Environment Counts | Carbon release rate during the Palaeocene–Eocene Thermal Maximum much less than anthropogenic carbon release :

Published
by geoff
on 2016-05-15

The Palaeocene–Eocene Thermal Maximum (PETM) is known to have had the highest carbon release rates of the past 66 million years. The PETM was associated with a ~5 °C surface temperature warming and an estimated total carbon release of thousands of  petagrams of carbon (Pg C). It has been thought that the PETM might be a suitable analogue to our current anthropogenic warming period which might provide information about the effects of rapid warming and rapid carbon release. But it has not been possible to determine the length and duration of the carbon release during the PETM. A recent study has analyzed carbon and oxygen isotopes captured in sedimentary records from the New Jersey shelf. The study found that the initial carbon release during the onset of the PETM occurred over at least 4,000 years. This constrains the maximum sustained carbon release rate during the PETM to less than 1.1 petagrams of carbon per year (Pg C/year). The authors conclude that the PETM is not a good analogue for the current anthropogenic warming period, because the current carbon release rate is an order of magnitude greater than during the PETM. Carbon release rates from anthropogenic sources reached a record high of ~10 petagrams of carbon per year (Pg C/year) in 2014. Richard E. Zeebe et al.,Anthropogenic carbon release rate unprecedented during the past 66 million years, Nature Geoscience 9, 325–329 (2016) doi:10.1038/ngeo2681