How hot will people get, how many dying, before someone tries geoengineering? Should scientists test out last-ditch solutions? Long-time journalist, film-maker, and author Dr. Gwynne Dyer says “yes” in his new book “Intervention Earth – Life-Saving Ideas from the World’s Climate Engineers”. You get in-depth discussion plus an update on the field and 20 cautions in this week’s Radio Ecoshock.

I’m Alex Smith. Let’s go.

Download or listen to this Radio Ecoshock show in CD Quality (57 MB) or Lo-Fi (14 MB)




Will extreme climate change drive humans toward war? Could wars prevent solutions for climate? Plus the pressing question: “What can be done?” One of the few people hunting those big answers is a British-Canadian military expert tracking climate. Gwynne Dyer is known in television, radio, and print. His latest of over a dozen books is just out, titled “Intervention Earth – Life-Saving Ideas from the World’s Climate Engineers”. We reached him in London.


Dyer has a Doctor of Philosophy in military and Middle Eastern history at King’s College London. In a dozen books he stayed true to military affairs as well as the Middle East. Then he realized the ultimate threat of climate change, producing books and articles on climate risks.

Download or listen to this 40 minute interview with Gwynne Dyer in CD Quality or Lo-Fi


Preparing for his 2008 book “Climate Wars”, Dyer interviewed dozens and dozens of experts . Now for his new work, he is back talking with 100 top scientists young and old – including pioneers in geoengineering research. I ask Gwynne if he sees changes in attitudes and concerns over those dozen and more years.

In a recent show, I just spoke with scientist Wolfgang Cramer, formerly with the Potsdam Institute and now a Professor in France. He thinks attributing the Syrian civil war or the Arab Spring to climate-driven drought sounded good, but fails on deeper inspection. In his view, we have not yet seen a war where climate change is a distinctive driver. To my surprise, Gwynne agrees saying he now finds wars directly attributed to climate stresses are less likely.

Drop The Distractions: Transcontinental Extreme Heat


On May 8, Damian Carrington at the Guardian published their poll of hundreds of climate scientists. Quoting from the Guardian: “Almost 80% of the respondents, all from the authoritative Intergovernmental Panel on Climate Change (IPCC), foresee at least 2.5C of global heating, while almost half anticipate at least 3C (5.4F)”. It is little wonder Gwynne Dyer found climate scientists working out ways to avoid this hot-house world.


In 2020, Potsdam Institute Director Johan Rockström told Dyer that emissions needed to start falling in 2020. Instead humans continue to expand fossil fuel burning and emissions to new heights. Will that bring risky geoengineering closer in time? Could a country unilaterally launch particles to block the sun in the 2030’s? Perhaps a leader may be wrongly advised they can immediately cool their own country as a short-term way to save crops for starving people – by launching reflective particles into the stratosphere.

But according to science I have seen, “local” geoengineering of the climate is not possible. Any particles put into the stratosphere spread around that hemisphere, and then more slowly, around the whole Earth. It sounds like local particle injection, say to save the Arctic ice, would have to be very heavy in that location, constantly, but that slowly creates potential changes over whole Earth systems. The monsoons of India cold change if solar radiation management is attempted in the Arctic. David Keith says the concept of regional Solar Radiation Management is meaningless.

In 2007, a former US diplomat and National Security Advisor wrote (as quoted in Dyer’s book): “Government with resources will be forced to engage in long, nightmarish episodes of triage deciding what and who can be salvaged from engulfment by a disorder environment.” If the military is used to assert government control does that not lead to a military government? Do you see that coming in a badly managed climate future?

Dyer’s new book title speaks of “Intervention” and “Life-Saving Ideas”. Humans already intervened in the biosphere and the results have not been good. I ask Gwynne about the life-saving ideas he encountered.

My impression is that Dyer is not pressing to USE geoengineering, but under the circumstances finds fears and resistance to researching the subject irrational. He tells us even tiny research projects with benign substances have been prohibited by authorities. Dyer thinks we should find out what can be done, in case we ever need these tools. My thoughts on all that are below.

In the book “Intervention Earth” Dyer writes:

Almost nobody in the climate science community really believes any more that we can stop the warming at a place that is relatively safe without direct human intervention of some sort in the climate system. Doing so merely by cutting emissions and planting lots of tree would have been possible (with a huge crash programme) in the year 2000, and it was still imaginable (just) in 2012, but it now hardly seems credible.

One thing to understand about Gwynne Dyer: he is one of the original old-school journalists. Like only a few authors, Dyer spends years building new interviews into a book. He contacts excellent experts with differing views, over a hundred of them for “Intervention Earth”. Dyer is pretty fearless in his writing, so he doesn’t duck hard criticisms or hide problems while he sells you the ONE great solution. Dyer makes your brain work.

I read the whole book “Intervention Earth – Life-Saving Ideas from the World’s Climate Engineers” and learned a lot. You can learn a lot just listening to this extended interview on Radio Ecoshock.

Download or listen to this week’s short climate geoengineering song “Shades of the Sun. The lyrics are at the bottom of this blog. Go ahead and use this song for any non-profit purpose (lyrics by Alex Smith, music generated by artificial intelligence).




They said the danger line was 1.5 degrees C. warmer than preindustrial. During the last 12 months, Earth was 1.65 degrees C. hotter, according to Robert Rohde from Berkeley Earth. Nobody can explain why. Gwynne Dyer published his take on May 12, 2024 suggesting, quote: “Unprecedented warming could be ocean feedback”. Dyer continues:

“This leaves us with the least desirable explanation. The heating humans already have caused carries us across a tipping point we cannot see, and unleashes a feedback: warming from non-human sources that we cannot turn off.”


Even some cloud scientists are unsure the seeming less intrusive plan of large-scale deployment of spray to brighten clouds will work. One example is University of Utah atmospheric scientist Tim Garrett on Radio Ecoshock in 2010. I play a couple of clips from that show.

I remember Garrett also suggesting this about marine cloud brightening by spraying salt into the atmosphere over the ocean: it is possible if you create more clouds in one place, fewer will appear in others. There may be a balancing mechanism. We don’t know, and it would be impossible to know until many millions were spent to fully implement that type of geoengineering. The project could fail, not only losing a lot of money, but also time while climate impacts get worse.


Alex Smith: Recently I recorded a speech by the former Whole Earth Catalog Guru Stewart Brand. He calls for an all out effort to geoengineer the planet to stave off a climate disaster. He likes the idea of making clouds brighter by shooting seawater into them. That’s supposed to reflect more sunlight, hoping to cool the earth. You are a scientist with expertise in clouds. What do you think about that?

Tim Garrett: I’m quite skeptical that that would work. I mean, geoengineering is, in some sense, it may be a question, not whether we should do it, but perhaps when we will do it, because one could imagine that civilization will always try to do whatever it can to optimize its capacity to grow. But with regards to brightening clouds, what that’s been suggested as perhaps a viable way of doing it, one popular way that’s been suggested is to produce lots of sea spray from some fancy ships, and this sea spray goes up into the clouds, and that makes them brighter because if there are lots of small aerosol particles, then there will be more droplets in the clouds and also smaller droplets. And that has two effects. One is that for some reasons I won’t describe, it, makes the clouds brighter just by having a large number of small droplets.

You have brighter clouds and clouds that have a small number of large droplets, but it also tends to shut off precipitation in the clouds. And because precipitation is a sink, it’s a means for losing water from clouds. It has been argued that the clouds will have longer lifetimes and therefore reflect more sunlight to space for a longer period of time. And because they’re brighter, they’ll reflect more.

These ideas have been around since the 1970s and 1980s, and it has since become apparent to a lot of researchers in this area that the effect is not nearly as strong as one might initially expect. There are all sorts of, again, negative feedbacks, and these negative feedbacks often act to entirely erase the brightening effect that you might expect from these aerosols going into the clouds.

I mean, just to give one example, the clouds that would be targeted are these large sheets of stratus clouds and strata cumulus clouds that are off the western coasts of continents.  So where you are, I guess you’re in Vancouver, are you? They’re probably very familiar with low level clouds. I used to live in Seattle. And in Seattle. The entire winter was covered with this large deck of low level clouds.

Now these clouds, if we brighten them, then they tend to be over the ocean. If we brighten them, then less solar radiation comes in to heat up the surface, and it is warming of the surface that enables the fluxes of moisture and heat from the oceans and the surface upwards into the atmosphere that enable the clouds to form in the first place. So let’s say the clouds become brighter, they cool the surface, and there’s less flux of heat and moisture to form the clouds, and then the clouds dissipate. So it could be that adding aerosols to clouds does not make them brighter and more long lived, but actually shorter lived and darker.

[end Tim Garrett Radio Ecoshock transcript]

Listen to or download that full interview with Tim Garrett in 2010 here in Lo-Fi (only)



You may want to listen to several other interviews in the Ecoshock archives about geoengineering, both pro can con. For example, in June 2020 I talked with Anna Lou Abatayo, an economist and research fellow at the prestigious Bocconi University. Her new study from Italy says “Solar geoengineering may lead to excessive cooling and high strategic uncertainty”.

Listen to or download this 18 minute interview with Anna Abatayo in CD Quality (only)



And check out the show “Fixing the Climate: Hopes and Hazards” posted February 2nd, 2022 with Wake Smith. His book is “Pandora’s Toolbox: The Hopes and Hazards of Climate Intervention.” It is a full meal investigating many aspects. In the book, Wake says:

Fixing the Climate: Hopes and Hazards

I think there would be demonstrations around the globe, on a scale quite literally never seen before, to demand further action. I can imagine riots that may coalesce into widespread armed insurrection as tens if not hundreds of millions of people watch their homes claimed by the sea and their crops wither. The members of the new Greatest Generation that whipped greenhouse gas emissions would not then meekly return to their desiccated farms and watch their children starve. That just doesn’t seem plausible. The world would demand more.

Wake recommends the 2021 report by the National Academy of Science titled “Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance.

As it stands, if Wake Smith could somehow magically deploy SAI – he is not ready to do it. Instead, he offers his expertise on what an SAI program could look like, if ever needed.

Listen to or download this Radio Ecoshock interview with Wake Smith in CD Quality or Lo-Fi



When people talk about geoengineering, for or against, one name keeps coming up. For over 20 years, scientist David Keith has kept open the door for discussion and research on climate modification. At Harvard University, David is a Professor in the School of Engineering and Applied Sciences. He’s also a Professor of Public Policy at the prestigious Harvard Kennedy School. Dr. Keith wins awards and criticism for talking about technology to stave off the worst of climate change.

Like most scientists, David Keith works hard to get a society with fewer greenhouse gas emissions. He also has a Calgary-based company trying to remove CO2 from the air. We pick David’s brain on technology to artificially cool the planet, by blocking out some of the sun’s rays. It’s called Solar Radiation Management, or SRM. David Keith’s landmark book “A Case for Climate Engineering” is available from MIT press

I interviewed David Keith in March 2015 about climate geoengineering – and also it’s conspiratorial twin “chemtrails”. It was a hot show drawing comments from all sides. Find the full blog here. Download or listen to this 24 minute Radio Ecoshock interview with David Keith in CD Quality or the faster-downloading but lower quality Lo-Fi version.

Climate Geoengineering and Chemtrails Conspiracy


David also appears as a panelist in this podcast that was rebroadcast by Radio Ecoshock in 2021. That was Episode 24 of the podcast called “Energy vs. Climate” hosted by Ed Whittingham.

Heat the Big Climate Killer


Others disagree strongly with geoengineering, like previous Radio Ecoshock guest Clive Hamilton, and probably every environment group there is, especially the ETC Group. I interviewed Australian Clive Hamilton about his book “Earthmasters” in 2013. That book is still on my office shelf for reference.

Who Will Control the Climate of the World?

Listen to/download the Clive Hamilton interview on “EarthMasters” (geoengineering 25 min) in CD Quality or Lo-Fi


And of course if you DO create more clouds, that triggers the Chemtrails Conspiracy of spraying for mind control – also covered by Radio Ecoshock with David Keith in the 2015 program linked above.


In January 2022, about 200 scientists called for a halt testing geoengineering. Find that letter and an article about it linked in my show blog at

New science, out in May 2024 in PNAS suggests recent heat waves in the north Pacific may be triggered by an air pollution cleanup in China. The paper title is: “Atmosphere teleconnections from abatement of China aerosol emissions exacerbate Northeast Pacific warm blob events.” This furthers arguments by James Hansen and Leon Simons that cleaning air pollution, on land in in ocean freighters, reveals previously hidden energy and heat in the system.

Another new paper in May, this time in Geophysical Research Letters, warns solar geoengineering could result in unexpected regional heating. The title is: “Side Effects of Sulfur-Based Geoengineering Due To Absorptivity of Sulfate Aerosols”. The authors conclude stratospheric aerosol intervention could cause regional changes as bad as carbon dioxide.


American scientist Alan Robock contributed to our survival when he published his work about “nuclear winter”. Essentially even a limited nuclear war would put so much dust and debris into the atmosphere the surface would go dark for as many as ten years. Most plant and animal life would die. That is why nuclear war cannot happen: everyone loses, no matter who launched and who was hit.

Robock then published about geoengineering, specifically those methods that inject either salty water or sulfates into the atmosphere. We discuss that in a 2015 interview that still works today. Here is an excerpt:



Alex Smith: And then looking at your graphs with the Arctic experiment, it looks like global mean temperatures go right back up to where they would’ve been within a decade or two of stopping injecting those aerosols into the atmosphere. Why would we stop once we start?

Alan Robock: Well, that’s true of any such scheme. Imagine you start doing geoengineering and there’s a big drought in China or floods in India, and they say, ’You damn geoengineers, you’re causing this. We demand that you stop it.’ and you say, ’well, there’s natural variability’. You can’t prove that this drought wouldn’t have happened anyway. They say, ’We don’t care. We think you’re doing it. Stop’. And so it would be very difficult to continue doing it in the light of that. And so I can imagine that society would lose the will or the means to do it, or some other catastrophic weather event happened, and whether or not you could connect it to the geoengineering, people would connect it and demand that it be stopped.

AS: So Alan, in the end, do you think we will become so desperate or so wedded to fossil fuels that we really will inject pollution into the sky to block the sun?

AR: So I’m a good weather forecaster. I’m not such a good forecaster of human behavior, but right now, I think, no. I think the governance aspects will not be soluble. How do we set the planetary thermostat? How do we decide what temperature we want the planet to be? Nations where it’s cold, like Canada, Russia, maybe in the U.S. wouldn’t mind a little bit warming because you could exploit the Arctic. But islands that are drowning in the tropics right now would like it to be even cooler than it is now. I don’t know how we could decide how to manage the planet.

AS: As we wrap up, I’ve always thought of nuclear weapons as a sign of basic insanity in the human race. And now we want to control the climate, the weather, and the rain with the same mentality. I’m wondering if we should add basic human insanity to your list of reasons why geoengineering may not be such a good idea.

AR: Well, Donald Rumsfeld was right about one thing. The are unknown unknowns, and so we don’t really know what we don’t know about what would happen. I mean, would you trust the whole world to this one technical solution? I mean, anybody who is in a car today and had their seatbelt on understands this concept. Anything made by humans and operated by humans can not function, can break or be operated poorly. And so that’s one of the reasons why it would be very scary to try and control the whole world on purpose like this.

AS: From New Jersey, we’ve been speaking with the distinguished professor of climate science at Rutgers University, Dr. Alan Robock.

Download or listen to this interview with Dr. Alan Robock in CD Quality or Lo-Fi



In a presentation, American scientist Alan Robock summarized “20 Reasons geoengineering may be a bad idea”. Here they are in quick note form.

Climate system response

1. Regional climate change, including temperature and precipitation

2. Continued ocean acidification

3. Ozone depletion

4. Effects on plants of changing the amount of solar radiation and partitioning between direct and diffuse

5. Enhanced acid precipitation

6. Effects on cirrus clouds as aerosols fall into the troposphere

7. Whitening of the sky (but nice sunsets)

8. Less solar radiation for solar power, especially for those requiring direct radiation

9. Rapid warming when it stops

10. How rapidly could effects be stopped?

11. Environmental impacts of aerosol injection, including producing and delivering aerosols


12. Human error

13. Unexpected consequences (How well can we predict the expected effects of geoengineering? What about unforeseen effects?)

Political, ethical and moral issues

14. Schemes perceived to work will lessen the incentive to mitigate greenhouse gas emissions

15.Use of the technology for military purposes. Are we developing weapons?

16.Commercial control of technology

17. Violates UN Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification


18. Could be tremendously expensive

19. Even if it works, whose hand will be on the thermostat? How could the world agree on the optimal climate?

20. Who has the moral right to advertently modify the global climate?

That was “20 Reasons geoengineering may be a bad idea” in point form, taken from a presentation by U.S. scientist Alan Robock.


Meanwhile from MIT, published in 2022 “The US government is developing a solar geoengineering research plan.According to CNBC, quote: “The White House Office of Science and Technology Policy is coordinating a five-year research plan to study ways of modifying the amount of sunlight that reaches the Earth in order to temporarily temper the effects of global warming.

Scientists have proposed a metric for the amount of SRM required, and for how long, for a particular amount of warming. This was proposed in 2013 as a “degree-year” “which quantifies the magnitude of SRM that would be needed to keep global temperatures under a given threshold.”


[probably yes, but the tests might take “several decades or longer”…]

Can we test geoengineering?
Douglas G. MacMynowski, David W. Keith Ken Caldeira and Ho-Jeong Shinc



For fall-back steps nobody wants to take, there is a lot of action on the geoengineering front.

The Union of concerned Scientists is opposed to deployment of solar geoengineering but supports more modeling and research. So does the Environmental Resources Defense Council. Meanwhile Harvard, UCLA and the Paris Peace forum have convened a group called “The Climate Overshoot Commission”. The European Union’s Chief Scientific Advisors released a “Scoping Paper: [on] Solar Radiation Modification” in August 2023.

As super heat waves manifest on both land and sea, calls for SRM research will just get louder. Personally, after some painful thought, I think research on solar management should go ahead.

Keep in mind, even experts like David Keither and Ken Caldeira said just the tests would take a decade or more to evaluate, that is, to know if any if the proposed techniques work. They say, quote: “tests could require several decades or longer to obtain accurate response estimates, particularly to understand the response of regional hydrological fields which are critical uncertainties.” They are talking about disturbances to rain patterns that could damage or crush agriculture with drought or floods or both.

Some say every weapon ever discovered was used, and likewise if we research and develop SRM some government or billionaire will deploy it. But is that true? We like to think some biological weapons were discovered but not released. Not every country that could build a nuclear weapon did so. Think Japan, probably South Korea, and likely Iran have gone to the edge of having materials and ability to make a nuclear weapon but have not done so yet. Just studying SRM does not guarantee it will be used – however, it might put such a tool into easier reach for desperate politicians with less time lag.

The road to climate Hell has two components: first – plans for more fossil fuel extraction announced by industry and governments go forward; second – geoengineering, like solar radiation management contains the resulting emergency as we continue to pollute.

Solar Radiation Management does not limit warming in any way. It just masks the reality, stalls it. the technology becomes the largest and most deadly addiction yet. If we go that route, humans could not stop purposefully polluting the atmosphere – even for a little while. The attempt to control cannot afford to fail, or all will be revealed: the sunset of the species in full advance into hothouse Earth.

We cannot have our cake and eat it too. If we try, the cake eats us.

I’m Alex Smith. Thank you for listening, and caring about our world.


LYRICS FOR NEW SONG “Shades of the Sun”

You can use the song for any non-profit purpose with a credit to Alex Smith. Lyrics by Alex Smith, music created by artificial intelligence. Creative Commons license. Or just plug these lyrics into any of the AI music generators and make your own version!

Too hot.
Way too hot.

[Verse 1]
Crops dying,
People dying.
Cool it down!
Whatever it takes,
They said.

Turn down the sun.
Cool it down.
Never mind tomorrow
Gotta cool it down

[Verse 2]
Climate engineers
Study the last days
Engaging our fears
Of changing our ways.

They said:
We can’t make the cut.
Turn down the sun!
No matter what.
Fix it.