BOULDER, Colo. — In a protected compound at the foot of the Rocky Mountains, government scientists are working on a new kind of global alarm system: one that can detect whether another country, or perhaps just an adventurous billionaire, tries to darken the sun.
Every few weeks, researchers in Boulder, Colorado, release a balloon that rises 17 miles into the sky. Similar balloons are launched less frequently from locations in Alaska, Hawaii and New Zealand; from Reunion Island, near the coast of Africa; and even Antarctica. They make up the building blocks of a system that would alert US scientists about geoengineering.
As the planet continues to warm, the idea of intentionally trying to block solar radiation — sometimes called solar radiation modification, solar geoengineering or climate intervention — is gaining attention. Governments, universities, investors and even environmentalists are investing millions of dollars in research and modeling of geoengineering systems.
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This could be a relatively quick way to cool the planet. But it could also unleash untold dangers.
Many worry that solar geoengineering could have unintended consequences, destroying regional weather patterns and harming everything from agriculture to local economies. And the first steps could be taken silently, by a rogue actor or another nation operating without regulations or controls.
So the United States is building a system that would allow it to determine if and when others might be trying to tamper with Earth’s thermostat.
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“It’s one of the most important stratospheric sciences happening in the world today,” said David W. Fahey, director of the National Oceanic and Atmospheric Administration’s (NOAA) Chemical Sciences Laboratory, which is building the network of sentinel balloons, in an afternoon. recent at his Boulder office.
Both NOAA and NASA have satellites that can detect large amounts of aerosols in the atmosphere, but cannot capture smaller amounts. That’s where balloons come in. Each carries a 6-pound device, about the size of a lunch box, filled with wires and tubes. The device measures tiny airborne particles, or aerosols. A sudden increase could indicate the presence of an unusual amount of aerosols in the stratosphere, possibly to divert some of the sun’s heat back into space.
Fahey’s team is building the ability to detect, track and understand the effects of any unusual aerosol releases.
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The early warning system for geoengineering is a piecemeal effort among federal agencies and laboratories. NOAA has the device to measure the concentration of aerosols and issue an alert in case of anomalies. NASA has high-altitude aircraft that can carry sophisticated testing equipment to locate an aerosol plume. Scientists at Sandia National Laboratory in New Mexico, working for the Department of Energy, have a tool that can estimate when and where an aerosol burst was emitted.
The researchers emphasize that these detection efforts are still in their infancy. So far, they believe that solar geoengineering has only been attempted on a very small scale, despite claims from conspiracy theorists.
But the work done at NOAA and Sandia demonstrates how geoengineering has transformed from a science fiction topic into a source of growing concern for the government.
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“If a country — a major ally or a major opponent — is developing capabilities, can our scientists tell us what they are trying to do and what the impact of that would be?” asked Kelly Wanser, founder and executive director of SilverLining, a nonprofit group that advocates for geoengineering research and helped convince Congress to fund NOAA’s program. “How dangerous is this? How quickly and firmly do we need to respond?”
The chemical sciences laboratory that NOAA operates in Boulder has the look and feel of a college campus. Some of the world’s top atmospheric scientists mill about the hallways wearing hiking boots and T-shirts, as if they’re ready to climb the Rocky Mountains visible through the windows. The only indication of the nature of their work are the armed guards at the gates, searching visiting vehicles for explosives.
In a windowless room, Alexandre Baron, a young French scientist who focuses on the microphysical properties of aerosols, showed off the insides of the boxes his team has been sending skyward. The device pulls air into an intake tube and scans it with a laser. Aerosols scatter light, making it possible to record its concentration and size.
Once the balloons carrying the devices ascend to 90,000 feet, nearly three times the cruising altitude of a commercial airliner, a valve opens to slowly release helium and float the balloons back to Earth. The round trip takes 3 1/2 hours, during which instruments send aerosol readings back to the ground by radio.
NOAA recovers most of the boxes, which cost around R$15,000 each, replacing components so they can be reused. (The agency lost some of the balloons over the ocean and in the Alaskan wilderness.)
Sometimes a balloon and its precious cargo get stuck in trees. Leaning against the wall in Baron’s room, among laboratory equipment, was a large tree pruner. “I definitely used it on one occasion where the payload was hanging,” said Troy Thornberry, the NOAA research scientist in charge of the program.
The immediate task of scientists in Boulder is to gather enough data on aerosol levels at different locations above Earth to create a baseline of normal concentrations, in the absence of some external event like a volcanic eruption. This would allow NOAA to determine when aerosol levels in any specific location are unusually high.
The program, which Congress began funding in 2020, fits into NOAA’s broader mission of studying the atmosphere, Thornberry said. The budget is less than R$1 million per year, he added.
To build a global baseline, NOAA has been working with researchers and government scientists from other countries. It is coordinating launches with researchers in Réunion, a French territory near Mauritius. This month, the NOAA team launched a balloon for the first time from Suriname, a small country on Brazil’s northern border, with plans for future launches undertaken by that country’s meteorological agency. NOAA plans to visit Palau, a small island nation between the Philippines and Guam, early next year, seeking a similar arrangement.
The United States wants to establish regular balloon launches from seven locations around the world and maintain those launches for three to five years, Thornberry said. At that point, the agency should have enough information to confidently identify unusual increases, he said.
Thornberry said he is not aware of other countries pursuing a similar surveillance effort. “Maybe because they just don’t talk about it,” he added.
If the balloon system detects a suspicious level of aerosols, Thornberry would then turn to another instrument at the NOAA laboratory. It is the world’s most sensitive device for detecting sulfur dioxide, the material most often cited as likely to be used to reflect radiation from Earth. An assembly of valves and tubes that resembles a race car engine, the instrument can measure concentrations as small as 1 part per trillion.
NOAA would load the device in the back of a truck, take it to Houston and attach it to the bottom of a plane. But not on any plane.
There are only a few planes that can reach the stratosphere. One model is the WB-57, three of which are housed at NASA’s Johnson Space Center. The plane, marked by a bulbous nose and extra-long wingspan, can fly above 60,000 feet.
Thornberry estimated that his team could get the device airborne within three weeks of detecting an aerosol plume and before it could dissipate. All it would take is to finance the flight time — somewhere in the range of R$1 million to R$1.5 million, he said.
A NASA spokesperson declined to make any agency staff members available for an interview.
About 400 miles south of Boulder, researchers at one of the nation’s top nuclear weapons labs have solved another part of the puzzle: how to pinpoint the location of an aerosol release.
Sandia National Laboratories, on the east end of Albuquerque, New Mexico, was started as part of the Manhattan Project, America’s clandestine effort to build a nuclear bomb. Today, the laboratory, which is operated by a subsidiary of Honeywell International under contract with the Department of Energy, has sophisticated computer-based models that can determine whether other countries are testing nuclear weapons.
Modern nuclear test ban treaties only work “because we would be able to know whether Russia conducted the tests,” said Erin Sikorsky, who previously led the U.S. intelligence community’s climate security analysis and now directs the Center for Climate and Security, a research group in Washington. “And it was Sandia scientists who developed the systems to be able to figure this out.”
This ability to build sophisticated detection models is useful in the era of solar geoengineering.
Laura Swiler, a senior scientist at Sandia, developed an algorithm that could take an aerosol plume observed from any source — say, a volcanic eruption or a large wildfire — and look back in time to estimate its size and point of origin.
The United States is still years away from being ready to detect a solar geoengineering effort, but it is at the forefront.
“We know more about important aspects of stratospheric aerosol as it exists today than any other group in the world,” Fahey said. “We are playing the long game.”
