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Image: Bioversity International

Another climate record falls – and this time its permanent

Earlier this year, scientists in Tasmania recorded atmospheric carbon dioxide levels slightly higher than the symbolic 400 parts per million that we were once warned that we should not exceed.  At the time, it was assumed that this was a blip and that in subsequent months CO2 levels would probably fall back.  New readings from the Mauna Loa observatory in Hawaii suggest that this was over optimistic.  As Brian Kahn at Climate Central notes:

“In the centuries to come, history books will likely look back on September 2016 as a major milestone for the world’s climate. At a time when atmospheric carbon dioxide is usually at its minimum, the monthly value failed to drop below 400 parts per million.

“That all but ensures that 2016 will be the year that carbon dioxide officially passed the symbolic 400 ppm mark, never to return below it in our lifetimes, according to scientists.”

September is usually the month when atmospheric CO2 levels are at their lowest at the end of a northern hemisphere growing season during which plants suck C02 out of the atmosphere.  And while it is possible that October 2016 may see slightly lower concentrations than those recorded in September, it would require a record breaking fall in C02 levels to take them back below 400ppm.

The new C02 readings mean that we are guaranteed to break the 1.5oC warming limit agreed in Paris last year, and mean that avoiding the 2oC upper limit can only be achieved by bringing forward carbon reduction measures planned for 2030.  As Kahn warns us:

“Even though there are some hopeful signs that world leaders will take actions to reduce emissions, those actions will have to happen on an accelerating timetable in order to avoid 2°C (3.6°F) of warming. That’s the level outlined by policymakers as a safe threshold for climate change. And even if the world limits warming to that benchmark, it will still likely spell doom for low-lying small island states and have serious repercussions around the world, from more extreme heat waves to droughts, coastal flooding and the extinction of many coral reefs.”

The sad reality is that none of the political leaders in the countries that can make a difference is prepared to take the kind of tough decisions needed for us to have even the remotest chance of avoiding runaway global warming.  And in large part, the reason for this is that we are not prepared to make the kind of sacrifices to our own lifestyles that would make such political action credible.

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