We use cookies to ensure that we give you the best experience on our website. You can change your cookie settings at any time. Otherwise, we'll assume you're OK to continue.

Institute of Advanced Study

Professor John (Jack) Williams

“ Conversations with other IAS fellows and the IAS lunch seminar discussions repeatedly highlighted interesting points of intersection among our fields.”

Professor Jack Williams, University of Wisconsin-Madison

IAS Fellow at Ustinov College, Durham University (January - March 2017)

John (Jack) Williams is a Professor in the Department of Geography at the University of Wisconsin-Madison in Madison, Wisconsin, USA, where he serves as the Director of the Center for Climatic Research, part of the Nelson Institute for Environmental Studies. Professor Williams also co-leads the Paleoecological Observatory Network (PalEON) and the Neotoma Paleoecology Database (, both spanning multiple universities, research groups, and disciplines.

Professor Williams’ research focuses on the responses of plant species and communities to past and future climate change. Much of his work uses the late Quaternary (the last 21,000 years) as model systems for understanding plant species and community responses to climate change, with a particular emphasis on the temperature rises and other climate changes accompanying the last deglaciation. Key research areas include understanding species responses to rapid warming, hydrological variability, the ecological consequences of the late-Quaternary megafaunal extinctions, and the emergence of climates and communities with no modern analog. His research works across scales spatially from individual sites to continental- to global-scale reconstructions and temporally from decades to millennia. He works closely with ecosystem and earth system modelers, combining models and data to understand the causes of past ecological dynamics and test the predictive ability of ecological forecasting models when forced to simulate conditions outside the modern domain. Professor Williams is increasingly engaged in ecoinformatic and geoinformatic initiatives to build community-supported data repositories suitable for modeling ecological and biodiversity dynamics across space and time.

Professor Williams received his PhD in 1999 from Brown University and Bachelor’s from Oberlin College, USA. He was a postdoctoral fellow at the National Center for Ecological Analysis and Synthesis (NCEAS) at the University of California, Santa Barbara and a research scientist at the Limnological Research Center at the University of Minnesota Twin Cities, and has been a faculty member at the University of Wisconsin since 2004.

Professor Williams has authored or co-authored more than 100 papers and book chapters and his work has been widely influential among ecologists, biogeographers, and conservation biologists seeking to understand how help species adapt to 21st-century climate change. Awards include the William Cooper Award from the Ecological Society of America, the Phil Certain Distinguished Faculty Award and a Romnes Faculty Fellowship from the University of Wisconsin, a Kavli Fellowship from the National Academy of Sciences, a Bullard Fellowship from Harvard University, and an Aldo Leopold Leadership Fellowship from the Stanford Woods Institute for the Environment.

While at Durham, Professor Williams will be collaborating with Professor Brian Huntley and others on shared interests in the biogeographic responses of species to Quaternary climate changes. More information can be found at or via Twitter @IceAgeEcologist.

IAS Fellow's Public Lecture - Species Responses to Changing Climates Across Time and Space: From 55 million years ago to 2100 CE

Climates have changed throughout geological history, providing a series of natural model systems for studying ecological and evolutionary responses to climate change, at timescales ranging from decades to many millions of years. In this talk, Professor Jack Williams will focus upon three periods of climate change that are particularly relevant to global change ecology. The Paleocene-Eocene Thermal Maximum (PETM), 56.1 million years ago, offers an example of a large and rapid perturbation to and recovery of the global carbon cycle, equivalent to burning all below-ground coal reserves. The biological effects of the PETM varied widely among taxa, with a wave of extinctions in marine foraminifera, large turnover in plant community composition, and evolutionary radiations in mammals. The end of the last ice age, 19,000 to 8,000 years ago, offers a natural system for studying species responses to a 4°C global warming, regionally abrupt climate change, the emergence of climates with no modern analog, and rising levels of atmospheric carbon dioxide. In response, species shifted their ranges by 100s of km and reassembled into communities also lacking any modern analog. The Holocene offers an example of enhanced hydrological variability during warming climates, characterized by decadal- to centennial-scale shifts in drought and flood regime and regionally abrupt collapses of tree populations. In all cases, at all timescales, these climate changes had major effects upon the distribution, abundance and diversity of species. Moreover, we can use the past as a testing ground for ecological models, testing their ability to predict ecological dynamics in a rapidly changing and novel world.

Listen to the lecture in full.

Professor Jack Williams Publications