Welcome! I am an Assistant professor of Environmental History at Georgetown University. I bridge the humanities and sciences to explore how societies and communities have historically thrived - or suffered - in the face of changes in the natural world. I focus on extreme environments and extreme environmental shocks. 
My first book, The Frigid Golden Age: Climate Change, the Little Ice Age, and the Dutch Republic, 1560-1720 (Cambridge University Press) was named by the Financial Times as one of the ten best history books of 2018. It explains how one society - the Dutch Republic - prospered as others faltered when volcanic eruptions cooled Earth's climate in the seventeenth century. My second book, Civilization and the Cosmos: An Environmental History of Humanity's Place in the Solar System (Harvard University Press/Penguin Random House), argues that dynamic environments across the solar system have played a bigger role in human history than previously imagined.
​When not writing books, I write articles and organize projects that pursue ''consilient'' history: the kind that transgresses disciplinary boundaries. New publications investigate the role of animal culture in shaping human responses to climate change; unearth connections between war and environmental change; and survey the global consequences of pre-industrial climate change.

​I currently lead two emerging groups of international scholars. The first traces cultural change among sentient animals in the Arctic over the past millennium, and the second finds examples of societal resilience to pre-industrial climate changes. While working on these projects, I teach courses at Georgetown on topics that include the Little Ice Age, global warming, the environmental history of outer space, big history, and the Anthropocene.
​Because I believe that studying the past can  help us confront the future, I work to bring the unique insights of environmental history to academics, journalists, policymakers, and the general public. My writing has appeared in the Washington Post and Aeon Magazine, among other publications, and I have been interviewed for articles that appeared in, for example, CNN, Axios, Popular Science, and Space.com.

I am also the founder and director of HistoricalClimatology.com, a popular website that explains the value of the past for understanding present-day climate change,  and the co-founder and co-director of the Climate History Network, an organization of nearly 200 academics in humanistic and scientific disciplines. I founded and host the Climate History Podcast, and recently established Climate Tipping Points, a student-driven project that aims to introduce a broad audience to the local consequences of climate change. Altogether, websites I founded receive nearly one million hits per year. I tweet at twitter.com/DagomarDegroot.