If you don’t do aggressive greenhouse mitigation starting now, you pretty much take geo-engineering off the table as a very limited (but still dubious) add-on strategy.
The only upside I can see to all of the media coverage Bjorn Lomborg is getting for his do-nothing climate “consensus” is this one sentence by NYT reporter John Broder:
Critics in the environmental movement call him a “delayer” who believes that the problem will solve itself through the miracle of as-yet-unidentified science.
Apparently all of my critiques haven’t gone for naught (see “The Bjorn Irrelevancy: Duke dean disses Danish delayer“). Well, ok, those critiques didn’t stop Broder from writing an unjustifiably warm piece on the pro-warming man I called “the second most famous Danish delayer after Hamlet (see “Lomborg’s main argument has collapsed“).
Note to Broder: I’m not in the “environmental movement” nor have I even been. I’m in the “stop humanity’s self-destruction movement,” which isn’t quite so easy to pigeonhole. But I digress.
Juliet Eilperin had a much better piece in the Washington Post, which actually included a response from real climate scientists:
The group, headed by statistician Bjorn Lomborg, issued a report by five economists that suggested it made more sense to spend money on marine cloud whitening research and green energy development than to protect forests, clean up diesel emissions or significantly raise the price of carbon….
Several scientists questioned whether focusing on geoengineered solutions at the expense of major carbon reductions would adequately address the effects of climate change. Carnegie Institution senior scientist Ken Caldeira, a geoengineering expert, said such a strategy “misses the point.”
“Geoengineering is not an alternative to carbon emissions reductions,” he said. “If emissions keep going up and up, and you use geoengineering as a way to deal with it, it’s pretty clear the endgame of that process is pretty ugly.”
Brad Warren, who directs the ocean health program at the advocacy group Sustainable Fisheries Partnership, noted that even if marine cloud whitening worked, it would fail to address the fact that human-generated carbon emissions are making the seas more acidic and threatening marine life.
“I haven’t seen anything in the area of geoengineering that protects the ocean from the chemical consequences of greenhouse gas emissions,” Warren said.
The group’s inane results are here, and I’ll discuss the voodoo economics behind them later. But the comment of Ken Caldeira caught my eye. I’ve known him for many years and I asked him if he could explain his remarks. His response (boldface added):
Nobody has written about this that I know of, but ….
If we keep emitting greenhouse gases with the intent of offsetting the global warming with ever increasing loadings of particles in the stratosphere, we will be heading to a planet with extremely high greenhouse gases and a thick stratospheric haze that we would need to main more-or-less indefinitely. This seems to be a dystopic world out of a science fiction story. First, we can assume the oceans have been heavily acidified with shellfish and corals largely a thing of the past. We can assume that ecosystems will be greatly affected by the high CO2 / low sunlight conditions — similar to what Earth experienced hundreds of millions years ago. The sunlight would likely be very diffuse — maybe good for portrait photography, but with unknown consequences for ecosystems.
We know also that CO2 and sunlight affect Earth’s climate system in different ways. For the same amount of change in rainfall, CO2 affects temperature more than sunlight, so if we are to try to correct for changes in precipitation patterns, we will be left with some residual warming that would grow with time.
And what will this increasing loading of particles in the stratosphere do to the ozone layer and the other parts of Earth’s climate system that we depend on?
On top of all of these environmental considerations, there are socio-political considerations: We we have a cooperative world government deciding exactly how much geoengineering to deploy where? What if China were to go into decades of drought? Would they sit idly by as the Climate Intervention Bureau apparently ignores their plight? And what if political instability where to mean that for a few years, the intervention system were not maintained … all of that accumulated pent-up climate change would be unleashed upon the Earth … and perhaps make “The Day After” movie look less silly than it does.
Long-term risk reduction depends on greenhouse gas emissions reduction. Nevertheless, there is a chance that some of these options might be able to diminish short-term risk in the event of a climate crisis.
I would add the grave risk that that after injecting massive amounts of sulfate aerosols into the atmosphere for a decade or more, we might discover some unexpected bad side effect that just gets worse and worse. After all, the top climate scientists underestimated the speed and scale of greenhouse gas impacts (and the magnitude of synergistic ones, like bark beetle infestations and forest fires).
We would be in incompletely unexplored territory — what I call an experimental chemotherapy and radiation therapy combined. There is no possible way of predicting the long-term effect of the thick stratospheric haze (which, unlike GHGs, has no recent or paleoclimate analog). If it turned out to have unexpected catastrophic impacts of its own (other than drought), we’d be totally screwed.
No surprise, then, that science advisor John Holdren told me in April that he stands by his critique:
“The ‘geo-engineering’ approaches considered so far appear to be afflicted with some combination of high costs, low leverage, and a high likelihood of serious side effects.”
Even geoengineering advocate Tom Wigley is only defending “a complementary combined mitigation/geoengineering scenario, an overshoot concentration pathway where atmospheric carbon dioxide reaches 530 ppm before falling back to 450 ppm, coupled with low-intensity geoengineering,” with the goal of stabilizing global temperature rise at 2°C, in case we can’t stabilize at 450 ppm. You can see a good discussion of that at the Bulletin of Atomic Scientists‘ expert roundtable response to Alan Robocks’ excellent piece, “20 reasons why geoengineering may be a bad idea.”
Well, stabilizing at 530 ppm requires doing a massive amount of mitigation starting now — only 2 or 3 fewer wedges than what is needed for 450 (see “How the world can (and will) stabilize at 350 to 450 ppm: The full global warming solution“).
Ignore the delayers, already, status quo media. The time for aggressive greenhouse gas reduction is now.
- Science on the Risks of Climate Engineering: “Optimism about a geoengineered ‘easy way out’ should be tempered by examination of currently observed climate changes”