Runaway Greenhouse Effect: The Real Scoop?

In the tradition of Peak Oil: The Real Scoop?, I submit the following:

What’s the real deal about runaway greenhouse effect? Do we need to worry? Can anything be done? Is anything being done?

This has a GQ feel to it, but the above referenced thread had a nice, lively debate, exactly the kind I’m interested in reading. They both deal with a lot of scientific speculation that is rich fodder for debate, anyway.

Peak oil and the runaway greenhouse effect are the two things on Exit Mundi that gave me the shivers. Knowing that the site uses hyperbole to inject entertainment value into its doom stories, I trotted over here to see multiple viewpoints. I found what I was looking for in the peak oil thread, but runaway greenhouse effect is even scarier and a search turned up very little.

I’m more troubled by this runaway greenhouse thing now, because after learning all about peak oil, I’m less worried about the economic reprecussions of peak oil than I am about a big shift in carbon emissions possibly triggering the runaway greenhouse effect. I swear I saw this suggested in one of the things I was reading about this peak oil stuff, but I can’t find it now.

Here’s the Exit Mundi article. I assume there is some hype there, but how real is this thing? (Keep in mind that the site’s modus operandi is to start out the article with a more “colorful” description, and ease up on the hyperbole towards the end of the page, so don’t quit reading in disgust before you finish it.)

I think Ben Bova wrote a Sci-Fi story that used this as one of its themes but I don’t remember what the title of the book was now (something about the Astroid Belt). Its seems pretty implausable to me that we’d suddenly have a major climatic shift on the scale of the article you cited but I’m not climate expert so I’ll await comment from some more knowledgable folks. I know that certain natural events (volcanos and such) have had a major impact on the weather in the past, so I guess it IS possible that the cumulative effect that mankind has had on the planet for the past few thousand years COULD spark a major (and perminent I assume) shift in climate.


Well, at least they do backward summersault hyperbole in their “The Big Chill” webpage.

I think this type of website is geared to whip up the teenage crowd to be ecowarriors or something of that ilk.

I’ve always lived by the words…“Nothing is permanent, it is all temporary.”

Well, as they say at the bottom of the pate:

Like I said, it seems pretty implausable to me that we’d suddenly (in 2015, presumably at 11:08pm EDT) have a major shift to the prelude of a Venus like atmosphere (and that tin and lead would literally…well, I’m sure you can all fill in the blanks by now :stuck_out_tongue: )…especially considering that todays environment isn’t even close to as bad as its been on earth in the past and we haven’t become Venus yet. Still, as I said, I suppose it IS possible…certainly I would go along with a prediction that we may be in for global climatic change, if not a runaway greenhouse effect.


We are currently at 378 parts per million (ppm) of CO[sub]2[/sub] . Most experts think that unpredictable “tipping points” start at 450 ppm We are currently rising at, on average, 3 ppm per year (a worldwide average, more concentrated in cities). So, we might have just 20 years before we must stop releasing CO[sub]2[/sub] at all.

Next year’s results from Hawaii will be important. If there is another 2ppm rise in CO[sub]2[/sub] high up in Hawaii next year, we should worry. If it continues for 5 years, we should start shitting bricks for our grandchildren and, literally, seeking to move inland and uphill some time in the next decade.

The global climate has undergone abrupt change many times in the past, for reasons which are poorly understood, but seem to involve disruption to the global conveyor It is as though we have found a device on the beach of a kind which has often been known to explode unpredictably. And we’re hitting it with a stick, increasingly hard.

You wanted a scary graph. Here it is. Our grandchildren are already cursing our myopia.

Exit Mundi isn’t a reliable source of information, and the scenario makes no sense at all.

Where did all this CO2 that we are producing come form? It came form oil and coal. And where did the oil and coal come form? From plants of course. And where did the plants get the CO2 from? From the air. So all that we are really doing is putting back into the air what was once there.

Now obviously when the CO2 was originally in the air the Earth was quite habitable, otherwise there wouldn’t have been plants. It wasn’t a Venusian atmosphere. Lead didn’t melt in the spring thaw.

That’s a little simplified because it is possible, though not likely, that we could release more carbon than was ever actually present at one time in the past. But that’s incredibly unlikely. And even if we did it wouldn’t be a doubling of atmospheric CO2 levels.

And it’s possible that the methane hydrates in the ocean weren’t released in the last warming events and that the atmospheric methane concentrations will be higher. But given that coal forms in swamps and methene has a short atmospheric residence time it’s highly unlikely that the atmospheric methane levels wouldn’t have been much higher in the carboniferous.

So realistically the runaway effect described there makes about as much sense as the scenarios about nanobots eating us all in our sleep. It’s interesting science fiction and there it ends.

And you don’t need to go back 50 million years to find the last warm period. A mere 3 million years ago it was warm enough to permit beech trees (or more accurately shrubs) to grow well up the slopes of the mountain ranges in Antarctica. Given that Antarctica was already in pretty much its current location by then that’s an impressively hot spell, although it didn’t last long. Needless to say for the Antarctic mountains to support softwood trees the ice caps at both poles were well and truly melted. And the greenhouse effect never ran away.

The reason why this recent extreme warming event is so significant to this debate is that 3 million years ago the world was ecologically and environmentally much as it is now We aren’t talking here about a climate that only supports giant insects and dinosaurs. At the time of the last warming event our ancestors were already well developed primates. Grasslands were starting to expand and support cereals and grazing mammals. In short even if the Greenhouse Effect ran away to the extent of melting all the polar icecaps leaving only high mountain glaciers andallwoing the people of anchorage to line their streets with deciduous trees it still wouldn’t be the end of the world or the end of humanity or even the end of civilisation. We would still be able to grow all our food crops, graze our cattle and sheep and so forth.

There are lots of good reasons to be worried about climate change, but this example of extremism ain’t one of them.

I think you’re missing the most important word, which is equilibrium. At any point in the past, oxygen and carbon were combining to be gradually stored, such that there was no point at which the CO[sub]2[/sub] concentration topped 500 ppm in the last 20 million years. The speed of the increase in atmospheric CO[sub]2[/sub] concentration in a geological blink from releasing it from underground storage all at once really does seem to be unique. Such a big, quick push off equilibrium might, possibly, not take us to the Eozoic or Paleozoic (and I agree that this is humanity-survivable) but indeed to Venus if the ocean floor methane is released.

Actually, if no action whatsoever is taken, it looks like it will double or even treble by the end of this century. I am not a climatologist and neither, I suspect, are you. Venusisation might well be sci-fi scaremongering, and the recent CO[sub]2[/sub] surges probably don’t herald it anyway. But Venusisation is still possible (heck, it happened to Venus!), and as you correctly point out abrupt climate change might effectively be just as bad (especially if the CIA is to be believed).

That the earth may have survived things like melted ice caps and drastic climate change in the past, even that life on Earth survived it admiraby, doesn’t mean it won’t be hugely uncomfortable, inconvenient and dangerous to humans, especially those living on coastlines and in environments that are already far from average in terms of temperature and rainfall.

SentientMeat my friend, I’m in general agreement with you but I do wish you’d find a better scary graph to link to. Graphs with no scales on the y-axis and no indication of where the zero should be don’t actually impart any real information!

Re the OP - we’re a fair bit further from the Sun than Venus, and the Venusian atmosphere is practically all CO2, whereas ours is only a small fraction CO2. Not really a viable proposition. On the other hand, abrupt climate changes in both directions have occurred in the past, and they are likely to be very disruptive while they are happening.

Heh heh, yes it’s hardly exact. That’s perhaps because it’s an indication of the many different models combined into one overall picture. The point is that whatever model you choose, the effects far outlast the initial stimulus, but I agree that it tells us nothing about exactly how bad those effects will be.

How long has this average been accurately calculated? And is there current consensus (if there is any) that the rate of change will remain constant, or is it too expected to increase?

If fossil fuel consumption is the primary reason for the increase, wouldn’t we expect to see an increase in the rate of increase as more large, populous countries (China, India, et. al.) industrialize?

The atmospheric CO[sub]2[/sub] concentration has been measured accurately (either directly or in ice samples) for, well, as long as you like: here’s the last 1000 years, which shows an increasing average yearly rise to today’s alarming 3ppm per year.

There is no consensus, but it seems like any good done by Kyoto signatories (and most will decrease emissions but not quite reach 1990 levels required by Kyoto) will be undone by US increases, to say nothing of India or China’s increases.

Yup. And they will argue, hey, you guys had your development, now it’s our turn. And if we cannot go way, way further than Kyoto, then literally nothing will be done, and the ppm will go through the roof by 2100.

thanks scince

ok the stupid of me. sorry

So other than obeying the Kyoto pack (which as far as i am aware we are not).

What can be done? I mean are there any kind of machines that can be used to pump green house gasses into the earth’s core?

I fully support the development of alternative energy sources and I think it is high time for the world as a whole to consider drastic population control measures.

Here’s hoping for that big chill

S/he says while sipping on an ice cold coke and typing on his computer to an internet message board after adjusting the thermostat (damn hot out, what?) on the way to use the bathroom…


Nope, we aren’t, though we aren’t doing nothing either (if by ‘we’ you mean the US). IIRC several European countries that DID sign the protocol (not ‘pack’) are or were behind on meeting their targets as well. In addition you make it sound like there is some kind of proof that following the Kyoto Protocol WILL solve this problem…afaik its a very definite ‘might’.

Depends. First off, you are assuming that humans are the cause, and the major cause to boot, of climatic change. That hasn’t been proven afaik, though evidence seems to point that way. If humans aren’t the cause then they are probably a contributing factor, but if so then we maybe simply speeding up (or slowing down) what was naturally occuring anyway. In that case I’m not sure there is anything we can ‘do’.

If we are in fact the cause, then I agree there is probably things we could do. The best one would be to go forth and shoot all the old style environmentalist hippy types you see. After that, push for a full scale and rapid conversion of our power generation system to nuclear and other power generation systems that don’t burn fosil fuels (geothermal, hydroelectric, wind, perhaps solar). Its mostly going to fall on nuclear though (thats why you need to shoot the enviro-hippies first). Doing this will cut our emmissions a hell of a lot and will, perhaps, pave the way to a hydrogen economy for personal transport sometime in the next decade or so…which will cut our emmissions even more.

Scary…very scary. I hesitate to ask, but exactly how do you propose to drastically reduce the population of the world? :eek:


Even if the US had ratified Kyoto it wouldn’t make much difference. Already several European countries that ratified Kyoto have failed to meet their targets, and Kyoto wouldn’t apply to third world countries like China and India.

There are machines that can pump carbon dioxide out of the atmoshere and store it in solid form, they’re called plants. Man-made machines that change atmoshperic CO2 back into carbon would take more energy than was gained by burning the fuel in the first place, better to use the energy powering the scrubbers to supply your power needs in the first place.

Nuclear power is the only source of non-CO2 producing energy available that can be scaled up dramatically without negative environmental effects. You think the environmentalists will be happy with more dams, millions of acres of wilderness covered in solar collectors, or millions of windmills spoiling the view and chopping up birds? “Green” energy is only green on a small scale. On a small scale burning fossil fuels is green since small amounts of CO2 will be used by plants. On a small scale peeing in your backyard is green, plants need the nitrogen. But if all 8 million people in New York city pee in their backyards every day they’d be ankle-deep in sewage. Hydro, wind, OTEC, tidal and solar seem like they don’t have an environmental impact, but they do…the question is whether that environmental impact is judged to be worthwhile. Nuclear fission will have a far smaller impact than any other non-CO2 producing energy source.

Oh, I agree Lemur866 (you probably knew that already), nuclear is clearly the way to go. I tossed in the other alternatives more as a bone than because I felt they would have any real, serious impact. If we are going to convert to an energy source in the very near future, scaled up to meet our realistic energy needs (instead of the eco-babble of those old style environmentalists pining to go back and live in the trees) nuclear is the only ‘green’ choice. Problem is getting past a generation of nuclear hysteria programmed into the public by the old school environmentalists.

Venus or irrational fears…whats it to be folks? :wink:


In my defense (not to say it was justifiably outburst) i am prone to panic attacks. Let’s just say a strong felling of anxity tends to hit me some times. I had to light up my Hookha (great health choice on my part :rolleyes:) and read some Frost to calm down.

Also fair.

By this i meant. We may need reveres our current growing world population. I.E. planed families of limited number. I am aware this has all kinds of cultural and logistic problems but i think it is some thing world needs to consider. As far as I understand it some first world countries are already experience negative population growth but second and third are growing rapidly.

But I also have ask, won’t a massive expansion in nuclear energy starts on a road toward peak plutonium?

While I am often amazed at what the combined energies of human race can do I have to admit I am worried that we simple don’t have the resource or technology to stop a disaster that is in progress.

But as Faulkner once said, “I decline to accept the end of man.” A sentence that comforts me greatly. But absolutely believe that an ideological shift is need in the world

Well, you are right about one thing…many countries in Europe are in negative growth patterns (IIRC but I’m pretty confident this is true) even with immigration. The US I think is positive, but not by that much, and mainly through immigration. However, afaik even countries like China and India are slowing as far as population growth goes, so its unlikely its going to be a major problem. Certainly trying to do planned parent hood world wide is completely impractical. In China, even under an iron fist, they have trouble keeping to the one child thing…and thats with using fairly draconian measures.

I’m not sure I understand what you mean by this. Are you saying that switching over to nuclear energy will cause the creation of more (weapons grade presumably) plutonium? That plutonium will become more readily available or something? If you could explain maybe I (or probably someone with more of a clue than me) could answer.

Well, again, it depends on exactly what is causing it and on how bad it becomes. If we are talking about climatic change on a global scale I’m sure that it will be disruptive…and probably cost a lot of loss of lives and property. However, we managed to survive several major climatic changes in the past…some that were probably as bad or worse than what is currently facing us. If we could survive and adapt when the extent of our technology was knowing how to build a fire and bang two pieces of flint together to make a sharp edge, I’m reasonably confident we can survive this.

And of course, we don’t know what ‘this’ is yet. ‘This’ may be global warming, the prelude to a new ice age, or just a turbulant time of climatic shift of weather patterns.

You do realise that that finding is regarded as being highly controversial at best? We don’t have particularly good records of atmospheric carbon for the last 50 years, never mind the last 20 million.

Well no. That’s not really true. The rate of population growth is declining rapidly everywhere (with an exception of 3 nations IIRC). Almost all developed nations have already reached a point of negative population growth and the rest of the world is predicted to follow suit by the middle of this century. Or to put it another way, you and I will probably live to see a fall in the world’s population. It should peak at about 9 billion, up a third from today’s figure.

The really ironic thing about this is that the only proven way to reduce population is to increase standard of living, and the only way to increase standards of living is to increase energy consumption. Attempts at actually controlling population endogenously simply don’t work, it has to be a personal decision made because people feel secure. So the best thing to do to reduce population is, ironically, to increase the use of energy and hence Greenhouse gas production.

The thing you need realise is that we have enough fissionable material available at today’s technology levels to last the planet for about 4000 years at current usage rates. Worrying about what will happen in 4000 years is totally futile. 4000 years ago your ancestors were probably worried about peak copper because their civilisation relied on copper. My ancestors were probably worrying about peak flint or peak game. 4000 years is such a staggeringly long time in terms of human technological development that it is quite futile to worry about trying to predict what will be needed then. Whatever civilisation relies on when Uranium/Plutonium peaks it’s safe to say that we have no idea what it will be. It might be atmospheric CO2 for all we know.

People have always felt that way, that’s why almost all cultures have some form of apocalypse myth. It’s built into the human brain. That doesn’t mean that the fears of Ragnarok or Armageddon are plausible.

The great thing is that the ideological shift has occurred and is occurring. The world has changed greatly in the last 200 years and even more greatly in the last 20 years. Ideology is changing, and the rate of change is accelerating. As people’s standard of living increases they become more aware of these problems. They also have more discretion about the way they use their money and energy, and so have more scope to deal with them.

This is precisely why ‘solutions’ to these problems have to be very careful not to limit choices so much that they prevent people from responding at all, but instead box them into just one lifestyle as an unavoidable part of the solution. That’s particularly true for solutions applied to developing countries.