Estimated effect of the permafrost carbon feedback on the zero emissions commitment to climate change
Zero Emissions Commitment (ZEC), the expected change in global temperature following the cessation of CO 2 emissions has recently been assessed by the Zero Emissions Commitment Model Intercomparison Project (ZECMIP). ZECMIP concluded that the component of ZEC from CO 2 emissions will likely be close...
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| Format: | Text |
| Language: | English |
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2021
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| Online Access: | https://doi.org/10.5194/bg-2021-136 https://bg.copernicus.org/preprints/bg-2021-136/ |
| Summary: | Zero Emissions Commitment (ZEC), the expected change in global temperature following the cessation of CO 2 emissions has recently been assessed by the Zero Emissions Commitment Model Intercomparison Project (ZECMIP). ZECMIP concluded that the component of ZEC from CO 2 emissions will likely be close to zero in the decades following the cessation of emissions. However, of the 18 Earth system models that participated in ZECMIP only two included a representation of the permafrost carbon feedback to climate change. To better assess the potential impact of permafrost carbon decay on ZEC a series of perturbed parameter experiments are here conducted with an Earth system model of intermediate complexity. The experiment suggest that the permafrost carbon cycle feedback will directly add 0.06 [0.02 to 0.14] °C to the benchmark ZEC value assesses 50 years after 1000 PgC of CO 2 has been emitted to the atmosphere. An additional 0.04 [0 to 0.06] °C is likely to been added relative to the benchmark ZEC value from the thaw-lag effect unaccounted for in the ZECMIP experiment design. Overall we assess that the permafrost carbon feedback is unlikely to change the assessment that ZEC is close to zero on decadal timescales, however the feedback is expected to become more important over the coming centuries. |
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