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Though his specialty is glaciology and much of his research falls squarely into the category of climate change, Fastook is first and foremost a classical physicist whose specialty is solving numerical equations through a computer.
“Ice is a nonlinear material, so all of the solutions need to be mathematical solutions,” Fastook says. “You can solve problems you can’t solve analytically.”
Whether on Earth or Mars, the challenges that ice presents are many. For starters, even though ice is solid, its movements are fluid. Ice sheets wax and wane for a variety of reasons — including internal physics, which Fastook’s model accounts for. To complicate matters even further, ice sheets themselves affect the climate by reflecting light and redirecting prevailing wind patterns.
“When I started out, this was a very obscure branch of Earth science, trying to understand the ice ages, why ice sheets disappeared and came back,” Fastook says. “At that time, we weren’t talking about climate change. Our question was, when will the next ice age start.”
But when the scientific community started raising questions about humans’ contribution to climate change, glaciologists such as Fastook rose from obscurity and became central to the conversation.
Some glaciers expand and retreat because of factors independent of climate. For example, the glaciers that covered Maine 14,000 years ago took some 2,000 years to collapse. But at the rate things are going today, the ice sheets in Greenland and Iceland could retreat within several hundred years. Fastook’s models of what happened in the past can help scientists predict and prepare for the future.
“Glaciers respond slowly to climate change. They filter out the noise of weather systems and respond to long-term changes. The kinds of changes we’re seeing in Greenland and Antarctica are true indicators that something is happening,” Fastook says. “In order to understand glaciers’ response to climate, we need to understand their internal physics, to understand their response to internal dynamics.”
Fastook’s models add to that understanding, whether the glacier is on Earth or on Mars. Most recently, he helped a Brown student who was trying to figure out the timing — and the implications — of a series of moraines near the equator of Mars. Were they the result of a 100,000-year climate oscillation, or was something else at play?
“They can look at the record and assign some chronology to the events they’re seeing,” Fastook explains. “Here, we have lots of methods to assign dates to things, like carbon 14 dating. With Mars and other planets, all you can look at are pictures and dating is a lot harder.”
The pictures raise interesting scenarios, though. Looking at images from the Mars Global Surveyor and the Mars Orbiter Laser Altimeter, Head saw eskers. Eskers mean that the bottom of an ice sheet is producing a lot of water as it moves. This suggests that at some point, Mars was warm enough for water, so Fastook built an ice sheet model of a warmer, wetter period on Mars.