The idea of artificially influencing and cooling the climate through so-called geoengineering has gained traction among researchers. Particularly, scientists from Bern have been exploring the potential of preventing the West Antarctic ice sheet from melting by artificially "dimming the sun". The findings, however, indicate that such artificial measures do not operate independently of decarbonization and come with significant risks.
Emergency Solutions to Halt Climate Change?
Geoengineering, or the use of technological interventions to manipulate the climate, has been under discussion for a while now. Most climate scientists, though, remain skeptical due to the high risks and the potential for unpredictable impacts on future generations.
In a recent article published in Nature Climate Change, a team of researchers led by Johannes Sutter from the Climate and Environmental Physics Division (KUP) at the Institute of Physics and the Oeschger Centre for Climate Research at the University of Bern delved into the possibility of halting the ice melt in West Antarctica by artificially manipulating solar radiation. They also cautioned about the unforeseen side effects of geoengineering.
Preventing a Key Climate Tipping Point
"The time frame to restrict the global temperature rise to under 2 degrees is rapidly shrinking," shares ice modeling expert Johannes Sutter, "This could lead to serious considerations of technical measures to control the climate in the future." As such, he advocates for the use of theoretical models to better understand the effects and risks of "solar radiation management" (SRM) - the practice of blocking solar radiation to cool Earth.
Growing interest in geoengineering stems from the need to prevent climate tipping points that could cause abrupt and irreversible changes, such as the melting of the West Antarctic and Greenland ice sheets and the resulting rise in sea levels. "Our observations of ice flows in West Antarctica suggest we are nearing or have already crossed this tipping point," says Sutter. "Our research aimed to establish if the ice sheet's collapse could theoretically be prevented using solar radiation management."
The Science of Artificially Dimming the Sun
In their research, Sutter and his team examined the potential consequences of using aerosols - particles suspended in gas - introduced into the stratosphere to block solar radiation from Earth, effectively 'dimming' the sun. Previous studies have focused on the global impacts of SRM, but this study from Bern is the first to use ice model simulations to assess its effect on the Antarctic ice sheet. The research took into account different future greenhouse gas scenarios and found mixed results: the collapse of the West Antarctic Ice Sheet could be delayed but not entirely averted if emissions continue unabated and SRM is implemented by mid-century. However, if emissions are moderate, and SRM is implemented by mid-century, it could slow or even prevent the ice sheet's collapse.
The study found that SRM is most effective when implemented as soon as possible and in conjunction with ambitious climate mitigation measures. However, the researchers stress, "our simulations show that the most potent method to prevent the long-term collapse of the West Antarctic Ice Sheet is rapid decarbonization." The best hope for maintaining a stable ice sheet long-term is to reduce greenhouse gas emissions to net-zero "without delay."
Possible side effects still hardly studied
But how should one imagine a dimming of the sun in practical terms? According to Johannes Sutter, a whole fleet of extremely high-flying airplanes would have to spread millions of tons of aerosols in the stratosphere. However, this technical intervention in the climate would have to be maintained without interruption and for centuries. If the intervention were stopped as long as the greenhouse concentration in the atmosphere remained high, the temperature on earth would quickly rise by several degrees
The consequences of such a termination shock, Johannes Sutter points out, are only one of the possible dangers posed by SRM. The potential side effects are still insufficiently researched and range from a shift in the monsoon regime to changes in ocean and atmospheric circulation. Ocean acidification would also continue. Critical voices also caution political and social effects: The use of techniques such as solar dimming could lead to climate protection measures being slowed down or even prevented. Thomas Stocker, professor of climate and environmental physics at the University of Bern and co-author of the study, says: "Geoengineering would be another global experiment and a potentially dangerous human intervention in the climate system, which should in any case be prevented according to Article 2 of the UN Framework Convention on Climate Change."
Reference: Sutter J, Jones A, Frölicher TL, Wirths C, Stocker TF. Climate intervention on a high-emissions pathway could delay but not prevent West Antarctic Ice Sheet demise. Nat Clim Chang. 2023. doi: 10.1038/s41558-023-01738-w
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