Reach 2025: Paul Hoffman
By Liz Do
A visionary who unraveled Earth's icy mysteries
When Paul Hoffman joined CIFAR’s Earth System Evolution program in 1995, he was widely recognized for demonstrating that plate tectonics have operated on Earth for billions of years. CIFAR’s support, however, allowed Hoffman to explore new, ambitious ideas beyond conventional thinking.
His curiosity led him to contribute to the Snowball Earth hypothesis, which proposes that the expansion of polar sea ice eventually reached a critical threshold, plunging the entire ocean into a global deep freeze that lasted millions of years. Over time, the gradual accumulation of volcanic greenhouse gases triggered a rapid and dramatic warming, leading to a period of intense heat until the excess gases were eventually drawn down. These extreme climate swings would have had profound effects on the evolution of microbial life, which was already well established by the time the Snowball Earth events are thought to have occurred.
Hoffman’s bold hypothesis was initially controversial, sparking extensive investigation and debate within the scientific community, and even within the Earth System Evolution program.
However, “CIFAR was very encouraging,” he says. “Why did I do the heavy slogging against a lot of opposition initially? Because I was reaffirmed every year when I met with CIFAR [researchers], and they, of course, accelerated my progress because I had world-leading experts I could meet and talk with.”
The Snowball Earth hypothesis is now a cornerstone of modern Earth system science research. This groundbreaking work led him to receive the prestigious Kyoto Prize in Basic Sciences in 2024, making him the first geologist to receive this distinction. "The most thrilling thing was having geology recognized as a basic science," he says.
Hoffman’s contributions have not only deepened the world’s understanding of Earth’s icy past, but his work inspires ongoing research into climate change and evolutionary biology. Today, research into earth sciences also remains ongoing at CIFAR through the Earth 4D: Subsurface Science & Exploration program.
Reflecting on his academic career, Hoffman emphasizes that CIFAR’s support for fundamental research and its interdisciplinary environment was essential in enabling his visionary work from the very beginning.
"Working with such a diverse group as we had in CIFAR and meeting on an annual basis to discuss our ongoing research was extremely valuable,” he says. “I could never have had the success I had with Snowball Earth without CIFAR.”
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