Precipitation in Northeast Mexico Primarily Controlled by the Relative Warming of Atlantic SSTs

• Published in: Geophysical research letters 2022-06, Vol.49 (11), p.n/a
• Main Authors: Wright, Kevin T., Johnson, Kathleen R., Bhattacharya, Tripti, Marks, Gabriela Serrato, McGee, David, Elsbury, Dillon, Peings, Yannick, Lacaille‐Muzquiz, Jean‐Louis, Lum, Gianna, Beramendi‐Orosco, Laura, Magnusdottir, Gudrun
• Format: Article
• Language: English
• Subjects: Annual; Annual precipitation; Annual rainfall; Atmospheric circulation; Atmospheric circulation models; Atmospheric precipitations; Climate change; Climate models; Common Era; Future precipitation; General circulation models; Hydroclimate; Mean annual precipitation; Mexico; paleoclimate; Precipitation; Rain; Rainfall; Sea surface; Sea surface temperature; speleothem; stable isotopes; Summer precipitation; Surface temperature; Tree rings; Trees; Tropical climate; Variability; Winter; Winter precipitation
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL098186

Reconstructing hydroclimate over the Common Era is essential for understanding the dominant mechanisms of precipitation change and improving climate model projections, which currently suggest Northeast Mexico will become drier in the future. Tree‐ring reconstructions have suggested regional rainfall is primarily controlled by Pacific sea‐surface temperatures (SSTs). However, tree ring records tend to reflect winter‐spring rainfall, and thus may not accurately record total annual precipitation. Using the first multiproxy speleothem record spanning the last millennium, combined with results from an atmospheric general circulation model, we demonstrate mean annual rainfall in Northeast Mexico is highly sensitive to Atlantic SST variability. Our findings suggest future precipitation in Northeast Mexico is more dependent upon the warming of Tropical Atlantic SSTs relative to the Tropical Pacific. Plain Language Summary We use geochemical markers of past rainfall in a rock from a cave (speleothem) to show that warming in Atlantic sea‐surface temperatures (SSTs) increases the amount of precipitation in Northeast Mexico. These finding are surprising, since previous rainfall reconstructions using tree rings have suggested a warmer Atlantic decreases precipitation in the region. We used a climate model to show that warming in the Atlantic increases precipitation during the summer but decreases precipitation during the winter. Although winter precipitation only accounts for 8% of annual rainfall in this region, tree rings are more reflective of the winter precipitation response. This is the first speleothem record from NE Mexico over this time‐period and suggests that projections of future rainfall should emphasize relative changes in Atlantic SST variability because it has a major impact on annual precipitation. Key Points We present the first speleothem record spanning the last millennium from NE Mexico using multiple geochemical proxies In contrast to tree ring reconstructions, we suggest regional precipitation is primarily controlled by Atlantic sea‐surface temperatures (SSTs) We utilize results from a forced‐SST climate model to further support our interpretation