WMO: Greenhouse gas concentrations reached record high in 2011

By RTCC Staff

The volume of greenhouse gases in the atmosphere reached a record high in 2011, according to the World Meteorological Organisation’s (WMO) Greenhouse Gas Bulletin.

The amount of carbon dioxide in the atmosphere – the primary source of greenhouse gases emitted by human activities – reached 390.9 parts per million (ppm) last year, 40% above the pre-industrial level.

It has increased by an average of two ppm per year for the last 10 years, and is growing at a similar rate to the previous decade.

The 2007 report from the Intergovernmental Panel on Climate Change (IPCC) found that is the world could stablise greenhouse gas emissions below 450 ppm there would be a 50-50 chance of stay within the target of a 2°C rise in temperature.

Some campaigners and scientists now call for actions which would help reduce this level to 350 ppm.

Since the start of the industrial era in 1750, fossil fuels have been the primary source of the 375 billion metric tonnes of carbon released into the atmosphere, according to the bulletin.

“The billions of tonnes of additional carbon dioxide in our atmosphere will remain there for centuries, causing our planet to warm further and impact on all aspects of life on earth,” said WMO Secretary-General Michel Jarraud. “Future emissions will only compound the situation.

“Until now, carbon sinks have absorbed nearly half of the carbon dioxide humans emitted in the atmosphere, but this will not necessarily continue in the future.”

Levels of methane, another long-lived greenhouse gas, have risen steadily in the past three years, after levelling off for about seven years previously. Levels of nitrous oxide also rose in 2011.

The WMO said these gases are all closely linked to human activities – fossil fuel use, deforestation and intensive agriculture – and have increased the warming effect on the climate by 30% between 1990 and 2011.

The Greenhouse Gas Bulletin reports on the atmospheric concentration of the gases, not emissions. Emissions represent what goes into the atmosphere, while concentrations are what remain in the atmosphere after the complex interactions between the atmosphere, the biosphere and the oceans.

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