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No Impact of Anthropogenic Aerosols on Early 21st Century Global Temperature Trends in a Large Initial‐Condition Ensemble
Author(s) -
Oudar Thomas,
Kushner Paul J.,
Fyfe John C.,
Sigmond Michael
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 - 10.1029/2018gl078841
Subject(s) - radiative forcing , climatology , forcing (mathematics) , pacific decadal oscillation , spurious relationship , environmental science , climate model , climate system , atlantic multidecadal oscillation , aerosol , atmospheric sciences , climate change , el niño southern oscillation , meteorology , north atlantic oscillation , geography , geology , oceanography , mathematics , statistics
Anthropogenic‐aerosol (AA) radiative forcing modulates multidecadal greenhouse radiative forcing. However, decadal climate responses to AA are poorly characterized given AA forcing uncertainty and internal climate variability. This motivates revisiting a recent claim that AA drove a negative trend in the Pacific Decadal Oscillation and an associated cooling influence in the 10–15 years following the late‐1990's El Niño. The average of a 50‐member initial condition ensemble of the second generation Canadian Earth System Model version 2 that was forced only with AA does not exhibit the negative‐Pacific Decadal Oscillation/slowdown response. However, spurious responses of this kind, that are artifacts of subsetting the large ensemble (LE) in a manner consistent with published literature, can readily be found. This illustrates the caution needed in interpreting regional‐ and decadal‐scale responses to AA and suggests that improved characterization of model uncertainty in AA over the recent period is required.