Solar radiation management (SRM or solar geoengineering) is a theoretical approach lớn reducing some of the impacts of climate change by reflecting a small amount of inbound sunlight back out inkhổng lồ space. It is in the early stages of retìm kiếm, but it is already a controversial topic. It is clear that SRM has the potential lớn be very helpful or very damaging for those people và species most threatened by climate change, but it is very unclear what its full effects would be.

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SRM would not directly reduce concentrations greenhouse gases, và therefore numerous expert reports have concluded that it could never be a complete solution lớn global warming và does not represent a substitute for mitigation of greenhouse gas emissions. However, they have sầu also concluded that it might be able lớn reduce some climate risks to lớn which Earth is already committed, though even for this more limited purpose whether it can be net positive khổng lồ humanity and the environment is unclear.


For instance, if it could be made khổng lồ work, SRM would be the only known method for quickly stopping the rise in global temperatures. It could even be used to lớn cool the planet, should that ever be deemed necessary. As such it might be able to lớn reduce some damages while humanity decarbonizes the global economy, or it might offer a method for dealing with some of the climate risks associated with those greenhouse gases that have sầu already been emitted lớn the atmosphere. The uncertainties around the effects of SRM are large though, & there is not nearly enough evidence yet available to evaluate whether use of SRM would increase or decrease the impacts of climate change, và where.

What would SRM involve?

Different SRM techniques have sầu been proposed, but the proposals receiving the most attention from researchers would involve sầu brightening marine clouds by spraying seawater into lớn the lower atmosphere, or replicating the cooling effect of volcanoes by spraying reflective sulfate particles inkhổng lồ the upper atmosphere (the stratosphere).

Stratospheric aerosol injectionWhen very large volcanoes erupt they blast millions of tonnes of reflective sầu sulphate particles into lớn the stratosphere. These particles circulate the planet on the powerful stratospheric winds, reflecting away a small amount of inbound sunlight và cooling the planet for a year or two. Stratospheric aerosol ejection would seek to replicate this effect, with aeroplanes or balloons used khổng lồ inject reflective sầu aerosol particles into the upper atmosphere.

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Marine cloud brighteningLarge areas of ocean are covered in marine stratus clouds. Scientists have proposed that spraying tiny droplets of seawater inkhổng lồ these clouds could make them lighter & more reflective. Whiter, brighter clouds reflect more sunlight bachồng out inlớn space, and would help cool the planet.

What about side effects?

It is not yet known what all the side effects of SRM could be, or whether they would be very damaging. Some possible side effects are known, however. For instance, stratospheric aerosols might delay the regeneration of the ozone layer. There might also be some health effects from the additional aerosols in the atmosphere, although these are not currently expected to lớn be large.


What about the societal & political dimensions?

The physical impacts of SRM are only one part of the story. Many people feel that the political dimensions could prove more difficult khổng lồ manage than the physical dimensions. For instance, what would happen if a country used SRM unilaterally, and then other countries experienced extreme weather events that might have been caused by the geoengineering? How would the world achieve widespread international agreement over how much SRM cooling to do? Some countries might want the world a degree or two warmer, và some might want it a degree or two cooler. Also, there are concerns that the idea of SRM could distract politicians from the task of implementing deep cuts to lớn greenhouse gas emissions.

SRM research & governance questions

Many people & organizations have sầu called for more research. Basic calculations have sầu indicated that SRM could be very cheap lớn deploy relative sầu to the costs of climate mitigation or adaptation, và so retìm kiếm & discussion usually focus on risks, benefits, uncertainties, & governance.

But research itself is controversial và it raises numerous questions:

Who decides if research proceeds, và what should be researched?Who pays for the research? Who benefits?What ensures that retìm kiếm is conducted in a transparent manner, & that all results are shared openly?How can the different research priorities of different groups be heard?What can be done to make sure that SRM retìm kiếm does not distract public & politicians from the task of cutting emissions of greenhouse gases?

These questions can shape the way that SRM develops, but there are no clear answers. A broad global conversation about SRM and the governance of related research is therefore required.

“I would lượt thích lớn have sầu a reverse button for whatever is put in the stratosphere.“