Must have PPT in disappointing issue of Nature devoted to “The Coming Climate Crunch”

One of the main purposes of this blog is to save you time.  As the Washington Post labels its TV columns on American Idol, “We watch … so you don’t have to.”

Nature has devoted much of its April 30 issue to “The Coming Climate Crunch” (subs. req’d).  Sadly, after sitting through pretty much the whole thing, I can’t actually recommend anybody else see buy it. Any regular reader of this blog will learn very little new from the dozen or so articles — and the issue fails utterly to provide its readers with the two must-haves in any comprehensive coverage of the issue:

  1. A clear and specific understanding of the plausible worst-case scenario impacts facing the world post-2050 on our current emissions path.
  2. A clear and specific understanding of the core climate solutions, policies for their rapid deployment, and an understanding of why the total cost of action is so darn low — one tenth of a penny on the dollar.

What is particularly embarrassing for Nature, whose coverage of this issue has been second to none, is that they don’t even bother with #2 — even though they have a full article devoted to geo-engineering (a puff piece by someone who “now participates in scientific research on the topic”), another full article on adaptation, and yet another full article just on capturing CO2 from the air, which even one of its major proponents is quoted as saying is “the most expensive climate-mitigation technology.”  What were the editors thinking?

The most useful thing in the entire issue is part of one of the figures in the article “Greenhouse-gas emission targets for limiting global warming to 2 °C” — which I’ve extracted and added to my must-have Powerpoint collection:

What is particularly “must-have” about this PPT is that it comes from a peer-reviewed article and clearly lays out the two choices:

  1. Halving 1990 levels of global greenhouse gas emissions by mid-century, which keeps total warming from preindustrial levels as close as possible to the “safe” level of 2°C.
  2. Staying anywhere near the business as usual path, which takes you to the worst-case IPCC scenario, A1F1 — or even worse than the worst (see U.S. media largely ignores latest warning from climate scientists: “Recent observations confirm “¦ the worst-case IPCC scenario trajectories (or even worse) are being realised” “” 1000 ppm).

Note that the results are quite in line with what the UK’s Hadley Center recently reported (see Hadley Center: “Catastrophic” 5-7°C warming by 2100 on current emissions path, but this is a better figure than Hadley’s, I think).  I’d note that Hadley sees a median warming of 5.5°C on our current emissions path, but presumably that’s because they model warming beyond A1F1 (see also M.I.T. joins climate realists, doubles its projection of global warming by 2100 to ~5.5°C from preindustrial levels).

Bottom line:  We are facing total warming of 5°C to 5.5°C by 2100.

What would be the impacts of 1000 ppm and 5°C warming or more by 2100?   Probably the most disappointing article in the entire issue is by one of the country’s leading climate experts, “The worst-case scenario:  Stephen Schneider explores what a world with 1,000 parts per million of CO2 in its atmosphere might look like.”  Except that he doesn’t really explore that world.

For a long time the vast majority of climate scientists never modeled the impacts of high CO2 concentrations because they assumed humanity would never be so self-destructive as to allow them to occur.  Today, however, a large and growing literature of high-emission-scenario climate impacts exists.  You won’t, however, find that literature cited by Schneider, so the most specific thing he says is just to repeat the temperature forecasts of the other articles:

… under A1FI, so there is a 5-17% chance that temperatures will go up by more than 6.4 °C by 2100.

Many will argue that warming above 6.4 °C is unthinkable.

Actually, many will argue that warming above 3°C is unthinkable, and certainly warming above 4°C leads to incomprehensibly incalculable impacts by 2100, none of which Schneider lays out with any specificity.  I try to summarize the literature in “An introduction to global warming impacts: Hell and High Water,” which notes that we’re looking at 3 to 7 feet of sea level rise by century’s end, followed by up to 1 to 2 inches a year rise for centuries, plus we turn up to one third of the planet or more into a Dust Bowl for centuries with projected loss (by the IPCC) of most species.  But I digress.

The most useful article for the reader unfamiliar with the literature is probably, “Warming caused by cumulative carbon emissions towards the trillionth tonne.”  They provide a very useful factoid, a very useful way for concisely talking about the required carbon target, which frankly I wish I had thought of myself:

Total anthropogenic emissions of one trillion tonnes of carbon (3.67 trillion tonnes of CO2), about half of which has already been emitted since industrialization began, results in a most likely peak carbon-dioxide-induced warming of 2 °C above pre-industrial temperatures, with a 5-95% confidence interval of 1.3-3.9 °C.

The fact that we can only “safely” emit another half a trillion tons of carbon this century is not news to the half dozen people who read the 2007 IPCC report closely (see “Nature publishes my climate analysis and solution“).  Indeed, buried in the IPCC’s Working Group I Report on “The Physical Science Basis” of climate change (from early 2007) was this bombshell:

Based on current understanding of climate carbon cycle feedback, model studies suggest that to stabilise at 450 ppm carbon dioxide, could require that cumulative emissions over the 21st century be reduced from an average of approximately 670 [630 to 710] GtC to approximately 490 [375 to 600] GtC.

In short, we can only emit about a half a trillion metric tons of carbon this century to have a shot at 450 ppm (ending with virtually no emissions in 2100 since we’re at about 9 GtC now).  And when you add that to the half a trillion tonnes we’ve already emitted, that gets you to the catchy “trillionth tonne” total.

Anyway, if you want to actually know how humanity is going to pull off this trick, you won’t find it in Nature.  Try here instead:

32 Responses to Must have PPT in disappointing issue of Nature devoted to “The Coming Climate Crunch”

  1. Joe, great article… you point out the crucial issue missing from so much climate discussion: the plausible worst case.

    Curiously we are starting to see more open discussion of the compressed timeline of change. Recent TV news report on the Arctic managed to mumble that it should be ice free in summer by the year 2013.

    But discussing cost is a political mine field. How much is a reasonable amount to spend on a future of the species? Science and engineering should set this policy – not politics. (although I fully realize that will not ever happen)

  2. Drew Jones says:

    Great post. Saved me a couple hours. You are the best.

  3. max says:

    Why can’t wind energy have thermal storage like CSP-couldn’t the electricity generated by wind turbines be used to heat salts like CSP to provide electricity storage when the wind isn’t blowing?

  4. SecularAnimist says:

    max wrote: “… couldn’t the electricity generated by wind turbines be used to heat salts like CSP to provide electricity storage when the wind isn’t blowing?”

    The difference between wind turbines and CSP is that CSP simply concentrates the sun’s heat energy, which can then be stored directly as heat, which is very efficient. Wind turbines generate electricity from kinetic energy, and the electricity would have to be converted to heat. Using electricity to produce heat is not very efficient.

    An alternative to thermal storage and chemical storage (batteries, hydrogen) is kinetic storage. Energy can be stored in flywheels, compressed air or pumped water. Flywheels and compressed air are interesting to me because they are scalable, from industrial utility scale down to residential scale (and even, with the compressed-air automobile engine developed in France, down to mobile scale) and they don’t have the drawbacks of chemical storage.

  5. To convert the wind based electric energy into heat to store it would be fine except that it would then be subject to the heat engine effect when being converted back into electric form.

    CSP has the same problem, only the electric energy output is not counted until the heat engine process has happened. One of those elusive technical facts is the efficiency of the CSP heat engines in actual operation.

  6. Bob Wright says:

    A good companion chart for the PPT would be one of ocean acidifcation on the same time scale, annotated when carbonate structures no longer form.

  7. ecostew says:

    Also see RealClimate:

  8. David B. Benson says:

    I am quite concerned about methyl clathrates under the shallower portions of the Arctic Ocean. If the water warms up by 2 K, likely to release over 500 gigatons of methane.

    Need a big refrigerator up north?

  9. Fred Heutte says:

    The 4&C conference at Oxford in September will delve into this in detail:

    “Format of conference

    1. Invited keynote talks that:

    a. provide state of the art assessments of the impacts of 4+°C climate change for a range of human, ecological and earth systems

    b. reframe the mitigation challenge in terms of steps necessary to avoid the significant risk of a 4-5 degree warming under different emissions reduction scenarios and the options open to enable a clear avoidance of such a risk.

    2. Open call for oral and poster papers in the above themes, with a focus on regional examples that complement keynote topics”

  10. Pat Richards says:

    According to an article in, there may have been a major breakthrough in converting CO2 gas into something beneficial in a cost-effective way — if it turns out to be something that can be verified and replicated in labs around the world and not just another premature announcement of something that doesn’t really work:

    “…a process for converting carbon dioxide into methanol at room temperature, developed by a team at the Institute of Bioengineering and Nanotechnology in Singapore (Angewandte Chemie International Edition, DOI: 10.1002/anie.200806058).

    Molecules of CO2 are very stable, so processes that convert the gas to methanol normally require high temperatures and pressure. They also use catalysts containing toxic metal ions. “Our catalyst isn’t toxic, and the reaction happens rapidly at room temperature,” says team leader Jackie Ying.

    The catalyst used by Ying’s team is a type of chemical called an N-heterocyclic carbene (NHC). The mechanism by which the NHC speeds up the conversion is uncertain, but it appears to change the shape of the CO2 molecule, “activating” it in a way that makes it easier for hydrogen to bond with its carbon atom, says team member Yugen Zhang.

    The catalyst may also help to release hydrogen from hydrosilane molecules, which are the source of hydrogen in the new process. Hydrosilane is an expensive chemical usually used to make computer chips, so the team wants to find a cheaper source.

    “Potentially, it’s a means for taking carbon dioxide out of the air and making it into something useful,” says Dongke Zhang, director of the Centre for Petroleum, Fuels and Energy at the University of Western Australia in Perth. As well as being a fuel, methanol can be used as a feedstock for the chemical industry.Zhang’s team is developing a technique for converting CO2 into methanol using high-frequency electromagnetic fields or plasmas to activate the gas.”

  11. Carl Chenery says:

    Bob Wright,
    Do you have such a chart of the ocean acidification on the same timescale?

  12. K Nockels says:

    Sorry Joe off topic Just heard we lost another chunck of an ice sheet in Antartic but I can’t find which one have you heard???

  13. K Nockels says:

    Has anybody heard how big or which ice sheet????

  14. Yuebing says:

    Dire must have ppt #3! Worse (as JR often points out):

    Global emissions are above the A1fi scenario and accelerating,

    Tipping elements are not included,

    Temperatures go up twice as fast over land for latitudes like the US’s.

    Mr. Specter, we need your vote on a carbon tax.

  15. K Nockels says:

    Report coming in by Jim Elliot of the British Antarctic Society another big chunk of Wilkins has gone away. Heat wave in Alaska 68 in Fairbanks today tomarrow it will be 70tt. Even Barrow got over 50 today.

  16. Lou Grinzo says:

    I’m pretty sure that this is Wilkins breaking up. If I recall correctly, the news from days ago was the bridge connecting it to something else (Antarctica?) breaking up, leaving the ice sheet itself “ready to go at any time”. It seems we’ve reached “any time”.

  17. Lou Grinzo says:

    Needless to say, the WSJ blog Environmental Capital is far more than “disappointed” in the same set of articles:

    Global Warming: Those Tipping Points Are Closer Than You Think

    Warning: Don’t read the comments on that post if you have a weak stomach.

  18. paulm says:

    Gail, There isn’t any hard factual analysis about this though.

    How do they reach this conclusion?

  19. Thanks for the great summary!
    What distrubs me most in Meinhausen’s article is that a 25% chance of passing a 2 C warming even if we “only” emit 1 trillion tons of CO2 by 2050 is described as “safe”. Who comes up with those ideas? Would anybody step into an airplane if 1 out of 4 would crash? Or do I misunderstand something? I have not seen any comment from anybody on this subject, or a response to my comment so far yet; so maybe, hopefully, I just misunderstood?

  20. Eric Fairfield says:

    Even when I disagree with your conclusions, you save me a lot of time and get me the data I need in order to draw my own conclusions. Keep it up.

  21. Lewis says:

    Article on further Wilkins break up:

    The ice bridge disintegrated in early-mid April and now the rest of the shelf is following. In 1992 the ice bridge alone was something like a 100km wide.

    Lots of pics on it their, look for the ‘webcam from space.’

  22. Robert says:

    The BBC’s take on it:

    “Writing in Nature, they say politicians should focus on limiting humanity’s total output of CO2 rather than setting a “safe” level for annual emissions. ”

    … and that is my take on it. Stopping digging the stuff up is the goal, not messing around with trading permits etc.

  23. Lennart van der Linde says:

    Maiken, I totally agree with you. A 25% chance of overshooting 2 degrees seems an unacceptable risk to me. I think we should aim at complete decarbonization by 2050 at the latest, but preferably sooner. Economists such as Terry Barker think this is not impossible, and might even be economically advantageous. See for example this quote by him on p.15 of this article:

    “Political economy has been portrayed by Thomas Carlyle as the dismal science, but on the contrary, a new understanding of the economy suggests that that a transition to a low-carbon, even zero-carbon, economy is feasible; and that if we choose a good mix of policies, such action will benefit economic performance and improve human well-being. Just as Thomas Malthus was wrong (so far!) in his predictions of population growth leading to economic collapse, so rapid decarbonisation need not ruin our economies, and for much the same reason: technological change. GHG-reducing technologies with carbon trading and carbon taxes can accelerate decarbonisation, reduce the risks of dangerous climate change, and contribute to economic development and human well being. The economic feasibility and benefit of a net-zero carbon economy have not been investigated, at least by 2050 or earlier as implied for a long-term “safe” climate. The technologies required for most sectors are available and extrapolation of available studies suggests that the economy could benefit, but the main technical and institutional options have not all been explored and the scale of the transition, especially for the energy sector, is immense. The immediate challenge however is one of devising, then agreeing, international policies and actions that can guarantee results and benefits for the more modest 50 percent target, recognising that this is not strong enough for a safe climate but much better than no target at all.”

  24. James Newberry says:

    We don’t know yet if we will encounter automatic tipping points with the radiative forcing yet to come from today’s contamination of about 390 ppm CO2 (higher with all gases included in CO2 eqivalent calculations). Implying that another one or two trillion tons of carbonic acid gas is an adequate limit is not science to me.

  25. Thanks, Lennart. Yes, I like Terry Barker’s realism. But reality is being hidden very well behind the naysayers who slow down this development to an extremely worrying snails pace. The question I have been asking myself keeps staying in the foreground of my mind: how do we mobilize enough people to exert the pressure needed to do the changes that are waiting to be realized? When I give presentations here in Germany, most people don’t even know that the Arctic sea-ice is NOT 1-30 km thick; people start to argue that science can always be wrong, and scientists justy want more funding….people seem to be able to come up with more and more excuses for inaction the worse it gets.

  26. Peter Wood says:

    What I have read so far of this issue of Nature suggests to me that its most important contribution is the message that the carbon budget is the best predictor of maximum temperature — better than the stabilisation target or the level of 2020 emissions or 2050 emissions. The two core papers both seem very good.

  27. Lennart van der Linde says:

    Maiken, I have the same question. Here in Holland the environmental and developmental ngo’s are slowly starting to come up to date with the latest science. They are just starting to realize now the great urgency to act very strongly immediately. We have to keep informing media, politicians and the general public that we’re playing Russian roulette, as John Schellnhuber, Joe Romm and others have been telling us. In the US Stephen Chu is using the Titanic metaphor. I think we need such strong and vivid language to make the urgency to act now as clear as possible. And I think the scientists themselves need to speak out more and more, and more clearly, as it seems most people really do not understand the implications of the more scientific language. Lester Brown has been speaking about ‘mobilizing to save civilization’. Al Gore already in 1992 wrote about ‘the earth in the balance’ and the need for a new global Marshall plan. We must be close to a social and political tipping point now, or else it may be too late to avoid (more) serious climatic tipping points. So let’s continue and intensify our mobilization efforts and hope for the best of humanity’s moral and rational impulses to prevail.

  28. jcwinnie says:

    “What were the editors thinking?”

  29. Shannon says:

    Good article and even better comments.