Northern Galápagos corals reveal twentieth century warming in the eastern tropical Pacific


Jimenez, Gloria
Cole, Julia E.
Thompson, Diane M.
and Tudhope, Alexander W.

Models and observations disagree regarding sea surface temperature (SST) trends in the eastern tropical Pacific (ETP). We present a new Sr/Ca-SST record that spans 1940-2010 from two Wolf Island corals (northern Galápagos). Trend analysis of the Wolf record shows significant warming on multiple timescales, which is also present in several other records and gridded instrumental products. Together, these datasets suggest that most of the ETP has warmed over the 20thcentury. In contrast, recent decades have been characterized by warming during boreal spring and summer (especially north of the equator), and subtropical cooling during boreal fall and winter (especially south of the equator). These SST trends are consistent with the effects of radiative forcing, mitigated by cooling due to wind forcing during boreal winter, as well as intensified upwelling and a strengthened Equatorial Undercurrent.

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Figure 1. (a) Climatologic setting of the ETP. SSTs (colors) are the average of 0.25° Optimum Interpolation Sea Surface Temperature (OISST) from 1982-2014; winds (vectors) are the 1000 mbar average over the same period from the 2° National Oceanic and Atmospheric Administration 20thCentury Reanalysis (20CR) v2 (Compo et al., 2011). Longest vector is 9.5 m/s; for display, vectors in all figures are cubically interpolated to 50% spatial resolution. (b)Expanded map from box in (a) shows Galápagos bathymetry from the National Geophysical Data Center 2-minuteGridded Global Relief Data v2 (2006). In all figures, stars indicate coral and instrumental sites (C: Clipperton, P: Palmyra, PA: Puerto Ayora, PC: Puerto Chicama, and W: Wolf).

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Geophysical Research Letters, February 21, 2018. DOI: 10.1002/2017GL075323