Climate Change Outpacing the PETM
56 million years ago, the planet warmed due to greenhouse gas emissions from methane hydrates, permafrost thawing, and volcanism, during a period known as the Paleocene-Eocene Thermal Maximum (PETM). This event, which occurred over several thousand years, raised global temperatures by 5-8°C and altered marine and terrestrial environments and climate. The PETM is the warmest period on earth since the extinction of dinosaurs approximately 66 million years ago.
During the PETM, the poles were almost tropical and did not have ice. The oceans increased in temperature, became more acidic, and deep waters were likely hypoxic. Large scale processes, like ocean circulation, was drastically altered due to these changes in surface and deep ocean water temperatures. These changes in climate during the PETM led to a global extinction event and accelerated evolution and diversification of life following the event in the oceans and on land, especially in mammalian groups.
The PETM period is of great scientific interest, as it provides a comparison to modern climate change. Scientists who study the PETM aim to understand how environmental changes might occur due to climate change today.
A new study, published in Paleoceanography and Paleoclimatology, compared the rate of greenhouse gas accumulation in the PETM to modern climate change today. Using a new mathematical approach, they find that anthropogenic carbon emissions at the present are occurring 9-10 times faster than during the PETM period. At the present rate of greenhouse gas emissions, the researchers calculated that we could expect to see PETM-scale climatic changes in as little as 140 to 359 years (approximately by year 2160), or within 4-5 human generations. The study findings add to the large body of research suggesting that without rapid emission reduction, modern climate change will have dramatic and negative consequences in a relatively short period of time.
Check out the study!
Philip D. Gingerich. Temporal Scaling of Carbon Emission and Accumulation Rates: Modern Anthropogenic Emissions Compared to Estimates of PETM-Onset Accumulation. Paleoceanography and Paleoclimatology, 2019; DOI: 10.1029/2018PA003379