Geography professor Justin Mankin co-authored a study published in April 2026 in the scientific journal Nature about the impacts of extreme precipitation events on dryness conditions. The study found that concentrated rain events lead to increased soil dryness.
The Dartmouth sat down with Mankin to discuss his research and how climate change will impact global precipitation trends and soil health.
Can you tell us about your background in climate modeling?
JM: I began exploring climate modeling in graduate school. I was initially interested in tracing the relationship between the environment and violent conflict, and had spent time in southern Afghanistan. However, my graduate program did not support doing field work there, so I turned to models as an alternative. That’s how I became a climate modeler. My previous training was in political science, development economics, philosophy and especially security studies, which all inform the perspective I bring to climate science. I try to understand how climate change and variability impact human welfare.
What was the rationale behind this research project? What were you hoping to learn?
JM: This research was born from earlier work led by a postdoctoral researcher in my group, Corey Lesk. A lot of my research program focuses on what determines water availability for people and ecosystems, and how we expect that to change with global warming. Rainfall comes in heavier downpours as we warm the planet’s system, so the initial question was whether we expect more of that water to be intercepted by the vegetation canopy. That then led us to step back and ask: What does intense rainfall do to how much water there is on the land?
What were your overall findings?
JM: We found that more intense rainfall is associated with less water availability in the land. That effect is true everywhere, in both dry places and in humid places like New England. We used to believe that drought is simply a function of how much water comes in from precipitation versus how much leaves via evaporation; what our research reveals is that the delivery of that supply is as important as its magnitude. As rainfall intensifies, you’re effectively asking the land surface to drink from a fire hose. More of that water gets shunted into surface ponding, which is much easier for the atmosphere to re-evaporate than otherwise would have been the case.
How did you analyze terrestrial water storage and precipitation concentration?
JM: We leveraged existing satellite data from the Gravity Recovery and Climate Experiment satellite mission. GRACE detects gravitational anomalies predominantly caused by the redistribution of water around our planet, which you can use to infer how much water is in the land or not. We also used daily scale precipitation data and borrowed causal inference techniques from the economics literature. We used the Gini coefficient, which typically shows how wealth is distributed across a population, to instead look at how precipitation was distributed across a year.
What challenges might New Hampshire communities and policymakers face amidst changing climates? What recommendations might you have for them?
JM: From a water management perspective, New Hampshire has a lot of interventions on rivers. We’re going to have to think carefully about how we manage the duality of flood risk from rain coming in heavy downpours and the enhanced drought risk that comes later. It’s not an “either-or,” but a “both-and” situation.
Overall, New Hampshire needs to embrace the platform of rapid climate mitigation and decarbonization. Our results are not a fait accompli, but are based on how we’ve decided to deliver energy for people when there are viable and affordable alternatives. The climate has warmed and the impacts are manifesting, and New Hampshire needs to adapt.
What recommendations do you have for students interested in climate modeling and exploring the impacts of climate change on our planet?
JM: Every student should pursue, to some extent, a course that offers them some insight into the climate problem — whether it’s politics, ethics, engineering or physics. Leaving Dartmouth without that understanding is a real opportunity missed.
This interview has been edited for clarity and length.
Sahil Gandhi ’29 is a reporter from Staten Island, N.Y., and is majoring in environmental studies and government modified with philosophy and economics. He loves word searches and falling down internet and Wikipedia rabbit holes.
