Solar Radiation Management

SRM – like wrapping the earth in faintly tinted sunglasses

On this page:-

• The good
• The bad
• The ugly

The good

The summary? Harvard Physics Professor David Keith says we can use Solar Radiation Management (SRM) to reduce human induced global warming by half, giving us decades longer to respond to climate change. SRM would fly wide-winged jets 20km up in the stratosphere to spread artificial diamond dust. This would cut less than a percent of incoming sunlight. It’s like wrapping the earth in faintly tinted sunglasses. We could apply it slowly, gradually cooling the planet and checking the results as we go.

It’s cheap and fast. I’ve seen many figures, but it should be under $10 billion a year to cool our planet and give us an extra few decades to build out clean energy, and it should start taking effect only several months into the SRM program. (The longest part would be designing and building the extra-wide wing cargo-planes to fly up 20km – and that link estimates an SRM program might cost under $3 billion a year to run.)

To conservationists it can sound alarming, like a planet wide experiment with huge potential side effects. But it mimics what we have already seen in nature. Volcanoes do exactly the same thing when they explode and blow huge amounts of dust high into the atmosphere. This cools the planet for a year or so. So if we take it slowly, a body like the United Nations should be able to monitor progress and any potential side-effects. After all, it is the climate scientists that are suggesting we might need a little SRM.

The reason it works so well? A small amount of dust can reflecting sunlight can prevent an enormous amount of heating.

According to estimates by the Council on Foreign Relations, “one kilogram of well placed sulfur in the stratosphere would roughly offset the warming effect of several hundred thousand kilograms of carbon dioxide.”
The Geoengineering Option: A Last Resort Against Global Warming?

The bad

The Ozone layer might be damaged if we use the wrong dust like sulfur. Too much sulfur could paint the sky white and hurt the ozone layer. But it cannot be too bad when one considers who is promoting this idea:

Professor Paul Crutzen, winner of the 1995 Nobel Prize for his work on the Antarctic ozone hole, has proposed an emergency geoengineering solution to cool off the planet: dump huge quantities of sulfur particles into the stratosphere to reflect sunlight. His paper, “Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma?” was published in the August 2006 issue of the journal Climatic Change. A recent editorial in the New York Times by Ken Caldeira called for more research into geoengineering schemes like this to cool the planet, proposing that 1% of the $3 billion federal Climate Change Technology Program should be spent thusly.

Indeed, the entire project is so focussed on sulfur it is sometimes called Stratospheric sulfur aerosols. But this seems too limiting as SRM does not have to use sulphur in the first place! So I prefer the generic term SRM, Solar Radiation Management. We could use Dr David Keith’s artificial diamond dust – as described in the video above.

The Indian Monsoon might shut down if we use too much SRM. Even SRM advocate Dr David Keith admits that there are side effects if we go too hard with this. He says we should cut half our warming, not all of it. Too much could shut down the Indian Monsoon – denying Asia some of the fresh water it needs. Radical changes in weather patterns and rainfall are one of the global warming symptoms we are trying to avoid. We do not want the cure to become as bad as the disease.

The ugly

The politics of this are diabolical. As I said on the Geo-engineering page prevention is safer and cheaper than any geo-engineering ‘cure’. But have we left it too late, especially as the pacific island nations want to limit warming to 1.5 degrees, not 2? Are we going to be forced to use this tool – and mature enough to have a global body like the United Nations set up a climate agency to run this? Here are some of the political and social risks.

Unilateral action: Who has their hand on the global thermostat? Who decides when to use SRM, and how much to use? What if America wakes up one day and finally realises that global warming is real after all – and decides to deploy enough SRM to cancel all human warming – and potentially throw much of Asia into a fresh water crisis? What if they cannot tolerate their bread basket drying up and decide to go it alone? SRM is seductively cheap – easily under $10 billion a year. The American military budget is $600 billion a year! SRM would only cost 1/60th of the American military budget to completely cool the planet – and make it comfortable for them. But what about everyone else? What if there’s a drought in Asia and people start to complain?

Might seduce us into getting lazy on cutting carbon: SRM might indeed be too tempting and too cheap. Some nations might see SRM alone as the answer and continue to burn coal, pumping CO2 into the atmosphere until we become addicted to SRM for the long term rather than the short term. We should only use it for a few decades to get our clean energy systems in order. But the world’s coal barons might see it as a licence to keep pushing their product for centuries. SRM might cool the planet, but it does not stop coal killing people with smoggy particulates or acidifying the oceans and killing coral reefs.

We can cut SRM at any time and it would wash out of the air in the following year. But would we? Who has their hands on the global sunglasses – and how dark those sunglasses really are? SRM could be an awful risk politically. What’s the worst that could happen? ABC’s Future Tense says “nuclear war.” I’m hopeful that a United Nations agency could run a more responsible program. But to me the risks are not technical or scientific, but geopolitical. SRM requires a level of international geopolitical maturity that I’m not sure we have – especially when America elects someone like Donald Trump. Click the image below for the full discussion of the benefits and risks of SRM by ABC’s Future Tense.