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The Effect of Obliquity‐Driven Changes on Paleoclimate Sensitivity During the Late Pleistocene
Author(s) -
Köhler Peter,
Knorr Gregor,
Stap Lennert B.,
Ganopolski Andrey,
Boer Bas,
Wal Roderik S. W.,
Barker Stephen,
Rüpke Lars H.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl077717
Subject(s) - paleoclimatology , climatology , extrapolation , radiative forcing , ice sheet , forcing (mathematics) , divergence (linguistics) , atmospheric sciences , geology , pleistocene , albedo (alchemy) , environmental science , climate sensitivity , climate model , climate change , mathematics , paleontology , geomorphology , oceanography , art , mathematical analysis , linguistics , philosophy , performance art , art history
We reanalyze existing paleodata of global mean surface temperature Δ T g and radiative forcing Δ R of CO 2 and land ice albedo for the last 800,000 years to show that a state‐dependency in paleoclimate sensitivity S , as previously suggested, is only found if Δ T g is based on reconstructions, and not when Δ T g is based on model simulations. Furthermore, during times of decreasing obliquity (periods of land ice sheet growth and sea level fall) the multimillennial component of reconstructed Δ T g diverges from CO 2 , while in simulations both variables vary more synchronously, suggesting that the differences during these times are due to relatively low rates of simulated land ice growth and associated cooling. To produce a reconstruction‐based extrapolation of S for the future, we exclude intervals with strong Δ T g ‐CO 2 divergence and find that S is less state‐dependent, or even constant state‐independent), yielding a mean equilibrium warming of 2–4 K for a doubling of CO 2 .