Sea ice in the Arctic continues to experience record-low levels, with both extent and thickness on track to break winter-minimum records over the coming weeks, and thicker, older ice becoming extremely rare. One team of scientists has published a radical new idea to reverse this sea ice decline: refreezing the Arctic by using wind-powered pumps to spray seawater over the ice cap.
Writing in Earth's Future, the journal of the American Geophysical Union, a team led by Steven Desch of Arizona State University proposes setting up millions of wind-powered pumps around the Arctic; these would spray sea water onto the surface of the ice, where it would freeze and thus thicken up the ice cap. The team predicts that, with enough pumps, their scheme could add a meter (3.25 feet) of ice over the course of a winter. "It is noteworthy that half of the Arctic sea ice currently has a mean annual thickness of only 1.5 meters [4.9 feet]," they write. "Adding 1 meter of ice in the course of one winter is a significant change."
Desch explains part of the motivation as being that present plans to reduce global warming seem unlikely to do enough.
"Our only strategy at present seems to be to tell people to stop burning fossil fuels," Desch told The Guardian. "It's a good idea but it is going to need a lot more than that to stop the Arctic's sea ice from disappearing."
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His team's proposal is the latest in the field of what is known as geoengineering: deliberately manipulating the environment on a large scale to affect Earth's climate and reduce warming. Most such proposals today center broadly around two particular areas: spreading a thin layer of sulfate particles in the stratosphere to reflect part of the sunlight hitting Earth; and what is known as Bioenergy with Carbon Capture and Storage, or BECCS - deriving energy from biofuels (which act as carbon sinks when growing) and capturing the CO2 emitted during their burning and burying it underground. But there have been plenty of other proposals, some outlandish and many highly controversial, from creating "artificial trees" to building a giant solar parasol.
Much of the controversy surrounding many geoengineering proposals concerns the issue of unintended consequences: Yes, a large-scale intervention might well reduce the amount of sunlight reaching the planet's surface, but at what cost? As NASA scientist Gavin Schmidt noted in 2009, "a planet with increased CO2 and ever-increasing levels of sulfates in the stratosphere is not going to be the same as one without either. The problem is that we don't know more than roughly what such a planet would be like."
One widely-discussed proposal - to 'fertilize' the ocean with iron, thus promoting growth of phytoplankton which would act as carbon sinks - has been heavily criticized, not least because of the potential impacts on marine environments.
Virtually all geoengineering proposals are also hugely expensive. Desch and his team, for example, concede that their plan would cost around $500 billion and require as much as 100 million tons of steel a year - more steel than the United States presently produces annually. Critics argue that such an expenditure is the wrong path to follow, given that alternative energy and energy conservation technologies are already available and becoming increasingly affordable and efficient. (BECCS is generally not subject to the same degree of criticism, although there are questions about the amount of land use that would be required and its ability to be effective on anything other than the long term.)
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As Jennifer Morgan, executive director of Greenpeace International, notes: "It's clear we're in a climate crisis. We know what's needed - emission cuts - and what's missing is not technical, it's political."
More generally, there are also concerns that the pursuit of geoengineering schemes detracts from, or diminishes the incentives toward, adopting existing technologies or adapting human behavior in response to climate change.
But, says Douglas MacMartin of the California Institute of Technology, while it is true that, "if we cut carbon emissions on the necessary scale, we don't need these other measures," it remains to be seen whether such cuts are truly on the table. There is a broad consensus that planetary warming should be, at worst, kept beneath 2 degrees Celsius, and arguably even 1.5 degrees; but, MacMartin continued, "if you look at all the commitments [to the 2015 Paris climate change accord] you're still left with a world that is 3 degrees warmer."
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Going even further, Jane Long, co-chair of the Task Force on Geoengineering for the Bipartisan Policy Center, argues that "models suggest there is no way we can stay below 2 degrees C without some kind of intervention."
For that reason, the U.S. Global Change Research Program (USGCRP) noted, in a climate-science planning report sent to Congress in January, that "[w]hile climate intervention cannot substitute for reducing greenhouse gas emissions and adapting to the changes in climate that occur, some types of deliberative climate intervention may someday be one of a portfolio of tools used in managing climate change." It recommended a research program that would provide "insight into the science needed to understand potential pathways for climate intervention or geoengineering and the possible consequences of any such measures, both intended and unintended."
Additionally, Thursday saw the formal launch of the Carnegie Climate Geoengineering Governance Initiative (C2G2), which aims to encourage dialogue on and to develop governance frameworks for climate geoengineering. Morgan, MacMartin and Long were speaking at a forum to mark that launch.
"Emissions reduction has to be the priority," said C2G2 Executive Director Janos Pasztor. But "we cannot say for sure how far intensive mitigation that countries have committed to will take us." Meanwhile, we "don't know enough to determine the viability [of geoengineering schemes]. We know even less about what governance frameworks we would need to ensure that research goes in certain ways, and that when decisions need to be made, they will allow the participation of all the different actors."
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Oliver Morton, senior editor at the Economist and author of "The Planet Remade: How Geoengineering Could Change the World," told the forum that, "Very, very few people in the field see geoengineering as an alternative to emissions reduction. I would see it as a complement: While doing emissions reduction, we can do other things that reduce actual harm." A key, from his perspective, is to develop both the science and the governance structures before it's too late. "We should absolutely not be thinking about this as an emergency response," he said. "Times of emergency are terrible periods of governance: 'It's an emergency, let's throw out all the rules.'"
Long argued that events would ultimately force the collective global hand. "People will begin feeling climate stress, such as in heatwaves, and asking, 'What can we do?' People are going to be making interventions on local and then regional, and then ever-growing scales until what they are doing does begin affecting the global climate."
Deciding whether to pursue geoengineering as a factor in addressing climate change will, suggested MacMartin, require addressing and answering difficult and uncomfortable questions.
"It's absolutely true that we could cool the planet by introducing particles into the stratosphere," he said. "Just because we could, doesn't mean we should. But there's a plausible argument that there's less risk in doing that than in allowing the planet to heat by 3 to 4 degrees."
The prospect of a potential climate solution involving some tough calls was a theme underlined by Long.
"Don't forget that the sulfur dioxide being put into the air by power plants, which is horrible for human health, is cooling the Earth," she said. "This is complicated. It's very, very complicated."
Photo: The 2016 Arctic sea ice summertime minimum is shown compared to the 1981-2010 average, shown as a gold line.
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