March 28, 2016

A study in Nature Geoscience compared the ongoing anthropogenic increase in carbon emissions with previous similar episodes. The only known analogous event –the Palaeocene-Eocene Thermal Maximum, or PETM- happened 56 million years ago during the Cenozoic era, when the Earth’s average temperature shot up by about 5 degrees Celsius. While the precise cause of that ancient spike is not yet known, geologic evidence shows that it took place gradually, over a period of 4,000 years. Subsequently the greenhouse effect acidified the oceans and unleashed a major die-off of some marine organisms.

Deep ocean core sediments off the coast of New Jersey revealed that the rate of accumulation during the PETM was about 1 billion tons of carbon per year. In contrast, today’s rate is 10 times higher, too fast for organisms to adapt. Since the current rate of carbon release is unprecedented, there is no time-tested way to determine if our species, at the top of the food chain, will survive the onslaught.