Few rivers are more important to the United States than the Mississippi River. It anchors agriculture, industry and transportation — sustaining millions of lives and billions in economic activity. Yet, with the rise of extreme climate conditions, its future has become increasingly uncertain. Will floods intensify, or will drought take hold? The stakes extend far beyond science, shaping the resilience of communities, the stability of economies and the security of food supplies across the country.
At Rice, graduate student Kelsey Murphy is working to find answers. Drawing on long-term climate model datasets, she looks at how the Mississippi River Basin has changed over the past 1,000 years and how it may respond to rising greenhouse gases and other human impacts in decades to come. Her research explores three big questions: How has the river’s flow changed over time? What forces drive those changes? And how do different parts of the basin contribute to the whole picture?
Murphy looks back over the last 1,000 years using climate model simulations to investigate how river flow may have responded to past climate conditions. The Mississippi naturally shifts between wetter and drier periods, but the last century stands out: Human-driven changes are amplifying extremes compared with preindustrial times.
By isolating factors like greenhouse gases and land use, Murphy finds that both play powerful but different roles. Greenhouse gases tend to dry the basin overall by reducing snowmelt and soil moisture, while land-use changes such as deforestation and agriculture can increase runoff and flood risk. “Changing how we use land may be the fastest way to deal with those extremes,” Murphy said. “Greenhouse gases stay in the atmosphere for a long time, and we’re already committed to much of their impact.”
Her work also shows that the Mississippi does not have a single future — some tributaries, like the Ohio River, could grow wetter, while others, such as the Missouri and Upper Mississippi, may get drier. “It’s not one river system,” she explained. “It’s many, and that makes planning for the future all the more complicated.”
These results highlight a troubling paradox: More rainfall doesn’t always mean more water security. Storms may grow stronger, but the interplay of snowmelt, runoff and soil moisture can still leave the basin drier. Murphy’s upcoming work will zoom out to investigate how large-scale atmospheric circulation patterns steer moisture toward the Mississippi basin and shape rainfall across the continental U.S.
Much like the Mississippi’s meandering flow, Murphy’s path was also not straightforward. She began in resort management, where the ski industry’s reliance on artificial snow made climate change impossible to ignore. A geology class at community college shifted her focus, and with encouragement from mentors during her undergraduate years, she turned toward paleoclimate and hydrology — eventually bringing her to Rice. “I didn’t grow up with geoscience classes,” she recalled. “It wasn’t until college that I realized how little I knew about climate change — and once I saw the scale of the problem, I couldn’t turn away from it.”
Today, she balances research with a passion for communication and outreach. From creating activities for Girl Scouts Day at Rice to fostering inclusive teaching practices, Murphy shows how Rice scientists connect discovery with education and community engagement.
As the School of Natural Sciences celebrates 50 years of discovery, Murphy’s work reflects its defining spirit: rigorous science paired with a drive to address society’s most pressing challenges. By clarifying the uncertain future of the Mississippi River Basin, her research not only advances our understanding of Earth’s climate systems but also helps communities prepare for the realities ahead.
— Aindrila Pal