Memo To Media: ‘Climate Sensitivity’ Is NOT The Same As Projected Future Warming, World Faces 10°F Rise


The major media continue to sow confusion on one of the central questions of our time: How much warming will we subject our children and countless future generations to?

The answer to that question depends primarily on four factors:

  1. The so-called “equilibrium climate sensitivity” – the sensitivity of the climate to fast feedbacks like sea ice and water vapor. The ECS is how much warming you get if we suddenly adopt a super-aggressive effort to cut carbon pollution and only double CO2 emissions to 560 ppm — and there are no major “slow” feedbacks.  We know the fast feedbacks, like water vapor, are strong by themselves (see Study: Water-vapor feedback is “strong and positive,” so we face “warming of several degrees Celsius” and Skeptical Science piece here).
  2. The actual CO2 concentration level we hit, which on our current emissions path is far, far beyond 550 ppm (see U.S. media largely ignores latest warning from climate scientists: “Recent observations confirm … the worst-case IPCC scenario trajectories are being realised” — 1000 ppm).
  3. The real-world slower (decade-scale) feedbacks, such as tundra melt (see “Carbon Feedback From Thawing Permafrost Will Likely Add 0.4°F – 1.5°F To Total Global Warming By 2100“).
  4. Where they live — since people who live in the mid-latitudes (like most Americans) are projected to warm considerably more than the global average.

The media, perhaps aided by some scientists who aren’t great at communications, tend to focus on just #1, a number the IPCC Fourth Assessment Report pegged as “likely to be in the range 2 to 4.5°C with a best estimate of about 3°C, and is very unlikely to be less than 1.5°C. Values substantially higher than 4.5°C cannot be excluded, but agreement of models with observations is not as good for those values.” While the majority of studies tend to be in the middle of the range, a couple have been near the low end, though some have been at the higher end.

In any case, focusing on the fast-feedback sensitivity perhaps made sense in the distant past when there was some reasonable chance of stabilizing at 560 parts per million atmospheric concentrations of carbon dioxide (double the preindustrial level) and some hope the slow feedbacks might not matter.

Indeed, the scientific community focused on a doubling I think in part because they didn’t believe humanity would be as self-destructive as brainless frogs and ignore the increasingly dire warnings for over two decades now.

As I explained in Nature online back in 2008 (here), once you factor in carbon-cycle feedbacks, even the uber-cautious Fourth Assessment report (AR4) of the IPCC makes clear we are headed toward 1000 ppm (the A1FI scenario). That conclusion has been supported by just about every major independent analysis, including a recent report by PricewaterhouseCoopers (see Study: We’re Headed To 11°F Warming And Even 7°F Requires “Nearly Quadrupling The Current Rate Of Decarbonisation“). That means it doesn’t matter terribly much whether the ECS is 3C, or, say, only 2.5C.

It is worth noting that while the Thawing Permafrost Could Cause 2.5 Times the Warming of Deforestation (!) and add up to 1.5°F to warming in 2100 by itself, “Participating modeling teams have completed their climate projections in support of the [IPCC’s] Fifth Assessment Report, but these projections do not include the permafrost carbon feedback.” D’oh!

Given that the Arctic is already losing ice decades faster than any AR4 model had projected, we should expect that the permafrost will go faster than the models suggest. Indeed a 2008 study by leading tundra experts found “Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss.” The study’s ominous conclusion:

We find that simulated western Arctic land warming trends during rapid sea ice loss are 3.5 times greater than secular 21st century climate-change trends. The accelerated warming signal penetrates up to 1500 km inland….

Anyone who tells you the recent literature suggests things will be better than we thought, hasn’t read the recent literature. In a 2010 AAAS presentation, the late William R. Freudenburg of UC Santa Barbara discussed his research on “the Asymmetry of Scientific Challenge“: New scientific findings since the 2007 IPCC report are found to be more than twenty times as likely to indicate that global climate disruption is “worse than previously expected,” rather than “not as bad as previously expected.”

Figure 7.

“Projections of global warming relative to pre-industrial for the A1FI emissions scenario” — the one we’re currently on. “Dark shading shows the mean ±1 s.d. [standard deviation] for the tunings to 19 AR4 GCMs [IPCC Fourth Assessment General Circulation Models] and the light shading shows the change in the uncertainty range when … climate-carbon-cycle feedbacks … are included.

Again, we are headed to 11F and just keeping to 7F will take a major effort. But warming beyond 7F is “incompatible with organized global community, is likely to be beyond ‘adaptation’, is devastating to the majority of ecosystems & has a high probability of not being stable (i.e.  4°C [7F] would be an interim temperature on the way to a much higher equilibrium level,” as climate expert Kevin Anderson explains here.

Everyone interested in what we face should should read the recent World Bank Climate Report, which concluded, “A 4°C [7°F] world can, and must, be avoided” to avert “devastating” impacts. Also worth reading is the Royal Society Special Issue on Global Warming, which details the “hellish vision” of 7°F (4°C) world (and is the source of the figure above). The concluding piece in the issue notes soberly:

… a 4°C world would be facing enormous adaptation challenges in the agricultural sector, with large areas of cropland becoming unsuitable for cultivation, and declining agricultural yields. This world would also rapidly be losing its ecosystem services, owing to large losses in biodiversity, forests, coastal wetlands, mangroves and saltmarshes, and terrestrial carbon stores, supported by an acidified and potentially dysfunctional marine ecosystem. Drought and desertification would be widespread….

In such a 4°C world, the limits for human adaptation are likely to be exceeded in many parts of the world, while the limits for adaptation for natural systems would largely be exceeded throughout the world.”

We have dawdled so long that even abundant, cheap natural gas can’t save us (see IEA’s “Golden Age of Gas Scenario” Leads to More Than 6°F Warming and Out-of-Control Climate Change). In fact, the IEA’s 6°F high-gas scenario — appropriately acronymed G.A.G. — super optimistically assumes that not only does oil consumption peak in 2020 and drop over 10% by 2035 — but so does coal! That won’t happen without very aggressive climate policies.

Steve Easterbrook’s post “A first glimpse at model results for the next IPCC assessment” shows that for the scenario where there is 9°F warming by 2100, you get another 7°F warming by 2300. Of course, folks that aren’t motivated to avoid the civilization-destroying 9°F by 2100 won’t be moved by whatever happens after that.

I will have more to say about “slow” carbon-cycle feedbacks in a subsequent post, but it is always worth noting that the paleoclimate record suggests the ultimate warming we are going to see is likely to be considerably higher than the fast-feedbacks sensitivity suggests:

  • Science (2009): CO2 levels haven’t been this high for 15 million years, when it was 5° to 10°F warmer and seas were 75 to 120 feet higher
  • Scientists analyzed data from a major expedition to retrieve deep marine sediments beneath the Arctic to understand the Paleocene Eocene thermal maximum, a brief period some 55 million years ago of “widespread, extreme climatic warming that was associated with massive atmospheric greenhouse gas input.” This 2006 study, published in Nature (subs. req’d), found Artic temperatures almost beyond imagination–above 23°C (74°F)–temperatures more than 18°F warmer than current climate models had predicted when applied to this period. The three dozen authors conclude that existing climate models are missing crucial feedbacks that can significantly amplify polar warming.
  • A study published in Geophysical Research Letters (subs. req’d) looked at temperature and atmospheric changes during the Middle Ages. This 2006 study found that the effect of amplifying feedbacks in the climate system-where global warming boosts atmospheric CO2 levels-”will promote warming by an extra 15 percent to 78 percent on a century-scale” compared to typical estimates by the U.N.’s Intergovernmental Panel on Climate Change. The study notes these results may even be “conservative” because they ignore other greenhouse gases such as methane, whose levels will likely be boosted as temperatures warm.
  • Another study published in Geophysical Research Letters, “Missing feedbacks, asymmetric uncertainties, and the underestimation of future warming” (subs. req’d), looked at temperature and atmospheric changes during the past 400,000 years. This study found evidence for significant increases in both CO2 and methane (CH4) levels as temperatures rise. The conclusion: If our current climate models correctly accounted for such “missing feedbacks,” then “we would be predicting a significantly greater increase in global warming than is currently forecast over the next century and beyond”–as much as 1.5°C warmer this century alone.
  • Science stunner (2011): On our current emissions path, CO2 levels in 2100 will hit levels last seen when the Earth was 29°F (16°C) hotter. Paleoclimate data suggests CO2 “may have at least twice the effect on global temperatures than currently projected by computer models.”

54 Responses to Memo To Media: ‘Climate Sensitivity’ Is NOT The Same As Projected Future Warming, World Faces 10°F Rise

  1. One perverse hope (and it is very perverse) is that the positive feedbacks implicit in the huge CO2 and temp numbers above may well be short-circuited by a strong negative feedback far earlier than they reach “hellish” levels.

    That negative feedback would be the collapse of agriculture, and the consequent collapse of the world economy. Of course, that’s saying that the very bad consequences will just come sooner. But possibly they would not be as bad–they may avoid the “Venus” scenario, for example. But it will still be a much lesser world, with a lot of suffering.

    The best hope, of course, is that we get in front of this problem big enough soon enough to avoid both of these nasty outcomes.

  2. Andy says:

    “In such a 4°C world, the limits for human adaptation are likely to be exceeded in many parts of the world, while the limits for adaptation for natural systems would largely be exceeded throughout the world.”

    I disagree with the really big assumption this statement makes. The same assumption made by many who report on global warming. That humans can exist on a world largely devoid of natural systems.

  3. Joe Romm says:

    Guess we’re going to find out….

  4. Thanks Joe,

    I’ve had a day of denier’s nonsense about the climate sensitivity issue, and it was refreshing to return to this post. There is another aspect to the problem. While I believe that you’re absolutely correct that we’re headed to 7ºF and probably higher unless we take big mitigation steps fast, I think that there is another aspect to the problem — namely, we’re already in trouble at .8ºC, and most of the devastating effects currently predicted for 4ºC (7ºF) will probably have occurred well before we ever get there.

    Revkin ran a post on Dot Earth today that attempted to make the situation seem less urgent that it actually is by talking about lowered sensitivity expectations in recent studies. Here’s the comment I posted on that article:

    All this focus on climate sensitivity estimates is a red herring.

    We’re currently at 0.8ºC(+) and on our way up.

    At 0.8ºC we’re witnessing the arctic sea ice disappear, sometimes at spectacular rates; the northern permafrost melt and begin to release its huge stores of methane and CO2; the oceans warm and acidify; continental interiors dry up causing crop failures and massive forest fires; invasive species and disease vectors migrate; record-smashing temperatures in many parts of the world; global glacier melt; a 5% increase in atmospheric water vapor and crazy weather.

    The carbon we’ve already spewed into the atmosphere will get us past 1.1ºC on it’s own, without counting any feedbacks such as the warming from Arctic albedo loss, additional carbon from failing forests, or, God forbid, an exponentially accelerating carbon dump from the northern permafrost. The IPCC AR5 doesn’t even consider natural feedbacks (or the loss of carbon sinks?) in its guesstimates, so they are immaterial.

    Put all this together, and you can make a reasonable case that (1) we’re already well on our way to 1.5-.6ºC and, (2) 1.5-6ºC is the new 2ºC which the UN, G8 and others say we must stay below to avoid “dangerous climate change.”

    So bickering about whether or not we’re at the high end of sensitivity estimates for 2100 is a nice academic exercise, but it has little to do with marshaling an appropriate response to the global warming crisis.

  5. Paul Klinkman says:

    Sorry, but I’m wishing for something more substantial. I know, we don’t have anything like that.

    A summary of what I read here is, “We don’t know.” So, the message typical reporters take away is “The scientists don’t know, and a couple of oil company executives say don’t worry, so don’t worry.”

    How bad will the Oklahoma droughts be? Don’t know.

    How bad will the tornado season be? Don’t know.

    How bad will ocean acidification be? When will the oyster population crash? Don’t know.

    When will the Arctic ice be gone? If current ice volume trends continue in a straight line, 4 years. Ah, something real to predict.

    How big will the hurricane seasons be? Don’t know.

  6. Wow where do you think oxygen and food comes from? Remember that little experiment to create an enclosed self contained ecosystem called Biosphere? Didn’t work out so well…

  7. Joan Savage says:

    And that 1000 ppm is only CO2?

    With what we have learned about rates of soot and methane, as well as sulfur dioxide, the Figure 2, FAQ 2.1, from the IPCC Fourth Assessment Report (2007), Chapter 2, is dreadfully out of date on estimates of relative contributions to radiative forcing.

    Climate sensitivity commonly refers ‘just’ to effect of radiative forcing on surface temperature, so it rather leaves out the messages about energy stored as heat in oceans, or energy in phase changes, or kinetic energy in weather systems.

    Those gaps in the picture could contribute to confusion among the media.

  8. Paul Magnus says:

    Toast. Where have I heard that term before. Now we are hearing it from the head of the IMF!!!!!!!!!!

    “Director of the International Monetary Fund (IMF) Christine Lagarde told the World Economic Forum in Davos, Switzerland: “Unless we take action on climate change, future generations will be roasted, toasted, fried and grilled.”

  9. Jack Burton says:

    A few years back I saw a program on research into past mega hurricanes. The evidence is found in the geological record in places like Florida for example. One can dig and uncover evidence of sea surges in the form of sea sand and other deposits characteristic of sediments left by hurricane caused surge events. In the distant past, when temperatures were a deal warmer than today, there is geologic evidence of massive sea surges indicative of mega hurricanes. These were storms that could have eliminated major coastal cities had they existed at the time. Now that we know that in a time when temperatures were only a few degrees warmer than today, the potential for mega hurricanes existed and that they occurred, we can more or less count of hurricanes increasing in strength as we warm the oceans. Sandy already can partly be blamed on the unusually warm Atlantic waters. My bet is that when the normal hurricane cycle delivers a harsh year, that the storms will be bigger than any expect. Sandy is clear evidence that this is beginning.
    My belief is that the real thing that grabs attention will not be hot spells, or reports of gradually warmer and warmer average temperatures, but what grabs our attention will be extreme weather events. They already are becoming commonplace, they will get ever so much worse and very fast.
    Imagine the trouble we are in with the minimal warming we have recorded to date, then imagine what the world would be given 3-4C! A hurricane in that world could on occasion be a mega storm and take a city like Miami and simply wipe it off the map. Geologic evidence in that very coast show that gives a couple degrees warmer and those storms DO and HAVE happened.
    And again I point out, nothing is being done. Instead governments and industry are pulling out all the stops to exploit every new fossil energy find they can. Tar Sands, Deep Water, Fracking, you name a fossil fuel source and every humanly possible effort is being made to access it and burn it. Nobody can offer a shred of evidence to show that governments and corporations plan do do anything but drill and drill and drill. Every nation that can find a fossil fuel source is going hell bent to exploit it. In fact, we already are seeing wars on the horizon over which nation will get to exploit the new oil sources.

  10. Paul Magnus says:

    “Were just a bunch of primates, out of control” Paul Watson

  11. Cowcharge says:

    People who want to try to intentionally change the climate scare me much more, infinitely more, than the worst-case global warming scenario you can come up with.

  12. mikel says:

    When pressed on what he thought the consensus on the climate sensitivity number had changed, Andy Revkin came out in his comment section with a jawdropping response that went largely unnoticed, on how he evaluated the science:

    — I’m saying my read is that analyses finding a sensitivity lower than 3oC are more likely to end up right, not based solely on the quality of the work, but the history of ideas. See my 1985 article on nuclear winter for an example of how things can play out. (Things trend toward “nuclear autumn,” although there are still some researchers seeing big climatic impacts from even a “small” nuclear war.)—

  13. Sasparilla says:

    Nicely said Philip and kudows for putting up some common sense on Revkin’s “things aren’t so bad” blog – I’ll leave off my comment of the morality of Revkin’s consistent message considering the human suffering being stacked in the CO2 pipeline.

  14. This is the old ‘uncertainty argument’ and it is a disservice to adaptation.

    If we are in a descending airplane that has run out of fuel, just because we don’t know exactly where we will hit the ground, does not mean that we are not gonna crash.

  15. Paul Magnus says:

    “warming beyond 7F is “incompatible with organized global community, is likely to be beyond ‘adaptation’”

    Warming beyond 1C is incompatible with organized global community.

    We are already starting to see the collapse… communities abandoning river areas and coastal areas with storm surge.

    The droughts have already arrived…

  16. Paul Magnus says:

    Director of the International Monetary Fund (IMF) Christine Lagarde told the World Economic Forum in Davos, Switzerland: “Unless we take action on climate change, future generations will be roasted, toasted, fried and grilled.”

  17. Good lord, what an inane remark!

    I suppose it’s possible for people to exist on a mostly devastated planet, hiding out in places where they don’t die from wet-bulb temperature fluxes; scrounging for whatever natural food is left since they won’t be able to grow enough to support all but a few folks with greenhouses (if that). A small population of humans, after all, survived the ice ages. But is that what you want?

  18. Thanks Sasparilla,

    As I said above, I’ve had a rough day dealing with climate sensitivity nonsense, starting with Revkin’s gloss over and confronting a particularly annoying denier at a talk I gave. I’m frustrated and pissed at the moment, and hearing some words of encouragement is really nice. That’s one good thing about Joe’s blog — we can communicate fruitfully and support one another.

  19. “Those gaps in the picture could contribute to confusion among the media.”

    True, but so could millions of dollars in petrobucks spent on disinformation.

  20. Taylor B says:

    Check your reading comprehension. What part of >4C don’t you understand? Just because you’re looking for precise answers to questions that hadn’t been asked, doesn’t mean the correct answer is to listen to oil company executives. Putting words in others’ mouths isn’t a good way to learn anything. Ask yourself whether the answers to your questions about “when” or “how bad” are likely to change how we should respond to the problem. Ask yourself what course of action you would recommend, if the answer to each of your questions is uncertain, but heavily weighted in a direction that is likely to significantly reduce the quality of life, if not the very survival of your children and their progeny. If you’d prefer to listen to the advice of oil company executives than to use your head, there’s no need to ask your questions.

  21. Paul Magnus says:

    It just amazes me how the destruction that a 4C warming will realize is just not in the radar of most people. They really do not have a clue about self preservation.

    Also amazes me how even people in the know are oblivious or choose to be oblivious to the fact that 2C is pretty much self destruction anyway.

  22. fj says:

    Proof that there are people in government that are starting to get the seriousness and scale of the calamity upon us:

    Cuomo Seeking Home Buyouts in Flood Zones

  23. Artful Dodger says:

    Yes Paul, except that 2012 was 1.9 C warmer than the 20th Century, at least in the U.S. where ~80% of climate catastrophe’s occurred.

    ‘It’s an ill wind that blows nobody any good’

  24. Lewis Cleverdon says:

    What is it about my tree-planting that frightens you so much ? I’d be first to say that if the requisite global program of Carbon Recovery is not in addition to rapid emissions control, it would be pointless.



  25. Mulga Mumblebrain says:

    That ‘negative feedback’, of agricultural and economic collapse, will lead to generalised warfare, probably going nuclear, which will geo-engineer a nuclear winter. It’s a hard way to cure the greenhouse warming.

  26. Mulga Mumblebrain says:

    Revkin ought to be starved of the oxygen of acknowledgement. He, like all the types of denier, is irredeemable, so why bother pointing out his errors? He won’t change, and kill his Golden Goose, and his acolytes, such as there may be, are not about to admit error-ever. Their gigantically over-inflated egos could not survive the shock.

  27. Icarus62 says:

    I think, Stephen and Philip, that you misunderstood Andy’s comment. He seems to be saying (reasonably enough) that there will be not much chance of us adapting to a world without functioning natural ecosystems.

  28. Joan Savage says:

    In a joint state budget hearing yesterday in Albany, the NYS DEC Commissioner was asked if the buy-out land would stay under state control or go to local government. The Commissioner emphasized that the buy-out purpose is for various kinds of storm barrier (I don’t recall his exact words), but that administration by state or local government was not decided.

    As such, it means there could be the ironic outcome that the people who built houses where they shouldna could get bought out, while others in slightly less dangerous locales wouldna get a buy-out from the state.

    As it is, two state legislators at the hearing had tales of previous attempts to establish storm barriers in their districts, one ended up unfunded and another blocked by a town council.

  29. catman306 says:

    A monkey island in outer space.

    CP is the place for the media to get their memos about climate. But the memos are still ignored. We’ve got to cost the media money, greatly reduce their bottom lines, before they’ll pay us any attention. Money is the only currency they know.

  30. Rabid Doomsayer says:

    Just how bad will the Holocene Anthropocene Thermal Maximum extinction event be? Make the PETM look like the teddy bears picnic?

    With a little more effort, we can surpass the End Permian

  31. Lewis Cleverdon says:

    Phillip – well said.

    Switching the focus to the near-term warming and its impacts is a necessary and seminal change. The fact that we’ve raised anthro CO2 in the 30 yrs since 1982 from ~22% above the pre-industrial to about 41% above, may help people put into perspective the timelagged warming we’re due in the next three decades.

    In addition to that anthro-warming (which must actually include the CO2 outputs of the earliest major carbon feedbacks) there is also as you say a timelagged warming due to the long-established water vapour and albedo loss feedbacks.

    In combination it’s my understanding that without commensurate mitigation we’d be very lucky to see only 1.5C to 1.6C by 2042.

    The damages between now and ’42 will plainly have a non-linear relation to the warming, as their track since 1980 shows. The GISS-NASA global land ocean temperature index shows that between 1925 and 1980 there was a mean warming of 0.38C, with a further 0.38C or 100% rise by 2010. Yet the Munich Re data in its graph of the rising number of catastrophic events from 1980 to 2010 shows a ~170% rise in floods, a ~240% rise in extreme heat events, and a ~260% rise in catastrophic storms.

    There is also a further non-linearity in the vulnerability to damages – another foot of sea surge, a few extra degrees of night temperature, or just an extra 12% of wind speed can transform the outcomes. For example, when a house built to regs to endure 100mph winds is hit by 112mph winds it suffers over 40% more wind-force than it’s designed for, very likely reducing it to an investment decision.

    Clearly the combination of both climatic and vulnerability non-linearities are already making the rising scale of damages look like step-changes to those on the receiving end – such as those inflicted by the insignificant little Hurricane Sandy via an overheated Gulf Stream and a blocking high over Greenland due to the perturbed Jetstream.

    The discussion of climate destabilization under the linear metric of degrees C of warming is thus exactly what highly-paid lemming-herders such as Revkin rely on for their deception to work. To discredit them and to advance the near-term focus we urgently need something like a ‘Destabilization-Damages’ metric – degrees DD – just as soon as some very bright spark can devise it.

    It seems the formal 2.0C threshold of ‘dangerous climate change’ is being quietly dropped in favour of an expedient 3 or 4 degree assumption, which is patently beyond global society’s endurance (US damages under just 0.8C in 2012 already matched most of the US GDP for the year) but which maintains the fiction of a feasible emissions-control-only response. This plainly needs to be challenged, preferably by the promotion of a new closer goal: a “1.5C Threshold of Calamitous Warming.”

    In my view it is damages sufficient to cause geo-political destabilization that warrant the term ‘calamitous’, since they’d likely end the prospect of the close global co-operation that is essential for controlling both GHG emissions and the consequences of the warming to which we’re already committed.

    A recent study out of Leeds Uni, “Food Security: Near future projections of the impact of drought in Asia” ( )
    puts the start date of such calamitous damages at between 10 and 15 years hence.
    China, Pakistan and Turkey are highlighted as the most seriously affected major producers of wheat and maize.

    From the press release:
    “Research released today shows that within the next 10 years large parts of Asia can expect increased risk of more severe droughts, which will impact regional and possibly even global food security.”

    “On average, across Asia, droughts lasting longer than three months will be more than twice as severe in terms of their soil moisture deficit compared to the 1990-2005 period. This is cause for concern as China and India have the world’s largest populations and are Asia’s largest food producers.”

    “Dr Lawrence Jackson, a co-author of the report, said: “Our work surprised us when we saw that the threat to food security was so imminent; the increased risk of severe droughts is only 10 years away for China and India. These are the world’s largest populations and food producers; and, as such, this poses a real threat to food security.”

    Those who launched the US policy of a brinkmanship of inaction with China back in 2000 may be encouraged by the news of the climatic destabilization of China’s govt perhaps within a decade, thereby ending China’s bid to displace US global economic dominance. Yet their recklessness ignores the US climate impacts rising much faster than in any comparable area, just as it ignore the possible outcomes of geo-political destabilization from food shortages in nuclear-armed Asian states, of which Pakistan has been badly infested by the extremist Saudi Islamic creed of Wahabism.

    You remark Philip your frustration in dealing with the circus of denial – well I’ll swop you for that of trying to encourage discussion of the ‘real-polique’ of the near-term climate threat, which appears essential for the task of marshalling a commensurate response.



  32. The confusion about CO2 vs “all gases” is an important one. You can actually calculate CO2 equivalent concentrations for all gases using the 2009 MIT study, and it’s about 1350 ppm CO2e:

    That’s 4.8 times preindustrial levels, or more than 2 doublings. So we’re talking about at least two doublings of GHG concentrations by 2100 on our current path, and if you multiply this by the mean climate sensitivity of 3C it implies ultimate warming of 6 C. And that’s not including the “slow feedbacks”, as Joe correctly points out.

    This is the simplest way I’ve figured out to explain it. I worked out the math and present the data in my latest book, Cold Cash, Cool Climate:

  33. Francois T says:


    Revkin works for one of the “pillars” of the mainstream media. This is an ecosystem where results and accuracy matters MUCH LESS than conformity.

    Contrary to the awesome Cenk Uygur who should have had the 6 PM anchor job at MSNBC and refused to take it because they demanded conformity, Revkin made his bed.

    Therefore, he cannot be trusted anymore. It’s a harsh judgment but climate change isn’t a topic where pussyfooting should be allowed anymore.

  34. Jan says:

    Thanks for explaining.

    As I said some time ago, it would be good to provide both Celsius AND Fahrenheit numbers throughout, not sometimes one or the other, sometimes both.

    I realise that’s probably because of quotations from the original studies and would be a hassle to do, but still would aid comparison and understanding.

    Or maybe you could put a climate calculator widget for conversion on the website (possibly also for carbon/CO2 etc.)?

  35. bedfordfalls says:

    This is in response to Taylor B’s answer to Klinkman’s 9:10 pm post; and also to Magnus’s 1:29 am comment, which was:

    “It just amazes me how the destruction that a 4C warming will realize is just not in the radar of most people. They really do not have a clue about self preservation.”

    –Well, I think it would help to put it in more concrete terms, as Klinkman also seems to say. For one, use F and not C. Also, say things like, “Corn will no longer grow in Iowa. There will be no water for cows in [state]. We will have ‘tropical’ diseases like malaria in [state].” And so on.

    “Dustbowlification” is good, I think.

    “Stretches of days over 110F, as happened in Oklahoma in [period of 2012],” — also good.

    I think concrete specifics would help.

    You can lecture me that I should “check my reading comprehension;” touche; but not helpful, I don’t think.

  36. Paul Magnus says:

    Yes. I think we have reached a global temp threshold that results in the large land mass areas of the continents to heat up rapidly during the summer season resulting in these continents racing past their record ave temps now.

    This is probably a result of the fact that at the 0.8C to 1C threshold the drying out effect on the soil due to the ave higher temps, especially at night times, results in this rapid increase in the overall land temp and consequently the extrem ave temp for the region. And of course the impact on the precipitation patterns due to various forcings.

    We have now seen this in Russia, the US and now Australia. And probably other areas that I have missed.

    Going forward now I think we are at a stage where these extreme regional and country averages are going to be broken on a regular basis. Maybe in 3yr cycles.

    These extreme heat waves are always associated with extreme weather events on unprecedented scales. ie the US and now Australia are fine examples.

    That is why I am of the opinion that the 1C rise in global temp will result in the collapse of modern civil society.

    We will not be able to cope with this onslaught of extreme events, even at the current rate that we have seen over the last few years.

  37. Paul Magnus says:

    I think we have reached a global temp threshold that results in the large land mass areas of the continents to heat up rapidly during the summer season resulting in these to racing past their record ave temps now on a regular basis.

    This is probably a result of the fact that at the 0.8C to 1C threshold the drying out effect on the soil due to the ave higher temps, especially at night times, results in this rapid increase in the overall land temp and consequently the extrem ave temp for the region. And of course the impact on the precipitation patterns due to various forcings.

    We have now seen this in Russia, the US and now Australia. And probably other areas that I have missed.

    Going forward now I think we are at a stage where these extreme regional and country averages are going to be broken on a regular basis. Maybe in 3yr cycles.

    These extreme heat waves are always associated with extreme weather events on unprecedented scales. ie the US and now Australia are fine examples.

    That is why I am of the opinion that the 1C rise in global temp will result in the collapse of modern civil society.

    We will not be able to cope with this onslaught of extreme events, even at the current rate that we have seen over the last few years.

  38. Nell says:

    Let’s hope world’s governments see the light and start a war on carbon before it’s too late.
    But I’m prepping.

  39. Lou Grinzo says:

    Not meaning to pile on, but I have to bring up, yet again, the “aerosol whiplash” effect that’s lurking. Currently, we’re seeing a substantial amount of cooling effect from sulfate aerosols (mostly from coal burning). But as the OECD countries continue to put scrubbers on coal plants, and even China and India are forced by horrendous air quality to do the same, that protection will literally rain out of the atmosphere in very short order and send warming into overdrive.

    See the bar chart of radiative forcings, which I believe is thew one Joan mention up-thread, and check out the bars for human-caused aerosols.

  40. Taylor B says:

    Perhaps I overreacted to Mr. Klingman’s comment, but he offered a “summary” of the article that had very little to do with what it was about. I was also reacting to the implication that the warnings of climate scientists should not be taken any more seriously than the bromides of oil executives if they don’t make predictions precisely enough to set one’s watch or schedule a dentist appointment in 20 years–a common rhetorical technique among certain self-described skeptics who aren’t really interested in the answers they demand.

    It’s fine to ask for more accurate projections if they have a bearing on decision making–but to criticize the article and put words in the author’s mouth because it doesn’t answer the reader’s specific questions–which the article wasn’t intended to address–or because it doesn’t meet arbitrary standards of certainty isn’t a very useful way to start a discussion on the topic.

  41. Mulga Mumblebrain says:

    It is surpassing mysterious, I must say. I won’t burden you with my ‘conspiratorial’ explanation, other than to say that there are human types who do not have much concern for the plight, or even existence, of others, and our current global economic and political dispensation favours these types greatly.

  42. Mulga Mumblebrain says:

    Therefore he must simply be ignored, as criticism is wasted effort.

  43. Mulga Mumblebrain says:

    A chicken and egg problem, or should I say ‘Goose and Golden Egg’ problem-which came first, the MSM geese, or their Golden Eggs?

  44. Mulga Mumblebrain says:

    However, we are not all equally guilty. The ‘psychotic ape’ is not a universal type, just that which capitalism prefers and advantages.

  45. Mulga Mumblebrain says:

    Pompous and preposterous gobbledegook. The ‘history of ideas’ (why, we have a real ‘deep thinker’ here!) turns out precisely how? And just how much uniformity, however measured, to these ‘outcomes’ show? It is nonsense raised to the power of dumb-and that’s a big number, indeed.

  46. Mulga Mumblebrain says:

    Yeah, but the first-class passengers want to party as long as possible.

  47. Mulga Mumblebrain says:

    Already hunger is stalking countries like Egypt. India is becoming more precarious from the point of view of food security. Pakistan is in continuing turmoil, and still churning out nukes. The re-colonisation of Africa has commenced. Geo-politics are taking on features comparable to the height of various pre-war periods. Japan is being incited to confront China by elements in the USA, and has a PM, Abe, who flatly denies all Japan’s crimes from the 1930s and 1940s. The pips are squeaking, just about everywhere.

  48. Mulga Mumblebrain says:

    I agree. The one degree Celsius rise and the consequent weather phenomena come on top of myriad other ecological derangements caused by the cancerous religion of endless economic growth. These are all worsening one another, and I cannot really think of an example of an ameliorative effect. Of course, smog is causing a degree of ‘global dimming’ as are high-altitude con-trails, but these are only masking and somewhat lessening dire changes. If we ended those pollutions, global warming would jump by a marked degree.

  49. schwankmoe says:

    don’t forget the rise in temperature once the arctic ice sheet disappears. that’s a lot of latent heat that will no longer be taken out of the air by melting.

  50. Lewis – excellent points all and thanks for link to CLCF rpt. There’s plenty of evidence that 1.5C isn’t safe, i.e. much of Africa will burn, coral reefs fail, sea level rise swamps low lying regions etc. By the time we get to 1.5C we’ll be terrified of going higher… and it will very, very late to prevent it.

  51. Solar Jim says:

    How about an oxygen indicator so we know when levels fall below that necessary for respiration (after forest and phytoplankton ecosystems falter). This way we can confirm deaths by asphyxiation.

  52. Solar Jim says:

    15,000 DOW (until it isn’t) and 80 foot sea level rise here we come. Impressive.

  53. Lewis Cleverdon says:

    Stephen – thanks for your response –

    The recognition that the delay of globally agreed action is a matter of US policy seems to me the critical change needed. With the challenge, exposure and termination of that policy we have the chance of achieving the commensurate triple mitigation –

    But as long as that policy prevails, we’re sliding toward the ruinous geo-political destabilization noted above, and also toward the terminal point (date unknown) when enough heat has gone into the oceans to later trigger a scale of feedbacks that is beyond the possibility of control via geo-e, i.e. toward the closure of our final window of opportunity for mitigation.

    It really is time that more progressives woke up to just what’s being done in their name.

    All the best,


  54. Joan Savage says:

    Very useful!

    As it is, the relative GHG contributions of soot, HFCs and methane have been shifting since Socolow et al (2009) and the earlier IPCC chart (2007), so I hope you would provide a revised second edition, if necessary.