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North American hydroclimate during past warms states: A proxy network-model comparison for the Last Interglacial and the mid-Holocene
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  • Cameron B. de Wet,
  • Daniel Enrique Ibarra,
  • Bryce K. Belanger,
  • Jessica Leigh Oster
Cameron B. de Wet
Vanderbilt University

Corresponding Author:[email protected]

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Daniel Enrique Ibarra
Brown University
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Bryce K. Belanger
Vanderbilt University
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Jessica Leigh Oster
Vanderbilt University
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Abstract

During the mid-Holocene (MH: ~6,000 years BP) and Last Interglacial LIG (LIG: ~129,000-116,000 years BP) differences in the seasonal and latitudinal distribution of insolation drove northern hemisphere high-latitude warming comparable to that projected in end-21st century low emissions scenarios, making these intervals potential analogs for future climate change in North America. However, terrestrial precipitation during past warm intervals is not well understood and PMIP4 models produce variable regional moisture patterns in North America during both intervals. To investigate the extent to which the latest generation of models reproduces moisture patterns indicated by proxy records, we compare hydroclimate output from 17 PMIP4 models with networks of moisture-sensitive proxies compiled for North America during the LIG (39 sites) and MH (257 sites). Agreement is lower for the MH, with models producing wet anomalies across the western United States (US) where a high concentration of proxies indicate aridity. The models that agree most closely with the LIG proxies differ from the PMIP4 ensemble by showing relative wetness in the eastern US and dryness in the northwest and central US. An assessment of atmospheric dynamics using an ensemble subset of the three models with the highest agreement suggests that LIG precipitation patterns are driven by weaker winter North Pacific pressure gradients and steeper summer North Pacific and Atlantic gradients. Comparison of this LIG subset ensemble with simulations of future low emissions scenarios indicates that the LIG may not be a sufficient analog for projected, end-21st century hydroclimatic change in North America.