Finding the right 'dose' for solar geoengineering

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One of the key misconceptions about solar geoengineering—putting aerosols into the atmosphere to reflect sunlight and reduce global warming—is that it could be used as a fix-all to reverse global warming trends and bring temperature back to pre-industrial levels.

It can't. Applying huge doses of to offset all warming from rising atmospheric C02 levels could worsen the problem—particularly rainfall patterns—in certain regions. But could smaller doses work in tandem with emission cuts to lower the risks of a changing climate?

New research from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), in collaboration with MIT and Princeton University, finds that if solar geoengineering is used to cut global temperature increases in half, there could be worldwide benefits without exacerbating change in any large geographic area.

"Some of the problems identified in earlier studies where solar geo-engineering offset all warming are examples of the old adage that the dose makes the poison," said David Keith, the Gordon McKay Professor of Applied Physics at SEAS and senior author of the study. "This study takes a big step towards using climate variables most relevant for human impacts and finds that no IPCC-defined region is made worse off in any of the major climate impact indicators. Big uncertainties remain, but suggest that geoengineering could enable surprisingly uniform benefits."

The research is published in Nature Climate Change.

To better understand what regions could experience worse climatic conditions if solar geoengineering were combined with emissions cuts, the researchers used a state-of-the-art high-resolution model to simulate extreme rainfall and tropical cyclones (a.k.a. hurricanes). It's the first time such a model has been used to study the potential impact of solar geoengineering.

Researchers looked at temperature and precipitation extremes, water availability, and a measure of the intensity of tropical storms. They found that halving warming with solar geoengineering not only cools the planet everywhere but also moderates changes in water availability and extreme precipitation in many places and offsets more than 85 percent of the increase in the intensity of hurricanes.

Less than 0.5 percent of the land would see the effects of climate change exacerbated, according to the model.

"The places where solar geoengineering exacerbates climate change were those that saw the least climate change to begin with," said Peter Irvine, Postdoctoral Research Fellow at SEAS and lead author of the study. "Previous work had assumed that solar geoengineering would inevitably lead to winners and losers with some regions suffering greater harms; our work challenges this assumption. We find a large reduction in climate risk overall without significantly greater risks to any region."

The researchers are quick to point out that this is a simplified experiment, which assumed doubled CO2 concentrations and represented solar geo-engineering by turning down the sun. However, it is a first step towards understanding how solar geoengineering could be used in tandem with other tools to mitigate some of the worse impacts of climate change.

"For years, geoengineering has focused on compensating for greenhouse gas induced without worrying too much about other quantities like rainfall and storms," said Kerry Emanuel, the Cecil & Ida Green Professor of Atmospheric Science at MIT and co-author of the study. "This study shows that a more modest engineered reduction in can lead to better outcomes for the climate as a whole."

"The analogy is not perfect but solar is a little like a drug which treats ," said Irvine. "An overdose would be harmful, but a well-chosen dose could reduce your risks. Of course, it's better to not have high blood pressure in the first place but once you have it, along with making healthier lifestyle choices, it's worth considering treatments that could lower your risks."


Explore further

Future of planet-cooling tech: Study creates roadmap for geoengineering research

More information: Halving warming with idealized solar geoengineering moderates key climate hazards, Nature Climate Change (2019). DOI: 10.1038/s41558-019-0398-8 , https://www.nature.com/articles/s41558-019-0398-8
Journal information: Nature Climate Change

Citation: Finding the right 'dose' for solar geoengineering (2019, March 11) retrieved 17 July 2019 from https://phys.org/news/2019-03-dose-solar-geoengineering.html
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Mar 11, 2019
First of all, if these fools had any clue of what climate is and/or what actually could affect it, then perhaps they might have something of value to say on the matter... But they don't!

Mar 11, 2019
This comment has been removed by a moderator.

Mar 11, 2019
Wonder how photosynthesis in the ocean is affected by less sunlight... we're already removing all the life in the sea, making life harder for sea critters seems counterproductive...

There are SO MANY unforeseen consequences to all "geo-engineering" proposals...

Mar 11, 2019
36,000 scientists just signed a report stating the global warming is a total hoax. The report has tons of data backing up the conclusions.

It's a hoax.

Mar 11, 2019
These fracking idiots will kill us all.

Mar 11, 2019
Egotistical people who confuse a degree with intelligence or wisdom, solving problems that likely don't exist. Only a small fraction of the Sun/Earth connection is considered by climate science, all climate models (including above) that fail to consider the full Sun/Earth connection are flawed in this regard.

Mar 12, 2019
Climate change is real, of course, and this might be a great way to mitigate it without harming the world economy.

Mar 12, 2019
Geoengineering...because dumping huge amounts of chemical substances in an uncontrolled (and unrecoverable) manner into the environment has always worked oh so well in the past.

Don't.
Just don't.

Mar 12, 2019
First of all, if these fools had any clue of what climate is and/or what actually could affect it,
rodkeh

False. Climate scientists have studied and researched the physics of climate for many years and know a lot more about it than me and you, especially you. You display the usual delusional arrogance of all the loonies posting here that have the delusional arrogance to think they know better than the experts on the subject.

Mar 12, 2019
Wonder how photosynthesis in the ocean is affected by less sunlight...
michael_frishberg

The proposals here would reduce sunlight to the surface by much less than 1% -such a tiny reduction that it would have negligible effect on photosynthesis.
In contrast, the effects on life in general if we do nothing may be rather more considerable.
I am not implying their proposal is a good one in particular (I have no opinion on that), merely that IF it is a bad one then it isn't bad for THAT specific reason but rather bad for OTHER reasons.

Mar 12, 2019
Egotistical people who confuse a degree with intelligence or wisdom, solving problems that likely don't exist. Only a small fraction of the Sun/Earth connection is considered by climate science, all climate models (including above) that fail to consider the full Sun/Earth connection are flawed in this regard.


Total nonsense. Stop making things up. It gets tiresome.

Mar 12, 2019
geoengineering == dangerous purified hubris.

The only credible or desirable way to protect our planet is to snuff out the anthropogenic sources of climate change, and live in sustainable balance with mother nature, full stop.

Mar 13, 2019
I see the usual amount of trolling accompanies this climate change article as any other climate change article. So many opinionated web pundits that know so little. The hubris is either incredible or these are professionals/bots.

Actually many of the comments above seem so crude and half off-topic that I suspect we are getting a lot of bots commenting. This is what we are up-against folks.

Mar 13, 2019
Geoengineering will probably be essential if our civilisation is to survive. More research funds for this please.

Mar 14, 2019
Geoengineering will probably be essential if our civilisation is to survive. More research funds for this please.

An ounce of prevention is worth a pound of cure. It's far far easier to live sustainably than to insert ourselves into planetary and natural systems in place of mother nature, systems we still admit in awe almost daily that we barely understand or didn't even realize existed.

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