Premium
Disentangling Global Warming, Multidecadal Variability, and El Niño in Pacific Temperatures
Author(s) -
Wills Robert C.,
Schneider Tapio,
Wallace John M.,
Battisti David S.,
Hartmann Dennis L.
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 - 10.1002/2017gl076327
Subject(s) - pacific decadal oscillation , climatology , teleconnection , middle latitudes , environmental science , forcing (mathematics) , sea surface temperature , global warming , el niño southern oscillation , climate model , atlantic multidecadal oscillation , climate change , geology , oceanography
A key challenge in climate science is to separate observed temperature changes into components due to internal variability and responses to external forcing. Extended integrations of forced and unforced climate models are often used for this purpose. Here we demonstrate a novel method to separate modes of internal variability from global warming based on differences in time scale and spatial pattern, without relying on climate models. We identify uncorrelated components of Pacific sea surface temperature variability due to global warming, the Pacific Decadal Oscillation (PDO), and the El Niño–Southern Oscillation (ENSO). Our results give statistical representations of PDO and ENSO that are consistent with their being separate processes, operating on different time scales, but are otherwise consistent with canonical definitions. We isolate the multidecadal variability of the PDO and find that it is confined to midlatitudes; tropical sea surface temperatures and their teleconnections mix in higher‐frequency variability. This implies that midlatitude PDO anomalies are more persistent than previously thought.