The last time there was this much CO2 in the atmosphere, the Arctic had no ice and the sea was 40m higher than it is today – three to five million years ago, before modern humans existed. Without serious efforts to curb the still-unchecked and still-rising levels of greenhouse gas emissions, it is expected that these conditions will return – with obvious dire consequences for the people that now blanket the globe.
For comparison, the level of CO2 in the atmosphere was 280 parts per million prior to industrialisation. The 400 ppm mark was recorded at Mauna Loa laboratory, in Hawaii – see the live daily update of atmospheric CO2 readings from this lab. The lab has been measuring the concentration of CO2 continuously since 1958.
Scientists say this CO2 milestone should be a real wake-up call, a sharp reminder that global CO2 emissions are soaring unchecked and drastic action is vital. The pace of change is unprecedented in any record – the warming we’re seeing is occurring some 75 more quickly than in the pre-industrial age. China and the US recently agreed to cooperate on clean technology. China’s 2011 to 2015 plan is promising, aiming to reverse the negative impacts of 30 years of growth and increase its use of renewable energy sources, for instance. But the UK’s Climate Change Committee recently released a statement saying that the UK’s contribution to global warming had actually increased, due to an increase in imported goods that cause CO2 emissions in other countries.
The governments of the world have agreed to try to keep global temperature rises to 2ºC – they’ve already risen 1ºC – but there has not yet been a change in emissions trends: the International Energy Agency has said that current trends will lead to a 6ºC rise in temperatures… and chaos. The UN summit in Paris in 2015 is seen as the deadline for setting a binding international treaty on reducing emissions.
- The Guardian: Global carbon dioxide in atmosphere passes milestone level
- BBC: Scientists call for action to tackle CO2 levels
- Daily updates of atmospheric CO2 concentrations from the Mauna Loa lab