The businessman, philanthropist, and YouTube personality Hank Green recently caused a minor controversy with a video about geoengineering. Discussing the evidence that international regulations on cargo ship fuel, and the resulting huge decline in oceanic aerosol pollution, are partly behind the record-shattering heat this summer, he argued that this was a golden opportunity to study the idea. By putting aerosols — sulfur dioxide or ocean water, possibly — into the atmosphere on purpose (also called solar radiation management), we could cut down on global temperatures.
So many people reacted with fury that the Radiolab podcast invited Green on to discuss the backlash. Many climate scientists also objected. Some argue that even studying geoengineering is unethical, but others raised a more nuanced objection.
“In order to do it intentionally, everyone needs to be on board. Geoengineering has global implications, therefore ethically, morally, it should be a global decision,” said climate scientist Miriam Nielsen in a response video. “I don’t want the use of geoengineering to stop us from making the next Paris Agreement, and I really think that it would,” she added in an interesting and informative conversation with Green and Adam Levy. “It already breaks a bunch of international laws … I would rather focus on — how do we bring the world together on mitigative efforts on reducing our emissions rather than combating future emissions.”
I have a lot of sympathy for this view, but ultimately I don’t accept it. It seems to me almost beyond question at this point that some country or group of countries will opt for geoengineering. The ethical qualms of scientists or climate activists will not stop it. And if the extant international frameworks for climate diplomacy get in the way, they will be torn up. It’s critical both to start research on the question, and to start building an international diplomatic framework to consider and regulate geoengineering.
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Here’s why. Many countries are extremely vulnerable to climate change, and some of them have more than enough economic might and international heft to carry out a unilateral geoengineering scheme. Such a scheme will be cheap compared to the damages inflicted by, say, 2-3 degrees of warming, which is what a recent UN report estimates we are likely to hit by 2100 along the current policy trajectory.
Importantly, that projection is actually a huge improvement relative to the business-as-usual projections from 10 or 20 years ago, when 6 degrees of warming was the status quo track. The world is now moving fairly aggressively on climate policy, thanks to the Inflation Reduction Act, Europe’s crash decarbonization campaign resulting from Vladimir Putin’s war on Ukraine, and massive investment in China. Renewable energy is now cheaper than any form of energy in history, and only getting cheaper. That fact alone will eventually stamp out the use of fossil fuels over time.
In short, the world has made substantial strides towards tackling climate change — but they just aren’t happening fast enough. National grids are clogged; offshore wind is running into financing issues; countries are struggling to assemble electric vehicle supply chains; sources of zero-carbon steel, concrete, and industrial heat are still in their early stages, and so on. Though it’s not yet impossible to keep warming under 1.5 degrees, given political realities around the globe, it is quite hard to imagine.
So consider what, say, China is facing. In 2022, it saw severe drought and heat waves that nearly broke the power grid, with only about 1 degree Celsius of warming. Climate science tells us that droughts and heat waves will be dramatically worse at 2-3 degrees of warming — and if a really severe heat wave coincides with (or causes) a major power outage in an urban center, the death toll could easily reach into the millions.
Then there is sea level rise. According to a 2019 study, along the current sea level rise trajectory, something like 93 million Chinese people will be at risk of annual flooding by 2050 — just 26 years away. A Financial Timesanalysis estimated that many trillions of dollars of Chinese investment will be threatened by sea level rise by 2100, including capital producing nearly $1 trillion in GDP annually in Shanghai alone.
The communist dictatorship in China is not exactly known for a kindly regard for international norms or environmental protection. On the contrary, it brutally crushed a pro-democracy movement in Hong Kong, it is committing cultural genocide against its Uyghur population, and it has wreaked environmental devastation across the country and the world in pursuit of ultra-rapid economic growth. Indeed, as of 2021 it emitted over 60 percent more carbon dioxide than the U.S. and the European Union put together.
Does this sound like a country likely to respect international agreements — or laws of any kind — if they stand in the way of what it sees as a cheap and easy way to protect the lives of literally tens of millions of its citizens along with its most valuable economic complexes? Even the most responsible liberal democracy would surely be tempted — and to be fair, a democracy might easily be the first to try, including the U.S.
Even if countries could somehow be coerced into halting their geoengineering — a ludicrous prospect with a country as powerful as China — that raises an even worse possibility. The most dangerous scenario here is for solar dimming programs to be started or stopped abruptly. One of the biggest reason climate change is a problem is that it is causing rapid and chaotic changes to weather patterns — severe drought followed by flooding, unseasonable heat followed by a cold snap, and so on, which damages ecosystems and drives species to extinction. Rapid, unplanned geoengineering schemes being switched on and off could cause the same problems even faster than greenhouse gas emissions have done.
Suppose some country suffers a seven-figure casualty event from a climate disaster, decides it is facing an existential threat, and attempts a half-baked solar dimming program in a panic. Then that causes unforeseen disruptions in precipitation patterns in a neighboring country, which responds by launching missile strikes on the solar dimming installations. The climate could be yanked back and forth by a half-degree Celsius or more in the space of years or months.
I can understand why climate scientists would want to preserve the nascent climate diplomacy system. But any international agreement is no match for raw power politics in a pinch. International law is already routinely ignored all over the world, and the frankly quite toothless diplomatic climate framework certainly won’t prevent a powerful nation that feels backed into a corner from exerting every effort to protect itself.
The way forward is to produce the strongest possible body of evidence on the question, so that the best solar dimming agents can be determined, along with the least harmful way they could be used, and to start international discussions to manage any future geoengineering program. That way it could be carried out with wide support, hopefully with some compensation funds available to nations that are negatively affected, with the overarching idea that it will only buy time before carbon removal technologies can be spun up.
It will no doubt be very difficult to assemble any kind of international consensus around this question. But the alternative is it happening anyway without enough planning or study.
Read more about geoengineering:
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