House Science Committee hearings on climate change are many things to many people. For members of the commission, it’s typical soapbox parades, with long, sassy statements punctuated by leading questions to witnesses who have been invited because they will give a desired answer. For well-known detractors who reject most of climate science’s conclusions, they are a platform to martyr over why the entire field doesn’t believe them. And for scientists (and humble journalists) who know the subject, they are first and foremost generators of personal contact and almost dangerously powerful eye-rolling.
On Wednesday, the committee held a hearing in which none of this was discussed.
To be fair, it was a subcommittee hearing that didn’t include the full list of members, but there’s reason to believe that made no difference. So why the departure? The subject of the hearing was not the human actions responsible for global warming or the emissions reductions needed to halt it. Instead, the committee discussed the science of geoengineering: the techniques that could potentially be used to intentionally manipulate the climate in a way that would limit climate change.
Dissonance gives way to cognition
Take, for example, Lamar Smith (R-TX), the chair of the Science Committee. Smith has subpoenaed NOAA climate scientists’ emails when he didn’t like their research, and he’s not shy about claiming that global warming is a hoax to justify government control over people’s lives. But while he categorically rejects the mechanisms by which humans have caused climate change, he apparently readily accepts that those same physical processes can be manipulated by geoengineering efforts many orders of magnitude smaller than the global infrastructure that burns fossil fuels.
Smith made his reasons clear. “As the climate continues to change, geoengineering can become a tool to curb the resulting impacts. Instead of forcing unworkable and costly government mandates on the American people, we should be looking to technology and innovation to lead the way to tackling climate change,” Smith said.
Expert witnesses included scientists Phil Rasch of Pacific Northwest National Laboratory and Douglas MacMartin of Cornell, both of whom study geoengineering; Kelly Wanser, the director of the University of Washington Marine Cloud Brightening Project; and Joseph Majkut of the Niskanen Center, a libertarian think tank. All of them – including Majkut – have given serious testimony that accurately describes the current state of geoengineering research and the challenges ahead.
The questions of the committee members to the expert witnesses were equally serious. Several Democrats did emphasize that climate change is man-made and that geoengineering cannot replace emission reductions – a point the experts also made clear. But in general, the committee members asked questions because they genuinely wanted to know the answers.
Technical options
The witnesses summarized several possible geoengineering techniques, including seeding low clouds over the ocean, injecting aerosol particles into the stratosphere to reflect some sunlight back into space, and actively removing carbon dioxide from the atmosphere. Afterwards, the committee wanted to know how the field was progressing. Many seemed quite surprised to learn that the subject had received almost no federal research funding and had only been studied by a handful of scientists. There was also concern about whether other countries were further along. (They are not.)
The committee asked where the greatest uncertainties lie, how the research can be supported and accelerated and on which other climate science programs it relies. Rep. Randy Weber (R-Texas) just piqued his curiosity and asked for an explanation of how ship emissions produce lines of cloud cover called “ship trails.”
That’s not to say there were no Disappointments. Rep. Bill Posey (R-Fla.) displayed an impressive pile of misconceptions when he said, “Any hard evidence for the effect subsurface activity has on the atmosphere? I mean, we know how the last Ice Age ended – it was an asteroid impact that basically created the Gulf of Mexico and darkened the Earth for many, many years, allowing it to freeze.
But overall, it seemed that the committee members were genuinely supportive of the geoengineering research and would try to secure consistent funding. It was certainly a long way from the confirmation hearing for White House Environmental Quality nominee Kathleen Hartnett White on Wednesday.
Hartnett White repeatedly claimed that the human role in climate change was unknown and a matter of scientific debate. Even them claimed that some scientists have concluded that less than half of the energy held by rising greenhouse gases has been absorbed by the oceans. The correct answer — by measurements — is that the number is around 93 percent, as the U.S. National Climate Assessment explained last week.
Meanwhile in the real world
Coincidentally, Douglas MacMartin — one of the expert witnesses at the House Science Committee hearing — also co-authored five geoengineering papers published together in the Journal of Geophysical Research-Atmospheres this week.
The studies mark a step forward for simulations of the injection of sunlight-reflecting aerosol particles into the stratosphere. Many previous simulations have used a simplified setup where aerosols are injected at a single point along the equator, where the intensity of sunlight is greatest. This results in low latitudes cooling more than high latitudes, which could mess with weather patterns.
So the researchers tried to simulate multiple, independent injection points at different latitudes. For example, they found that injecting at latitudes of 15 degrees north and south was most effective because the sunlight is intense and atmospheric circulation helps the particles circulate more towards the poles. By adjusting injections at multiple latitudes over time, they found they could not only meet global average temperature targets, but also maintain the temperature gradient between the northern and southern hemispheres and between the equator and the poles.
But the studies also point to a well-known side effect of this technique: a reduction in precipitation. Global warming is increasing precipitation because a warmer atmosphere can hold more moisture. But because sunlight reflection cools the surface more than the upper atmosphere (the opposite of greenhouse warming), it actually suppresses precipitation a little more than a simple denial of warming would.
While these studies represent progress, they also illustrate how much work would need to be done before geoengineering techniques could be seriously considered. The expert witnesses at the committee hearing tried to provide a timeline for aggressive research projects — maybe after 10 years of work we could identify the best options, they said, and after 20 years have something ready to try at scale.
But that’s assuming the field gets a lot more money than it’s survived so far.