Editor’s note: Marshall Brain – futurist, inventor, NCSU professor, writer and creator of “How Stuff Works” is a contributor to WRAL TechWire.  Brain takes a serious as well as entertaining look at a world of possibilities for Earth and the human race.  He’s also author of “The Doomsday Book: The Science Behind Humanity’s Greatest Threats.” In this column, Brain talks about a possible way to limit the effects of the sun. With “heat domes” driving up in areas such as around Phoenix to record levels, what’s to be done? He has an idea: A sun dimmer.

Note to readers: WRAL TechWire would like to hear from you about views expressed by our contributors. Please send email to: info@wraltechwire.com.


RALEIGH – Imagine that we were watching a blockbuster disaster movie together. In this movie, the humans on planet Earth are starting to get desperate.  The environment is changing so fast and so drastically due to global heating that humanity can actually see the ecosystem starting to collapse. Therefore, the world’s most powerful leaders are giving serious consideration to what was once unthinkable: geoengineering.

As in the “dimming the sun” kinds of geoengineering.

Humanity is considering the possibility of reflecting some of the sun’s rays away from planet Earth so that Earth can cool down. This is a huge decision point in the movie. Is this step drastic? Yes. Is this step fraught with possible side-effects? Yes. But it looks like humanity will have no other choice. The scene is tense. The dramatic music is heightening. The leaders’ brows are furrowing and sweating. Will humanity actually pull the trigger and dim the sun across the planet???

But this is not a movie. This is really starting to happen. The level of concern has risen all the way up to the nation’s highest office. These headlines tell the tale:

How might this kind of geoengineering work? The third article offers this perspective:

“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.”

What does this quote mean when it says, “humanity will overshoot its emission targets”? It means that humanity is addicted to fossil fuels, and it seems impossible for humanity to stop burning fossil fuels:

Global carbon emissions at record levels with no signs of shrinking, new data shows. Humanity has a monumental task ahead

“This year, the world is projected to emit 40.6 billion tonnes of CO₂ from all human activities, leaving 380 billion tonnes of CO₂ as the remaining carbon budget. This amount of emissions is disastrous for the climate – at current levels, there is a 50% chance the planet will reach the 1.5℃ global average temperature rise in just nine years.”

The steps are easy to understand.

  • Step 1: Humans continue to burn unbelievable amounts of fossil fuels: oil, coal, and natural gas.
  • Step 2: Therefore, humans add 40 billion tons of carbon dioxide to the atmosphere each year.
  • Step 3: All this carbon dioxide traps heat, causing global heating.
  • Step 4: The global heating and its side-effects are now ripping apart the ecosystem.

So many problems

We can now see the ecosystem collapsing in so many different ways that the collapse cannot be ignored. Here are just a few of the effects, plucked from recent headlines:

And so, humanity is now stuck between a rock and a hard place. The rock is fossil fuels – Humanity seems unable to stop burning fossil fuels. The hard place is the collapse of the ecosystem – If humanity keeps burning fossil fuels and releasing more and more carbon dioxide, the ecosystem can and will collapse because the planet will be too hot. It looks like the only way out will be geoengineering, also known as “dimming the sun”. The basic steps for the most likely form of geoengineering are:

  • Release millions of tons of hydrogen sulfide or sulfur dioxide into the stratosphere, also known as stratospheric aerosol injection
  • These sulfur compounds have the effect of reflecting some of the sun’s rays back into space, rather than letting it hit and warm the surface of the Earth.
  • Because less sunlight is hitting the ground, the planet cools down a bit.
  • And hopefully a cooler planet means that things like droughts, floods, arctic melting, heat waves and the like start declining rather than increasing.

Why is humanity considering this drastic step? It all comes down to economics. As this article points out: “Early studies suggest that stratospheric aerosol injection might have a relatively low direct cost. The annual cost of delivering 5 million tons of an albedo enhancing aerosol (sufficient to offset the expected warming over the next century) to an altitude of 20 to 30 km is estimated at US$2 billion to 8 billion. In comparison, the annual cost estimates for climate damage or emission mitigation range from US$200 billion to 2 trillion.” Not to mention the fact that once sea levels rise or the Amazon rainforest collapses, there is no way to reverse these processes.

It also has to do with natural precedents. When a major volcano erupts, it will sometimes inject millions of tons of hydrogen sulfide into the stratosphere, and the planet does cool down. We have seen this type of eruption happen and we know that the planet cools down. We have seen this idea work before, so we are simply replicating a natural process. As this article points out: “Scientists have long known of the cooling effect of major volcanic eruptions, which spew large amounts of light-scattering aerosols into the stratosphere. The Philippines’ Mount Pinatubo, for example, cooled Earth by a few tenths of a degree Celsius for months after it blew its top in June 1991.”

What will happen next?

Here is how this might unfold? The current proposal by the White House is that scientists spend five years studying the possibility of dimming the sun. That sounds reasonable, but we probably do not have five years. By next summer, or the following summer or two, something really bad will happen and it will be so bad that it finally wakes people up.

  • Maybe a million people die in a week during a heat wave.
  • Maybe there is a major crop failure and millions of people starve.
  • Maybe a big city gets wiped out in the first Category 6 hurricane.
  • Maybe sea level rise rapidly increases and something valuable gets inundated.

Something massive like this can and will happen, it will really frighten the general population, and the politicians will start with the geoengineering because there is no other economically viable alternative.

Unfortunately, this is not a movie. Earth’s ecosystem is collapsing before our very eyes, and things are going to get much worse unless we do something. Ending the use of fossil fuels is the obvious thing to do, but it appears that humanity if irretrievably addicted to fossil fuels at least in the short term. It looks like humanity will be forced to start geoengineering whether we like it or not.

(Note:Marshall is taking a break for the holidays. This column is a reprint. Marshall will be back soon.)


  1. https://www.newyorker.com/news/annals-of-a-warming-planet/dimming-the-sun-to-cool-the-planet-is-a-desperate-idea-yet-were-inching-toward-it
  2. https://www.popularmechanics.com/science/green-tech/a41911533/solar-geoengineering-can-reflect-the-suns-rays/
  3. https://interestingengineering.com/innovation/cooling-the-earth-by-reflecting-sunlight-how-it-would-work
  4. https://www.cnbc.com/2022/10/13/what-is-solar-geoengineering-sunlight-reflection-risks-and-benefits.html
  5. https://news.yahoo.com/white-house-admits-might-block-094049223.html
  6. https://theconversation.com/global-carbon-emissions-at-record-levels-with-no-signs-of-shrinking-new-data-shows-humanity-has-a-monumental-task-ahead-193108
  7. https://www.space.com/us-sea-levels-rising-faster-than-thought
  8. https://www.nytimes.com/2022/11/27/opinion/environment/mississippi-river-drought-colorado.html
  9. https://www.pressenza.com/2022/11/greenland-is-worse-than-ever-much-worse/
  10. https://www.bbc.com/future/article/20221117-how-borders-might-change-to-cope-with-climate-migration
  11. https://www.wired.com/story/a-caustic-shift-is-coming-for-the-arctic-ocean/
  12. https://www.smithsonianmag.com/smart-news/a-massive-freshwater-river-is-flowing-under-antarcticas-ice-180981119/
  13. https://www.youtube.com/watch?v=wJCl-T2HUvI – Historic megaflood reveals major risk, in the United States’ driest region?
  14. https://www.washingtonpost.com/climate-environment/2022/11/11/cop27-egypt-carbon-budget-gas-projects
  15. https://www.theguardian.com/environment/2022/nov/07/melting-arctic-sea-ice-summer-report
  16. https://en.wikipedia.org/wiki/Stratospheric_aerosol_injection
  17. https://www.science.org/content/article/thanks-volcanoes-earth-cooler-expected-due-recent-eruptions
  18. https://wraltechwire.com/2022/10/14/fighting-doomsday-what-a-real-war-on-climate-change-look-like-marshall-brain-explains/
  19. https://wraltechwire.com/2022/09/23/doomsday-warning-its-time-to-start-moving-coastal-cities-to-higher-ground-heres-why/
  20. https://wraltechwire.com/2022/09/16/climate-change-doomsday-irreversible-tipping-points-may-mean-end-of-human-civilization/
  21. https://wraltechwire.com/2022/09/02/climate-change-catastrophe-august-2022-31-days-of-global-drought-flood/
  22. https://wraltechwire.com/2022/07/22/doomsday-earth-as-our-planet-heats-up-more-and-more-heres-what-happens/
  23. https://wraltechwire.com/2022/05/27/geoengineering-could-be-key-to-combating-climate-change-check-out-these-ideas/
  24. https://wraltechwire.com/2022/05/06/true-terror-ten-worst-things-climate-change-will-soon-deliver-to-our-world/
  25. https://wraltechwire.com/2022/04/08/doomsday-shrinking-rain-forests-and-us-why-we-must-turn-the-tide/
  26. https://wraltechwire.com/2022/04/01/slap-yourself-and-pay-attention-the-doomsday-glacier-is-a-global-risk/


Note: This column was originally published in December 2022.