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Geoengineering: Can we dim the sun to avoid climate tipping points?

Could dimming the sun’s intensity be a potential solution to halting the melting of the West Antarctic ice sheet? A team of researchers from the University of Bern has recently explored this question.

Geoengineering is an intentional and large-scale intervention in the Earth’s climate system which has been a controversial topic in climate discussions. Some scientists hope to artificially manipulate the climate in order to cool it. 

However, the concept of geoengineering is met with enormous skepticism among experts who believe that the unpredictable outcomes are far too risky.

The latest research was led by Johannes Sutter from the Climate and Environmental Physics Division (KUP) at the University of Bern. The results are published in the journal Nature Climate Change.

Manipulating solar radiation

In particular, the researchers explored the possibility of counteracting West Antarctica’s ice melt by manipulating solar radiation. The results of this inquiry, however, confirm that the unpredictable consequences of geoengineering could be monumental.

“The window of opportunity to limit the global temperature increase to below 2 degrees is closing fast,” said Johannes Sutter, an expert in ice modeling. He suggests that in light of this, humanity might soon resort to such technical interventions. 

This means that understanding the implications of “solar radiation management” (SRM) – techniques aimed at blocking solar rays to cool Earth – becomes paramount.

Climate tipping points

The urgency surrounding geoengineering arises from a looming threat: climate tipping points. These are critical junctures beyond which the climate might undergo irrevocable shifts. 

Notably, the melting of the West Antarctic and Greenland ice sheets could result in catastrophic sea-level rises. 

“Observations of ice flows in West Antarctica indicate that we are very close to a so-called tipping point or have already passed it,” said Sutter. His team’s study was a quest to determine whether solar radiation management could theoretically halt the ice sheet’s collapse.

Focus of the study

The researchers evaluated the potential of using aerosols, or suspended particles in a gas, introduced into the stratosphere to block sunlight, thus creating an artificial dimming effect. 

While previous inquiries delved into SRM’s global implications, this study stands out as the first to use ice model simulations to gauge the impact of solar radiation management on the Antarctic ice sheet.

What the researchers discovered 

The findings were mixed. If we persist in our current greenhouse gas emissions trajectory and implement SRM mid-century, we might delay but not avert the West Antarctic Ice Sheet’s demise. 

However, in a scenario of moderated emissions, solar radiation management could be a potent weapon against ice sheet degradation. The researchers concluded that the blend of early SRM application and aggressive climate mitigation strategies yields the best results. 

Yet, the experts noted: “Rapid decarbonization remains the most effective path to preserving the West Antarctic Ice Sheet in the long run.”

Is geoengineering practical?

When it comes to sun dimming, Sutter describes an almost futuristic scene – fleets of high-altitude planes dispersing millions of tons of aerosols into the stratosphere. 

But this endeavor isn’t a one-time fix; it demands continuous upkeep for centuries. Halting it prematurely, given the prevailing high greenhouse gas concentrations, would cause Earth’s temperature to spike dramatically.

Termination shock 

Sutter emphasized the dangers of what he terms a “termination shock,” stressing that it’s but one of many potential hazards associated with solar radiation management. 

From unsettling the monsoon patterns to altering oceanic and atmospheric circulations, the side effects of this grand experiment remain largely unknown. 

Furthermore, there’s apprehension about the societal repercussions, as such endeavors might detract from genuine climate mitigation efforts.

Radical interventions 

“Geoengineering would be another global experiment and a potentially dangerous human intervention in the climate system,” said study co-author Professor Thomas Stocker. He references the UN Framework Convention on Climate Change, urging caution in undertaking such radical interventions.

Overall, the research suggests that while sun dimming poses an intriguing possibility in the fight against climate change, it comes along with profound uncertainties and risks.


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