What would be the price tag for shielding the Earth from global warming using a chemical cloud? It might be just $1 billion to $3 billion, making a sun-reflecting project much cheaper than combating climate change by reducing emissions and preserving forests to take up carbon dioxide, a new study has found.
That doesn't mean the study's authors recommend sun-reflecting projects over other measures suggested to help prevent global warming and slow climate change, such as cutting back on electricity use, they say. "Such a claim could be sensibly made only after thorough investigation of the implications of risks and of the imperfect climate compensation offered by SRM [solar radiation management]," business and environment analysts from different U.S. institutions wrote in their paper, published yesterday (Aug. 30) in the journal Environmental Research Letters. Their paper isn't intended to evaluate the effectiveness or risk of such measures, just cost, they said.
"We hope our study will help other scientists looking at more novel methods for dispersing particles," Jay Apt, one of the paper's authors and a professor of business, engineering and public policy at Carnegie Mellon University, said in a statement.
A controversial topic
The new paper estimates the price of sending aircraft into the stratosphere to blow 1 million tons or more of sulfur or another chemical into the air. The chemicals are intended to reflect some sunlight away from Earth, keeping the planet cooler in case of catastrophic global warming in the future. [ Changing Earth: 7 Ideas to Geoengineer Our Planet ]
The study is one of the few to closely analyze the cost of launching and sustaining a geoengineering project. (Geoengineering projects are huge, Earth-altering installations meant to slow the effects of climate change.) "As economists are beginning to explore the role of several types of geoengineering, it is important that a cost analysis of SRM is carried out," Apt said.
Humankind is in little danger of seeing such projects happen any time soon, two researchers who study geoengineering policy told InnovationNewsDaily for a previous story. Research into extreme global warming reversal is still in its earliest stages. In addition, because such projects would have dramatic, worldwide effects — both good and ill — scientists consider them last resorts that won't be needed for decades, if at all. Some environmental groups oppose geoengineering altogether because of the harm it could cause certain parts of the planet.
By plane, platform or blimp
Nevertheless, some researchers have started to examine the scientific tests and new policies that would be needed before national governments or other groups begin to undertake geoengineering projects.
In the new study, researchers used the same cost-estimating methods that the aerospace industry uses. Indeed, a member of the team, Justin McClellan, normally makes cost estimates for Aurora Flight Sciences Corporation in Cambridge, Mass. McClellan, Apt and their colleague David Keith of Harvard University are the first to use the aerospace industry's modeling tools to determine the price of geoengineering, they said in their paper.
They examined several ways of lofting chemicals 12 to 19 miles (20 to 30 kilometers) above the Earth.
The researchers found it would take about $800 million to buy and modify the 14 Boeing 747-400s needed for a year's worth of sun-reflecting. It would cost another $1 billion a year to cover operational costs after the planes were bought and fitted. Several planes are needed because existing jets are designed to fly far distances efficiently, rather than fly straight up, so they are not able to carry large loads into the stratosphere, the researchers wrote.
In the future, would-be geoengineers may also develop new aircraft for their needs. If they created a craft that is able to fly 13 miles (21 km) into the air, carrying 1.1 tons (one metric ton) of sunlight-reflecting particles, it would cost a little more than $1.5 billion a year, including research costs, the analysts said. Higher altitudes, as well as higher carrying capacities, would cost more.
An airship — an aircraft that flies using mostly buoyant forces, like a blimp does — may also work for carrying sun-reflecting particles into the stratosphere. An airship that flies 13 miles into the air and carries 1.1 tons would cost a little more than $1 billion a year, the researchers said. The most promising types of airships for this work are still in their earliest stages of research, however, the paper's authors noted. [ DIY Space Program Breaks Records with Airship Flight ]
Even earlier in their research life are lighter-than-air, floating platforms that are tethered to the Earth with a pipe. Such "space elevators" may be especially economical to maintain, the study authors said. However, scientists haven't yet discovered material that is light enough, yet strong enough, to tether such a platform, so the analysts added that it's difficult to estimate this method's true costs.
Overall, the estimated cost of sending up a cloud of sun-reflecting chemicals is less than 1 percent of the cost of mitigating climate change, researchers wrote. They cited a paper that found climate mitigation would cost $200 billion to $2 trillion a year.
Yet, they wrote, "We are not making a cost-effectiveness argument."
"It simply means that an attribute of SRM is that it is comparatively inexpensive," they said.