6th Mass Extinction Update

Thanks to Rob Ford, Principal at Wyedean School and Sixth Form College in the UK, for sending this link to a source – New Atlas – with which I was not familiar. Most of Rob’s students should expect to be alive by 2100 which is the possible ‘tipping point’ identified used by the MIT study described  in the article. The tipping point would be triggered by the increase in atmospheric CO2. The article starts:

In the history of life on Earth, there have been five mass extinction events, with the most extreme example, the Permian extinction, wiping out some 95 percent of all marine life. Now, an MIT professor has analyzed the changes that took place in the carbon cycle leading up to these five main events – as well as dozens of smaller ones – and found that the end of this century could mark the tipping point for a sixth mass extinction event.

Each of the five major extinction events can effectively be traced back to one little troublemaker: carbon. As respiring organisms inhale oxygen and exhale carbon dioxide, and photosynthesizing plants do the opposite, the Earth naturally cycles carbon through the atmosphere and ocean. But disruptions to that process can throw the whole planet’s climate out of whack, either by adding too much carbon at once or by speeding up the rate at which it’s being added….

Rothman calculated how much carbon it would take today to tip us over the threshold. According to his calculations, if an extra 310 gigatons of carbon is added – say, through human action – it would tip the carbon cycle into “unknown territory” that may lead to mass extinction….

If 310 gigatons sounds like a lot, we have some bad news: humans are full steam ahead towards smashing that figure by the end of the century. According to the latest report from the Intergovernmental Panel on Climate Change, the best-case scenario for how much carbon humans will add to the oceans by the year 2100 is about 300 gigatons. In the worst case scenario, that number could surpass 500 gigatons.

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