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Insufficient forcing uncertainty underestimates the risk of high climate sensitivity
Author(s) -
Tanaka Katsumasa,
Raddatz Thomas,
O'Neill Brian C.,
Reick Christian H.
Publication year - 2009
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 - 10.1029/2009gl039642
Subject(s) - climate sensitivity , radiative forcing , forcing (mathematics) , sensitivity (control systems) , climatology , climate commitment , environmental science , climate change , climate model , cloud forcing , atmospheric sciences , global warming , geology , effects of global warming , oceanography , electronic engineering , engineering
Uncertainty in climate sensitivity is a fundamental problem for projections of the future climate. Equilibrium climate sensitivity is defined as the asymptotic response of global‐mean surface air temperature to a doubling of the atmospheric CO 2 concentration from the preindustrial level (≈280 ppm). In spite of various efforts to estimate its value, climate sensitivity is still not well constrained. Here we show that the probability of high climate sensitivity is higher than previously thought because uncertainty in historical radiative forcing has not been sufficiently considered. The greater the uncertainty that is considered for radiative forcing, the more difficult it is to rule out high climate sensitivity, although low climate sensitivity (<2°C) remains unlikely. We call for further research on how best to represent forcing uncertainty.