-General Michel Jarraud said. "Future emissions will only compound the situation."
CO2 is the most significant of the long-lived greenhouse gases, so named because they trap radiation within the Earth's atmosphere causing it to warm.
The National Oceanic and Atmospheric Administration's Annual Greenhouse Gas Index, included in the WMO bulletin, shows from 1990 to 2011 radiative forcing -- the difference between sunlight being absorbed by the atmosphere compared to the amount reflected back into space -- by long-lived greenhouse gases increased by 30 percent, with CO2 accounting for about 80 percent of this increase.