Congratulations to HAS Professor and University Distinguished Scholar Jennifer McIntosh Elected 2026 AGU Fellow

Dr. Jennifer McIntosh, a University of Arizona hydrologist whose research explores water, gases, and microbial life deep beneath Earth’s surface, has been named a Fellow of the American Geophysical Union, one of the organization’s highest honors.  

McIntosh said the recognition was both a significant professional achievement and an honor she never expected to receive.  

“It is a huge honor and something I never saw in the cards for me,” McIntosh said. “I appreciate my colleagues and my peer mentoring group of female faculty at the U of A that have supported me and been my cheerleaders."   

The AGU Fellows program recognizes members who have made exceptional contributions to Earth and space science through a breakthrough, discovery, or innovation. Fellows are also recognized for scientific leadership, mentoring, public engagement, and communication.  

McIntosh serves as the Thomas Meixner Endowed Chair in Hydrology and Atmospheric Sciences, University Distinguished Scholar, Professor and Associate Head of Hydrology and Atmospheric Sciences, and Joint Professor of Geosciences.  

She has spent nearly two decades at the U of A, where her research focuses on the limits of water and microbial life deep within Earth’s crust. She studies the origin, movement, and characteristics of water, gases, and microorganisms underground, researching applications ranging from groundwater resources to critical minerals and energy production and storage.  

Her interest in hydrology began with chemistry. McIntosh was a chemistry major in college when she took a geology course and became interested in how chemistry could be applied to the landscape.   

“I was always interested in water, and then I went on a family trip to Yellowstone National Park, which is one of the most spectacular places where you can see chemistry, hydrology and microbiology all in action,” McIntosh said. “That’s what propelled me to graduate school. I consider myself a hydrogeochemist.”  

When McIntosh received a job offer from the U of A she had never been to Arizona, but the university’s reputation in hydrology was enough to convince her to make the move.  

“I knew it was the top program in hydrology in the United States and renowned globally, so I couldn’t say no,” she recalls.  

Early in her career, she discovered that groundwater in the Great Lakes region came from melting ice sheets from the last Ice Age. She also found the glacial meltwater activated microbes deep underground that generated methane.  

More recently, a paper led by her Ph.D. student Chandler Noyes found that well water being used on the U of A campus is more than 15,000 years old. The groundwater dates to the end of the last Ice Age, when the climate was colder and wetter and recharge rates were higher.  

McIntosh also leads a large National Science Foundation-funded project studying subsurface microbe, rock and fluid systems, known as SMRFS, in the Colorado Plateau. The project examines how downcutting of the Colorado River over millions of years eroded the landscape and created steep topographic gradients that moved rain and snowmelt deep into the subsurface, flushing out ancient saline water and bringing microbes underground.  

Those microbes are capable of degrading oil and generating methane and hydrogen sulfide. She said the research has implications for emerging subsurface resources, including lithium and helium, as well as the storage of hydrogen and carbon dioxide.  

As society moves toward greener energy sources, McIntosh said the subsurface will become increasingly important for both alternative energy production and storage.  

She calls the growing use of underground environments the “acceleration of the subsurface.”  

Arizona provides a particularly important setting for this work.   

“People think of Arizona as being so dry, but that means we are even more dependent on groundwater resources,” McIntosh said. “Especially if you read the news about the Colorado River and the prolonged drought, we are going to be even more dependent on groundwater.”  

McIntosh’s work also extends beyond research. She has served as a scientific adviser for organizations including the National Academies of Sciences, Engineering, and Medicine, the UK Royal Society and the International Atomic Energy Agency. She hopes the AGU fellowship will create additional opportunities to advise government and scientific organizations on policy and future research directions.  

Mentoring is another important part of her career. McIntosh has advised more than 77 undergraduate and graduate students and postdoctoral fellows, many of whom have gone on to careers in academia, government agencies and environmental consulting. She said her students have also helped push her research into new directions.  

“They've been pivotal in pushing us forward in new directions, discovering new things,” McIntosh said.  

For students interested in Earth or environmental science, McIntosh advises getting involved in research early.  

“Find a lab or research group to work in as an undergraduate student,” she said.  

For McIntosh, the AGU fellowship recognizes not only her scientific work but the career, mentorship and research relationships that helped her get there.  

After nearly 20 years in Tucson, the scientist who arrived in Arizona without ever having visited the state has become part of a community she now helps shape through her research, teaching and mentorship.