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This article is about the Mid-Miocene Climate Optimum, which was a period of 5 degrees C of warming about 15 million years ago. Another similar event is the Pa
by antognini 8y ago
This article is about the Mid-Miocene Climate Optimum, which was a period of 5 degrees C of warming about 15 million years ago. Another similar event is the Paleocene-Eocene Thermal Maximum, which was a period of warming (6 degrees C in 20,000 years) about 55 million years ago. The PETM was in response to a massive increase in atmospheric CO2 (several times more than humans have added), though what caused the injection of CO2 is currently unknown. Interestingly, although during the PETM the Earth had no polar ice caps to begin with there was still a rise in sea levels simply due to the thermal expansion of the ocean. There was a great deep dive into the event on the podcast In Our Time by three climatologists: https://www.bbc.co.uk/programmes/b08hpmmf https://www.bbc.co.uk/programmes/b08hpmmf
- throwaway5752 8y agoYou should note that the PETM CO2 increase was over multiple orders of magnitude (appr. 20,000 year vs 100) and theoretical rate of emission was 1-2 orders of magnitude less than the current rate.
- antognini 8y agoWhile that's probably true, it's not known for certain what the rate of emission was. 20,000 years is only an upper bound. It's possible that the process that led to the CO2 emissions happened over very short timescales (e.g., a comet impact or volcanic activity). Until we know the process, we can't constrain the rate.
- throwaway5752 8y agoI upvoted you, thank you for replying, but please give me a bit of charity and understand I was replying with the standard geological uncertainties assumed. But my understanding is the best fit is volcanic activity by peat or coal beds over a much longer relative timeframe than current emissions.