The peak rate of carbon emissions during the Palaeocene-Eocene Thermal Maximum (PETM) was far lower than that of today, suggests a paper published online in Nature Geoscience. The PETM — an ancient warming event that occurred about 56 million years ago — is often cited as a potential analogue for future climate change. However these findings indicate that this event may not represent as abrupt a rate of environmental change as previously suspected.
Ying Cui, Lee Kump and colleagues combined sediment records and computer modelling to assess the timing and magnitude of carbon release during the PETM, which persisted for about 170,000 years. Their simulations suggest that the carbon was added in three pulses and that the rate of emissions during these pulses did not exceed around 1.7 petagrams of carbon per year. In comparison, current fossil fuel emissions exceed 8 petagrams of carbon per year.
The researchers point out that the amount of carbon released during the PETM is approximately the same quantity that could be injected to the atmosphere if we burnt the full amount of fossil fuel stocks currently estimated to be available.