So far, there are very few countries that have taken decisive action to mitigate climate change. Fears that the timid efforts of the major industrialized countries are coming too late are great, and not only among scientists. In fact, every effective method that helps to limit global warming as much as possible would be welcome, which is why technical approaches emerged several years ago, e.g. to remove greenhouse gases from the atmosphere. California researchers have now proposed a method to slow the melting process of Arctic sea ice.

The most important characteristic of sea ice is its ability to reflect sunlight. At least since the appearance of Homo sapiens on Earth, the frozen seas around the poles have acted like a giant parasol, helping to keep the planet cool and its climate stable. At least since the appearance of Homo sapiens on Earth, the frozen seas around the poles have acted like a giant parasol, helping to keep the planet cool and its climate stable.

But now much of this ice is disappearing at a rapid pace. The rising temperatures have trapped the Arctic in a self-destructive feedback loop: The warmer it gets, the more reflective ice disappears and more of the dark, solar heat-absorbing water surface is exposed. The warmer water accelerates the melting process, which means even greater absorption of heat that drives further melting – and so on in a vicious cycle, which is one of the reasons why the Arctic is warming about twice as fast as the rest of the planet. The rising temperatures have trapped the Arctic in a self-destructive feedback loop: The warmer it gets, the more reflective ice disappears and more of the dark, solar heat-absorbing water surface is exposed. The warmer water accelerates the melting process, which means even greater absorption of heat that drives further melting – and so on in a vicious cycle, which is one of the reasons why the Arctic is warming about twice as fast as the rest of the planet.

Some researchers feel driven to take unconventional measures in view of the gloomy outlook. A proposal by the California-based non-profit organization Arctic Ice Project seems as bold as it is bizarre. Their idea is to sprinkle a thin layer of reflective glass powder over parts of the Arctic to protect them from the sun’s rays and promote the regrowth of ice. “We’re trying to break this feedback loop and start rebuilding”, says engineer Leslie Field, a lecturer at Stanford University and founder of the organization. She hopes that by restoring the sea ice, it will resume its function as a planetary air conditioning system.

Among (climate) scientists, such technological interventions in the Earth’s natural system, known as “geoengineering”, are highly controversial, as the consequences are not foreseeable and possible side effects could cause further damage.

Emily Cox studies climate policy and public attitudes towards geoengineering at Cardiff University and says that “the utter lack of progress on climate mitigation is really opening up a space for all of these [Geo-Engineering] things to be discussed.” The uncertainty cannot be taken away by the urgency. “What do you do if something goes wrong… especially in the Arctic, which is already a fairly fragile ecosystem?”

Field launched the Arctic Ice Project in 2008. Her plan is to apply reflective material to fresh sea ice to protect it during the summer months. This additional protection could create stable, perennial ice. She decided to use tiny, reflective beads of silica, or silicon dioxide, as a material that occurs naturally in most sands and is used to make glass. These small glass beads with a diameter of 65 microns are hollow, so they float on the water and reflect the sunlight even when the ice begins to melt.

Tests in lakes and ponds in Canada and the USA have shown encouraging results: Ice on a pond in Minnesota became 20 percent more reflective by the application of silica beads. After the untreated ice had already melted, there was still ice about 30 centimeters thick in the treated section.

In the Arctic, according to Field, the beads should only be deployed in regions where the ice is melting particularly fast, such as in the Fram Strait between Greenland and Spitsbergen. Field explains that the silica beads are safe because silica is so abundant in nature. Field explains that the silica beads are safe because silica is so abundant in nature.

Although scientists agree on the good intentions, they are concerned about the possible effects on the Arctic ecosystem. On one hand, too much light could be reflected by the pearls, which would not be available to the phytoplankton living under the sea ice. Furthermore, the beads are about the size of diatoms, which serve as food for zooplankton. Karina Giesbrecht, ocean chemist and ecologist at the Canadian University of Victoria, fears that copepods could feed on the pearls without taking in nutrients. If the animals starve to death at the base of the food web, this has consequences for all the species above.
Field plans to investigate the effects on plankton and, if necessary, adjust the beads to make them safer.

Cecilia Bitz, atmospheric scientist at the University of Washington, and Mark Serreze, climate scientist at the US National Snow and Ice Data Center at the University of Colorado Boulder, consider such approaches to be an emergency solution to climate change, as they only treat individual symptoms – in the case of silica powder the temperatures – and do nothing about the cause of climate change. If Field’s strategy works as intended, “that’s wonderful”, says Bitz, “but I know that not emitting CO2 in the first place will work.”

Field agrees that geoengineering is in no way a substitute for reducing carbon dioxide emissions. Rather, she sees it as an opportunity to buy the time that world economies need to decarbonize and fend off the worst effects of climate change. The silica pearls, she says, is “the backup plan I hoped we would never need.”

Julia Hager, PolarJournal; Source: BBC, Katya Zimmer

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