FN Archimer Export Format PT J TI North Pacific response to hemispheric warming forces Holocene drought BT AF Todd, Victoria Shanahan, Timothy DiNezio, Pedro Klavans, Jeremy Fawcett, Peter Anderson, R. Scott Jimenez-Moreno, Gonzalo LeGrande, Allegra Pausata, Francesco Thompson, Alex Zhu, Jiang AS 1:1;2:1;3:2;4:2;5:3;6:4;7:5;8:6,7;9:8;10:9;11:10; FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:;11:; C1 Jackson School of Geosciences, The University of Texas at Austin, usa Department of Atmospheric and Oceanic Sciences, The University of Colorado-Boulder, USa The Department of Earth and Planetary Sciences, The University of New Mexico, USA School of Earth and Sustainability, Northern Arizona University, USA Departamento de Estratigrafía y Paleontología, Universidad de Granada, 18002, Granada, Spain Center for Climate Systems Research, Columbia University, New York, NY, USA NASA Goddard Institute for Space Studies, New York, NY, USA Centre ESCER and GEOTOP, Department of Earth and Atmospheric Sciences, University of 18 Quebec in Montreal, Montreal, QC, Canada Department of Earth and Planetary Sciences, Washington University, St. Louis, usa Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, 21 CO, USA C2 UNIV TEXAS AUSTIN, USA UNIV COLORADO BOULDER, USA UNIV NEW MEXICO, USA UNIV NORTH ARIZONA, USA UNIV GRANADA, SPAIN UNIV COLUMBIA, USA NASA, USA UNIV QUEBEC (UQAM-GEOTOP), CANADA UNIV WASHINGTON, USA NCAR, USA TC 0 UR https://archimer.ifremer.fr/doc/00854/96631/105099.pdf LA English DT Article CR IMAGES 3-IPHIS-MD106 IMAGES 4-MD111 MD 122 / WEPAMA MD 126 / MONA MD 127 / PAGE MD 130 / CADO MD 131 / AUSCAN MD159 / PACHIDERME BO Marion Dufresne AB The Southwest United States is prone to severe and persistent drought1, but the influence of anthropogenic forcing on current and future precipitation remains uncertain2-7. To improve our understanding of the drivers of Southwest drought, we quantified precipitation and temperature changes in the southern Rockies and combined these with a multi-model ensemble of climate simulations for the mid-Holocene, a past interval when the region experienced exceptional and persistent drought. Reconstructed mid-Holocene warming in the Rockies is consistent with existing proxy reconstructions. In most models, this warming only occurs in simulations with prescribed mid-Holocene vegetation, including a “greening” of the Sahara, supporting the hypothesis that expanded vegetation was critical for producing warming consistent with proxy data15. In response to this hemispheric warming, a distinct pattern of higher temperatures resembling the negative phase of the Pacific Decadal Oscillation emerges in the models, increasing the magnitude of wintertime precipitation declines across the western US, in better agreement with proxy reconstructions. A similar forced response could be excited by anthropogenic forcings, enhancing future drought across the Southwest US. However, reductions in winter precipitation associated with the development of this pattern of North Pacific warming are underestimated in simulations of both the mid-Holocene and the instrumental period, suggesting that current projections may underestimate the magnitude and the risk of persistent human-made drought in the future. PY 2023 PD SEP SO Under Review at Nature Portfolio PU Research Square Platform LLC DI 10.21203/rs.3.rs-3317761/v1 ID 96631 ER EF