Yesterday the World Meterological Organisation (WMO) announced that levels of atmospheric carbon dioxide (CO2) were at the highest level ever recorded during 2012. Last year there were 393.1 parts per million (ppm) of CO2 in the atmosphere, an increase of 2.2ppm on 2011 and 141% of the atmospheric CO2 level in the year 1750, when CO2 was at 278 ppm.
So how is the CO2 getting there? Well, whenever we create energy or heat by carbon-based fuels, the process of burning the fuel (oil, coal, wood etc.) produces carbon dioxide, which is released into the atmnosphere. About half of the CO2 we create is absorbed by the oceans, plants and trees. But the rest stays in the atmosphere. In May of this year, a daily measurement of atmospheric CO2 went over 400ppm for the first time. The WMO estimates that the global annual average will exceed 400ppm by 2016.
The reason the increase in CO2 levels is important is that CO2 is the most abundant greenhouse gas, which helps trap the sun's heat in the atmosphere and which is gradually increasing global temperatures. In the last decade or so, global warming has actually been slowing down, but scientists believe that the reason for this is that the extra heat has been absorbed by the world's oceans. Strong warming is expected in the future.
The good news is that there is some evidence that the rate at which emissions of CO2 caused by humans are increasing may be slowing down. But the bad news is that gases can continue to concentrate in the atmosphere for centuries.