Quirks & Quarks

Scientists say we don't know enough about the potential of using geoengineering to fight climate change

Solar geoengineering is an unproven technique that could cool down the Earth by blocking out the sun, but there are huge unknowns and potential risks, say scientists.

The technique would cool down the Earth by blocking out the sun, but there are risks

Solar geoengineering would involve injecting particles into the stratosphere to reflect sunlight back out into space, much like what happens naturally when volcanoes erupt. (SASTRAWAN GINTING/AFP via Getty Images)

As world leaders gathered this week to discuss greenhouse gas reduction targets, some scientists are suggesting we need to look at a backup plan in case emissions can't be cut fast enough to curb global warming.

"If we take the climate change impacts seriously, we start to think that we are beyond the point in which we could just rely solely on emissions reductions," Juan Moreno-Cruz told Quirks & Quarks host Bob McDonald.

One possible strategy is solar geoengineering, a technique that in its best known form could involve airplanes flying high up in the stratosphere and releasing aerosol particles. These particles would act as mirrors and reflect sunlight back into space, to temporarily cool the planet.

But the idea comes with huge unknowns and potential risks.  And scientists are calling for more research to make the potential risks and benefits of geoengineering clearer.

"Geoengineering is not anti-climate change, it's a different type of climate change that happens to compensate for the climate change caused by greenhouse gas emissions. But it's not perfect at doing that," said Moreno-Cruz.

Equity in geoengineering

Moreno-Cruz is Canada Research Chair in Energy Transitions at the University of Waterloo, and also a co-author of a recent report from the U.S. National Academies of Sciences, Engineering and Medicine (NASEM). The report is in response to a  lack of substantive research about solar geoengineering, and features recommendations for how to move forward with research in way that doesn't disadvantage poorer or less politically influential countries.

A major concern with geoengineering is that, similar to the way regions are affected by climate change in different ways,  local results from solar geoengineering could vary wildly.

"Some regions are going to be overcompensating [for temperature change] on average and some others are going to be under compensating," for changing temperatures, said Moreno-Cruz. "Only a few are going to be able to have a say on this. And there are other countries that are just going to have to sit and hope for the best."

The white snow and ice in the Arctic allow solar radiation to be reflected back into space. But with accelerated warming in the region, the exposed dark water absorbs that heat, causing more melting. Solar geoengineering would allow for some of that that solar radiation to be reflected from the stratosphere out into space. (David Goldman/Associated Press)

"And that worries me because that possibility could result in conflict," he said.

The big concern for Moreno-Cruz and his colleagues on the NASEM report is the lack of basic knowledge, like real-world research to show whether solar geoengineering would actually help or hurt the planet.

"We really don't know if the technique works," he said. "We don't understand enough of the atmospheric chemistry and transportation mechanisms to actually say that a particular release of aerosol particles is going to have a desired effect." 

Effects on animals and vegetation unknown

One area that's been mostly neglected in solar geoengineering discussions and research efforts is the effect it would have on life on our planet.

"If we're going to step into another potential future here and moderate or affect the climate even further, we need to be really clear about what those potential impacts are before we even decide to do that," said Phoebe Zarnetske, a community ecologist at Michigan State University.

Zarnetske is the co-lead of the Climate Intervention Biology Working Group, and co-author on a recent paper looking at the many unknowns of the ecological effects of solar geoengineering.

"We know from a lot of climate change studies that certain organisms are especially sensitive to changes in temperature, for example, but geoengineering with sulfate injections would actually also increase UV," she said. This would affect the life cycle of animals such as frogs and amphibians, and could also affect invasive species management by limiting cold temperatures needed to kill invasive insect populations in certain areas.

A woman puts sunscreen on her face at the Reñaca Beach in Chile. Solar geoengineering could potentially increase ground level UV rays. (MARTIN BERNETTI/AFP via Getty Images)

Also unknown is how this would affect the planet's vegetation. 

"It's a complex topic because there's a lot of different [feedback] involved between the Earth's surface, the vegetation and the climate system that ultimately impact different types of crops in different ways. And so we're looking at probably some just really varied changes," she said.

One thing that is certain, she adds, is that solar geoengineering would not do anything to mitigate ocean acidification, which is another symptom of climate change that must be addressed.

Geoengineering as a tool, but not the only solution

Zarnetske said that solar geoengineering could be used in concert with other mitigation techniques, and gradually reduced once the desired effect is reached.

"If we're able to reduce our emissions, we may be able to use solar geoengineering to kind of increase the cooling to some degree," she said. "But that would have to be in concert with also reducing our emissions and dependence on fossil fuels."

Moreno-Cruz adds that some research has suggested that simply introducing the possibility of using geoengineering can be enough to scare the public into taking stronger action to reduce their emissions. Ultimately, he says, more research needs to be done before trying such a large-scale endeavour such as this.

"We really have no clear answer to those questions. I just think everybody needs to know as much as we can."

Produced by Sonya Buyting. Written by Amanda Buckiewicz.