The U.S. National Academy of Sciences has released two very pessimistic reports on geoengineering.
Well, actually the reports are on “climate intervention,” because the Academy panel rejects the widely used term “geoengineering.” Why? Because “we felt ‘engineering’ implied a level of control that is illusory,” explained Dr. Marcia McNutt who led the report committee. The word “intervention” makes it clearer that the “precise outcome” could not be known in advance
The first report is on “Carbon Dioxide Removal and Reliable Sequestration,” which covers everything that could permanently remove CO2 out of the air — from reforestation to direct capture of CO2 from the air.
The second report is on “Reflecting Sunlight,” which covers the more exotic climate-altering strategies to increase the reflectivity (albedo) of the Earth. The best studied of these is injecting vast quantities of sulfate aerosols into the stratosphere to mimic the cooling effect of volcanos. The authors also reject the widely used umbrella term for these strategies, “solar radiation management,” in favor of “albedo modification” because, again, “management” implies a level of control of the outcome that the committee does not believe we have.
These mammoth reports can be summarized with a paraphrase of a line attributed to Samuel Johnson, “Your proposed climate intervention strategies are both safe and affordable. But the strategies that are safe are not affordable, and the strategies that are affordable are not safe.” Indeed, it is because the two types of climate intervention are flawed in such different ways that the committee did not want to conflate them. That’s why they ultimately decided to split their report in two.
Because of the problems with climate intervention, the scientists at the press conference echoed the central point the Academy makes in the report. “There is no substitute for dramatic reductions in the emissions of CO2 and other greenhouse gases to mitigate the negative consequences of climate change, and concurrently to reduce ocean acidification,” the report read.
I have likened geoengineering to a dangerous, never tested, course of chemotherapy prescribed to treat a condition curable through diet and exercise — or, in this case, cuts in greenhouse gas emissions. If your actual doctor were to prescribe such a treatment, you would get another doctor.
I have also written many times about how dubious and unsafe the reflecting sunlight strategies are, including aerosol injection. For one thing, as the Academy report makes clear, they do nothing at all to slow the devastating impacts of ocean acidification (or any other impact that would be associated with rising carbon dioxide levels).
The scientific literature has repeatedly explained that the aerosol-cooling strategy — or indeed any large-scale effort to manipulate sunlight — is very dangerous. In November, the UK Guardian reported that the aerosol strategy “risks ‘terrifying’ consequences including droughts and conflicts,” according to recent studies. “Billions of people would suffer worse floods and droughts if technology was used to block warming sunlight, the research found.” And this is considered the best albedo modification strategy!
No doubt that is why the Academy concludes:
Recommendation 3: Albedo modification at scales sufficient to alter climate should not be deployed at this time.
There is significant potential for unanticipated, unmanageable, and regrettable consequences in multiple human dimensions from albedo modification at climate altering scales, including political, social, legal, economic, and ethical dimensions.
The Academy does endorse a program of mostly basic research into albedo modification in order to better “understand” it. That said, leading experts have long explained that “Stratospheric geoengineering cannot be tested in the atmosphere without full-scale implementation” — see here. Researchers found “weather and climate variability preclude observation of the climate response without a large, decade-long forcing. Such full-scale implementation could disrupt food production on a large scale” — for two billion people!
In fact, one of the Academy’s panel members, Ken Caldeira, a well-known advocate for research into albedo modification, was recently interviewed by Newsweek. They reported, “Caldeira doesn’t believe any method of geoengineering is really a good solution to fighting climate change — we can’t test them on a large scale, and implementing them blindly could be dangerous.”
The Academy report itself explains:
Albedo modification presents a number of risks and expected repercussions. Observed effects from volcanic eruptions include stratospheric ozone loss, changes to precipitation (both amounts and patterns), and likely increased growth rates of forests caused by an increase in diffuse solar radiation. Large volcanic eruptions are by their nature uncontrolled and short-lived, and have in rare cases led to widespread crop failure and famine (e.g., the Tambora eruption in 1815). However, effects of a sustained albedo modification by introduction of aerosol particles may differ substantially from effects of a brief volcanic eruption. Models also indicate that there would be consequences of concern, such as some ozone depletion or a reduction in global precipitation associated with sustained albedo modification. Further, albedo modification does nothing to reduce the build-up of atmospheric CO2, which is already changing the make-up of terrestrial ecosystems and causing ocean acidification and associated impacts on oceanic ecosystems.
As McNutt — editor in chief of the journal Science — said at the press conference, nobody should think that we can simply keep changing the climate with unrestricted carbon pollution and have any confidence we could intervene after the fact to fix things: “There is no silver bullet here, we cannot continue to release carbon dioxide and hope to clean it up later.”
I have written at length about how incredibly expensive carbon capture and storage is for coal plants. But while extracting the carbon dioxide from coal burning (either pre-combustion or post-combustion) is certainly cheaper than any of the Carbon Dioxide Removal (CDR) strategies the Academy looked at, it doesn’t count as CDR itself because you are not removing net CO2 from the air with coal CCS (you are just not adding new CO2 into the air). As you might expect, direct air capture — simply pulling massive amounts of CO2 out of the air — is incredibly expensive and difficult to scale given that atmospheric CO2 is so diffuse, only 400 parts per million.
The Academy explains further:
The barriers to deployment of CDR approaches are largely related to slow implementation, limited capacity, policy considerations, and high costs of presently available technologies. Additional research and analysis will provide information to help address those challenges. For these reasons, if carbon removal technologies are to be widely deployed, it is critical to embark now on a research program to lower the technical barriers to efficacy and affordability. In the end, any actions to decrease the excess burden of atmospheric CO2 serve to decrease, or at least slow the onset of, the risks posed by climate change. Environmental risks vary among CDR approaches but are generally much lower than the risks associated with albedo modification approaches. However, it is also less risky environmentally to avoid a given CO2 emission to the atmosphere than to emit it with the expectation that it will be purposefully removed from the atmosphere at some later time.
Not putting CO2 in the air is much less risky and vastly cheaper than trying to pull it out later. So, let’s try that!