Cenozoic Proxy Constraints on Earth System Sensitivity to Greenhouse Gases

Autor: S. J. Ring, S. G. Mutz, T. A. Ehlers
Rok vydání: 2022
Předmět:
Zdroj: Paleoceanography and Paleoclimatology
ISSN: 2572-4525
2572-4517
DOI: 10.1029/2021pa004364
Popis: It is not well known how much Earth’s surface temperature will change over the next few millennia as a result of increasing atmospheric CO2 concentrations. This is because we still have a limited understanding of many slow climate feedback mechanisms activated by climate change that will become important in the future. Most climate models project eventual global warming of 3–4°C for doubled CO2 concentration but exclude many slow climate feedbacks, such as shrinking ice sheets. The distant (geologic) past provides additional clues about the future because the climate system and all of its feedbacks were in equilibrium with naturally elevated CO2. Using up-to-date geologic information of the last 50 million years, we find that Earth’s climate history is best described by a switch from a moderate sensitivity, close to that found in climate models, to a much higher sensitivity in the last 3 million years. If Earth behaves the same way today as it has done in the past, melting ice sheets, natural aerosols, and shifting vegetation patterns will slowly continue to raise global warming above the 2°C target during the next few thousand years even if the human contribution does not increase any further.
Databáze: OpenAIRE
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