Geoengineering is the study, and potential practice of, intentional large-scale changes to the Earth’s systems. Most ethicists are very cautious about it, but recent news of potential carbon-spikes suggests an area where it may be absolutely necessary: the oceans.
We have solutions for the causes of global warming. Geoengineering as it’s commonly understood is a bandaid on the symptoms of it, in my opinion.
I had this conversation with one of the pre-eminent global geoengineering advocates and engineers, David Keith of Harvard, recently. He saw the potential need long ago, and his first paper on the subject was published in 1992. That makes him one of the pre-eminent authorities on the subject, so please understand that I’m not asserting that I know more than he does. However, my opinion (which he disagreed with) is that if we have to use geoengineering as he envisions it, we’ve probably failed and the results will be worse. I’m sure if we’d had more time and that had been the focus of the discussion as opposed to a sideline, our views would more substantially overlap.
Let’s define geoengineering briefly. The premise Keith and others advance is that we can increase the albedo — reflectivity — of the Earth’s atmosphere slightly to decrease the energy from the Sun that reaches the ground. This in turn reduces the infrared that the ground emits that’s trapped by greenhouse gases. The technology proposed uses sulphur dioxide in the high atmosphere, millions of tons of it a year.
In theory, it’s possible. In practice, the downsides are unknown and we are trying to stabilize a chaotic system by directly controlling it. The odds of unexpected feedback oscillation and other adverse effects are high. Further, ethicists point out the likelihood that using it to mask the impacts of fossil fuel greenhouse gas emissions would lead to both more use of fossil fuels, and to an inevitable failure in the future when we stop the geoengineering effort. Part of my concern is that fossil fuel companies will jump on the geoengineering bandwagon as they have jumped on the carbon capture bandwagon, and prevent the actually necessary actions.
And that’s already happening. The Center for Investigative Reporting published a lengthy assessment of the climate change skeptics close to President Trump, who were backing geoengineering efforts early in 2018. Keith is on record as being unnerved by the potential for this, saying in a 2017 conference:
In some ways the thing we fear the most is a tweet from Trump saying, “Solar geoengineering solves everything! It’s great! We don’t need to bother to cut emissions.”
In our recent conversation, Keith seemed unaware that this was already underway, although President Trump’s tweets have focused more on vicious attacks than global warming in the past year.
Of course, putting 20 million tons of anything into the high atmosphere every year is non-trivial as well. Who will pay for the program? What countries will host the fleets of planes? Where will the chemicals come from?
My preference for thinking related to solar geoengineering is best embodied in the Oxford Principles. (Full disclosure: I have a degree of separation on that as well, as I was speaking recently with the CEO of a firm whose chief scientist, Tim Kruger, collaborated on the Principles)
The Principles basically say that it’s an incredibly complex and risky thing to do, that independent actors have to be prevented from doing it, and that it should only be done under the auspices of a global governance agency, if at all. There’s a case for keeping it in our back pockets and using it after we’ve done the real job of eliminating CO2 emissions, following Mark Z. Jacobson’s prescriptions for 100% renewables by 2050 for every US state, and for 139 countries globally. (More degrees of separation: Jacobson wrote the preface to my upcoming CleanTechnica case study on Keith’s Carbon Engineering company, which as been described hyperbolically and inaccurately as a ‘magic bullet’ by none other than the BBC)
Enter the work of Daniel Rothman, professor of geophysics in the MIT Department of Earth, Atmospheric and Planetary Sciences, and co-director of MIT’s Lorenz Center. He’s one of a small number of climate scientists exploring the potential for truly catastrophic outcomes of our current unintentional geoengineering (global warming due to massive burning of fossil fuels). His most recent publication (peer-reviewed in the Proceedings of the National Academy of Sciences in July 2019), Characteristic disruptions of an excitable carbon cycle, quantifies his observation that mass extinction events historically are tied to spikes in ocean carbon uptake. Whether very slow but steady increases of atmospheric carbon or very abrupt changes in atmospheric carbon can cross the threshold to cause very large changes to ocean chemistry in very brief periods of time, per his models.
I have been thinking recently that some form of geoengineering might be necessary to reduce ocean acidity, and Rothman’s work suggests that the effort might be even more important. Let’s look at the oceanic acidification problem briefly.
Oceans are key to the carbon cycle. They’ve absorbed between a third and half of the CO2 that humans have emitted since the beginning of the Industrial Revolution, and the process lags atmospheric CO2 increases. More CO2 will end up in the oceans. The challenge is that CO2 binds with carbonate in the ocean to make carbonic acid, reducing the amount available for shellfish to make their shells. That leads to weaker shells, and species-level threats for key components of the food chain, in addition to the direct impacts of the increased acidity.
That is a very big problem of a very different nature than warming, but with the same root cause. We have to stop emitting CO2 so that oceans don’t acidify even more than absolutely necessary, but even if we stopped now, oceans would be getting more acidic for the next century or two, and that could be fatal to pretty much all of us.
I reached out to Jacobson for his thoughts. There is both good news and bad news in his opinion:
I am not aware of any way to draw down carbon from the oceans that is not energy intensive. Once energy is required to remove anything from anywhere, then the question always becomes, where does that energy come from? If the answer is fossils, the proposal fails. If the answer is renewables, then the proposal also fails because that renewable energy could instead replace fossil fuels at lower cost while also eliminating air pollution and energy security, which removing carbon from the oceans or air does not do, no matter how efficient it is.
Also, I’m not sure I agree with Rothman’s premise. The K-T extinction was not caused by a massive flux of carbon to or from the oceans, it was caused by a comet or asteroid kicking up debris to the stratosphere, spreading horizontally and blocking the sun.
The bad news is that like air carbon capture approaches, money and energy spent on oceanic geoengineering to reduce the impacts would reduce the amount of money and energy necessary to fix the cause of the problem. The good news is that at least one globally respected scholar in this space is skeptical of one aspect of the oceanic carbon challenge.
We obviously have to stop emitting CO2. Solar geoengineering is a bandaid on the symptoms, not a cure for the causes. It’s like putting out the fires caused by an arsonist wandering around with a flamethrower instead of confiscating and shutting off the flamethrower itself. Global heating would slow and stabilize if we stopped forcing more CO2 into the system.
But it’s unclear if that’s as true for oceanic carbon uptake. Between the basic acidification and Rothman’s working on extinction-level events, more might be required there.
Rothman has been asked for comments as well, and the article will be updated if he replies.
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