December 22, 2016
Interdisciplinary group works with students to find a way to make plan work in region where climate-change effects are severe
The idea started after a depressing climate conference in 2012: ASU’s School of Earth and Space Exploration (SESE) professor Steve Desch walked away feeling that the only scientific solution anyone was proposing to combat climate change was to radically reduce CO2 emissions, a near impossibility in a world filled with people and their machines.
“We can’t put the world back the way it was,” Desch thought, “so how can we at least work on fixing part of the problem?”
He started thinking about solutions that might work in the Arctic, where the effects of climate change are some of the most severe. In the Arctic, thawing of permafrost and melting sea ice has led to a positive feedback, an ever-increasing cause-and-effect loop, on Earth’s climate. So Desch started looking for ways to reverse the sea ice loss.
The idea he pursued, beautiful in its simplicity, is to build millions of windmill pumps to make more ice.
Desch, a theoretical astrophysicist, joined forces with SESE’s Christopher Groppi, a systems engineer, and Hilairy Hartnett, an oceanographer with SESE and the Julie Ann Wrigley Global Institute of Sustainability, to teach a course at ASU that would focus on this idea: a windmill pump on a buoy with a hose, a device that would artificially increase the thickness of ice in the Arctic. Together with their students, they essentially combined three interdisciplinary creative strengths to find a way to make their plan work.
They called the innovative course “Geodesigning the Arctic,” and the class’s research and proposed solution is presented in a recently published article titled “Arctic Ice Management” in the American Geophysical Union’s journal Earth’s Future.
Ice in the Arctic is melting faster in the summer and not building enough in the winter. This represents a strong positive feedback on climate because while ice reflects 90 percent of sunlight, the ocean absorbs 90 percent of sunlight, so the less ice there is, the more heat the planet absorbs. In addition, when Arctic permafrost ground melts, it releases methane, amplifying the greenhouse effect in the atmosphere just like CO2. All told, we’re quickly running out of time to reverse this vicious cycle of cause and effect.
Leading climatologists estimate that we have fewer than 20 years to make serious changes, or this sequence of less Arctic ice in the winter and more melting during hotter summers will lead to the Arctic Ocean being completely ice-free in summer as soon as 2030, driving temperatures even higher throughout our planet.
Arctic sea-ice extent (area covered at least 15 percent by sea ice) in September 2007 (white area). The red curve denotes the 1981-2010 average. Sea-ice extent in 2016 was the second lowest ever recorded. Image courtesy of the National Snow and Ice Data Center
“Ice-free summers are in our future,” Desch said. “We have to do something now, and we have to do it in the Arctic.”
Since human habits are unlikely to change so dramatically that this cycle can be reversed, the question to scientists now, argues this research team, is how to make more ice in the winter or keep it frozen in summer.
Scientists and students in the ASU class focused on the first half of the puzzle, building models and consulting observations to determine how ice freezes and thickens. They calculated that 1.4 meters of seawater pumped to the frigid surface during the long Arctic winter night lets it freeze more readily and produces an additional 1 meter of ice in a single winter. This would help the Arctic do what is already does naturally in the winter: make ice.
This is where the windmill pump on a buoy with a hose takes center stage. If water in the Arctic could be pumped to the surface, it would freeze faster. The Arctic already provides a steady, renewable source of wind power; the windmill would give power to the pump, the buoy would keep the contraption afloat in summer, and the force of the water from the hose would help distribute the water around the windmill.
Each windmill-powered pump could spread ice over about a 0.1-square-kilometer area in the Arctic. About 10 million windmills would be needed to cover a large enough area to be effective. At an estimated cost of $50,000 per windmill, implementation over 10 years would cost about $50 billion per year.
“The scale of climate change and associated problems is so large it paralyzes us into inaction,” Desch said. “But we can make real progress in the Arctic by putting people to work and using just a fraction of the industrial capacity that accidentally caused climate change in the first place.”
If the design works, the windmill-powered pump could effectively reverse the ice-loss trend and even potentially make more ice. And there’s an added benefit to humans in creating ice. If sea ice stays frozen for several years, its salt leaches out, leaving potable water. Polar explorers relied on this, and harvesting polar ice could help supply fresh water to cities and farms.
“Maybe trying to make more ice in the Arctic using windmills and pumps and hoses is a crazy idea,” Desch admitted, “but what’s really crazy is doing nothing while the Arctic melts.”
The next step the team proposes is to work with colleagues internationally to promote the idea of Artic ice management and apply these ideas to saving, and perhaps creating, more Arctic ice. They will then need to build prototypes of the windmill pump to see what would work in the real world. They also propose working on the second half of the puzzle, using other ice-saving ideas like marine cloud brightening, essentially making fog and blocking sunlight, to stop the ice from melting in the summer.
Most of all, they want the discussion to broaden beyond scientific circles, to include policy makers and other stakeholders in the Arctic.
“We hope to provoke discussion and action,” Desch said. “Whether we choose to be in or not, we’re in charge of the climate now, so let’s all do the best we can.”
Top photo: Arctic sea ice and melt ponds in the Chukchi Sea. Image courtesy of NASA/Kathryn Hansen