Climate scientists from the United States government will study two geoengineering proposals to counter global warming.
The chief climate change scientist for the National Oceanic and Atmospheric Administration (NOAA) said he received $ 4 million from Congress and his agency's permission to study two emergency and controversial methods of cooling Earth if the United States and other nations fail to reduce the global greenhouse gas emissions.
David Fahey, director of the Division of Chemical Sciences at NOAA's Earth System Research Laboratory, told his staff yesterday that the federal government is ready to examine the science behind "geoengineering," what he called a "Plan B" for climate change.
Fahey said he was supported to explore two approaches:
One is to inject sulfur dioxide or a similar aerosol into the stratosphere to help protect Earth from the most intense sunlight. It is based on a natural solution: volcanic eruptions, which have been found to cool the Earth by emitting huge clouds of sulfur dioxide.
The second approach would use an aerosol of sea salt particles to enhance the ability of low-lying clouds over the ocean to act as a shade.
This technique is borrowed from "ship tracks", or the long clouds left by passing ocean freighters that satellites see as reflective roads. They could be enlarged by injections of seawater vapor by specialized ships to create shadow effects.
Research in both techniques, Fahey emphasized, is recommended in an upcoming study by the National Academies of Sciences, Engineering and Medicine entitled "Climate intervention strategies that reflect sunlight in cold earth."
But in sign of how controversial the issue is, Fahey recommended changing the geoengineering nomenclature to "climate intervention," which he described as a "more neutral word."
Fahey also emphasized that this is not an approval to move forward with geoengineering. Rather, it is about preparing the US government for a political decision if the world fails to adequately limit the increase in global warming.
"Geoengineering is this tangled ball of problems and science is just one of them," he said.
"One of the things I'm interested in doing is separating science," he added. The idea is to give policymakers a clear vision of how a hasty bid to save the planet would work.
Even then, the results would probably not be immediate. Fahey showed slides and graphs indicating that a Plan B could take up to the next century to complete the cooldown. Still, better science could "buy time" to improve efforts, he said.
He noted that there would be drawbacks after a researcher asked if injections of sulfur dioxide into the atmosphere could reduce shellfish by acidifying the oceans.
"When you put aerosols into the atmosphere, a lot happens," Fahey replied. "That opens up this whole menu of things you should be worrying about," he added.
He said other aerosols such as calcite or titania “might have less impact, but nobody knows. We want to see them in the lab. "
Several smaller nations have complained that using airplanes to inject aerosols into the atmosphere could alter the climate or destroy the ozone layer, which protects humans from some of the most damaging radiation in sunlight.
Fahey suggested that a scientific approach would require solving a list of unknowns, including tests to discover what is in the stratosphere today and how to get aerosols to spread there homogeneously. Another likely area of investigation: unintended consequences.
"We have to use atmospheric observations to find out what we are doing," he added.
At the moment, the government has no planned experiments and NOAA's authority extends to the stratosphere. But there is a bill in Congress called the "Climate Intervention Investigation Act" that would expand its jurisdiction. "There could be more than $ 100 million attached to this, I am told," he explained.
So far, neither Congress nor the administration has ventured to address the issue of Plan B. The closest thing to testing it is a project sponsored by Harvard University called the "Controlled Stratospheric Disturbance Experiment" (SCoPEx).
He proposes a small-scale test using a propeller-driven balloon. It would ascend 12 miles above New Mexico and then release less than 1kg of calcium carbonate.
The idea was to create a tubular area in the sky, about 1 kilometer long and 100 meters in diameter, through which the sensor-filled balloon could move slowly back and forth, mixing the air and monitoring the solar reflection abilities of the scattered materials. . It would also track the impact of the treated area on the surrounding atmosphere. But we don't know when SCoPEx will happen.
Sensitive to the question of how to govern such experiments, Harvard has appointed an external advisory committee to help monitor and evaluate the test. According to DavidKeith, a Harvard physicist who is one of the project leaders, the external committee would help determine if and when the experiment should move forward.
Funding for the experiment will come from Harvard research funds and a list of external contributors to a fund controlled by the Harvard Solar Geoengineering Research Program. Compared to US space, defense, and weather-related experiments, the cost of the effort would be miniscule.
Keith could not be reached for comment on Fahey's announcement, but Fahey said that NOAA supports Harvard's stratospheric test and has contributed an instrument to help him measure particle scattering.
“We will have to give up a few things to get into Plan B. That's why we would be motivated to try designer sprays, but we may not have time,” Fahey explained.
"That is what Harvard wants to do. It goes back to the question of which path you want to be on, ”he added, pointing out the difference between a possible international decision to cut greenhouse gas emissions or being late and being forced to implement a Plan B to stop runaway climate change.
"I don't want to be late, but the question is what paths will open to us," he said. “I think that nobody can play all the chess moves on this subject. It's very complicated".