Date of Award
Spring 6-15-2025
Document Type
Thesis (Master's)
Department or Program
Earth Sciences
First Advisor
Jonathan M. Winter
Second Advisor
Erich C. Osterberg
Third Advisor
Justin S. Mankin
Abstract
Climate change has the potential to enhance hydrologic and agricultural drought risk in the northeastern United States, yet the Northeast has experienced observed total and extreme precipitation increases. Here, we investigate whether observed regional drought risk has changed over the last century despite well-documented hydrologic intensification. We use the Palmer Drought Severity Index (PDSI) calculated with station data from the Global Historical Climatology Network to assess seasonal drought from 1901 to 2022. We find that Northeast drought across all months is both less frequent and less severe over the last 40 years, decreasing by 59.1% and 18.7% respectively, relative to 1901-1983. Drought frequency decreased by 56.3% and intensity decreased by 16.2% during the warm season, when drought poses the greatest agricultural risks. Reduced hydrologic and agricultural drought risk is largely consistent throughout the Northeast and across stations. The variance in dry and wet events has not significantly changed over time, suggesting that the Northeast hydroclimate is not any more volatile at the monthly timescale than it has been in the past. These findings suggest that precipitation increases to date have outpaced increased evapotranspiration demand from warming, but do not preclude the possibility of future increases in drought risk with additional warming. Collectively, our findings contextualize recent trends in seasonal Northeast drought, finding a marked reduction in seasonal root zone drought and represent a stark contrast with the enhanced regional warm-season surface soil moisture drought risks consistently projected across model ensembles. Our results inform current and future water management decisions, from agricultural to residential water use, as well as efforts to prioritize climate change hazards across the Northeast.
Recommended Citation
Wargo, Janelle Lenore, "Observed Decreases in Seasonal Drought Across the Northeastern United States" (2025). Dartmouth College Master’s Theses. 228.
https://digitalcommons.dartmouth.edu/masters_theses/228
