Gwynne Dyer: When feedbacks are triggered, climate change becomes a runaway engine

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      Campaign strategist James Carville coined the phrase “It’s the economy, stupid” to focus the attention of campaign workers on the one key issue that would get Bill Clinton elected president in the 1992 U.S. election.

      Alas, the authors of the Fifth Assessment of the Intergovernmental Panel on Climate Change (IPCC), which will be published on Friday (September 27), have no such sage to guide them. They’ll have to make do with me.

      The 800-odd authors of the report are selected by their fellow scientists in the various disciplines relevant to climate change as the acknowledged leaders in their field of study. Their job was to review all 14,000 scientific papers on climate change published in the past five years. And they are doing this work at the behest of the world’s governments, not as some random pressure group; it is the Intergovernmental Panel on Climate Change.

      Scientists are very cautious people. They won’t go one millimetre beyond what the evidence makes indisputable, knowing that they will be attacked by rival scientists if they do. They are much more comfortable talking about probabilities rather than certainties. They are, in other words, a nightmare for journalists who have to transmit their findings to the world.

      Of the nearly 100 scientists I have interviewed on climate change over the past five years, not one doubted that global warming is a big and frightening problem. Indeed, there was often an undercurrent of panic in their remarks. But when it comes to writing official reports, they retreat into science-speak.

      So the Second Assessment of the IPCC, published in 1995, said that it was more than 50 percent likely that human emissions of greenhouse gases were contributing to global warming. The Third Assessment, in 2001, raised the likelihood to 66 percent. The Fourth, in 2007, upped the ante to 90 percent, and the Fifth, this week, says 95 percent.

      But how do you make a headline out of that? How much warming? How fast? And with what effects on human beings? The latest report will run, in its final version, to 3,000 pages, and the answers are buried among the statistics. What would Jim (Carville) do? He’d say: it’s the feedbacks, stupid.

      Without the feedbacks, we could go on burning fossil fuels and cutting down the forests, and the average global temperature would creep up gradually, but so slowly that most of the inhabited parts of the planet would stay livable for a long time. But if we trigger the feedbacks, the whole thing goes runaway.

      The feedbacks are natural sources of warming that we activate by raising the average global temperature just a modest amount with our own greenhouse gas emissions. The consensus number used to be plus 2 degrees Celsius, but some scientists now argue that the real threshold may be as low as +1.5 degrees C. There are three main feedbacks.

      As the highly reflective ice and snow that covers most of the polar regions melts, the rate at which the sun’s heat is absorbed goes up steeply over a large part of the planet. We are creating a new warming engine that will shift the planet’s heat balance, and once it has started we can’t turn it off again.

      There is reason to believe that it’s already too late to avoid this one. The protective covering of floating ice that has shielded the Arctic Ocean from solar heating for so long is now going fast, and we will probably see an ice-free Arctic Ocean in the August-September period as early as the 2020s. Mercifully, this is the smallest of the three major feedbacks in terms of its impact— but it triggers a bigger one.

      The warmer air and water in the Arctic then starts to melt the permanently frozen ground and coastal seabed (permafrost) that extends over more than 10 million square kilometres of territory, a considerably larger area than Australia. This melting releases a huge amount of methane that has been locked into the ground for millions of years. Methane is a far more effective warming agent than carbon dioxide, and so we spin closer to runaway.

      Finally the oceans, as they warm, release some of the vast quantities of carbon dioxide they absorbed in the past, simply because warmer water can contain less dissolved gas. Most of the excess heat in the Earth system has been going into the oceans in the past few decades, which is why the rise in land temperatures seems to have slowed down. But that is no real consolation: it just means that the biggest feedback is also being activated.

      Those are the killer feedbacks. Earth has lurched suddenly into a climate 5-6 degrees C higher than now a number of times in the past. The original warming usually came from massive, long-lasting volcanic eruptions that put a large amount of CO2 into the atmosphere—but in every case it was feedbacks like these that carried the planet up into a temperature regime where there was a massive dieback of animals and plants.

      We are the volcanoes now. Our own emissions would take a long time to get us up to really high average temperatures worldwide, but all we have to do is pull the trigger on the feedbacks. The rest is automatic.




      Sep 26, 2013 at 11:50am

      Succinct explanation of the problem we face if we don't do anything. But, of course, we won't because our politicians require the funds from people with a short term profit interest in the status quo and especially oil futures.

      Another big challenge is hubris that we can engineer a solution. Or worse that this effect people after we are dead. Or far worse that this will kill off humans, animals and plants in other places on the globe but not here.

      We'll make great pets."

      John-Albert Eadie

      Sep 26, 2013 at 6:02pm

      7 degrees Celsius predicted by 'Gaius Publius' The point is, though, that it is real, and is seemingly inevitable. The flat-earthers are getting a lot of press from the IPCC #5 admission to error, but there is no error with respect to the basic human / animal / plant problem we are facing - RIght NOw. Thanks to M. Dyer.


      Sep 26, 2013 at 7:02pm

      A super-volcano erupted some 250 million years ago causing the mass extinction of up to 95% of all plant and animal species.

      And yet life on earth came back from that brink.

      If humankind manages to foul the nest that badly and wipe out ourselves and much of life on the planet, we can only hope that the evolution of life will produce a sentient species with far greater compassion, spirituality, and smarts to live WITH the biosphere... rather than mutating into the ravening cancer we have become this time around.

      Jill Shipman

      Sep 26, 2013 at 7:08pm

      Science never agreed it WILL be a crisis so why are YOU saying it believer?
      There wasn't ever any consensus, it was just an unsustainable consensus of nothing because for 30 years they have never agreed on anything beyond "could be" and have never said or agreed it WILL be an inevitable crisis like they love to say comet hits are. A climate crisis IS a comet hit.What has to happen now for science to end this costly debate and give us a real warning for a real crisis by agreeing it WILL happen not just might happen? Don't scientists have doomed kids as well?


      Sep 26, 2013 at 7:08pm

      Usually I agree with what Mr. Dyer has to say, he's smart, witty and not afraid to buck the consensus. However, the recent admission that the land and air is not warming, for the last fifteen years at any rate,mhas finally pushed me into the sceptic camp. The idea that the extra heat is going into the oceans seems like a post facto rationalization and isn't really testable as we have very little knowledge of what is going on in the deep and we certainly lack reliable widespread measurements of ocean temperatures. The problem is that claims have been made for two decades now about what will happen and those claims have been mostly wrong. There is something wrong with the theory.


      Sep 26, 2013 at 11:56pm

      We have Argo probes tracking the ocean warming in considerable detail. We have satellites tracking ocean level rise, glacier loss, and water movement around the planet. We also have physical surveys of the glacial melt, especially in places like Greenland, which helps validate the satellite data.

      Our measurements of glacial melt, the water we're adding to the ocean, do not match our measurements of ocean level rise. However, when we add the thermal expansion of water from the heating we measure with the ARGO project, then we get agreement. Glacial melt + thermal expansion = ocean level rise. And we're tracking these differences on a monthly basis or better.

      I'd like to hear what other readers think about this. I seem to recall warnings around the late 90s that the Northwest Passage could be open around 2030. Well, turns out that happened about 25 years early. Meanwhile we have a federal administration that can deny climate change and shut down environmental science as fast as possible, while preparing to make as much money as possible from the open water in the Arctic. Turns out past predictions of glacial melt in Greenland were terribly conservative. In the last 10 years the melt has progressed much faster than earlier models indicated, and in a pattern that no one predicted. Yes, climate scientists have gotten a lot of things wrong.

      John Wilson

      Sep 27, 2013 at 5:02am


      You would be wrong. It is true that the sampling of deep ocean water temperature is sketchy, but there are indications. It took me 5 minutes to find

      triple w dot

      which contains the following:
      "Oceanographers measure the abyssal ocean to depths of 6,000 meters by lowering accurate recording thermometers and other instruments to the ocean floor on long cables from research vessels. During the 1980s and 1990s, an international program called the World Ocean Circulation Experiment collected thousands of such profiles around the globe.

      During the 2000s, we and our fellow oceanographers returned and re-measured ocean properties at many of those sites. We detected a consistent warming signal in the abyssal ocean around the globe. The strongest warming is occurring in the Southern Ocean, around Antarctica, at a rate of approximately 0.03 degrees Celsius per decade."

      I do think that more research is required to confirm this effect, and to confirm what is causing this effect.

      But, the climate is a large, extremely complex system that we are only just beginning to get a handle on. Scientists are making new discoveries all the time about how it works, and there are (and will continue to be) a few surprises every now and then. Some of these surprises will make things seem less bad.

      But the basic problem is thermodynamics, the flow of heat, which is pretty well understood. When you increase the heat flowing into a system, it gets hotter. It's that simple. Climate deniers like to say that it isn't getting warmer, or that it's natural cycles or whatever - but they have no way of explaining the data away (most have stopped denying that it's happening) or explaining how these "natural cycles" work to produce the kind of warming we're seeing today - warming that is happening in the course of a couple of centuries that normally takes tens of thousands of years. They can't, because they haven't done the science. Climatologists and others have done the science and shown that it's extremely unlikely to be natural cycles causing our current warming climate.

      Until deniers can produce a 3000 page report based on 14,000 peer-reviewed papers saying it ain't so, don't bother listening to them. Wishful thinking doesn't make it so.


      Sep 27, 2013 at 8:39am

      We should be cautious when calling the IPCC scientists cautious. Many of them (including their intrepid leader) spent over 5 years calling themselves Nobel Laureates when in fact they are not. Self serving may be a better description.

      Lee L

      Sep 27, 2013 at 9:16am

      Mr Dyer's been indoctrinated I'm afraid.

      We do need to remember that the 'normal' state of the planet for the last many millions of years is not what we have today but rather is ICEBALL with very short ( 20,000 years or so ) intervals of warmth like we are in now. This present interglacial is scheduled to end within a few millennia at which time the planet will likely plunge back into ICEBALL.

      Mr Dyer puts all too much faith in the IPCC as it has been losing credibility for a decade, ever since 'climategate' emails showed what shenanigans the so called conservative climate scientists were up to.

      Further, the IPCC does indeed attempt to present an air of deep authority by engaging leading scientists in its process as authors. It also, however, engages many not so leading individuals for a variety of political reasons. This has resulted in some very embarrassing errors such as the prediction that the Himalayas would be ice free by 2035. This made it into an IPCC assessment report but was in fact traced to a magazine article and not to some erudite scientific journal, peer reviewed by the climate intelligentsia.
      Further, some of the past IPCC Lead Authors, all highly qualified, such as Richard Lindzen (who worked on 2 IPCC assesement reports), are deeply skeptical of the alarming kind of predictions being made. Lindzen has refused further association with what he sees as a political rather than scientific process. The quiet infiltration of this process by deep environmental advocacy groups further tarnishes the shine of unbiased authority. Indeed, not all authors are in fact scientists at all, but are government appointees.
      You can find out more about this by out Donna Laframboise's website or her books. It is pretty interesting stuff and not something Davey Suzuki will tell you about.

      By the way there is a video of an interview with Dave done on Australian ABC-TV wherein a question from the audience references a number of the main earth temperature data sets in common use in climate science( HadCrut, GISS, RSS, UAH...) which are well known to even neophytes. David shocked everyone by being unable to recognize these references. In fact it is so shocking, I find myself wondering if he were purposely playing dumb but for what purpose, I cannot fathom.

      Not Lee L

      Sep 27, 2013 at 11:39am

      The last few million years of glaciation with short interglacial periods has been mainly due to the continents trapping ice at the north pole, which has generally cooled the planet. Before that (i.e. the previous several billion years), when the continents were farther apart and no ice was trapped at the north pole, the earth was much hotter. Now that humans are causing the melting of the northern ice cap, a runaway warming effect such as that described by Mr. Dyer may well overcome the glaciation cycle.