As a scholar of environmental governance in Latin America, Hennessy’s research bridges political ecology, environmental history, multispecies studies, and science and technology studies to reveal how diverse ways of knowing the world structure political conflicts surrounding charismatic and economically important species. She combines place-based ethnographic and archival research to analyze how relationships among scientific understandings of life, the political economy of development, and local livelihoods shape resource-based development and conservation strategies in Ecuador.

Her first book, On the Backs of Tortoises: Darwin, the Galápagos and the Fate of an Evolutionary Eden was published by Yale University Press in October 2019 and was a finalist for the 2020 PEN/E.O. Wilson Literary Science Writing Award. She is currently working on a new project examining how the production of palm oil has reshaped relationships among land tenure, labor, and local ecologies in continental Ecuador.

Hennessy completed her PhD in Geography at the University of North Carolina at Chapel Hill in 2014. Her research has been funded by the U.S. National Science Foundation, the Mellon Foundation/Social Science Research Council, the Mellon Foundation/American Council of Learned Societies, and the Rachel Carson Center for Environment and Society.

At the University of Wisconsin–Madison, Hennessy advises graduate students in History, the History of Science, Medicine, and Technology, the Nelson Institute for Environmental Studies, and Geography. For three years (2015-2018), she was the faculty advising editor for Edge Effects, a digital magazine run by graduate students associated with the Center for Culture, History, and the Environment.