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When Global Catastrophes Collide: The Climate Engineering Double Catastrophe

The views expressed are those of the author and are not necessarily those of Scientific American.

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It could be difficult for human civilization to survive a global catastrophe like rapid climate change, nuclear war, or a pandemic disease outbreak. But imagine if two catastrophes strike at the same time. The damages could be even worse. Unfortunately, most research only looks at one catastrophe at a time, so we have little understanding of how they interact. My colleagues and I at the Global Catastrophic Risk Institute are beginning to fill this void, starting with a new paper [1] involving climate engineering and a separate catastrophe combining for a “double catastrophe”. It’s a grim prospect that could even result in human extinction, but we can also work to avoid it.

Let’s start at the beginning of the scenario. Yes, the climate is changing, and we’re already seeing damages from it. But our planet is, as they say, just starting to warm up. Unless we do something to keep temperatures down, things could get much worse. One grim possibility is that large portions of Earth become uninhabitable to mammals [2]. (That includes us.) Temperature and humidity get too high for mammals to cool our bodies through perspiration – even if the wind’s blowing – and so we overheat and die. By continuing to put greenhouse gases into the atmosphere, we are tempting an extremely dangerous fate.

Alarmingly, we have been slow to reduce greenhouse gas emissions, and the climate is changing faster than ever. Because of this, some people – myself included – have been interested in alternative ways to cool things down, mainly by engineering the planet. There are several approaches to climate engineering (also known as geoengineering). The most popular approach involves putting little particles into the atmosphere to reflect incoming sunlight back out to space. The more particles we put up there, the less sunlight reaches the surface, and the cooler temperatures will be. If it works, it could help us avoid the worst harms of climate change.

But there’s a big catch. The particles don’t just stay in the atmosphere where we put them. They gradually drift towards the North and South Poles and fall to the surface. That takes about 5 years. And so if we stop putting particles into the atmosphere, we get a very rapid temperature increase, until temperatures finally stabilize at where they would have been without the particles. This rapid temperature increase is many times faster than that of climate change alone and would be very damaging.

All this is well established within climate change research. Here’s where our paper starts introducing new ideas. First, it’s unlikely that society would just stop putting particles into the atmosphere, because of how harmful that would be. We’d be fools to impose that rapid temperature increase upon ourselves. However, if a big enough catastrophe occurred, then we could lose the capacity to continue the climate engineering. The catastrophe could be something like a major war or disease outbreak. If this causes society to stop climate engineering, then the rapid temperature increase would hit a population already very vulnerable from the initial catastrophe. The result is a double catastrophe that could be very devastating for humanity.

The graphic below shows one possible version of the double catastrophe. The temperatures shown are adapted from prior research using climate models to study climate engineering [3]. The details of the curves depend on when the initial catastrophe occurs and how much greenhouse gas has been put into the atmosphere prior to the initial catastrophe. The more greenhouse gas is in the atmosphere, the larger and more rapid the temperature increase will be when the climate engineering stops.

One possible version of the double catastrophe scenario.
One possible version of the double catastrophe scenario.

Just how devastating would it be? This is a difficult question to answer. Catastrophes like this have never happened before, and so we have no prior experience to draw from. We can use climate modeling (as in [3]) to assess how climates would change after we stop putting particles into the atmosphere. But the key question is how humans would respond. This remains an open research question. Right now, I’m especially worried about agriculture. In general, crops are sensitive to climatic conditions [4]. If temperatures increase too rapidly, then we may not know which crops are best to plant in any given year. Food security would be a concern anyway after a big catastrophe. Rapid temperature increase would make it that much more of a problem. And of course, without food, humans cannot survive. So I believe that, in the worst case, the double catastrophe could result in human extinction.

There are several lessons to be learned from the double catastrophe scenario. The simplest lesson is that we really, really need to reduce greenhouse emissions. The less we emit, the less the climate will change and the less we need to resort to climate engineering. And if we do try climate engineering, lower emissions means less rapid temperature increase in the event that we stop putting the particles up. Reducing emissions will take a lot of effort, but in the end I believe it will be just fine for our lives and our economy, despite what the fossil fuel lobby would sometimes have us believe. A good start is to put climate policy at the top of the new Congress’s agenda, and to that effect recent debates about political strategy (e.g. this and this) strike me as productive.

The second lesson is that if we do implement climate engineering, we should design it to avoid the double catastrophe. This could mean decentralizing the capacity to put particles into the atmosphere, so if catastrophe strikes one group, then others can continue. Given how important it is to avoid rapid temperature increase, this could be an important step. Or, it could mean pursuing a completely different approach to climate engineering. One alternative is to put reflecting objects into orbit between Earth and the Sun. This would be much more difficult than using particles, but the objects could be designed to stay in place even during a catastrophe.

Perhaps the most important lesson is that we need to look at multiple catastrophes together. Climate change and, say, pandemics are not separate issues. But all too often, we have separate conversations about them. This is a major mistake, as the double catastrophe scenario demonstrates. Climate engineering may be able to keep temperatures low, unless some other catastrophe occurs. Thus whether climate engineering is a good idea depends on how likely it is that some other catastrophe occurs, how that other catastrophe would affect our ability to continue climate engineering, and how it would affect our ability to endure rapid temperature increase. We can only answer these questions by studying it all together.

To be sure, understanding what happens when global catastrophes collide is a difficult challenge. Each catastrophe is complicated enough on its own. For the sake of our species’ survival, we should rise to this challenge.


[1] Baum SD, Maher TM Jr., Haqq-Misra J. Double catastrophe: Intermittent stratospheric geoengineering induced by societal collapse. Environment, Systems and Decisions, forthcoming. DOI 10.1007/s10669-012-9429-y

[2] Sherwood SC, Huber M (2010). An adaptability limit to climate change due to heat stress. Proceedings of the National Academy of Sciences 107:9552–9555.

[3] Matthews HD, Caldeira K (2007) Transient climate–carbon simulations of planetary geoengineering. Proceedings of the National Academy of Sciences 104:9949–9954.

[4] Tubiello FN, Soussana JF, Howden SM (2007) Crop and pasture response to climate change. Proceedings of the National Academy of Sciences 104:19686–19690.

Seth Baum About the Author: Seth Baum is the Executive Director of the Global Catastrophic Risk Institute, a think tank studying the breadth of major catastrophes. Baum has a Ph.D. in Geography from Pennsylvania State University. All views expressed here are entirely his own. Follow on Twitter @SethBaum.

The views expressed are those of the author and are not necessarily those of Scientific American.

Comments 16 Comments

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  1. 1. Forsythkid 11:39 am 02/6/2013

    I fail to see how we can bring a world of people together on this issue when you can’t get more than three people to agree on any one topic. My bet is for humanity to continue onwards ever faster to an ultimate apocalypse.

    Link to this
  2. 2. dwbd 2:46 pm 02/6/2013

    The double catastophe is pretty obvious, Global Warming or Runaway Global Warming and Peak Oil.

    Link to this
  3. 3. jgrosay 4:04 pm 02/6/2013

    Is the wet Greenhouse an actual possibility? I mean temperatures reaching a point when water vapor in the atmosphere grows so much, that as it’s a molecule with a very high greenhouse effect, the positive feedback leads to more water evaporating, and the phenomenon ending in atmospheric pressures and surface temperatures close to the ones in Venus? Or is a generalized drought, changing all continents into deserts, a real risk?

    Link to this
  4. 4. jtdwyer 4:05 pm 02/6/2013

    Perhaps the natural order here is overpopulation combined with industrial development begets climate change, resource depletion and food shortages, famine and plague.

    If that’s not complicated enough, we could add geoengineering into the mix as a random variable…

    Link to this
  5. 5. Seth Baum 5:18 pm 02/6/2013

    Forsythkid, fair point, but let’s hope you’re wrong!

    dwbd, check out Peak Phosphorus. It’s less well known than peak oil, but potentially more important.

    jgrosay, the runaway greenhouse effect that ends when the oceans evaporate is a valid concept but it’s not going to happen any time soon. Not enough greenhouse gasses. See

    jtdwyer, I’m not sure what you mean by ‘natural order’. What you describe sounds pretty artificial to me. Or did you mean something else?

    Link to this
  6. 6. dwbd 8:07 pm 02/6/2013

    Seth, I am aware of the supposed Peak Phosphorus problem, but it is not nearly of the scale that Peak Oil is. Most people don’t realize how reliant we are on rapidly depleting Oil supplies – and that includes agriculture. As-a-matter-of-fact, the Peak Oil problem is even more dangerous than the Global Warming one.

    Link to this
  7. 7. Michael Jensen 10:13 pm 02/6/2013

    Welcome to the club, Seth!

    The Apocadocs call these things “converging emergencies,” the worst holy-shit events, in which species disruptions intersect with climate chaos, or resource depletions intersect with a tipping point of ambient toxicity, or climate chaos converges with an economic meltdown (preventing any rational response to climate horrors), or worse.

    See the pen-penultimate chapter in — the free HTML version of the book “Humoring the Horror of the Converging Emergencies” (2010).

    The book as a whole is now a bit dated, but alas, mostly still right. Dammit!

    For example:

    “Plant-based protein rises in price, but unexpected pest plagues (brought on by the collapse of bats, birds and other top insect predators) result in bad crop yields (except in those areas that use severe pesticides, which inevitably result in pest-predator collapses a few years later) — all of which results in outrageously high costs for the basic element of human life: food. “Eating out” becomes a luxury again, and restaurants worldwide close, along with all aspiring-actor jobs. “Dollar Meals” become only bread and a meatish wafer.”

    Most appallingly, these converging emergencies have been obvious for a long time. The Apocadocs site has been documenting news stories about them for more than five years, gathering more than 7,000 items during that period.

    Yeah, I know I’m pimping our site on SA, but mostly I hope you treat the site as a source for exploring topics and themes that the Global Catastrophic Risk Institute might be interested in pursuing, along the “converging emergencies” line.

    Because we recognize what is happening, we have a responsibility to act upon that recognition.

    Our time is short; we must work together; we must make it a fun problem to solve, or else civilization is screwed.

    In a different world, we wouldn’t need to make it funny or interesting to confront. But apparently, one of the possible converging emergencies is “western civilization abdicates engagement in its own survival, because it’s such a nuisance to think about.”

    It’s sort of tragic that an Onion-like-headline might become our headstone’s engraving. I hope we Apocadocs can assist in galvanizing people who already recognize that things are awry — and hope that what you’re doing will also help wake up those who need to be awakened.

    Link to this
  8. 8. jtdwyer 10:41 pm 02/6/2013

    Seth Baum – Perhaps I should have said something like:
    The unnatural effects of industrial development multiplied by overpopulation naturally produces climate change, resource depletion and food shortages, famine and plague.
    I hope that’s a little clearer…

    Link to this
  9. 9. anumakonda 1:58 am 02/7/2013

    Outstanding article.Author’s views need to be seriously considered by one and all especially planners and Governments.
    Dr.A.Jagadeesh Nellore(AP),India

    Link to this
  10. 10. Seth Baum 11:59 am 02/7/2013

    dwbd, I’m curious, what’s your advice on what to do about it?

    Michael Jensen, thanks for sharing! I hadn’t seen your sight. I think there’s an important role for humor in global catastrophic risk, to keep things in perspective and offer that ‘spoonfull of sugar’.

    jtdwyer, thanks for the clarification. Of course industrial development can also help with these issues. I suppose it all depends on which development…

    anumakonda, thanks!

    And for anyone who wants to stay in the loop, here’s the Global Catastrophic Risk Institute’s monthly email newsletter:

    Link to this
  11. 11. OrcinusOrca 1:13 pm 02/7/2013

    I am reminded of a chemistry experiment from high school.

    A beaker of water and ice at 32 Degrees. We put a small bunsen burner under it to add heat and monitored the temperature of the water. No matter how much heat was put into the water by the burner, the water continued to stay at 32 Degrees UNTIL all the ice had melted, the only change was the rate at which the ice melted. Only then did the temperature of the water start to rise.

    This state change, from ice to liquid is known as the “Heat of Fusion”

    Simple physics and science the ‘experts’ seem to have forgotten for some reason.

    The point being that until and not before all the ice on the globe melts, polar ice caps, glaciers, etc., will we experience the true effects of global warming. The “canary in the coal mine” is the ever increasing melting of the polar ice caps, glaciers and other large bodies of ice around the world that no one seems to understand the true significance of. We may well be beyond the ‘tipping point’ of global warming and just do not realize it yet.

    Link to this
  12. 12. dwbd 11:11 pm 02/7/2013

    Seth, I will tell you what the solution is. Ban all political contributions of any sort, shape, color or size. Election campaigns are publicly funded by 100.0000000%. NO EXCEPTIONS. Paying money to a politician in any way, shape or form is a serious criminal offense. We should jump up and down and sing in glee to have our tax money go to funding EVERY PENNY of an election campaign and every single aspect of ALL political life. And politicians are NOT allowed to take cushy jobs as consultants/lobbyists/corporate directors after exit. In return we happily pay them the BEST pensions, and we DO NOT complain one little bit about that.

    As long as Vested Interests can buy politicians, like hogs at an auction, there is little hope for serious action, i.e. not phony political spin BS, on these major problems confronting our civilization. Just one example, Obama is MR. GLOBAL WARMING, he is a dedicated servant of the Oiligarchy, and doing his damnedest to ensure they will maintain their Energy Hegemony. Meanwhile he spends great effort pretending to be striving to reduce GHG emissions, i.e. “we are putting up solar panels”, woopedy-f’in do, like that will do lots. That is called SPIN, and modern corporate sycophant politicians have replaced, honesty, integrity & rationality with SPIN.

    After we clean up politics, then we need to clean up the mainstream media. NO SINGLE CORPORATION can own more than 10% of media. That would be a good start. Right now 4 giant international globalist corporations own virtually all of the mainstream media in the West. That is where the public is getting their information from. Any serious issues, like Energy, it is 90% BS.

    Link to this
  13. 13. Postman1 8:56 pm 02/8/2013

    dwdb- You forgot term limits, probably the most effective way to fix congress.

    Link to this
  14. 14. dwbd 9:39 pm 02/8/2013

    postman, also get rid of that IDIOTIC First-Past-the-Post election system which is the STUPIDEST & most primitive way to conduct an election. The ONLY justification for it was it was more convenient back in the days of the horse and buggy with no computers, or communication systems except pony express.

    The easiest, simplest and best method would be Instant- Runoff Voting. Runoff Voting is commonly used worldwide, instant runoff is a more convenient & practical way of doing that. Gives third party alternatives an opportunity to grow and replace the totally corrupted “RepBLOODicans” and “DemoCRIPPS”.

    Instant-Runoff Voting Explained:

    Link to this
  15. 15. Daniel35 6:28 pm 02/10/2013

    Why does it seem only the worst kinds of solutions, namely putting pollution into the air or panels in space, are called “geoengineering”? Shouldn’t that term mean all engineering expected to affect the whole earth?

    In lieu of sensibly reducing especially energy consumption and population, what was so wrong with fertilizing the oceans with iron? True, carbon-burniing animals eat some of the phytoplankton that are generated. But they also get eaten and eventually all end up on the ocean floor. More ocean life in general seems eventually to mean more carbon deposited.

    Link to this
  16. 16. Mnestheus 4:04 pm 04/4/2015

    Multiple Catastrophes?

    What would befall the street cred of Scientific American if , in a single generation, the Population Bomb imploded, Nuclear Winter melted down by two orders of magnitude and the Energy Crisis gave way to the Oil Glut?

    Credulity seems to be accelerating faster than history in these parts.

    Link to this

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