The White House is coordinating a meeting to study ways to modify the amount of sunlight reaching Earth to mitigate the effects of global warming , a process sometimes called solar geoengineering or sunlight reflection.
From the Office of Science and Technology Policy of Congress ordered that the research plan be produced in , that .
Some of the techniques, such as spraying sulfur dioxide into the atmosphere, have harmful effects on the environment and human health. But scientists and climate leaders who are concerned that humanity will exceed its emissions targets say research is important to figure out how best to balance these risks against a rise in Earth’s temperature.
Preparing to investigate an issue is a preliminary step, but it’s notable that the White House is formally committing itself to what has largely been seen as a dystopian fantasy.
Chris Sacca, the founder of the climate technology investment fund, said it’s prudent for the White House to spearhead the investigative effort.
“Sunlight reflection has the potential to safeguard the livelihoods of billions of people, and it is a signal from White House leadership that they are advancing research so that any future decisions can be based on science and not in politics,” Sacca told CNBC.
, who first worked on the issue in 1989, said he is now taking it much more seriously.
Keith pointed to the formal statements of support for the Fund’s sunlight reflection research, the , the , and the creation of a new group he advises called , an international group of scientists and policymakers that are evaluating climate interventions in preparation. for a world that warms beyond what is recommended by the Paris Climate Agreement.
To be clear, no one is saying that modifying the reflection of sunlight is the solution to climate change. Reducing emissions remains the priority.
“You cannot judge what the country is doing in modifying solar radiation without looking at what it is doing in reducing emissions, because the priority is emission reductions,” said , executive director of . “Modifying solar radiation will never be a solution to the climate crisis.”
Three ways to reduce sunlight
The idea of reflecting sunlight first appeared prominently in a 1965 report to President Lyndon B. Johnson, titled Keith told CNBC. The report floated the idea of spraying particles over the ocean at a cost of $100 per square mile. A one percent change in Earth’s reflectivity would cost $500 million per year, which “does not seem excessive,” the report said, “considering the extraordinary economic and human importance of climate.”
The estimated price has since gone up. The current estimate is $10 billion per year to run a program that cools the Earth by 1 degree Celsius, at the UCLA law school. But that figure is considered remarkably cheap compared to other climate change mitigation initiatives.
One por las addressed three types of solar geoengineering: stratospheric aerosol injection, marine cloud thinning, and cirrus thinning.
spray injection
Stratospheric aerosol injection would involve flying planes into the Earth, or 10 to 30 miles into the sky, and spraying a fine mist that would float in the air, reflecting some of the sun’s radiation back into space.
One option for an aerosol is sulfur dioxide, whose cooling effects are well known from the 1991 Mount Pinatubo eruption, for example, it spewed into the stratosphere, causing global temperatures to rise, according to the US Geological Survey.
There is also precedent for factories burning fossil fuels, especially coal. Coal has some sulfur in it that oxidizes when burned, creating sulfur dioxide. That sulfur dioxide goes through other chemical reactions and eventually falls to earth as sulfuric acid in the form of rain. But for as long as sulfur pollution remains in the air, it serves as a kind of insulation from the sun’s heat.
Ironically, as the world cuts down on coal burning to curb the carbon dioxide emissions that cause global warming, we’ll also be cutting out the sulfur dioxide emissions that mask some of that warming.
“The sulfur pollution coming out of the smokestacks right now is masking a third to a half of the warming signal from greenhouse gases that humans have already emitted into the atmosphere,” Parson said.
In other words, we’ve been doing a form of sunlight reflection for decades, but in an uncontrolled way, explained , executive director of , an organization that promotes research and governance of climate interventions.
Clearing of marine clouds
It involves increasing the reflectivity of clouds that are relatively close to the ocean surface with techniques such as spraying sea salt crystals into the air. Marine cloud glow typically gets less attention than stratospheric aerosol injection because it affects half a dozen to a few dozen miles and would only last for hours to days, Parson told CNBC.
Cirrus thinning
Cirrus thinning, the third category addressed in the National Academies’ 2021 report, involves the thinning of mid-level clouds, between 3.7 and 8.1 miles high, to allow heat to escape from the Earth’s surface. Technically, it does not fall under the umbrella category of “solar geoengineering” because it does not involve reflecting sunlight, but instead involves increasing the release of thermal radiation.
