Warnings on greenhouse gas levels

The concentration of greenhouse gases in the Earth's atmosphere reached a record level in 2011, according to the World Meteorological Organization (WMO). A United Nations report says the chance to meet emission targets is slipping away.

"These billions of tonnes of additional carbon dioxide in our atmosphere will remain there for centuries, causing our planet to warm further and impacting all aspects of life on Earth."

Michel Jarraud
WMO secretary general

In the latest edition of its Greenhouse Gas Bulletin, the WMO estimates that the amount of carbon dioxide (CO2) - the single most important long-lived greenhouse gas - in the atmosphere reached 390.0 parts per million (ppm) in 2011. This represents 140% of the pre-industrial level of 280 ppm. The increase between 2010 and 2011 was similar to the average annual growth rate of 2 ppm over the past ten years.

The pre-industrial level of some 280 ppm CO2 represented a "balance of fluxes between the atmosphere, the oceans and the biosphere," according to the WMO. Some 375 gigatonnes (Gt) of carbon have been released into the atmosphere as CO2 - primarily from the burning of fossil fuels - since the start of the industrial era in 1750, the WMO estimates. Some 55% of this CO2 remains in the atmosphere, with the rest being absorbed by the oceans and terrestrial biosphere.

WMO secretary general Michel Jarraud commented, "These billions of tonnes of additional carbon dioxide in our atmosphere will remain there for centuries, causing our planet to warm further and impacting all aspects of life on Earth."

Limiting emissions

A target to limit global warming by 2ºC was formally agreed at COP-15 in Copenhagen in December 2009 but a new report from the United Nations Environment Program (UNEP) shows that greenhouse gas emissions remain some 14% higher than where they need to be in 2020 in order to meet that target.

If prompt action is not taken, emissions will be some 58 Gt in 2020, UNEP's latest Emissions Gap Report suggests. Previous reports have said that emissions need to average around 44 Gt or less at that time "to lay the path for the even bigger reductions needed at a cost that is manageable."

UNEP notes, "Even if the most ambitious level of pledges and commitments were implemented by all countries - and under the strictest set of rules - there will now be a gap of 8 Gt of CO2 equivalent by 2020."

"The opportunity for meeting the 44 Gt target is narrowing annually," said UN under-secretary general and UNEP executive director Achim Steiner.

Researched and written
by World Nuclear News