Solar geoengineering

From Harvard's Solar Geoengineering Program

Solar geoengineering refers to a process in which dust is sprayed into the atmosphere in order to "reflect solar radiation back to space" with the intent to dim the sun and therefore, avert global warming. Bill Gates and the Biden administration have supported study into Solar geoengineering.

After controversy erupted over the "horribly stupid" plan, multiple "fact checkers" came to Bill Gates defense.,,,

Sun Dimming Method

David Keith, Frank Keutsch, Debra Weisenstein and John Dykema from Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) wrote the initial paper on a method of Solar geoengineering "that may be able to cool the planet while simultaneously repairing ozone damage."

Abstract:

"Injecting sulfate aerosol into the stratosphere, the most frequently analyzed proposal for solar geoengineering, may reduce some climate risks, but it would also entail new risks, including ozone loss and heating of the lower tropical stratosphere, which, in turn, would increase water vapor concentration causing additional ozone loss and surface warming. We propose a method for stratospheric aerosol climate modification that uses a solid aerosol composed of alkaline metal salts that will convert hydrogen halides and nitric and sulfuric acids into stable salts to enable stratospheric geoengineering while reducing or reversing ozone depletion. Rather than minimizing reactive effects by reducing surface area using high refractive index materials, this method tailors the chemical reactivity. Specifically, we calculate that injection of calcite (CaCO3) aerosol particles might reduce net radiative forcing while simultaneously increasing column ozone toward its preanthropogenic baseline. A radiative forcing of −1 W⋅m−2, for example, might be achieved with a simultaneous 3.8% increase in column ozone using 2.1 Tg⋅y−1 of 275-nm radius calcite aerosol. Moreover, the radiative heating of the lower stratosphere would be roughly 10-fold less than if that same radiative forcing had been produced using sulfate aerosol. Although solar geoengineering cannot substitute for emissions cuts, it may supplement them by reducing some of the risks of climate change. Further research on this and similar methods could lead to reductions in risks and improved efficacy of solar geoengineering methods.

Scientists Push for Solar Geoengineering

A letter dated February 27, 2023 signed by scientists affirm "support for research on atmospheric aerosols and their potential to increase the reflection of sunlight from the atmosphere to address climate risk":

From the introduction:

Given the severity of climate change, scientists and scientific bodies have recommended research on potential approaches to increasing the reflection of sunlight (or release of long wave radiation) from the atmosphere, referred to as “solar radiation modification” (SRM), to slow climate warming and reduce climate impacts. In particular, this research is important for understanding their potential for responding to climate change rapidly, in order to reduce the dangers to people and ecosystems of the climate warming that is projected to occur over the next few decades while society reduces greenhouse gas emissions and concentrations in the atmosphere.

Signatories

• Sarah J. Doherty PhD, Atmospheric Sciences, University of Washington, Seattle (USA)
• Philip J. Rasch PhD, Atmospheric Sciences, University of Washington, Retired, Seattle (USA)
• Robert Wood PhD, Atmospheric Sciences, University of Washington, Seattle (USA)
• Jim Haywood, PhD, University of Exeter (UK)
• Piers M. Forster PhD, Atmospheric Sciences, University of Leeds (UK)
• James E. Hansen, PhD, Columbia University Earth Institute, New York, NY (USA)
• Govindasamy Bala PhD, Atmospheric and Oceanic Science, Indian Institute of Science, Bengaluru (India)
• Alan Robock PhD, Dept. of Environmental Sciences, Rutgers University, NJ (USA)
• Hansi Singh PhD, School of Earth and Ocean Sciences, University of Victoria, BC (Canada)
• Olivier Boucher PhD, Institute Pierre-Simon Laplace, Sorbonne Université / CNRS, Paris (France)
• Paolo Artaxo PhD, Instituto de Fisica, Universidade de Sao Paulo (Brazil)
• David L. Mitchell PhD, Desert Research Institute, Reno, Nevada (USA)
• Seong Soo Yum PhD, Atmospheric Sciences, Yonsei University (South Korea)
• Michael S. Diamond PhD, Earth, Ocean, & Atmospheric Science, Florida State University (USA)
• Anna Possner PhD, Atmospheric Sciences, Geothe University, Frankfurt, Hesse (Germany)
• Philip Stier PhD, Department of Physics, University of Oxford (UK)
• Stephen G. Warren PhD, Atmospheric Sciences, University of Washington, Seattle (USA)
• Prof. Heri Kuswanto, Center for Disaster Management and Climate Change, Institut Teknologi Sepuluh Nopember (ITS) (Indonesia)
• David Keith PhD, Environmental Science & Engineering and Kennedy School, Harvard University, Cambridge MA (USA)
• Trude Storelvmo PhD, Department of Geoscience, University of Oslo (Norway)
• Timothy S. Bates, PhD, CICOES, University of Washington, Seattle, WA (USA)
• Haruki Hirasawa PhD, School of Earth and Ocean Sciences, University of Victoria, BC (Canada)
• Fabian Hoffmann, Dr., Meteorological Institute, Ludwig Maximilian University Munich (Germany)
• John T. Fasullo PhD, Astrophysical, Planetary and Atmospheric Sciences, University of Colorado, Boulder (USA)
• Douglas MacMartin, Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY (USA)
• Amadou Coulibaly PhD, Institut Polytechnique Rural de Formation et de Recherche Appliquée [IPR/IFRA] de Katibougou, Bamako (Mali)
• Becky Alexander PhD, Atmospheric Sciences, University of Washington, Seattle (USA)
• Daniele Visioni, PhD Atmospheric Chemistry and Physics, Cornell University, Ithaca NY (USA)
• Pornampai Narenpitak PhD, National Electronics and Computer Technology Center [NECTEC], National Science and Technology Development Agency (NSTDA), Pathum Thani (Thailand)
• Ben Kravitz PhD, Atmospheric Sciences, Indiana University, Bloomington (USA)
• Franklin J. Opijah PhD, Earth and Climate Sciences, University of Nairobi (Kenya)
• Tianle Yuan, PhD, GESTAR-II, University of Maryland, Baltimore County and Climate and Radiation Lab, NASA Goddard Space Flight Center (USA)
• Abu Syed PhD, Climate Change Adaptation and Risk Assessment Expert, C4RE, Dhaka (Bangladesh)
• Ehsan Erfani PhD, Desert Research Institute, Reno, NV (USA)
• Ryan Eastman PhD, Atmospheric Sciences, University of Washington, Seattle (USA)
• Duncan Watson-Parris PhD, Scripps Institute of Oceanography, University of California San Diego (USA)
• Mou Leong Tan PhD, Hydroclimatic Modelling, Universiti Sains Malaysia (Malaysia)
• Lili Xia PhD, Dept. of Environmental Sciences, Rutgers University, NJ (USA)
• Lucas McMichael PhD, Atmospheric Sciences, University of Washington, Seattle (USA)
• Matthew Henry PhD, Atmospheric and Oceanic Sciences, University of Exeter (UK)
• Abdoulaye Ballo PhD, West African Science Service Center on Climate Change and Adapted Land Use (WASCAL) Competence Centre (CoC), Ouagadougou (Burkina Faso)
• Valentina Aquila, PhD, American University (USA)
• Sebastian D. Eastham PhD, Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, MA (USA)
• Gabriel Chiodo PhD, Atmospheric Sciences, Swiss Federal Institute of Technology, Zurich (Switzerland)
• Armin Sorooshian PhD, Chemical and Environmental Engineering, University of Arizona, Tucson, AZ (USA)
• Blaz Gasparini, PhD, University of Vienna, Vienna (Austria)
• Kelsey E. Roberts PhD, Marine Science, Louisiana State University, Baton Rouge, LA (USA)
• Joel Thornton PhD, Atmospheric Sciences, University of Washington (USA)
• Timofei Sukhodolov PhD, Chemistry-Climate Modelling, Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center, Davos (Switzerland)
• Khalil Karami, PhD, Leipzig University, Leipzig (Germany)
• Paul B. Goddard PhD, Earth and Atmospheric Sciences, Indiana University, Bloomington, IN (USA)
• Alfonso Fernandez PhD, Department of Geography, Universidad de Concepción, Concepción (Chile)
• Cheng-En Yang, PhD, Civil and Environmental Engineering, University of Tennessee, Knoxville, TN (USA)
• Frank N. Keutsch PhD, Department of Chemistry and Chemical Biology, Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA (USA)
• Hosea O. Patrick PhD, Geography, Geomatics, and Environment, University of Toronto (Canada)
• Valerio Lembo PhD, CNR-ISAC, Rome (Italy)
• Kyoungock Choi PhD, Atmospheric Sciences, University of Washington, Seattle (USA)
• Forrest M. Hoffman PhD, Climate Change Science Institute, Oak Ridge National Lab, Tennessee (USA)
• Robyn Schofield PhD, School of Geography, Earth and Atmospheric Sciences, University of Melbourne (Australia)
• Jyoti Singh PhD, Dept. of Environmental Sciences, Rutgers University, NJ (USA)
• Claudia Wieners PhD, Institute for Marine and Atmospheric research, Utrecht (IMAU), Utrecht University, Utrecht (Netherlands)
• Arshad Arjunan Nair PhD, University at Albany, State University of New York (USA)
• Chris Lennard PhD, University of Cape Town (South Africa)
• Paris Rivera PhD, Universidad Mariano Gálvez de Guatemala (Guatemala)
• Alan Gadian PhD, National Centre for Atmospheric Sciences, University of Leeds (UK)
• Bassem Sabra PhD, Notre Dame University, Louaize (Lebanon)
• Sir David King PhD, Centre for Climate Repair at Cambridge University (UK)
• Isabelle Steinke PhD, Delft University of Technology (Netherlands)
• Michael Schulz PhD, Norwegian Meteorological Institute, Oslo (Norway)
• Herman Russchenberg PhD, Delft University of Technology (Netherlands)
• Nicholas Lutsko PhD, Scripps Institution of Oceanography/UCSD, San Diego, California (USA)
• Kate Ricke PhD, Scripps Institution of Oceanography and School of Global Policy & Strategy, University of California San Diego, San Diego, CA (USA)
• Richard Gammon PhD, University of Washington Professor Emeritus, Chemistry, Oceanography, Atmospheric Sciences, Seattle (USA)
• Wener Ochoa PhD, University of San Carlos of Guatemala (Guatemala)
• Albin J. Gasiewski PhD, University of Colorado at Boulder, Center for Environmental Technology, Dept of ECEE, Boulder, CO (USA)
• Fangqun Yu PhD, Atmospheric Sciences Research Center, State University of New York at Albany (USA)
• Gerrit de Leeuw PhD, Professor Emeritus (Netherlands)
• Don Wuebbles PhD, University of Illinois (USA)
• Russell Seitz PhD, Fellow of the Department of Physics, Emeritus, Harvard University, Cambridge, MA (USA)
• Jorge Ivan Cifuentes Castillo, University of San Carlos of Guatemala, Water and Circular Economy Researcher (Guatemala)
• Yaping Zhou PhD, University of Maryland Baltimore County & NASA Goddard Space Flight Center (USA)
• Baylor Fox-Kemper PhD, Brown University, Providence, Rhode Island (USA)
• Alicia Karspeck PhD, SilverLining (USA)
• Shaun Fitzgerald, Centre for Climate Repair at Cambridge University (UK)
• Alice Wells, PhD Candidate, Environmental Intelligence, University of Exeter (UK)
• Mahjabeen Rahman, PhD Candidate, Rutgers University, NJ (USA)
• Ilaria Quaglia, PhD student, Università degli Studi dell’Aquila (Italy)
• Travis Aerenson, PhD Candidate, Atmospheric Sciences, University of Washington, Seattle (USA)
• Hongwei Sun, PhD Candidate, Harvard University, Cambridge, MA (USA)
• Adrian Hindes, PhD Candidate, Fenner School of Environment and Society, Australian National University, Canberra, ACT (Australia)
• Celeste Tong, PhD student, Atmospheric Sciences, University of Washington, Seattle (USA)
• Yan Zhang, PhD Candidate, Mechanical Engineering, Cornell University, Ithaca, NY (USA)
• Burgess Langshaw Power, PhD Candidate, Balsillie School of International Affairs – University of Waterloo, Waterloo, ON (Canada)
• Marc Alessi, PhD Candidate, Atmospheric Science, Colorado State University, Fort Collins, CO (USA)
• Nina Grant, PhD student, Atmospheric Science, Rutgers University, New Brunswick, NJ (USA)
• Jessica S. Wan, PhD student, Climate Sciences, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA (USA)
• Iris de Vries, PhD student, Climate Physics, ETH Zurich (Switzerland)
• John Virgin, PhD student, University of Waterloo, Department of Geography of Environmental Management, Waterloo, Ontario (Canada)
• Alistair Duffey, PhD student, Centre for Polar Observation and Modelling, Earth Sciences, University College London (UK)
• Marissa Saenger, PhD student, Scripps Institution of Oceanography, UC San Diego (USA)
• Cindy Wang, PhD student, Atmospheric & Oceanic Sciences, Princeton University, Princeton, NJ (USA)

Biden Administration Support

From an article at CNBC titled "White House is pushing ahead research to cool Earth by reflecting back sunlight" dated October 13, 2022:

The White House is coordinating a five-year research plan to study ways of modifying the amount of sunlight that reaches the earth to temper the effects of global warming, a process sometimes called solar geoengineering or sunlight reflection.

The research plan will assess climate interventions, including spraying aerosols into the stratosphere to reflect sunlight back into space, and should include goals for research, what’s necessary to analyze the atmosphere, and what impact these kinds of climate interventions may have on Earth, according to the White House’s Office of Science and Technology Policy. Congress directed the research plan be produced in its spending plan for 2022, which President Joe Biden signed in March.

Some of the techniques, such as spraying sulfur dioxide into the atmosphere, are known to have harmful effects on the environment and human health. But scientists and climate leaders who are concerned that humanity will overshoot its emissions targets say research is important to figure out how best to balance these risks against a possibly catastrophic rise in the Earth’s temperature.

Getting ready to research a topic is a very preliminary step, but it’s notable the White House is formally engaging with what has largely been seen as the stuff of dystopian fantasy. In Kim Stanley Robinson’s science fiction novel, “The Ministry for the Future,” a heat wave in India kills 20 million people and out of desperation, India decides to implement its own strategy of limiting the sunlight that gets to Earth.

Chris Sacca, the founder of climate tech investment fund Lowercarbon Capital, said it’s prudent for the White House to be spearheading the research effort.

“Sunlight reflection has the potential to safeguard the livelihoods of billions of people, and it’s a sign of the White House’s leadership that they’re advancing the research so that any future decisions can be rooted in science not geopolitical brinkmanship,” Sacca told CNBC. (Sacca has donated money to support research in the area, but said he has “zero financial interests beyond philanthropy” in the idea and does not think there should be private business models in the space, he told CNBC.)

Harvard professor David Keith, who first worked on the topic in 1989, said it’s being taken much more seriously now. He points to formal statements of support for researching sunlight reflection from the Environmental Defense Fund, the Union of Concerned Scientists, and the Natural Resources Defense Council, and the creation of a new group he advises called the Climate Overshoot Commission, an international group of scientists and lawmakers that’s evaluating climate interventions in preparation for a world that warms beyond what the Paris Climate Accord recommended.

To be clear, nobody is saying sunlight-reflection modification is the solution to climate change. Reducing emissions remains the priority.

“You cannot judge what the country does on solar-radiation modification without looking at what it is doing in emission reductions, because the priority is emission reductions,” said Janos Pasztor, executive director of the Carnegie Climate Governance Initiative. “Solar-radiation modification will never be a solution to the climate crisis.”

Three ways to reduce sunlight

The idea of sunlight reflection first appeared prominently in a 1965 report to President Lyndon B. Johnson, entitled “Restoring the Quality of Our Environment,” Keith told CNBC. The report floated the idea of spreading particles over the ocean at a cost of $100 per square mile. A one percent change in the reflectivity of the Earth 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 tag has gone up since then. The current estimate is that it would cost $10 billion per year to run a program that cools the Earth by 1 degree Celsius, said Edward A. Parson, a professor of environmental law at UCLA’s law school. But that figure is seen to be remarkably cheap compared to other climate change mitigation initiatives.

A landmark report released in March 2021 from the National Academies of Sciences, Engineering, and Medicine addressed three kinds of solar geoengineering: stratospheric aerosol injection, marine cloud brightening, and cirrus cloud thinning.

Stratospheric aerosol injection would involve flying aircraft into the stratosphere, or between 10 miles and 30 miles skyward, and spraying a fine mist that would hang in the air, reflecting some of the sun’s radiation back into space.

“The stratosphere is calm, and things stay up there for a long time,” Parson told CNBC. “The atmospheric life of stuff that’s injected in the stratosphere is between six months and two years.”

Stratospheric aerosol injection “would immediately take the high end off hot extremes,” Parson said. And also it would “pretty much immediately” slow extreme precipitation events, he said.

“The top-line slogan about stratospheric aerosol injection, which I wrote in a paper more than 10 years ago — but it’s still apt — is fast, cheap and imperfect. Fast is crucial. Nothing else that we do for climate change is fast. Cheap, it’s so cheap,” Parson told CNBC.

“And it’s not imperfect because we haven’t got it right yet. It’s imperfect because the imperfection is embedded in the way it works. The same reason it’s fast is the reason that it’s imperfect, and there’s no way to get around that.”

One option for an aerosol is sulfur dioxide, the cooling effects of which are well known from volcanic eruptions. The 1991 eruption of Mount Pinatubo, for instance, spewed thousands of tons of sulfur dioxide into the stratosphere, causing global temperatures to drop temporarily by about 1 degree Fahrenheit, according to the U.S. Geological Survey.

There’s also a precedent in factories that burn fossil fuels, especially coal. Coal has some sulfur that oxidizes when burned, creating sulfur dioxide. That sulfur dioxide goes through other chemical reactions and eventually falls to the earth as sulfuric acid in rain. But during the time that the sulfur pollution sits in the air, it does serve as a kind of insulation from the heat of the sun.

Ironically, as the world reduces coal burning to curb the carbon dioxide emissions that cause global warming, we’ll also be eliminating the sulfur dioxide emissions that mask some of that warming.

“Sulfur pollution that’s coming out of smokestacks right now is masking between a third and a half of the heating signal from the greenhouse gases humans have already emitted into the atmosphere,” Parson said.

In other words, we’ve been doing one form of sunlight reflection for decades already, but in an uncontrolled fashion, explained Kelly Wanser, the executive director of SilverLining, an organization promoting research and governance of climate interventions.

“This isn’t something totally new and Frankenstein — we’re already doing it; we’re doing it in the most dirty, unplanned way you could possibly do it, and we don’t understand what we’re doing,” Wanser told CNBC.

Spraying sulfur in the stratosphere is not the only way of manipulating the amount of sunlight that gets to the Earth, and some say it’s not the best option.

“Sulfur dioxide is likely not the best aerosol and is by no means the only technique for this. Cloud brightening is a very promising technique as well, for example,” Sacca told CNBC.

Marine cloud brightening involves increasing the reflectivity of clouds that are relatively close to the surface of the ocean with techniques like spraying sea salt crystals into the air. Marine cloud brightening generally gets less attention than stratospheric aerosol injection because it affects a half dozen to a few dozen miles and would potentially only last hours to days, Parson told CNBC.

Cirrus cloud thinning, the third category addressed in the 2021 report from the National Academies, involves thinning mid-level clouds, between 3.7 and 8.1 miles high, to allow heat to escape from the Earth’s surface. It is not technically part of the “solar geoengineering” umbrella category because it does not involve reflecting sunlight, but instead involves increasing the release of thermal radiation.

Known risks to people and the environment

There are significant and well-known risks to some of these techniques — sulfur dioxide aerosol injection, in particular.

First, spraying sulfur into the atmosphere will “mess with the ozone chemistry in a way that might delay the recovery of the ozone layer,” Parson told CNBC.

The Montreal Protocol adopted in 1987 regulates and phases out the use of ozone depleting substances, such as hydrochlorofluorocarbons (HCFCs) which were commonly used in refrigeration and air conditioners, but that healing process is still going on.

Also, sulfates injected into the atmosphere eventually come down as acid rain, which affects soil, water reservoirs, and local ecosystems.

Third, the sulfur in the atmosphere forms very fine particulates that can cause respiratory illness.

The question, then, is whether these known effects are more or less harmful than the warming they would offset.

“Yes, damaging the ozone is bad, acid deposition is bad, respiratory illness is bad, absolutely. And spraying sulfur in the stratosphere would contribute in the bad direction to all of those effects,” Parson told CNBC. “But you also have to ask, how much and relative to what?”

The sulfur already being emitted from the burning of fossil fuels is causing environmental damage and is already killing between 10 million to 20 million people a year due to respiratory illness, said Parson. “So that’s the way we live already,” he said.

Meanwhile, “the world is getting hotter, and there will be catastrophic impacts for many people in the world,” said Pasztor.

“There’s already too much carbon out there. And even if you stop all emissions today, the global temperature will still be high and will remain high for hundreds of years. So, that’s why scientists are saying maybe we need something else, in addition — not instead of — but maybe in addition to everything else that is being done,” he said. “The current action/nonaction of countries collectively — we are committing millions of people to death. That’s what we’re doing.”

For sunlight-reflection technology to become a tool in the climate change mitigation toolbox, awareness among the public and lawmakers has to grow slowly and steadily, according to Tyler Felgenhauer, a researcher at Duke University who studies public policy and risk.

“If it is to rise on to the agenda, it’ll be kind of an evolutionary development where more and more environmental groups are willing to state publicly that they’re for research,” Felgenhauer told CNBC. “We’re arguing it’s not going to be some sort of one big, bad climate event that makes us all suddenly adopt or be open to solar geoengineering — there will be more of a gradual process.”

Research it now or be caught off guard later?

Some environmentalists consider sunlight relfection [sic] a “moral hazard,” because it offers a relatively easy and inexpensive alternative to doing the work of reducing emissions.

One experiment to study stratospheric aerosols by the Keutsch Group at Harvard was called off in 2021 due to opposition. The experiment would “threaten the reputation and credibility of the climate leadership Sweden wants and must pursue as the only way to deal effectively with the climate crisis: powerful measures for a rapid and just transition to zero emission societies, 100% renewable energy and shutdown of the fossil fuel industry,” an open letter from opponents said.

But proponents insist that researching sunlight-modification technologies should not preclude emissions-reduction work.

“Even the people like me who think it’s very important to do research on these things and to develop the capabilities all agree that the urgent top priority for managing climate change is cutting emissions,” Parson told CNBC.

Keith of Harvard agreed, saying that “we learn more and develop better mechanism[s] for governance.”

Doing research is also important because many onlookers expect that some country, facing an unprecedented climate disaster, will act unilaterally to will try some version of sunlight modification anyway — even if it hasn’t been carefully studied.

“In my opinion, it’s more than 90 percent likely that within the next 20 years, some major nation wants to do this,” Parson said.

Sacca put the odds even higher.

“The odds are 100 percent that some country pursues sunlight reflection, particularly in the wake of seeing millions of their citizens die from extreme weather,” Sacca told CNBC. “The world will not stand idly by and leaders will feel compelled to take action. Our only hope is that by doing the research now, and in public, the world can collaboratively understand the upsides and best methods for any future project.”

Correction: The Climate Overshoot Commission has not issued a formal statement of support for sunlight reflection.

Bill Gates and Friends

On February 17, 2021, the Sovereign Wealth Fund Institute, reported that "...Bill Gates is financially backing the development of technology that could dim the sun."

"The Paris Agreement is an agreement within the United Nations Framework Convention on Climate Change, on climate change mitigation, adaptation, and finance, signed in 2016. There are many attempts and experiments trying to control global warming. Solar geoengineering refers to proposed approaches to cool the Earth by reflecting solar radiation back to space. Some of these experimental ideas range from sending a giant mirror into space to spraying aerosols in the stratosphere. The two main approaches being researched are stratospheric aerosol injection (SAI) and marine cloud brightening (MCB). Microsoft’s billionaire founder Bill Gates is financially backing the development of technology that could dim the sun. The Stratospheric Controlled Perturbation Experiment (SCoPEx) was launched by Harvard University scientists. The goal of the experiment is to examine this solution by spraying calcium carbonate (CaCO3) dust into the atmosphere. Stratospheric aerosol injections could cool the planet in a similar way to a large volcanic eruption. For example, when a volcano erupts, it sends an ash cloud high into the atmosphere. Released sulphur dioxide in the plume combines with water to form sulfuric acid aerosols. These aerosols are able to reflect incoming sunlight. According to the USGS, “Yes, volcanoes can affect weather and the Earth’s climate. Following the 1991 eruption of Mount Pinatubo in the Philippines, cooler than normal temperatures were recorded worldwide and brilliant sunsets and sunrises were attributed to this eruption that sent fine ash and gases high into the stratosphere, forming a large volcanic cloud that drifted around the world.”

In a December 15, 2020, Harvard University article by SEAS press team, “Injecting light-reflecting aerosols into the stratosphere — known as solar geoengineering —could be used in conjunction with emissions reduction to lower the risks of a climate change and cool the planet. But deliberately introducing particles into the atmosphere may also carry significant risks, and those dangers may increase depending on what aerosols are used. Sulfate aerosols, for example, could contribute to ozone damage and stratospheric heating.

In 2016, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) used computer models to find that calcium carbonate (CaCO3) could not only reflect light and cool the planet but also counter ozone loss by neutralizing emissions-borne acids in the stratosphere — like an antiacid for the atmosphere.”

The Intergovernmental Panel on Climate Change issued a report that suggests the SCoPEx procedure could possibly lower global temperatures by a full 1.5° C. However, global cooling could bring serious risks, such as crop failures and cold weather freezes. The United States, Brazil, and Saudi Arabia blocked a 2019 United Nations assessment of global geoengineering plans.

Harvard’s Solar Geoengineering Research Program (SGRP) is funded by the following foundations and individuals. All donations are philanthropic gifts.

• J. Baker Foundation
• The Blue Marble Fund
• OW Caspersen Foundation
• The Crows Nest Foundation
• The William and Flora Hewlett Foundation
• Constance C. and Linwood A. Lacy Jr. Foundation
• The Open Philanthropy Project
• Pritzker Innovation Fund
• Ronin Private Investments LLC
• The Alfred P. Sloan Foundation
• The Tansy Foundation
• Teza Technologies LLC
• VoLo Foundation
• The Weatherhead Center for International Affairs
• Laura and John Arnold
• G. Leonard Baker, Jr.
• Alan Eustace
• Howard Fischer
• Ross Garon
• Bill Gates
• Jonathan Goldberg
• Drew Myers
• John Rapaport
• Chris and Crystal Sacca
• Michael Smith
• Andrew Stark
• Bill Trenchard

SCoPEx also received in-kind support from NOAA, which provided the POPS instrument that will provide size-resolved measurements of particle concentration.