High Latitude Modulation of the Holocene North American Monsoon

Cody C. Routson, Michael P. Erb, Nicholas P. McKay

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


The North American monsoon (NAM) is an important source of rainfall to much of Mexico and southwestern United States. Westerly winds (westerlies) can suppress monsoon circulation and impact monsoon timing, intensity, and extent. Recent Arctic warming is reducing the temperature gradient between the equator and the pole, which could weaken the westerlies; however, the implications of these changes on the NAM are uncertain. Here we present a new composite index of the Holocene NAM. We find monsoon strength reached a maximum circa 7,000 years ago and has weakened since then. Proxy observations of temperature, hydroclimate and upwelling, along with model simulations, show that the NAM was modulated by the westerlies over the Holocene. If the observed Holocene pattern holds for current warming, a weaker meridional temperature gradient and weaker westerlies could lead to a stronger future NAM.

Original languageEnglish (US)
Article numbere2022GL099772
JournalGeophysical Research Letters
Issue number16
StatePublished - Aug 28 2022

ASJC Scopus subject areas

  • Geophysics
  • General Earth and Planetary Sciences


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