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Six Degrees

Filed under: — eric @ 25 November 2007

“Alarmism” is a term that gets bandied about a lot. It is often said that one should not call out “fire” in a crowded building. But it really depends, one might say, on whether the “calling out” is done in such a way as to simultaneously prevent a stampede and prevent anyone getting burned.

This riddle was very much on my mind as I sat down to write my thoughts on Mark Lynas’s book, Six Degrees: Our Future on a Hotter Planet (London: Fourth Estate, 2007). I don’t read much popular science literature, and I doubt I would have read this book if I hadn’t made the mistake of referring to it (in a negative manner) in the comments section of a RealClimate post. I don’t think my error was very grave. What I actually said was that if what I had heard about the book from the press materials were true, then the book was probably alarmist and not worth reading. But I don’t blame the author for asking me to read the book and see for myself. He said that the press (in this case Sunday Times (London)) had misconstrued what he says in the book, and he assured me that is was all based on very careful review of the scientific literature. I was thus both curious and obligated to read the book.

Mark Lynas will no doubt be pleased that I very much like the book. To be sure, it is alarming, but the question of whether it is alarmist is a more difficult one, and I don’t think the answer lies in debating the book. Rather, it lies in looking closely at the underlying science the book builds on. I don’t intend to do that here, but I do think that all climate scientists (particularly those that talk to the public) ought to read this book, and ask themselves a question. I’ll get to that question at the end, after saying a bit more about the book.

Six Degrees, as the title suggests, is comprised of six main chapters (plus an introduction and a conclusion). Each of the main chapters examine what the earth might look like as we raise the planet’s temperature by 1o, 2o, etc. degrees Celsius, based on what the scientific literature has to say about it. Laying out the book this way makes for a good logical progression of ideas, and a fair bit of suspense. Very few people, Lynas says, have got “the slightest idea what two, four or six degrees of average warming actually means in reality, and I’m sure he is right.

In Chapter 1, at 1o, we have predictions of, for example, an annually ice free Arctic ocean. Yes, quite plausible and supported by the literature, and perhaps occurring a little sooner than expected. At 2o, we have, “so whilst southern China can expect more flooding as the two-degree line is approached, the oceanic time lag means that it may take much longer for the rain-bearing summer monsoon to reach the drought-stricken north.” Yes, certainly plausible based on the studies Lynas cites. At 4o, we have “with global sea levels half a meter or more above current levels, [the Egyptian city of] Alexandria’s long lifespan will be drawing to a close. Even in today’s climate, a substantial part of the city lies below sea level, and by the latter part of this century a terminal inundation will have begun. … a rise in sea levels of 50 cm would displace 1.5 million people and cause $35 billion of damage.” Alarmist? Hardly. A 50 cm rise in sea level, is well within the conservative IPCC projections, even for temperature rises less than four degrees.

At 5o and 6o, the book really does start to sound alarmist, with the analogy to Dante’s Inferno – used to good literary effect throughout the book – coming very much to the fore. At five degrees, we have “an entirely new planet is coming into being – one largely unrecognizable from the Earth we know today. At six degrees, “… the pump is primed … not for flourishing palm trees in Alaska, but for the worst of all earthly outcomes: mass extinction.”

Aha, say the skeptics! It is alarmist after all. But is it? Lynas’s reference to the “entirely different planet” actually refers to the fact that at five degrees, the “remaining ice sheets are eventually eliminated from both poles.” That’s entirely true. And unlike in Gore’s discussion of sea level in Inconvenient Truth Lynas does emphasize the long timescales (thousands of years) in this case. Furthermore, there is published research that raises the likelihood of the significant loss of ice sheets at lower temperatures, and Lynas could have claimed certainty of a disappearing Greenland ice sheet in an earlier chapter. That he doesn’t do that is characteristic of the book: it doesn’t tend to go beyond the published literature. This is what Lynas claims at the outset — “all of the material in the book comes from the peer-reviewed scientific literature” – and I think he does an admirable job.

And that brings us back to the question I promised to raise at the beginning, which is this:

If a reading of the published scientific literature paints such a frightening picture of the future as Six Degrees suggests – even while it honestly represents that literature – then are we being too provocative in the way we write our scientific papers? Or are we being too cautious in the way we talk about the implications of the results?

173 Responses to “Six Degrees”

  1. 151

    Correction to 149

    I spoke of a UN base being at the location I gave, but actually the UN regards it as an environmental hotspot because it is a designated free trade area which is also the host to a great many species of birds. But in any case, the UN symbol should help you find it.

  2. 152

    Nick Gotts (#150) wrote:

    I worked on AI in the 1980s and 1990s, and have continued to follow it; I see no prospect of anything you could reasonably call conscious computing in the next few decades – going on the pace of progress over the last 50.


    I think you should really have a look at this.

  3. 153
    Joseph O'Sullivan says:

    The question of scientists being too conservative or not is an interesting one. It reminds me of two things I read. The first is PZ Myers observation that wildlife biologists and conservation ecologists are some of the most depressing people you will meet because of what they know and Ross Gelbspan’s observation in a NY Times review of “Just Cool It” that it is a curse to know about these issues as intimately as climate scientists do. I would say the sober and often boring (for the non-scientist) science literature is just right. It for the most part just gives the facts.

    Raypierre’s comment about wrong ideas in science being very useful is a very valuable insight into how science works. I will repeat a theme I go on about on RealClimate that showing people how science works is just as valuable as the details of the climate science for interested lay people.

    For the all the talk about about doomsday predictions, like from Mr. Seitz, I will bring up the fact that opponents of environmental regulation claimed economic meltdowns would occur if environmental regulations were enacted. These prophesies proved to be wrong. For one example the then CEO of Chyrsler Lee Iaccoca predicted air pollution laws would cripple the auto makers. Now in his latest book he is critical of US car makers for fighting environmental regulations.

  4. 154
    Fernando Magyar says:

    Re #144 Gavin, I do understand that in the climate business all you have is ever more circumstantial evidence and that only in mathematics can you expect to come up with something like a proof. That wasn’t my quibble.
    My poorly made and rather unimportant point was simply that while your example would be accepted as logical in the scientific sense and would add to the consensus that the arsonist is to blame for the fire, it doesn’t communicate well to the layperson’s experience of what might occur for example in a court of law. The person with the kerosene can might even be absolved and get off scott free if he can get the right lawyer. This I beleive underscores some of the issues with the communication of scientific concepts and the meaning of words such as theory (in the scientific sense) to the general public. You are not speaking the same language. We need translators who are fluent in both cultures. Obviously I’m not suited for that position.

    [Response: Actually I think you make an excellent point. The analogy of good lawyers getting their clients off when they were caught red-handed could be very aptly applied to some of the contrarian think tanks. – gavin]

  5. 155
    J.S. McIntyre says:

    Regarding new tech applications aimed at curbing AGW, something interesting a friend came across.

    Of course, that’s a lot of sodium bicarbonate…

    Picture of the pilot plant, if anyone is interested.

  6. 156
    Lynn Vincentnathan says:

    RE #154, I think an important point to this crime analogy is that most human-caused environmental harms are not crime (though they are most certainly sins, if done with some knowledge), so no one is facing the death penalty for killing people through AGW, for which the legal standard would be “beyond a reasonable doubt” — a standard probably more stringent than scientists requiring 95% confidence.

    We (collectively) are not even facing a civil suit, for which the legal standard would be “preponderance of evidence” — which (as a judge explained to us jurors) amounts to a greater than 50/50 chance we did it. With that standard we lose our case that we didn’t do it, since the scientific evidence re AGW is happening is very strong now.

    What we (collectively) are facing is harm, for which a MEDICAL STANDARD or MODEL is needed. And this is opposite the scientific and legal models of avoiding false positives (avoiding claims and decisions when they are false). We need to avoid the false negative (doing nothing to stop or prevent the harm, when it is real).

    And since this SIX DEGREES shows us the very great magnitude of the possible harm – based on the best science (to date of the writing), rightly including and focusing on the worse case possibilities (as doctors should), it behooves us to take immediate action to halt this harm, even if these worst scenarios are only slightly probable. This magnitude of harm greatly lowers our requirements for proof. We are morally required to mitigate, even if the science were only at 10% or 5% probability that not mitigating would cause great harm.

    If there were a one in twenty chance a child would die if he/she went on, say, an old, delapidated rollercoaster, would the parents pay for the ride and allow him/her to do so? That’s sort of what it’s like. We can reduce our GHGs cost effectively, and not doing so it like staying on some very dangerous rollercoaster ride for the sake of some frivolous ride that gets us nowhere.

    The energy/resource conservative/efficient technology is here, the knowledge about reduce/reuse/recycle is here, alternative energy is here. Let’s just do it and get off this dangerous and frivolous ride ASAP.

  7. 157
    SecularAnimist says:

    Joe Duck wrote: “Nick I don’t accept the premise that disaster is looming”

    Nick replied: “Joe, a disaster is unlikely to *happen* in the next 10 years, but … we could well have only 10 years to avoid a disaster further in the future.”

    I disagree with Nick. According to the international relief and development organization Oxfam, disaster is upon us now:

    Weather-related disasters have quadrupled over the last two decades, from an average of 120 a year in the early 1980s to as many as 500 today, according to international agency Oxfam America in a new report. The increase in these extreme climatic events is in line with climate models developed by the international scientific community.

    The number of people affected by disasters has risen by 68 percent, from an average of 174 million a year between 1985 to 1994, to 254 million a year between 1995 to 2004, according to Oxfam. Earlier this year the Asian floods alone affected 248 million people. There has been a six-fold increase in floods since 1980. The number of floods and windstorms have risen from 60 in 1980 to 240 last year. Meanwhile the number of geothermal events, such as earthquakes and volcanic eruptions, has stayed relatively static.

    “In 2007, we have seen floods in South Asia, Africa, and Mexico that have affected more than 250 million people. But this is no freak year, it follows a pattern of more frequent, more erratic, more unpredictable and more extreme weather events that are affecting more people,” said Raymond C. Offenheiser, president of Oxfam America. “What we need now is action to prepare for more disasters or humanitarian assistance will be overwhelmed and recent advances in human development will go into reverse.”

    Though colossal crises such as the African famines of the early 1980s, the Bangladesh cyclone of 1991 and the Asian tsunami cause enormous loss of life, the new worrying trend is the increase in small to medium-sized disasters. The death toll caused by these disasters has risen from an average of 6,000 in 1980 to 14,000 in 2005.

    With regard to further climate-change disasters that are “likely” within the next 10 years: prolonged (multi-year), intense drought affecting one or more of the Earth’s most productive agricultural regions, eg. North America, leading to worldwide food shortages, could happen at any time. There are indications that drought is already becoming chronic in North American agricultural regions.

    In my view, mega-droughts are a more alarming and imminent concern than sea-level rise. As far as I can tell, even the most rapid plausible rise in sea levels would likely take decades to disastrously affect coastal areas, inundate cities, etc. Whereas a mega-drought could start any time — this year, next year — and last indefinitely. The vast grain fields of North America could be deserts in 10 years.

  8. 158
    Aaron Lewis says:

    It did not happen because Red Adair/ Bechtel Team put out the KOil fires out faster than any (off- project) scientist thought possible. It is truly amazing what can be done by a motivated team of the very brave and the very smart.

    We need to apply similar bravery, intellegence, and motivated teamwork to aspects of AGW. The current AGW situation is just as grave as the KOIL fires. The only difference is that the current phase of AGW does not provide the stunning 15-second video bite for the evening news. (And, big oil companies are not watching their profits go up in flames.)

  9. 159
    Jim Galasyn says:

    Re climate disasters in 157, check out the Climate Hot Map for a good collection of documented climate-change effects. Unfortunately, it’s a bit dated — their last refresh was in 2002. They assured me in a recent email that they’ll be updating soon.

  10. 160
    Aaron Lewis says:

    To the editors:
    Please add to your list of links.

    It is Dr. Naomi Oreskes summary of the history and rational of the science of AGW. It is the talking points for each argument.

  11. 161
    David B. Benson says:

    J.S. McIntyre (155) — Thank you for the post and the links! :-)

  12. 162
    larry W says:

    Probably the best indicator of earth warming is the 180 year trend of the glacier shortening rate. The rate is not significant different from period of slow CO2 increases and that since heavy use of fossil fuel. The 150 year trend for ocean level rise supports the above.
    A ten year look at the melting of both poles (1992-2002)showed it to be a small contribution to sea level rise (2%) of nearly 3mm a year. Some recent new guesses might up that to 10%.
    The Hadley Centre global mean temperature data shows no warming the last four years and a different study showed the ocean was cooling significantly but recently found some error and now say it is either flat or slightly cooling.
    If you look at the whole picture you will also find that the removal of sulfur from fossil fuels is probably going to warm the earth more than the CO2 and we certainly have more certaintly in these estimates from the volcano experiences. CO2 is not a pollutant, it is necessary for plant growth which is already increasing with CO2.
    Technology will give us solar power to use all over the world and it will happen well before all the dire thinks I see in the above posts. In the 1890’s they were wondering what to do with all the horse shit in New York and we had the first car in less than 20 years. We should go to nuclear power to free us from foriegn oil and reduce the terror threats that seem to be in part against us using the worlds resourses.
    Yes I believe CO2 is a green house gas, however, all things it brings are not bad.

  13. 163
    pete best says:

    Thermal interia guarantees another of 0.6C of warming making 1.4C in total so far. If climate sensitivity increases from 0.2C per decade to 0.3 or 0.4C due to not taken into account long CO2 feedbacks then 6C is possible. I know that the paleoclimatic data limits viable temperature rises but real world data seems to be contradicting the IPCC models to some degree.

  14. 164
    David B. Benson says:

    Now that I understand the concern regarding the oceans producing H2S, I think that rather unlikely to occur in massive quantities at a mere 6 degrees (shudder). Here is a paleotemperature chart:

    Looking at PETM, 55 million years ago, we see that it was very hot, but does not seem to be associated with an H2S crisis as most plants and many animals survived this event. As for its cause, the linked article suggests massive vulcanism:

    But going back to look again at the paleotemperature graph, 6 degrees would put the world back into the mid-Miocene and 12 degrees in the mid-Eocene. In either case many species would survive, provided the transition proceeds, geologically speaking, fairly slowly.

    Neither seems particularly promising for Homo spaiens, a large, cold adapted, mammalian species…

  15. 165
    Ray Ladbury says:

    Larry, Let me see if I can summarize your argument:

    We’re not warming and if we are it’s natural, and if we’re doing it then it will be good for us.

    That about got it? Does anything motivate you other than complacency?

  16. 166
    Jim Galasyn says:

    Re the PETM in 164, it’s worth noting that we’re dumping carbon into the atmosphere at a much higher rate than the vulcanism did — we’ll put as much carbon into the atmosphere in a few centuries as the PETM did over 10,000 years.

    It was also a pretty serious marine extinction — some sources call it the worst in 90 million years. For 50,000 years, the oceans were too acidic to support calcareous life; shells dissolved in that low-pH solution.

    McClatchy ran a good story last year:

    Global warming may be an accelerated version of ancient heat wave

  17. 167
    Jim Eager says:

    Re larry w @ 162: “A ten year look at the melting of both poles (1992-2002)showed it to be a small contribution to sea level rise (2%) of nearly 3mm a year. Some recent new guesses might up that to 10%.”

    I think you may want to bring your understanding of the glacier shortening rate and the rate of sea level rise a little more up to date. You might not then be so prone to dismiss the observed and measured increases as mere ‘guesses.’

    “The Hadley Centre global mean temperature data shows no warming the last four years”

    Did you do the running mean calculations on the data yourself, or do you just believe what someone else told you they show?

    “CO2 is not a pollutant, it is necessary for plant growth which is already increasing with CO2.”

    Why thanks for sharing that with us, but I seem to recall hearing it from the Competitive Enterprise Institute a while ago. Perhaps you saw their commercial “They Call It Pollution. We Call It Life?”

    One last question, did you really think anyone here would take your stock talking points seriously?

  18. 168
    Richard LaRosa says:

    Re 157 SecularAnimist, drought is indeed a serious problem. Check out my comment#35. Using solar energy to evaporate sea water into the atmosphere won’t work everywhere, but I believe it will work where there is a consistent air current toward a mountain range that has been known to produce orographic rainfall in the past.

  19. 169
    James says:

    Re #166: [(The PETM) was also a pretty serious marine extinction — some sources call it the worst in 90 million years. For 50,000 years, the oceans were too acidic to support calcareous life; shells dissolved in that low-pH solution.]

    Perhaps this is a bit off-topic, but I’m puzzled. If the oceans couldn’t support shelled creatures for that long a period, how is it that we find them still existing today?

    Also, if shells would actually dissolve, wouldn’t various carbonate rocks do likewise? And wouldn’t that neutralize the the low pH?

    Or have I answered my own question: areas of exposed carbonate rocks created refugia where shelled creatures managed to survive?

  20. 170
    Hank Roberts says:

    James, I think that’s a good question (I’m an amateur, not a scientist, just reading along). Looking it up, a couple of papers seem to help answer that:

    Note the difference in the species present at that time compared to those that currently make shells. You can look up how long ago the current shell-forming species evolved. Like the ability to make eyes, or wings, the ability to make shells shows up repeatedly over time in different organisms. The great extinction events lost a lot of species, and new ones evolved.

    Science 15 December 2006:
    Vol. 314. no. 5806, pp. 1770 – 1773
    DOI: 10.1126/science.1133902
    Nannoplankton Extinction and Origination Across the Paleocene-Eocene Thermal Maximum
    The Paleocene-Eocene Thermal Maximum (PETM, ~55 million years ago) was an interval of global warming and ocean acidification attributed to rapid release and oxidation of buried carbon. We show that the onset of the PETM coincided with a prominent increase in the origination and extinction of calcareous phytoplankton. Yet major perturbation of the surface-water saturation state across the PETM was not detrimental to the survival of most calcareous nannoplankton taxa and did not impart a calcification or ecological bias to the pattern of evolutionary turnover. Instead, the rate of environmental change appears to have driven turnover, preferentially affecting rare taxa living close to their viable limits.
    ———-end abstract——–

    The Late Palaeocene Early Eocene and Toarcian (Early Jurassic) carbon isotope excursions: a comparison of their time scales, associated environmental changes, causes and consequences.
    A. S. Cohen, A. L. Coe, and D. B. Kemp (2007)
    Journal of the Geological Society 164, 1093-1108
    Although the Earth’s environment is constantly changing, there have been a few unusual episodes over the last c. 200 Ma when change was extreme in terms of its rapidity, severity, long-lasting consequences and unpredictability. The geochemical and biotic records for two of these episodes, the Palaeocene–Eocene thermal maximum and the Toarcian Oceanic Anoxic Event (Early Jurassic), possess many significant similarities. Each event was associated with a major carbon isotope excursion, significant levels of biotic extinctions, severe global warming, an enhanced hydrological cycle, and evidence for widespread seawater anoxia. Both carbon isotope excursions can be subdivided into distinct stages with broadly similar characteristics and durations; based on a detailed comparison, the Palaeocene–Eocene thermal maximum may have been an incipient Oceanic Anoxic Event. The geochemical and biotic changes during these two events are most readily explained by the abrupt, large-scale dissociation of methane hydrate that followed a period of more gradual environmental change linked to the emplacement of a large igneous province. Carbon release rates at those times were of the same order of magnitude as the current anthropogenic release rate of carbon to the atmosphere, indicating that ancient events such as these may usefully serve as analogues for present-day environmental change.
    —— end abstract——

    This gives a perspective on why people worry that the current rate of change, going to the same extremes but far faster than any of the previous events, is going to be troublesome.

    When you hear people saying there’s no way to compare what’s happening now with what’s happened in the past, well, just think about how fast we’re changing the world now compared to the natural major events. If hitting a wall at one mile per hour hurts, how will hitting a wall at one hundred miles an hour feel? We’ll see.

  21. 171
    Michael says:

    162. “CO2 is not a pollutant, it is necessary for plant growth which is already increasing with CO2”

    You have forgotten about stomata closure with increasing CO2. AGW may jeopardise operational integrity of many of the carbon-capture machines (plants, trees, …) that are currently installed across the planet’s surface. Have a read of “The private life of trees. How they live and why they matter” by Colin Tudge.

  22. 172
    pete best says:

    In a recent Nov 2007 report written by carbonequity they look at the fact that the IPCC may have played it too conservative. James Hansen (quoted widely in the report) and other learned climate scientists are quoted and pronouncements made in conjunction with current thinking on the subject and real world data (rate of Arctic Seal Ice shrinkage for example).

    Hansen says that because Ice Dynamics of ice sheets are little understood real world data is rushing ahead of the models and quotes of what was predicted 5 years ago are already incorrect and out of date. The graph shown states that IPCC projections for Arctic Sea ice are cureently far behind the real world data and presently 2020 to 2040 gives us a summer ice free arctic and WAIS is vulnerable to warming oceans as it is tied to the bedrock below sea level. Arctic ice thinkness and surface area and volume have dropped dramatically in the summer and winter ice is not as extensive either when the spring comes around.

    One climate scientists quoted states that we are seeing in some instances arctic ice levels in the real world not predicted to happen for 100 years.

    In Six Degrees, Lynas states in a table in the end chapter “Choosing Our Future” on page 274 that 1.1 to 2.0C is all set for 400 to 450 ppm with a chance of 3C at 450 ppm. Is he right here? Is climate sensitivity so low ?

    real climate states 550 ppm for greatest probability of 3C, Lynas states that 550 ppm is 3 to 4C probability and see it as the threshold for siberian methane feedback whilst the threshold for carbon cycle feedback happens at between 400 to 450 ppm.

    What seems to be happenning is that people are talking up the chances of 3C at 450 ppm as opposed to 550 ppm with 400 ppm giving us 2C. Is this right ?

    [Response: The best answer to your question is simply that the climate sensitivity is a probabilty distribution. We don’t really know its shape (though there is a case made that we do, in the paper discussed here but are quite sure that the bulk of it is in the 2-6 degree range for doubling — that is, for 560 ppm. See here and here for quite a bit of discussion on this. -eric]

  23. 173
    John Finn says:

    Hank Re: #95

    The warmest year prediction was issued by Hadley themselves see

    They clearly hadn’t noticed that the El Nino that was active at the time was fading and that the development of a La Nina was a strong possibility. Still – you can’t expect the climate experts to get everything right.

    [Response: I have now turned off Comments, since the discussion is rather far from the post. No offense intended to any of the commentors. I always welcome your input and I am glad that this post sparked some interesting discussion.–eric]