Yes, Virginia, We Can Block the Sun (Maybe). No, We Shouldn’t.

There’s recently been a little more attention paid to geoengineering, the idea of fighting global warming not just through decarbonization or regulation, but through using technology to lower the temperature of the Earth.

Scientists are proposing an ingenious but as-yet-unproven way to tackle climate change: spraying sun-dimming chemicals into the Earth’s atmosphere.

The research by scientists at Harvard and Yale universities, published in the journal Environmental Research Letters, proposes using a technique known as stratospheric aerosol injection, which they say could cut the rate of global warming in half.

The technique would involve spraying large amounts of sulfate particles into the Earth’s lower stratosphere at altitudes as high as 12 miles. The scientists propose delivering the sulfates with specially designed high-altitude aircraft, balloons or large naval-style guns.

In fact, there is soon to be a balloon-borne experiment designed to test out the idea using calcium carbonate, which has the advantage over the sulfates of not, you know, destroying the ozone layer, which is only just beginning to recover from our little inadvertent geoengineering experiment involving HCFCs.

Technically speaking, it is possible to do something like this. Global warming is when the temperature of the planet rises because increasing amounts of carbon dioxide (among other things) trap more infrared radiation, warming the planet up. However, the planet will cool if the amount of aerosols in the atmosphere increases. The most common culprit for this are volcanos — the Mount Pinatubo eruption famously dropped the temperature of the planet by over half a degree (temporarily). And the brief “global cooling” fad of the 1970s was based on the idea that aerosols in the atmosphere were proving to be a more powerful influence than global warming, a thesis was discarded by the end of the 1970s.

So … it could work. In theory. The technology and infrastructure for such a colossal undertaking does not actually exist. But now that scientists from Harvard and Yale have weighed in, the idea is being taken seriously by people who, frankly, should know better.

Yes, know better. Because geoengineering is a terrible idea. Vox did a good rundown of the problems with geoengineering as a solution, but I’ll elaborate on it.

• Once you start, you can’t stop. Let’s say that we implement this plan and greenhouse gas emissions continue unabated or only moderately abated. That means that we have an ongoing and rising warming influence from greenhouse gases. Countering this means continuing to pump chemicals into our atmosphere. If you stop, then the planet starts warming very quickly as it “catches up”. That kind of sudden warming would be much much worse than a gradual warming, causing sudden shifts in growing patterns, rapid oceans rises and other phenomena we can’t predict.
• It doesn’t solve many of the other problems associated with CO2 emissions, such as ocean acidification.
• What happens if there are unpredicted secondary effects? What happens to growing seasons? What happens to weather patterns? The reason global warming is such a concern is that we are already doing a massive geoengineering experiment and we don’t know exactly what the results will be. Why counter that with another vast geoengineering experiment?
• Probably my biggest concern is that you can’t simply adjust the planetary thermostat so willy-nilly. The potential for disaster looms very large. Up until recently, global cooling was a much bigger concern than global warming. 75,000 years ago, the Toba supervolcano exploded, causing global temperatures to plunge. The human race was almost was wiped out, being reduced to maybe a few thousand individuals. As you’ll see in a future Thursday Throughput, 536 AD may have been the worst year to be alive, thanks to global famines caused by plunging temperatures. The 1815 Tambora eruption resulted in the Year Without A Summer, causing massive food shortages. If a supervolcanic eruption occurred today, it would be a global crisis. If it occurred after we had already polluted the atmosphere with sun-blocking chemicals, it could be a Snowpiercer level catastrophe. Looked at this way, geoengineering is an attempt to balance two environmental catastrophes against each other. This does not strike me as an optimal approach.

For all the press given to these Harvard and Yale scientists — because clearly if Harvard and Yale speak, the world must listen — this is an Ian Malcolm level discussion. We probably can do it; we definitely shouldn’t.

Look, I get the motivation here. Our civilization is powered by fossil fuels. Alternative energy is nice, but passenger planes don’t run on solar panels and cargo ships don’t run on wind. There are huge problems with energy storage and consumption (the “duck curve”) and plans to store alternative energy are absurdly unrealistic. In fact, many of the G-20 countries that signed the Paris Accord are seeing their emissions increase, thanks in large part to ongoing efforts to end nuclear power (ironically, the US is the one country that is seeing a big reduction, thanks in part to moving from coal to natural gas). So I can the desperation.

But, to paraphrase Margaret Thatcher, there is no alternative to decarbonization. However we achieve it, it has to be done. I once wrote out my ideas for a conservative-libertarian plan for dealing with global warming. It’s lost in the mists but is quite similar to climate skeptic Warren Meyer’s transpartisan global warming plan: a carbon tax offset by payroll tax reductions (to which I’d add a corporate tax elimination offset by income tax hikes), eliminate subsidies for borderline tech (to which I’d add increase funding for basic research), revamping of our nuclear regulatory regime and helping Asian countries clean up their energy production.

I also think, at some level, we will need some adaptation. Even if we woke up tomorrow and discovered that cheap nuclear fusion power was suddenly available to everyone, it would take a while for the effect to be felt. The planet is going to continue to warm for a while and should find ways to deal with that — sea walls, migration, whatever — instead of pretending it’s not going to happen.

But geoengineering would be the last solution I would consider, and I would probably take doing nothing over it, to be completely honest. We don’t know nearly enough about our planet to engage in this kind of experiment. And even we did, as I noted above, you are trying to balance two environmental disasters against each other, with catastrophe looming on either end.