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Contributions of Internal Variability and External Forcing to the Recent Pacific Decadal Variations
Author(s) -
Hua Wenjian,
Dai Aiguo,
Qin Minhua
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 - 10.1029/2018gl079033
Subject(s) - pacific decadal oscillation , forcing (mathematics) , climatology , environmental science , volcano , greenhouse gas , climate model , atmospheric sciences , el niño southern oscillation , climate change , oceanography , geology , seismology
Abstract There is substantial uncertainty in the relative contributions of internal variability and external forcing to the recent Pacific decadal variability, especially regarding their linkage with the Interdecadal Pacific Oscillation. By analyzing observations and large ensembles of coupled climate model simulations, here we show that observed Pacific decadal variations since 1920 resulted primarily from internal variability, although greenhouse gas (GHG) and other external forcing did modulate decadal variations in Pacific sea surface temperatures (SSTs) significantly, especially for the period since the early 1990s. Specifically, the GHG‐induced warming and the recovery from the volcanic cooling caused by the 1991 Pinatubo eruption led to large warming in the tropical Pacific during 1993–2012, while recent anthropogenic aerosols contributed to Pacific regional SST variations on multiyear to decadal scales, causing a La Niña‐like cooling pattern in the Pacific since 1998 in some of the models. Our results provide new evidence that both internal variability and external forcing have contributed to the recent decadal variations in Pacific SSTs since the early 1990s, although large uncertainties exist among the model‐simulated effects of anthropogenic aerosols.