杏吧原创

Even if carbon dioxide levels stopped rising today, the world would still warm by 1.6聽掳C above pre-industrial levels 鈥搘hich is more than three-quarters of the way to the 2聽掳C limit the world is supposed to be aiming for. That is the implication of two sets of figures announced on Monday.

Global average levels of carbon dioxide in the atmosphere temporarily broke the 400 parts per million level earlier this year for the first time, the .

Meanwhile, the UK Met Office confirmed what New 杏吧原创 reported first in July 鈥� that the world has now warmed by 1聽掳C relative to pre-industrial times.

Climate models show that even if CO₂ levels stopped rising, the world would still warm by around 0.6聽掳C. So the latest figures mean that even if the world slashed emissions by 60 per cent immediately, which is what it would take to stabilise CO₂ levels, we would still hit 1.6聽掳C.

Climate scientist Gavin Schmidt of NASA points out that if emissions stopped altogether, CO₂ levels would soon fall. 鈥淭hat would lead to a smaller eventual temperature rise,鈥� he says.

鈥楾is the season

Unfortunately, even if countries stick to what they are proposing to do as part of the global climate treaty now being negotiated, emissions and CO₂ levels will continue to climb well past 2030. It therefore appears unlikely that warming can be limited to 2聽掳C.

CO₂ levels vary from place to place and with the seasons, depending on the balance between plants taking up CO₂ as they grow and releasing it as they decay.

CO₂ levels above 400 parts per million were first recorded in 2012 in a few places. In 2013, the Mauna Loa Observatory in Hawaii, which has been monitoring CO₂ since 1956, recorded levels above 400 parts per million for the first time.

Now the monthly global average has passed 400 parts per million. Because the global average rises and falls by several parts per million every year, this is temporary 鈥� it will drop again this year, but next year it will rise even higher. Soon it will remain permanently above 400 parts per million.

Last year the global annual 鈥� rather than monthly 鈥� average was 398 parts per million. Because CO₂ levels tend to jump extra high in El Ni帽o years 鈥� because of events such as the fires in Indonesia 鈥� .

Read more: 鈥�Climate downgrade: Human emissions鈥�

Image credit: NOAA