Doctor of Philosophy — PhD

As a PhD student at the Yale School of the Environment, Helen Siegel ’19 MEM, ’24 PhD spent three years collecting groundwater samples across Pennsylvania, Ohio, and West Virginia to better understand the sources and risks of contamination in the northern Appalachian Basin. Her research revealed that while fracking wasn’t the primary culprit, pollution from waste spills, road salt, and mine drainage posed serious risks  which are shaped, in part,  by local geology. 

Now a postdoctoral fellow at The University of Texas at Austin, Siegel partners with underserved communities to study PFAS exposure and co-create practical, locally informed solutions rooted in equity.

As the state of Connecticut’s urban forester, Danica Doroski ’21 PhD is working with municipalities, nonprofits, and residents to grow and maintain urban forests. 

“Investments in urban tree cover is a vital environmental justice issue,” Doroski says. “Urban areas with fewer trees can be as much as 20 degrees hotter than surrounding rural areas. By increasing tree cover, we can keep our cities cooler, which translates to both health and energy benefits.”

Forests help mitigate climate change because of their ability to remove and store carbon dioxide from the atmosphere, but they become carbon emitters during wildfires. PhD student Reid Lewis '20 MF is researching how satellite data and machine learning models can help fire-prone forests become more resilient.

“When we make these forests more fire resilient, we can not only store more carbon, we can also help protect human communities, foster wildlife habitat, safeguard watersheds, and can use the process of restoration to partner with and empower Indigenous nations,” says Lewis.

As co-leader of Black Marble, NASA’s light dataset, Eleanor Stokes '18 PhD is currently tracking the effects of Russian military strikes on Ukraine’s infrastructure and climate-induced natural disasters across the world. NASA’s Black Marble science team, which uses data from the Visible Infrared Imaging Radiometer Suite aboard NASA’s Suomi NPP satellite spacecraft  to map disaster impacts in vulnerable communities, was awarded the 2020 NASA Group Achievement Award for helping realize the vision of the NASA-ESA-JAXA COVID dashboard and enabling international partnership in a time of need.  “Humanity is facing major global risks from extreme weather and rising sea levels,” Stokes says. “It’s very important to have a satellite record that can speak to the human piece of the puzzle.

Matt Ashenfarb, a YSE doctoral candidate is studying the effects of the Inflation Reduction Act (IRA) on local economies, specifically its role in expanding clean energy investments. In one study, Ashenfarb and coauthors found that investment in clean energy projects roughly doubled in economically disadvantaged communities and parts of the country typically reliant on fossil fuel production. “The preliminary data suggest that IRA policies are working as intended,” Ashenfarb said. “Clean investments are growing everywhere, but particularly in those places that otherwise stood to lose most from the transition to a clean-energy economy.”

In the Tibetan Plateau, Yufang Gao ’14 MESc, ’23 PhD interviews, observes, and travels with Tibetan herders and Buddhist monks. He sets up camera traps and collects scat to analyze the diet of snow leopards. And he has hiked a mountainside 15,000 feet above sea level — all in pursuit of data for his dissertation focused on the quest for harmonious coexistence between people and large carnivores. What is needed for human-wildlife coexistence is a different perspective about conflict, Gao says. “Conflict,” he has found, “is part of coexistence.”

Daniel Piotto ’06 MF, ’11 PhD was well into his career when a meeting with YSE Professors Mark Ashton and Florencia Montagnini inspired him to apply to the one-year Master of Forestry program.

Six years and two YSE degrees later, Piotto went on to join faculty of the then-new Federal University of Southern Bahia, where he has led numerous studies on forest restoration and plantation forests in the region.

“My experience at YSE was my formation into who I am as a scientist and a professor,” said Piotto, who still retains his YSE ties, hosting students in Bahia and teaching courses for the ELTI certificate program.

Richard Guldin ’76 MFS, ’79 PhD has helped reinvent the U.S. Forest Service’s Forest Inventory and Analysis (FIA) program by integrating new sampling designs, field procedures, and innovative software to create an annual inventory that has become a global model. His work earned him the Society of American Foresters’ Sir William Schlich Award.