THE Arctic is in a death spiral. The top of our world is heating up faster than anywhere else on the planet, setting new records for the speed and area of ice melt. We are on track this year to have one of the lowest summer sea ice coverages so far. It is a huge problem, because what happens in the Arctic doesn’t stay in the Arctic.
What’s more, the Greenland ice sheet, which alone contains enough water to raise global sea levels by 6 metres, is disappearing. The frozen Arctic soil and sediment, or permafrost, is melting, releasing more and more carbon dioxide and methane into the atmosphere. This year, vast wildfires in the peatlands of Siberia have blazed for more than a month, and the Arctic warming is playing havoc with weather systems in the northern hemisphere too. But if you prefer to think simply in terms of money, the economic impact of unmitigated Arctic warming by the end of this century was recently estimated to be $67 trillion. As US congressman Jerry McNerney says: “When it comes to the Arctic, we’re in deep shit.”
You’ve heard the slogans: we are living in a time of climate emergency. But it is no good declaring an emergency without summoning help. So here it is: let’s refreeze the Arctic. There are several imaginative ideas to manipulate its climate system to get the ice back. They won’t be cheap or easy, but some researchers argue that the crisis in the north is too serious not to at least investigate ways to engineer the return of the ice.
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Climate intervention in the Arctic might be more necessary than it first appears because the region’s death spiral is a feedback loop. As the shiny ice melts, models and satellite images suggest we could get a sea ice-free summer any year now. When the ocean is exposed, instead of reflecting sunlight, the dark water absorbs more of the sun’s heat. Over the past 30 years, this change corresponds to a warming equivalent to a quarter of all the carbon dioxide released by human activity during that time. The warming is weakening the polar jet stream – the fast-flowing, high-altitude air current – in the northern hemisphere, resulting in more”blocked” weather patterns, and corresponding droughts, floods and heatwaves.
The global risks are huge. “Allowing the Arctic to change in unrecoverable ways poses an enormous safety risk to communities around the world and could move the climate system beyond our ability to recover,” says Kelly Wanser, director of SilverLining, a geoengineering NGO based in Washington DC.
“It is no good declaring a climate emergency without summoning help. So here it is: let’s refreeze the Arctic”
Of course, we could have prevented the Arctic from warming as much as it has if we had cut global greenhouse gas emissions when scientists first started advising us to do so, decades ago. But we didn’t, and nor are we now. “It’s a pious hope and anyway it would take a while,” says Peter Wadhams, head of the Polar Ocean Physics Group at the University of Cambridge.
This is why a growing number of scientists argue that, if we want to save the Arctic, we need to intervene directly by manipulating its climate system. There are three main proposals for doing this: increasing the extent of sea ice; artificially brightening the surface of the ice to reflect more sunlight; and cooling the Arctic air by brightening the clouds to deflect sunlight.
All three ideas are forms of geoengineering: intervention in the environment on a scale big enough to counteract climate change. The concept bothers many scientists because they fear that the idea of a technological fix will undermine efforts to cut carbon dioxide emissions. “Well, we’re not making them anyway,” says Cecilia Bitz, a sea ice physicist at the University of Washington in Seattle. “Maybe intervention would be positive, showing that we have the capacity to improve the environment.”
For those advocating such action, a big concern is the methane already streaming out of the seabed as microbes break down thawed organic matter. “The fear is that this will grow from being a set of methane plumes to an outbreak,” says Wadhams. “So we need to bring back the ice around the coastal seas, and that might save us from a catastrophic methane burst.” As well as this methane trapped under the sea, an estimated 1 trillion tonnes of carbon are in the top 3 metres of Arctic soils. If only a small fraction of this reaches the atmosphere, it will overwhelm any cuts in emissions we have made. “It seems that nature offers us a choice: instant methane from the seabed giving us a huge immediate burst of warming, or longer, slower warming from complex chemical processes as terrestrial permafrost thaws. Except that it’s not an ‘or’, it’s an ‘and’.”
The first potential solution comes from Steve Desch, an astrophysicist at Arizona State University. His plan is to build windmills that pump seawater onto surface ice during the winter, where it will freeze, thickening the sea ice and extending its coverage. This method was recently proposed to prevent the collapse of the Antarctic ice sheet too.
“Arctic sea ice may be restored by brightening ocean stratocumulus clouds”
Sea ice moves around, so Desch’s idea is to locate the windmill-pumps on sea ice in the north of the Arctic. This would help thicken chunks of ice that are then protected from melting when they move south. “While that may seem like an impossible task, since the Arctic is a very large place, we outlined a mechanism, using simple, brute-force, steampunk technology that is not impossible, but enormous in scope,” he says. “It’s not like a space mirror larger than the Earth or something. It’s pretty simple, but just a big job.”
Desch has calculated that we would need 10 million windmills across the entire Arctic to refreeze it, at a cost of $500 billion. That is a huge sum, but just a fraction of the estimated $67 trillion economic impact of Arctic warming if we don’t act. Bitz has evaluated Desch’s idea in a paper currently submitted for publication. “The physics can work,” she says. “The basic principles make sense. To me that’s promising.” But so far, Desch only has a prototype windmill that works in the lab. For a true test, field trials are essential.
The second proposal for geoengineering the Arctic has had some success outside the lab. It involves covering the ice with shiny, white beads. The idea is that these microbeads increase the reflectiveness, or albedo, of thin, young ice, so protecting it from the sun. The leading advocate is Leslie Field, an engineer at Stanford University in California, who also runs Ice911 Research, a non-profit organisation exploring methods of restoring Arctic ice, mainly using hollow silica microspheres. These bright, non-toxic beads are chemically and physically similar to sand but smaller, more like powder, with a diameter of about 65 micrometres (0.065 millimetres).
Field and her colleagues have tested the idea, most notably on about 4200 square metres of North Meadow Lake in Alaska. They have shown that the microspheres increase albedo by around 20 per cent and slow the ice melting. To cover 25,000 square kilometres of the Arctic with the stuff would cost about $300 million for the materials alone, says Field. This represents just 0.7 per cent of summer ice coverage at its lowest extent on record: 3.4 million square kilometres in 2012. Yet many questions remain, not least whether it works on sea ice – so far it has only been tested on frozen lakes. And what happens to the beads when ice melts? Some sink and are incorporated into the mud on the lake floor, says Field.
There are, however, concerns about the biological hazards of this approach. Bitz says she is worried about the ecological impact of adding millions of tonnes of silica to the Arctic. “For me this raises a red flag,” she says.
Reflective microspheres are being used to preserve winter ice in North American lakes (below)
Alexander Sholtz
Ken Caldeira, who researches geoengineering at the Carnegie Institution for Science in California, has doubts about the workability of modifying the surface of the ice – whether by the methods proposed by Field or Desch – and about whether this could be an effective tool against climate change. “I am highly sceptical that this approach will prove feasible and desirable at scales required to be climatically substantial,” he says.
For Bitz, Wadhams and several other climate scientists who spoke to New Scientist, the most promising potential intervention is one that doesn’t involve tinkering with the ice directly. Instead, it entails brightening the clouds over the Arctic.
Alexander Sholtz
The idea dates back to the 1990s, when John Latham, now at the University of Manchester, UK, started thinking about ways of limiting the greenhouse effect by reducing the amount of sunshine reaching the planet’s surface. Latham was fascinated by something called the Twomey effect, which describes how the amount of solar radiation that clouds reflect back into space depends on the concentration of tiny particles around which cloud droplets form. He realised that you could increase this concentration over oceans by seeding clouds with tiny droplets of salt water.
We know from satellite images of ship tracks – the equivalent of the contrails left by airplanes – that clouds can be seeded by the sulphate emissions from ships. Latham and his colleagues have produced computer models showing how Arctic sea ice may be restored by brightening ocean stratocumulus clouds. These large, rounded clouds are by far the most common kind seen in the Arctic, and are usually found in groups covering huge areas.
On paper, it looks promising, but testing it for real is quite another matter. To do so will require a system that can spray an ultra-fine mist of sea water into the lower atmosphere over a large area of ocean. Stephen Salter, an engineer at the University of Edinburgh, UK, has well-advanced plans for this, having developed proposals for remotely operated drone ships able to deliver the spray, which he presented to the UK government’s Environmental Audit Committee’s 2017 inquiry into Arctic sustainability. The thing holding him back is lack of funding.
For the price of Neymar
Shortly after I started corresponding with Salter, he sent me a photo of Brazilian footballer Neymar, beaming as his transfer to Paris St Germain was announced in 2017 at a cost to the French club of £198 million. Salter’s point was made clear when he detailed the costs of his cloud-seeding project. For the price of Neymar, researchers could conduct all the preliminary trials and then run an entire fleet of ships for two years that might start to restore the damage done to the Arctic.
“Among ideas to prevent Arctic collapse, the most viable in terms of the scale and nature of the problem involve increasing the reflection of sunlight from the atmosphere,” says Wanser, who is also an adviser to the University of Washington’s Marine Cloud Brightening Project. “However, our effective level of investment in sunlight reflection is zero. This leaves us with an enormous exposure to near-term climate risk and not enough fast-acting options to keep warming within safe levels.” Several scientific assessments have identified marine cloud brightening as one of the most promising methods to manage sunlight levels, says Rob Wood at the University of Washington.
We don’t yet know how effective cloud brightening might be. But there is another reason to do this research: it could help solve one of the biggest puzzles related to how warm our planet could get (see “Cloudbusting”).
In the meantime, the region continues to turn from white to blue. Wadhams, who has led 40 expeditions to the Arctic, has seen enormous change in that time. “When I started going to the Arctic, you could think of the whole of the northern hemisphere as a solid continent,” he says. “Ice connected Eurasia and North America. But now you have blue ocean. Physically and psychologically, the world is fragmented, and I think that is having an important change in how people think.”
Cloudbusting
Predicting warming means deciphering the role of clouds
NASA/Robert Simmon &Jesse Allen/Jeff Schmaltz, MODIS Rapid Response Team
Clouds play a vital part in controlling our climate. Their reflection of the sun’s rays, especially at the tropics, is essential for cooling Earth. But we don’t know how cloud formation will change as the planet gets hotter. This means we don’t know how much warmer Earth will become for a given increase in carbon dioxide concentration in the air.
Climate change deniers often point out that there is too much variability in the predictions climate models make about warming. One reason is a lack of certainty about so-called climate sensitivity. This is a measure of the amount of warming that results from a doubling of carbon dioxide in the atmosphere. In climate models, it ranges from 2°C to 5°C.
We don’t know if our climate is particularly sensitive – in that a doubling of CO gives a correspondingly large increase in heating – or if it is resilient. But Tapio Schneider, a climate scientist at California Institute of Technology in Pasadena, says evidence from improved recent climate models points towards the planet being more sensitive than we thought, which means we should be very worried. If it is that sensitive, then we will get 1°C of additional warming from adding a mere 70 parts per million or so of CO to the atmosphere – which would take about 20 years at the current rate. That would take us over 2°C of global warming since pre-industrial times, the level at which “severe impacts” are expected: more wildfires, longer periods of drought in some regions and an increase in the number and intensity of tropical storms.
Cloud formation is boosted by atmospheric particles called aerosols, many of which are pollutants from dirty industrial processes and fossil fuels. As these particles have a cooling effect on the planet, both directly and through their action on cloud formation, phasing out their sources will unmask previously concealed greenhouse gas warming. So to understand the extra bump of warming we can expect when the atmosphere gets cleaner, we need to figure out how clouds contribute to climate sensitivity.
“Marine cloud-brightening experiments have the potential to shed light on one of the most vexing and important questions in climate science, namely how aerosols affect clouds,” says Schneider. “It behooves us to do everything we can to understand the climate system better, before we try to manipulate it.”