House Science Committee hearings on climate change are many things to many people. For members of the committee, they are typically soapbox pageants, with long, blustery declarations punctuated by leading questions to witnesses who have been invited because they will give a desired answer. For well-known contrarians who reject most of the conclusions of climate science, they are a platform to wax martyrish about why the entire field doesn't believe them. And for scientists (and humble journalists) who know the topic, they are primarily generators of head-to-desk contact and almost hazardously vigorous eye-rolling.

On Wednesday, the committee held a hearing that was none of these things.

To be fair, it was a subcommittee hearing that didn't feature the full roster of members, but there is reason to believe that made no difference. So why the departure? The topic of the hearing was not the human actions responsible for global warming or the emissions cuts necessary to halt it. Instead, the committee discussed the science of geoengineering: the techniques that could potentially be employed to intentionally manipulate the climate in ways that would limit climate change.

Dissonance gives way to cognition

Take Lamar Smith (R-TX), the chair of the Science Committee, for example. Smith has subpoenaed the e-mails of NOAA climate scientists when he didn’t like their research, and he isn’t shy about claiming that global warming is a hoax to justify government control of 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 could be manipulated by geoengineering efforts many orders of magnitude smaller than the world’s fossil-fuel-burning infrastructure.

Smith made his reasons clear. “As the climate continues to change, geoengineering could become a tool to curb resulting impacts. Instead of forcing unworkable and costly government mandates on the American people, we should look to technology and innovation to lead the way to address climate change,” Smith said.

The 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’s Marine Cloud Brightening Project; and Joseph Majkut of the Niskanen Center, a libertarian think tank. All of them—Majkut included—gave serious testimony that accurately described the current status of geoengineering research and the challenges ahead of it.

The committee members' questions for the expert witnesses were equally serious. Several Democrats did make a point of emphasizing that climate change is human-caused and that geoengineering cannot replace emissions cuts—a point the experts made clear, as well. But generally, the committee members asked questions because they genuinely wanted to learn the answers.

Engineering options

The witnesses summarized several possible geoengineering techniques, including the seeding of low clouds over the ocean, injection of aerosol particles into the stratosphere to reflect a little sunlight back out to space, and actively removing carbon dioxide from the atmosphere. Afterward, the committee wanted to learn about how the field has progressed. Many seemed quite surprised to learn that the topic had received almost no federal research funding and has only been studied by a handful of scientists. There was also concern about whether other countries were further along. (They aren’t.)

The committee asked about where the biggest uncertainties are, how the research could be supported and accelerated, and what other climate science programs it relied on. Rep. Randy Weber (R-Texas) simply got his curiosity piqued and asked for an explanation of how emissions from ships produce lines of cloud cover called “ship tracks.”

That’s not to say there were no letdowns. Rep. Bill Posey (R-Fla.) displayed an impressive pile of misconceptions when he said, “Any hard evidence on the effect that subsurface activity has on the atmosphere? I mean, we know what ended the last Ice Age—it was an asteroid strike that basically created the Gulf of Mexico and darkened the Earth for many, many years, allowed it to freeze over.”

But generally, it seemed that the committee members were genuinely supportive of geoengineering research and would seek to establish some consistent funding. It was certainly a far cry from the confirmation hearing for White House Council on 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. She even claimed that some scientists have concluded that less than half of the energy trapped by rising greenhouse gases has been absorbed by the oceans. The correct answer—according to measurements—is that the number is around 93 percent, as the US National Climate Assessment released last week explains.

Meanwhile, in the real world

As it happens, Douglas MacMartin—one of the expert witnesses at the House Science Committee hearing—is also a co-author on 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 past 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 has the effect of cooling low latitudes more strongly than high latitudes, which could mess with weather patterns.

So the researchers tried simulating multiple, independent injection points at different latitudes. They found, for example, that injecting at 15 degrees north and south latitude was most effective, as the sunlight is intense, and atmospheric circulation better circulates particles poleward. By adjusting injections at multiple latitudes over time, they found they were able to hit not just global average temperature targets, but they were also able to preserve the temperature gradient between the North and South Hemispheres and between the equator and the poles.

But the studies also highlight one well-known side-effect of this technique—a reduction in precipitation. Global warming is causing precipitation to increase, as 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 negation of warming would.

Even as these studies represent progress, they also illustrate how much work would have to be done before geoengineering techniques could be seriously considered. The expert witnesses at the committee hearing tried to offer up a timeline for aggressive research projects—perhaps we could identify the best options after a decade of work, they said, and have something ready to attempt at scale after 20 years.

But that’s assuming that the field gets much more funding than it has survived on so far.