Fact Check: Is Bill Gates Trying to Block the Sun?

Billionaire philanthropist and Microsoft co-founder Bill Gates is no stranger to conspiracy theories and speculation about the projects he funds.

One that has persisted in recent weeks involves an experiment by a team of scientists at Harvard University, known as the Stratospheric Controlled Perturbation Experiment (SCoPEx), that is testing aerosols that might be relevant to solar geoengineering.

Solar geoengineering, also known as radiation management, is based on the idea of using technologies to fight climate change by reflecting sunlight back into space.

With Bill Gates attempt to “block out the sun”, I don’t believe Texas winter storm was a fluke 🤷🏾‍♂️

— Tom Johnson III (@Tom2x_) March 1, 2021

The Claim

The claim among Twitter users is that Gates' involvement with the academic project is somehow nefarious, and that he ultimately wants to "block the sun" from the Earth.

The claim gained traction in mid-February as residents in the state of Texas faced deadly winter storms but continued to circulate on the social network this week. Gates' financial involvement with SCoPEx has been documented since November 2018.

Despite simmering on the internet in recent weeks, Google Trends data suggested that people are still searching for answers. A snapshot of searches between March 1 and 2 included breakout results largely based around: "Bill Gates trying to block sun."


— is typing... (@1jacks_) March 1, 2021

The Facts

As previously detailed by Snopes, a fact-checking organization, the assertion is largely based on sensationalist reports about the scope and ability of the SCoPEx project.

The conservative news website The Western Journal reported in December last year that Gates' plan for the project included "blotting out the sun to make the world cooler," citing a Reuters report about the scientists applying for a test flight experiment in June 2021.

The Daily Mail, a British tabloid newspaper, reported in August 2019 that Gates "wants to spray millions of tonnes of dust into the stratosphere to stop global warming."

As noted by Nature in 2018, the concept in a broad sense is designed to spray particles into the stratosphere that may cool the planet by reflecting some of the Sun's rays.

#BillGates is buying out all of the farmlands and trying to figure out ways to block out the SUN for THREE DAYS!!! Meanwhile China is building a generator as a second sun... in order to heat the earth. 🤔

— 🇹🇹 No_EyeDee (@Blk_B4_errTHANG) March 2, 2021

But the SCoPEx website says the current project's scope remains limited. SCoPEx said its ongoing experiment aims to improve computer models of solar geoengineering by obtaining some real-world data about how chemicals react in the skies.

"It is not a test of solar geoengineering per se," the SCoPEx website says on its website. "Instead, it will observe how particles interact with one another, with the background stratospheric air, and with solar and infrared radiation. Improved understanding of these processes will help answer applied questions such as, is it possible to find aerosols that can reduce or eliminate ozone loss, without increasing other physical risks?"

In a future test, the team is planning to use a high-altitude balloon to lift a package holding calcium carbonate approximately 20 km into the atmosphere.

A small amount of the substance, between 100g to 2kg, will be released to create an air mass roughly one kilometer long and one hundred meters in diameter. The balloon will be used to measure resulting changes, including atmospheric chemistry.

The ultimate aim is to measure how the aerosol alters stratospheric chemistry. The data could improve the ability of computer models to predict how large-scale geoengineering may possibly disrupt out planet's ozone, the Harvard scientists explained.

The team noted: "The test will pose no significant hazard to people or the environment. Calcium carbonate is a nontoxic chemical commonly found in nature.

"We are not, for example, testing whether it's possible to scatter sunlight back to space, because there is no meaningful scientific uncertainty about that question."

The Swedish Space Corporation has agreed to help launch a balloon close to the town of Kiruna, Forbes reported. It will only test the balloon, not release any aerosols.

Ultimately, Gates' involvement is financial.

SCoPEx is partially funded by Harvard's own Solar Geoengineering Research Program (SGRP), which lists Gates as one of its many philanthropic donors.

Snopes said SCoPEx is also financed by the Fund for Innovative Climate and Energy Research (FICER), a fund for research grants co-created by Gates in 2007.

"Grants for research are provided to Harvard University from gifts made by Bill Gates from his personal funds," the Harvard University website has said, noting the activities of the grant fund are totally unrelated to the Bill & Melinda Gates Foundation.

The Verdict


Bill Gates has provided undisclosed amounts of funding to academic research into solar geoengineering research, which in turn helps to fund the SCoPEx project. But there is no suggestion he is in favor of blocking all sunlight from reaching Earth.

The SCoPEx team is aiming to collect data to enhance computer models and has said it plans to release a nontoxic chemical, but not to scatter sunlight back into space.

Bill Gates
Microsoft founder Bill Gates delivers a speech at the conference of Global Fund to Fight HIV, Tuberculosis and Malaria on October 10, 2019, in France. Some have alleged Gates wants to block the sun. LUDOVIC MARIN/AFP/Getty