Should World Governments Spray SO2 to Combat Climate Change?

Last updated: Aug 6, 2022 @ 5:14 pm by Christopher Turnbull

*Climate Intervention Methods. Credit: Chelsea Thompson, NOAA/CIRES. Source: NOAA Research News.*

What is the deal with Sulfur Dioxide (SO2) and why are scientists looking into spraying SO2 aerosols into the stratosphere? Will it help fight climate change? Is it a solution to climate change? Or is it more trouble than it’s worth?

With the impacts of climate change continuing to get worse every day, from rising sea levels to worsening droughts and floods, scientists are working to find different ways to reduce these impacts. Stratospheric Aerosol Injection (SAI) has come out in recent news as a way to lower the Earth’s temperatures. But is it really a viable solution or will it do more harm than good?

Evidence for Rapid, Human-Caused Climate Change

Human activities are estimated to have caused approximately 1.0°C of global warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C. Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate. (high confidence)
IPCC Special report SP15 (Oct 2018)

Climate Change Basics

Check out this video on the basics of climate change with Bill Nye. Published by National Geographic in December 2015, the video goes over the fundamentals of climate change science, which have not changed since 2015.

The video provides a good overall understanding of what’s causing our current climate to change and why we should care. According to the Intergovernmental Panel on Climate Change (IPCC):

Climate-related risks to health, livelihoods, food security, water supply, human security, and economic growth are projected to increase with global warming of 1.5°C and increase further with 2°C.
IPCC SPEcial report sp15 (oct 2018)

Ice Sheets	Sea Level Rise	Climate Science
Rising Waters: Out-of-Balance Ice Sheets	Sea level rise is so much more than melting ice	Climate Change: How does it really work?
Why scientists are so worried about this glacier	—	A History of Earth’s Climate

Role of Sulfur Dioxide on the Earth’s Climate

To start, we need to talk about what Sulfur Dioxide is and why scientists are interested in this gas. Over the course of Earth’s history, significant (explosive) eruptions have released SO₂into the atmosphere.

It reacts with the atmosphere to form Sulfuric Acid (H₂SO₄), which then forms into aerosol particles. In significant quantities, typically at least several trillion grams, these aerosols can have a cooling effect on the Earth over the course of a year or two. These aerosols help reflect solar radiation back to space, leading to a temporary cooling effect.

Scientists are trying to figure out if it would be feasible to spray the lower stratosphere with Sulfur Dioxide to help fight human-caused climate change. Image courtesy of the USGS. Below, is a list of some of the potential risks involved with spraying the atmosphere with sulfur dioxide aerosols and what we should be doing instead to fight climate change.

Potential Issues of Stratospheric Aerosol Injections (SAI)

While SO₂ has the potential to cool the Earth, there are potential ramifications should world governments decide to start spraying SO₂ aerosols into the atmosphere.

Some unintended consequences include:

Increasing global precipitation deficits
Delaying the recovery of the stratospheric ozone hole
Disrupting the Quasi-Biennial Oscillation
Enhancing the positive phase of the wintertime North Atlantic Oscillation (Copernicus Publications, 2022)

Other ramifications include:

Spraying cannot reverse damages caused by increasing atmospheric greenhouse gases
- e.g., cannot reverse ocean acidification

It’s a long-term commitment. Each year of spraying SO2 will require more and more SO2 as greenhouse concentrations continue to rise

Suddenly stopping SO₂ injections could cause significant, rapid warming of the planet… will need to continue spraying for the foreseeable future

Research into the viability, impacts and risks of spraying some SO2 along with reducing emissions may take decades to complete (U.S. House of Representatives, 2017)

No aircraft are currently capable of fulfilling this mission (IOP Publishing, 2018)

Some research, however, has suggested that the potential benefits outweigh the drawbacks. A reduction of atmospheric carbon following these injections could help minimize the loss of permafrost, promote forest growth, and reduce the need to cool buildings. High-resolution models indicate that most regions of the world would benefit from solar geoengineering, but there still remains widespread uncertainty regarding the science and the model’s assumptions (Nature, 2018).

Most scientists and environmentalists say that we should be treating the underlying issue rather than come out with a “band-aid” solution. Mitigation and adaption are two ways we should be dealing with climate change.

What We Should Be Doing Instead to Fight Climate Change

SAI is like putting a band aid over a major injury. Even if it stops the bleeding, it won’t stop or reverse the internal damage. It’s temporary and comes with significant risks. The only permanent solution to anthropogenic climate change is reducing our emissions. Without reducing our emissions from the burning of fossil fuels, cement manufacturing, agriculture, deforestation, and other processes, we won’t be able to get global temperatures to stabilize and the impacts will continue to get worse.

What we should be doing is mitigation and adaption.

Mitigation involves reducing emissions to net-zero (not zero as that is not realistic). What we emit must be able to be absorbed by the Earth’s oceans, wetlands, and forests. Once we reach net-zero emissions, global surface temperatures will stabilize.

Reduce sources of greenhouse gases (e.g., the burning of fossil fuels for electricity, heat, transport, etc.)
Enhancing the “sinks” that accumulate and store greenhouse gases (oceans, forests, soil)

Adaption is how we adjust to our current and future climate and how to live with the worsening effects of climate change. Sea-level rise, increasing frequency and intensity of extreme weather events, and food insecurity are some of the biggest challenges that we will need to adapt to.