I’ve finally got round to reading a number of the many climate change-related books that have been published in recent months. These books seem to have caught the public imagination in ways that are different than in the past, and so it’s worth examining how they do. The three I’ve read are; Eugene Linden’s The Winds of Change, Elizabeth Kolbert’s Field Notes from a Catastrophe and Tim Flannery’s The Weather Makers. The first two writers are journalists, while the third is a scientist by background, and while there is some overlap in contents all of them, they are clearly distinct works in quite different styles. I’ll mostly stick to commenting on the science though…
Eugene Linden’s book is very well written and sets up the book as a prosecutorial case that climate change can have (and has had) serious impacts on human society. He picks out a number of purported climate changes – the 8.2 kyr event, two less well-defined changes around 5200 and 4200 years ago, a mysterious (volcanic?) event in 536 AD, the Mayan collapse around 800 AD, and the Norse colony collapse in Greenland to make his case that societies can be vulnerable to abrupt shifts in rainfall, temperature etc. The 8.2 kyr event qualifies as an abrupt change by almost any definition (except that adopted by the NRC panel on the subject curiously) and was most likely tied to the catastrophic final draining of paleo-lake Agassiz and subsequent changes in the North Atlantic ocean circulation (see a summary of some of our recent research on the topic). This mechanism is not relevant to the other highlighted changes, and unfortunately no well supported ’causes’ have yet been demonstrated for the events in 5200 and 4200 BP. Solar forcing has been suggested for the Mayans and for the Little Ice Age, but hard evidence is difficult to come by.
Societal impacts linked to the 8.2kyr event involve potential changes in the Natufian culture in the Levant, but while intriguing, the imprecision of dating and lack of written evidence mean that this link remains speculative. However, evidence for societal impacts are tied to drought on ancient civilisations is much stronger – the ancient ‘Curse of Akkad’ describing the droughts affecting the Akkadian Empire; the Mayan collapse etc. – and this is well brought out in the text.
One example that I wasn’t previously aware of, were the climate events of 536 AD – ‘dry fogs’, crop failures, ‘dim suns’ and yellow snow etc. – features consistent with a large volcanic eruption, possibly near the site of Krakatoa – and which correlates with evidence of a sulphate peak in the North GRIP ice core at the same time. Linden quotes David Keyes as suggesting that the societal impacts of this event included the plague and the onset of the European ‘Dark Ages’. You don’t necessarily need to buy into this to get a sense of how disruptive this event was though.
Linden talks to the right people and makes a strong case, but I think he errs in seeing all of the climate changes as being analogous. The effects of circulation change in the North Atlantic are different to (potentially solar-driven) rainfall variability in the sub-tropics and are different again from the impacts of changing frequency and intensity in El Nino patterns. He unfortunately makes a large over-estimate in describing the magnitude of the 8.2 kyr event (claiming it lead to 5 deg C of global cooling, instead of a local result for Greenland), and then compares other ‘events’ to this more (climatically) well-documented case. There are a few more minor errors – isotopes are denoted by a pre-subscript (18O) instead of a superscript (18O) but we can probably blame the copy-editor for that. Linden appears to take seriously a suggestion that the Mayans were aware of multi-decadal variations in the sun’s irradiance and built them into their calendar – something that seems extremely unlikely to me. Overall though, the evidence for serious climatic impacts on societies is pretty strong and he swayed this member of the jury.
Next up is Elizabeth Kolbert’s book based on her extremely readable three-part series in the New Yorker last year. (I should note that I talked quite extensively to Elizabeth when she was doing the research, so I may be a bit biased). The benefit of having the famously pedantic New Yorker fact checking department (Hi Louisa!) working on your behalf is very clear as I wasn’t able to find a single mis-statement on the science. There is some overlap in material with Linden’s book – for instance both authors spend some time with Harvey Weiss talking about drought and the Akkadians. But Kolbert’s book is much more closely tied to the scientists and the environments in which they work than Linden’s, and as such, is a more personable and well rounded portrait of how the science is being done and why the scientists have come to the conclusions they have.
Kolbert spends time in the field in the Arctic, in Greenland, in the smoke-free rooms at the UN, in the dark corridors of a climate modelling centre and even includes a few lines of Fortran code from the GISS climate model – gobbledygook possibly even to the scientists that wrote it! But it’s an indication that she spent the time down in the trenches and that’s pretty impressive.
Finally, Tim Flannery. His book appears to have made the most noise and Flannery himself has generated a lot of media attention (and controversy) on his book tours. As befitting a book by a scientist, this one has by far the most ‘content’ of the three, and unsurprisingly, is a tougher (though still accessible) read. The sheer speed at which different studies and subjects are covered make it difficult to get into anything in depth. In itself, that isn’t bad – there is a lot of ground to cover – but it does mean that subtleties and caveats get lost.
As a scientist, one of the things I look for in popular science accounts is an appropriate recognition of the difference between a suggestion made in a single paper and the description of any ‘consensus’ on the issues (such as described in the IPCC reports for instance). We have made the point repeatedly here that single papers need to be placed in context and don’t necessarily overturn previous work. In the three books discussed here, I have the impression that Kolbert most recognises this, but unfortunately that recognition is not at all obvious in Flannery’s text.
In case after case, Flannery quotes a single paper as an absolute proof of the particular contention. One example taken at random, is in relation to the MSU satellite record (which we’ve discussed here before, so skip this next section if you’ve heard it all already). Flannery raises the issue of the at-one-time apparent contradiction between the satellite records (usually taken to be MSU 2LT from the UAH group) and the surface temperature records. He quotes the Fu et al paper (which discussed the stratospheric contribution to MSU 2) as providing the final word on the subject. Now while this contribution was useful (and fitted nicely with previous work), it did not reconcile the different records. That had to wait until August last year when errors in the UAH algorithm were brought to light, and for a re-analysis by RSS demonstrating the sensitivity of the results to methodological issues in the treatment of the raw data. Obviously, one cannot fault Flannery for not knowing ahead of time what would be discovered, but he can be faulted for assuming that the one paper he quotes ‘solved’ the problem. Flannery is quite critical of the IPCC process, describing it as ‘lowest common denominator science’ and claiming that it must be assumed that things are likely to be worse than are described in those reports. I think he is fundamentally mistaken on this point and his too-frequent absolutist statements based on preliminary science are a classic example of why ‘consensus’ reports are both more careful and more correct than an individual opinion. For instance, there is no way that a ‘consensus’ statement that climate sensitivity is probably around 3ºC (plus or minus a degree) should be interpreted as implying that climate sensitivity is more like 6ºC. In science, ‘conservatism’ implies proper acknowledgment of the uncertainties, it does not imply that systematic underestimation of effects.
There are also a number of careless errors in Flannery’s book that frequently deduct from his main points. How many interglacials before our own was the one 430,000 years ago? Five according to the Flannery (p68), four according to everyone else. How much flow in the Amazon? 1 Sv (106 m3/s) in the book (p192), a fifth of that in the real world. Has the Gulf Stream ‘stopped’ three times in the Holocene? No. Does global dimming indicate that we will be required to take CO2 out of the atmosphere in order to stabilize Earth’s climate? (p302). No. And there are more…
All of the authors end by emphasising the concern most scientists in this field feel for the ongoing climate changes and the potential for future serious impacts. Flannery is actually good on this point and discusses a number of the options for reducing emissions, some of which are likely only to make the practitioners feel good, some of which may actually do some good. But in terms of which books make a better case that climate change should be taken seriously as a problem, Kolbert’s and Linden’s are the more persuasive. Flannery’s is too polemical to appeal to those not already convinced. This is a shame, because contrary to Bill Bryson’s endorsement of the book ‘It would be hard to imagine a better or more important book’, I can easily imagine a better one. A rewrite using a lot more ‘suggest’s, ‘may’s and ‘possibly’s would go a long way to making the text more scientifically defensible.
And so, if you are looking for some informative and easy (though troubling) reading this summer, I would highly recommend Kolbert’s book (closely followed by Linden’s). Good reading!
Thank you for these reviews. It’s helpful to know what experts think (as opposed to just critics). I’m curious as to what you might think about Mr. Gore’s movie “An Inconvenient Truth.” I’m especially interested to know whether thie movie (or the books you review) touch upon the ‘dimming’ effects as per the recent Nova report.
[Response:I saw the movie in a pre-screening on Tuesday. I liked it. Look for a short review early next week. — eric]
Have you read the book “On Thin Ice” about Lonnie Thompson’s work? I found it to be quite engaging and a very good introduction to climate science, covering both historical and contemporary work quite nicely.
Hi!
Although not a book, but a magazine http://www.co2science.org would be nice to hear some thought about it…
[Response: Agenda-driven cherry picking – gavin]
Tim Flannery appeared very concerned (to my mind) about current warming from the ecosystem point of view and probably got carried out somewhat in stating this.
He did mention the work of the guys who believe that mankind started burning (clearing forests) 8000 years ago and averted a big freeze that got a major article in Scientific American around a year ago (as if it was the truth as opposed to being his scientific belief) and that the interglacials seem to cast doubt on that work which is why anyone reading Scientific American would have thouigh it was true.
Strange World we live in where science meets media is concerned. That is why RC is the best as at least it is run by scientists who can communicate with the semi intelligent arm chair scientist like myself.
Keep it up please.
Accepting faults you find in Flannery’s The Weather Makers, I think his book still has merits – including with regard to some aspects of the politics, viz criticism of the behaviour of the Australian government, an important ally of the US administration on climate issues. And he continues this in, for example, the NY Review of Books (The Ominous New Pact, 23 Feb 06) regarding the AP6 (Asia Pacific Partnership on Clean Development and Climate).
“The Science and Politics of Global Climate Change, a Guide to the Debate” by Andrew Dessler and Edward Parson (Cambridge, 2006) is more comprehensive, gives a better-rounded brief treatment of each issue, is much better on the extra science issues, and more thoughtful than the books in Gavin’s review, as good as they are. It is about the same length, more expensive, not a pop style but very readable. I’d be curious to see what others think of it.
Thanks for this review. Flannery’s is the only book I’ve read so far, and his suggestion that the IPCC reports have been watered down by consensus jumped out at me, too. I worried this was true (sounded plausible enough to me), so it was good to read your take on it. Having heard him speak in Hamilton, Ontario, a few weeks ago, (his presentation is excellent, by the way, and contains the very best parts of his book) I got the sense that, like Gore, he’s a man on a mission.
What he does very well, IMO, is to give people a starting point for personal action. He argues that CO2 reductions of 70% might take governments decades, but can be achieved in a matter of months by individuals. That’s certainly been true for our household.
Real Climate is the most reliable source for information. Your articles are detailed, yet readable, technical, yet accessible. This really is the best climate site on the internet. Thank you so much for doing it.
I was delighted to find RealClimate via a recent article on Salon.com and quickly added RealClimate.org to my Google homepage. Of these three books I have read The Weather Makers and am looking forward to Kolbert’s and Linden’s books later this summer.
I do not think Flannery’s book is intended for an audience that needs to be convinced of climate change. For me, The Weather Makers was an extraorinary eye-opener, illustrating the connectness of our planet’s systems and fragility of our civilization. Tim is doing a wonderful job promoting the book and igniting much-needed debate among mainstream consumers. Since The Weather Makers has received so much media attention, many people have read it and you can talk about it with a wide array of people.
I just found this review following a hint at the end of the ‘Methane burp’ thread by Brad Arnold, and am going to go hunt up the book.
Leggett, J. (2001). The Carbon War: Global Warming and the End of the Oil Era. New York, NY, Routledge
Anyone read it? It’s a historical piece now (the author began as an academic geologist and moved to Greenpeace; the book ends 10 years ago, and focused on the political maneuvering during the decade before that, which is by now very long ago)
Review here:
http://www.google.com/search?q=cache:UGzLiGJ3t74J:people.ucsc.edu/~mboykoff/Leggett.review.CNS.2003.pdf
Re 3
Try the Touchgraph Googlebrowser and check out co2science’s link network. I put a static version here.
Of course, scientific arguments should stand on their own merits, regardless of who likes & links to them. How about this one:
“Growth-enhancing effects of CO2 create an impetus for cooling. Carbon dioxide is a powerful aerial fertilizer, directly enhancing the growth of almost all terrestrial plants and many aquatic plants as its atmospheric concentration rises. And just as increased algal productivity at sea increases the emission of sulfur gases to the atmosphere, ultimately leading to more and brighter clouds over the world’s oceans, so too do CO2-induced increases in terrestrial plant productivity lead to enhanced emissions of various sulfur gases over land, where they likewise ultimately cool the planet. In addition, many non-sulfur-based biogenic materials of the terrestrial environment play major roles as water- and ice-nucleating aerosols; and the airborne presence of these materials should also be enhanced by rising levels of atmospheric CO2. Hence, it is possible that incorporation of this multifaceted CO2-induced cooling effect into the suite of equations that comprise the current generation of global climate models might actually tip the climatic scales in favor of global cooling in the face of continued growth of anthropogenic CO2 emissions.” (Source)
I agree that policy makers should generally wait for assessments that give a broad view of the literature, since they are often unable to tell which papers in journals are most compelling. However, I think one can go too far with such assessments, and I hope we never reach the point where scientists themselves feel that such things are necessary before they form an opinion of what’s the likely truth. Sometimes, an individual paper can indeed be sufficiently compelling to count as a breakthrough in itself — particularly when it restores consistency between observations and general theoretical expectations which one has independent reasons to trust. Opinions can differ, but I think the Fu et al paper could reasonably be considered in the category of single-papers that deserve a lot of weight. Hence, I myself wouldn’t come down too hard on Flannery for his reliance on this paper. I do agree that his description of the IPCC process as “least-common-denominator” science is wholly unwarranted.
Another frustrating misstatement in Flannery’s book is the suggestion that young forests are better carbon sinks than old forests, which misses the relaitvley larger carbon pool (both above and below ground) associated with older forests. A more sound approach would recognize that (1) converting old forest to young forests releases significant amounts of carbon (both above and below ground), (2) young forests are only good carbon sinks if they are allowed to grow and hold onto the carbon for centuries, yet there are too few economic incentives for doing so, and (2) the fraction of carbon that is put into long-term storage after logging is very small, i.e. old forests are better at storing carbon than our disposable culture. Sound public policy would (a) protect old forests, (b) grow young forests into older forests (aka, longer rotations), and (c) when logging, retain significant residual trees both live and dead.
Thank you very much for these reviews. I look forward to the review of Mr. Gore’s movie.
RE 10 (Fiddaman):
Outstanding link sir. Thank you.
Best,
D
It’s rather unlike that the 8200 (cal) BP event and the drainage of lake agassiz are related. There is a small dating gap. The drainage appears to have happened between ~10,000 and 9,600 carbon years according to Lowell et al EOS 2005
http://www.eeescience.utoledo.edu/Faculty/Fisher/Lowell_etal_EOS05.pdf
The dates calibrate to ~11,400 Cal BP – 11,200 cal BP (INTCAL04 calibration) which is closer to the Younger Dryas than the authors would have realized, but the link with the 8200 BP event is less clear than ever. Note that this latter event codates with the massive Storegga landslide.
[Response: You are confused. The event Lowell et al were talking about is not the same event as Barber et al (1999) looked at – that was the final drainage of Lakes Agassiz + Ojibway and that was carbon dated to 7800 to 7600 radio-carbon years, and calibrated to 8470+/-200 years calender BP. -gavin]
RE: #9. I have not read it but seeing mention of it prompted me to comment about the end of the oil era. In most of California, we do not use oil for electricity generation. Natural gas is the fossil fuel of choice, where that method is even used at all. We use more wind, solar and hydro than most states. In essence, in terms of the electricity grid, we are beyond oil, interstate transfers during unusual peak periods notwithstanding. Downsides? Well you all read about our brownouts and blackouts a few years ago. But we adapted. We use less electricity per capita.
In terms of transportation, we drive generally smaller vehicles than they use in other states. I think we’ve probably passed our peak of the big SUV craze (but it was never really as much of a craze here as in other states). Our fuel prices have long been higher than the national average due to both a stringent “clean air” regulatorily mandated formulation and very high fuel taxes. Significantly, now that our Legislature has passed a carbon tax and Arnie signed it into law, we will approach some of the lesser expensive European locales in terms of fuel costs. Hello Smart Cars?
Bottom line is, in this state we are being soft landed into the Age After Oil. It hurts, but it’s not deadly.
Re:10 and 14,
that is a very interesting link. The connections between websites are quite revealing.
Try looking at http://www.RealClimate.org ‘s link too.
cheers,
Robert.
Here in the UK free newspapers are delivered through our doors. We call them Freebies. They do not have the authority of the (London) Times, or even the Washington Times, but I was interested in a report of a talk in my local Community Magazine by a Dr Mayer Hillman which read “The tipping point has passed. We cannot reverse the process of temperatures rising. Climate scientists”, he said “haven’t got the guts to tell governments the truth …”
Gavin, you criticised Tim Flannery and wrote “Does global dimming indicate that we will be required to take CO2 out of the atmosphere in order to stabilize Earth’s climate? (p302).” You know that the Greenland ice sheet is melting. How else, apart from getting CO2 levels below those which cause ice sheet melting, do you propose we should implement to halt a process which will lead to the 100 million population of Bangladesh disappearing below the waves?
I read Tim Flannery’s book wanted to know the facts – decided I had had my head in the sand long enough. I quickly realised (and should have thought, having read some of his other books) that he was never going to be the scientist setting out the pros and cons in a sober way. I still found it very convincing, though.
Your review is a good summary of why I should have been more cautious, as a generalist reader, but from someone starting out as a sceptic, it convinced me.
Actually, one of the things I found most thought provoking was his description of the media habit of always having a commentator from each side of a controversial issue – doesn’t matter where the balance of probabilities are – if there is a controversy, both sides get equal time.
In my view, this is one issue where the mainstream media (at least in Australia) has comprehensively failed to present the facts, instead falling back on providing opinion from both sides.
I’ll look out for the other two books.
I would recommend William Calvins’ book – A Brain for All Seasons: Human Evolution and Abrupt Climate Change.
It describes how climate changes (which we’d dearly like to avoid) seem to have shaped the development of our species. As a young man I followed archeological finds avidly, but stopped doing so. The much deeper understanding of our ancestors which we now have was very interesting for me. The discussions of abrupt climate change in the book helped me stitch together information I’d only seen parts of in newspaper and general magazine articles, and eventually led me here.
[Response: Calvin’s book is very engaging, but he seems to have overly bought into the invalid view that shutdown of the thermohaline circulation could bring on a European ice age in the future. This exaggeration shows up more in his Atlantic Monthly article (cover with icebergs along the Florida beach), but there are places where Calvin’s thin understanding of climate science leaks into the “Brain” book, too. He even may be overstating some of the remote impacts of abrupt change in the past. Abrupt change is indeed a valid concern for the future, but we shouldn’t take the Younger Dryas as an archetype for all abrupt change, or assume that a THC shutdown would have a similar effect on a warm climate as it does in a cold climate. Apropos of abrupt change, I was ironically amused by Gavin’s remark that the 8.2K event doesn’t fit the definition of abrupt change in the NRC report. I was an author of this report, and I never thought it was a good idea to attempt a precise definition of abrupt change, but a certain member of the panel (who shall remain un-named here) vehemently argued for precise definitions, which not only wasted a lot of time but wound up with a definition that I myself don’t think was very satisfactory to anybody. I was in favor of just loosely defining abrupt change by reference to a number of examples from the past record — and I would have included the 8.2K event as one of that list. –raypierre]
Re #15 Gavin’s comment.
You’re right I overlooked a few dozen publications about the 8200 event and the Hudson bay drainage. My bad. However ducking into it, I notice that there is quite a discrepancy in dating. Several other proxies (d18O GISP, delta 14C INTCAL04, Venado Cave monsoon record, Cariaco sediment core gray scale) suggest that the event was triggered around ~8260 Cal years BP. (INTCAL04: 8270+/-5) not the 8400 years BP of Barber et al.
Furthermore, the ice dam scenario as well as the Hudson bay location seems to be challenged here:
http://gsa.confex.com/gsa/2004AM/finalprogram/abstract_79908.htm
Rapid post glacial isostatic rebounce perhaps?
And then, if the ocean surface water was “diluted” with isotopic light melt water, would this not be reflected with a similar drop in the Greenland ice cores, just by a changing isotope signature of the source, instead of a temperature drop?
[Response: The dates are within the error bars, but the test is whether the consequences of the Lake drainage are consistent with the observed response. Read our paper and decide for yourself: http://pubs.giss.nasa.gov/abstracts/2006/LeGrande_etal.html – gavin]
Re 12:
Surely the ability of forests to sink carbon depends on the frequency of fire, the forest type, and a host of other factors.
I read Flannery’s book, liked it and am not sure what you mean by saying it is “too polemical to appeal to those not already convinced”. If there is a need for someone to write a book that does for climate change what Silent Spring did for pesticides, it is important to note that the latter was and is considered polemic – and had many predictions of the sort that would probably not pass review in today’s instantaneous and expert review environment. The book that helps inform and involve more of the public in the climate change issue will be judged mainly on how well it accomplishes that task.
Could you please comment on this? It this just garbage? Especially the last sentence.
Joel
SOLAR CYCLES 24 AND 25 AND PREDICTED CLIMATE RESPONSE
David C. Archibald
Summa Development Limited, Perth, WA, Australia,
ABSTRACT
Projections of weak solar maxima for solar cycles 24 and 25 are correlated with the terrestrial climate response to solar cycles over the last three hundred years, derived from a review of the literature. Based on solar maxima of approximately 50 for solar cycles 24 and 25, a global temperature decline of 1.5°C is predicted to 2020, equating to the experience of the Dalton Minimum. To provide a baseline for projecting temperature to the projected maximum of solar cycle 25, data from five rural, continental US stations with data from 1905 to 2003 was averaged and smoothed. The profile indicates that temperatures remain below the average over the first half of the twentieth century.
[Response: Hmmm. I wonder why only five weather stations out of ~6000 were chosen… -gavin]
Since this is the book review thread, I’ll review a book that some of you, with access to a good library or who are wealthy, might find interesting:
S. Albeverio, et al.,
“Extreme Events in Nature and Society”,
Springer, 2006.
Each of the 15 chapters are written by a different set of authors, which, other than the introductory chapter, treat a different aspect of ‘extreme events’, or ‘Xevents’ as the carfully edited book will term such. No chapter goes into great depth, although some require knowledge of mathematics and statistics. In return, each offers some aspects of Xevents, all are well written and all offer an extensive bibliography for further exploration.
No chapter direcctly treats matters of climate; the one mention of climate. in chapter 3, should better be called weather. There are three chapters on aspects of weather: one each on wind, avalanches and a thoroughly fascinating one on rogue waves. However, the chapter on the mathematics of Xevents might have some applications to climate and the chapter on ‘Endogeneous versus Exogenous Origins of Crises’ might also provoke some new conceptions.
For those interested in who holds various views on climate, or other matters, can be held by a populace, the chapter on ‘Computer Simulations of Opinions and their Reactions to Extreme Events’
will be illuminating, with some conclusions I found rather surprising.
Springer books are never inexpensive. As this one has 115 figures, with 7 in color, I don’t even want to go find the cost.
Instead, have your local research library buy it.
Apropos Ray’s comments on my two excursions into climate (and he’s one of my favorite commentators on climate subjects), that Atlantic Monthly cover story was written nine years ago and the book about five years ago.
Re the worldwide consequences of a D-O event, I have long realized that the evidence is mostly limited to the YD. I generally emphasize that the temperature changes at the equator at sea level are more like 3C/5F, that it is the drought that gets civilizations into big trouble well before the consequences of cooling arrive. It is difficult to imagine any D-O event — even the smaller and exponentially relaxing 8200-yr event — as not having major consequences in the present-day world, dependent as we are on efficiently feeding a huge urban population without interruptions. For the climate scientist, it is important to our understanding to differentiate between YD and the others re worldwide spread of consequences. For more general readers, I remain to be persuaded. If there is any suggestion that our present warm climate would be significantly less sensitive than glacial and transition times (rather than there simply being a gap in our knowledge there), I’d sure like to know it.
For most purposes re public policy on climate flips, it is the demonstrated instability and the role played by freshening the North Atlantic that needs emphasis, along with the melt water from Greenland adding to the effects of increased rainfall in the very places where downwelling seems to be most efficiently conducted, the Larador and Greenland Seas.
[Response:Thanks, William. I hope I remain one of your favorites, despite my gently critical remarks. One of the main developments over the last nine years has been a growing understanding of the role that sea ice plays in amplifying the influence of THC shutdown such as presumably was involved in the YD. This is far from a settled story, but most of the scientists I know now have the feeling that in a high CO2 world with less sea ice, the chill from a THC shutdown would be a lot less. This is more or less the stance Wally Broecker took at his recent talk at the Adler Planetarium here in Chicago. It’s not a done deal, but that’s where things are heading. I agree with your sentiment that drought is the big driver on impact, and Wally emphasized the possibility for mega-droughts as something to worry about re future abrupt changes. The problem is that so far, we have a rather poor understanding of what kind of situation could bring on such events abruptly. Unlike the case of the D-O events and Younger Dryas which tell us something about what abrupt change is like in cold climates, we have no analogous climates we can look at to see what abrupt changes might be like in a hothouse world. The Cretaceous would do nicely, or even the Miocene or Pliocene, but the time resolution of the geological record there, to my knowledge, precludes looking at abrupt changes. –raypierre]
Thanks Ray. Unfortunately the system keeps losing me (maybe IE7??) and that was a draft, not the final, which follows:
Apropos Ray’s comments on my two excursions into climate (and he’s one of my favorite commentators on climate subjects), that Atlantic Monthly cover story was written nine years ago and the Brain for All Seasons book about five years ago. In most of the places where I was worried about overstating the science, a rereading persuades me that things were even more alarmng than I’d thought at the time, even where I’d now reword things to take account of new evidence.
Re the worldwide consequences of a D-O event, I have long realized that the evidence is mostly limited to the YD. I generally emphasize that the temperature changes at the equator at sea level are more like 3C/5F, that it is the drought that gets civilizations into big trouble well before the consequences of cooling arrive. It is difficult to imagine any D-O event — even the smaller and exponentially relaxing 8400-yr event — as not having major consequences in the present-day world, dependent as we are on efficiently feeding a huge urban population without interruptions. Interruptions risk resource wars and genocide, not to mention disease and civil disorder.
For the climate scientist, it is important to our understanding to differentiate between YD and the others re worldwide spread of consequences. For more general readers, I remain to be persuaded that the data gap is newsworthy.
If there is any suggestion that our present warm climate would be significantly less sensitive than glacial and transition times (rather than there simply being a gap in our knowledge there), I’d sure like to know it. What I emphasize is that the NADW has been declining but that we don’t know where the failure threshold really is — then show Tom Stocker’s 100 runs of threshold straddling and emphasize that even getting close to threshold gives wild fluctuations.
For the merely rapid changes such as sea level rise, the public policy implications are not much affected by the scientific uncertainties in what happens at the base of ice sheets to grease the skids; it suffices to say that 2m/century were seen in the past and that this may understate the problem because our projected temperature rise may be 8x quicker. For most purposes re public policy on abrupt climate flips, it is the demonstrated instability and the role played by freshening the North Atlantic that needs emphasis.
We’re scientists: we’re always going to be dissatisfied with the uncertainties and remind each other of them. But people wanting to postpone change have been eagerly taking our standard scientific uncertainty out of context, the same way patients do with a suspected cancer. Physicians have to remember that the doc who waits until dead certain before acting may run a substantial risk of winding up with a dead patient.
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I read the coments, especially the cooling events kiloyears ago. Some questions.
The poles cool, so heat moves out of the poles to where? Ocean? Atmosphere? Radiation? The tropics get warmer?
Where is there a strong equitorial responce to the Y-D? I was under the impression that it was hard to find in PNG and Indonesia, and generally absent from the southern Hemisphere.
Gavin
You are very unfair to Tim Flannery in my humble view. The IPCC 2001 report got the magnitude of Greenland and Antarctic melting wrong according to several articles in Mar 24, Science. In the case of Greenland glacial physics wasn’t well understood. The IPCC report did not take into account thawing permafrost and the subsequent release of methane. Meanwhile the environmental situation is much worse today than that report would have us believe as the human impact is not simply limited to carbon dioxide release in the atmosphere. We are losing species at a higher rate, the gulf is warming faster. New Orleans is still not rebuilt. The genocide in Sudan is spreading to Chad. The Amazon is smaller than previously thought, mountaintop removal minding is spreading its evil ugliness further into Appalachia. We already have a catastrophe the likes of which homo sapiens have never before experienced. Simply measuring a few degrees rise in temperature and guessing the effect on storms and sea levels tells only a very small part of the story on man’s effect on our environment. You need to get out from behind that computer up in New York and visit Larry Gibson in the Coal River Valley, West Virginia. It will blow you away.
And we have no solutions. Coal is dirty. We cannot sequester carbon dioxide and we cannot remove coal from the Earth cleanly. Nuclear power is insane. There was a brilliant article in the LA times a few days ago describing the warning signs the government is planning on using for Yuca Mountain. How do you make an effective sign which reads “Don’t dig here until the year 20000” and make it last for 20000 years? INSANE.
Instead of bashing Flannery, we need to help people understand that the catastorphe has already begun. Flannery’s book is five stars even if it does have a modest flaw here or there.
The Earth’s carrying capacity is maybe at a stretch 4 billion people. How do you see us getting down to that number? I know how Bush will try to engineer that.
The Weather Makers is spot on. We need more books and media which scare the #@$% out of people.
Best regards
[Response: Uncertainty goes both ways and scientists can only describe what they know. Assuming that everything that is uncertain must be worse than expected is irrational. My point was not to claim that the IPCC process is perfect – it is not. But where there are serious uncertainties those were acknowledged in TAR. Your points are well taken, but the license to agitate for change should not be a license to be careless or be more certain than warranted. It is not that I dis-approve of Flannery’s thrust – far from it – but this was not the book it could have been, and as a reflection of science, as opposed to political advocacy, it is unfortunately lacking. – gavin]
Re: 26
I long ago hit the point where I felt like I was the equivalent of Poe’s raven on the agricultural dangers of GW. Calvin says, “It is difficult to imagine any D-O event — even the smaller and exponentially relaxing 8200-yr event — as not having major consequences in the present-day world, dependent as we are on efficiently feeding a huge urban population without interruptions.”
Temperatures don’t need to warm much to produce those interruptions. A farmer’s horizon is 2 years. He will plant next year in response to this year’s weather. He has no other choice. An increase of energy in the atmosphere all but guarantees an increase in climate variability.
When the polar regions cool the amount of sea ice increases. Ice has a much higher albedo than open water, so it reflects more energy from the sun back into space. So the short answer is that the heat radiates into space.
RE “Flannery is quite critical of the IPCC process, describing it as ‘lowest common denominator science’ and claiming that it must be assumed that things are likely to be worse than are described in those reports.”
Though I highly respect IPCC & am very thankful to its contributors and committees & all their hard work, I feel a bit as Flannery does about it. I think that’s mainly because of my penchant for avoiding false negatives (r/t scientists’ need to avoid false positives to protect their reputations). My eyes are more trained on the high end predictions, than low end (worse) predictions. Expect (and try to avert) the worst, and hope for the best.
Also, I think the IPCC reports (their somewhat centrist positions) go in the direction of worse & worse problems and impacts for humanity (in addition to stronger & stronger evidence). Correct me if I’m wrong, but doesn’t SAR have GW worse & causing more problems than FAR has these, and TAR worse than SAR? (I’ve been too busy to read more than the brief summaries.)
Thanks, Blair, I thought so. So, the THC reduces, the North Sea cools by radiation and ice reflection increases. This cools the Northern land masses by convection. Heat transfer shifts from a ocean transport to atmospheric transport. Water gets moved from the tropics to the North via storms.
The Co2 forcing kicks in and forces the cycles to its extremes. And something turn the THC back on at the bottom.
Is this the basic current thinking?
Re #15 & 21
Gavin, has there been any consideration of the draining of the Baltic Ice Lake as a possible cause of the 8,200 BP event? I looked at the drainage sequence several years ago and at the time, the last drainage appeared to have occurred at roughly 8,200 BP. Might that have an impact on the del18O data for the East Norwegian Sea noted in your paper with LeGrande? My interest was the result of hearing a conference presentation in 1993 in which a geological marker was mentioned appearing at roughly that time at a site which indicated a drainage from the Baltic.
Just curious…
[Response: Judging from the descriptions http://www.pgi.gov.pl/pgi_en/index.php?option=news&task=viewarticle&sid=4&Itemid=2 and on http://en.wikipedia.org/wiki/Baltic_ice_lake the timing for the reconnection of the Yodia Sea/Lake to the Atlantic appears close – but the changes in sea level at that point seem minimal, and so the amount of the freshwater that could get into the Atlantic was probably small. However, I haven’t seen a properly worked out estimate of potential effects. – gavin]
Very nice reviews! But would you please comment on the global warming on Jupiter, Triton, Enceladus, Saturn, Pluto, Mars, and Venus?
http://motls.blogspot.com/2006/05/global-warming-on-jupiter.html
I am very confused. It seems that the skeptics are right and they have proved that the global warming is of natural origin.
[Response: Why is it that people who appear to be good at spotting basically falacious arguments in their own fields are so woefully bad at seeing them in others? None of these examples are at all relevant to the issues on Earth as a moment’s reflection would demonstrate – how many seasonal cycles do the Pluto observations cover? How ‘global’ are any of the measurements? Please. See here for more info: https://www.realclimate.org/index.php/archives/2005/10/global-warming-on-mars/ -gavin]
Re #37: It takes a certain amount of chutzpah for Motl to use Venus as an example of global warming when that warming is not recent even on geological timescales…and is actually a poster-child for the CO2 greenhouse effect. But, hey, all is fair when you are doing proselytizing and not science.
Also, since Motl noted all these examples of warming, I assume he must have some universal theory…or at least hypothesis…to explain them…I am hoping for something a bit better than “Well, the sun is somehow getting hotter even though our measurements don’t detect this.” Note that the more exotic proposed mechanisms (like intergalactic cosmic rays effects on clouds) that some people have dreamed up to provide amplification for the sun’s effect here on earth won’t work on these other bodies.
My favorite is the claim about Pluto. AFAIUI, the evidence we are talking about is a few occultation events over fifteen years that indicate changes in atmospheric pressure. Pluto’s year is almost 300 earth years.
So on earth we have thousands of stations taking daily readings for decades to centuries plus so many other lines of evidence and the septics are still not sure it is real. On pluto we have one very indirect reading of an indirect indicator over a time period equivalent to about a month on earth and it is proof positive! Plus we must ignore the direct solar monitoring we have at our finger tips in favor of this new “smoking gun”!
http://illconsidered.blogspot.com/2006/02/theres-global-warming-on-mars-too.html
Also, here on Earth, Katrina being attributed to GW is an outrage of environmental extremism. One new storm starting up on Jupiter however…
File those under “Puh-leeze”
Re# 36
Thanks Gavin. I was actually thinking of one stage in the history, that of the Ancylus Lake, which drained about 8 kyr BP. I had seen maps seen in Figure 2 at this URL;
http://www.helsinki.fi/maantiede/geofi/fennia/demo/pages/oksanen.htm
which appeared in this summary report;
Bjorck S (1995). A review of the history of the Baltic Sea, 13.0-8.0 ka BP. Quaternary International 27, 19-40.
>Another frustrating misstatement in Flannery’s book is the suggestion that young forests are better carbon sinks than old forests, which misses the relaitvley larger carbon pool (both above and below ground) associated with older forests.
Also I seem to remember that old forests adapt better to extreme events than young forests; young forests (especially during the first ten years of life) tend to seqester very little carbon during drougts, floods and so on. In addition don’t mature trees survive fire much better than young trees – which during forest fire act as tinder?
Given that Pluto is currently on the outward-bound leg of its highly eccentric orbit, warming there would be very strange indeed.
Unfortunately, I think that this article suggests what we are in for in the 21st century, and suggests further that “polemics” about the urgency of dealing with global warming may be appropriate at this point:
Eric Swanson: I am a good enough amateur geologist to be able to read the three papers, two linked by Gavin and one by you. As I read it, the Ancylus Lake drained slowly, with low hydrological head. So the drainage was not likely to have created a salinity crisis in the North Atlantic.
[Response: Actually, that’s what it looks like to me too. But it is an interesting topic – I’ll ask around next time I’m at a relevant meeting and see what has been looked into to. – gavin]
Re: Climate change on Jupiter. Do you think the skeptics will notice that the change was predicted with a computer model?
(actually it is believed to be part of a 70 year cycle.)
Thought you might be interested in reading what FactCheck.org says about preventing global warming. This Web site tries to distill the wheat from the chaff on a wide range of topics, as a public service.
Curt Schroeder
Regina, Saskatchewan
Can you prevent global warming?
[full text replaced with link]
On the subject of meltwater release and thermohaline and abrupt climate change, we have the following recent paper:
Tarasov, L. and Peltier, W.R. (2006) A calibrated deglacial drainage chronology for the North American continent: evidence of an Arctic trigger for the Younger Dryas. Quaternary Science Reviews, 25, 659-688.
We present a new deglacial meltwater drainage chronology for the North American ice-sheet complex using a 3D glacial systems model calibrated against a large set of paleo-proxies. Results indicate that North America was responsible for a significant fraction of mwp1-a, with order 1.5 dSv or larger (100 year mean) peak discharges into both the Gulf of Mexico and the Eastern Atlantic and less than 1 dSv into the Arctic Ocean.
Our most significant result concerns discharge into the Arctic Ocean. The largest total discharge into the Arctic Ocean (ensemble mean values of 1.0 – 2.2 dSv) occurs during the onset of the Younger Dryas. The large majority of this discharge is locally sourced with reduction of the Keewatin ice dome being the largest contributor. Given that the only outlet from the Arctic Basin at this time was via Fram Strait into the Greenland-Iceland-Norwegian Seas, we hypothesize that this pulse was the trigger for the re-organization of thermohaline circulation that is thought to have been responsible for the Younger Dryas cold interval. In contradistinction with past inferences and subject to the imperfectly constrained ice-margin chronology, we also find that the Northwest outlet likely dominated much of the post -13 ka drainage of Lake Agassiz.
Of course, lets not forget:
Wunsch, C. (2006) Abrupt climate change: An alternative view. Quaternary Research, 65, 191-203.
Hypotheses and inferences concerning the nature of abrupt climate change, exemplified by the Dansgaard-Oeschger (D/O) events, are reviewed. There is little concrete evidence that these events are more than a regional Greenland phenomenon. The partial coherence of ice core d18O and CH4 is a possible exception. Claims, however, of D/O presence in most remote locations cannot be distinguished from the hypothesis that many regions are just exhibiting temporal variability in climate proxies with approximately similar frequency content. Further suggestions that D/O events in Greenland are generated by shifts in the North Atlantic ocean circulation seem highly implausible, given the weak contribution of the high latitude ocean to the meridional flux of heat. A more likely scenario is that changes in the ocean circulation are a consequence of wind shifts. The disappearance of D/O events in the Holocene coincides with the disappearance also of the Laurentide and Fennoscandian ice sheets. It is thus suggested that D/O events are a consequence of interactions of the windfield with the continental ice sheets and that better understanding of the wind field in the glacial periods is the highest priority. Wind fields are capable of great volatility and very rapid global-scale teleconnections, and they are efficient generators of oceanic circulation changes and (more speculatively) of multiple states relative to great ice sheets. Connection of D/O events to the possibility of modern abrupt climate change rests on a very weak chain of assumptions.
I reckon you realclimate guys should discuss the Wunsch paper, particularly in light of the final line of the abstract. His paper is certainly stimulating, but like the attack on Milankovitch, I was unconvinced by his alternative.
Re #46, I noted the sources of that article are Patrick Michael & Pielke.
See, if everyone had just listened to me in 1990, and started reducing GHGs (we’ve done so by over 2/3 cost-effectively & are saving money & with a higher living standard), we’d really be on the road to mitigating GW. But, oh no, people have to take their money and burn it in their yards like so may fall leaves.
Yes, it will take time for Sunfrost to make more refrigerators (which use 1/10 the energy), and EV companies to crank out more EVs, and Green Mountain to establish more wind farms. But 1st people have to want these things that save them money & help the earth in many more ways than simply mitigating GW. Only then will green companies step up production.
BTW, it doesn’t cost a penny to turn off lights not in use. What I found is that there are 100s of solutions, most very small, but they do add up.
Re:#46 The factcheck.org item strikes me as a good-faith attempt at balance that fell prey to the usual journalistic pitfall; that is, it poses on one side the IPCC consensus view and on the other individual detractors like Patrick Michaels (citing 3 blog entries by him, no less — not peer-reviewed papers). Sadly, in trying to provide a service, they end up doing a disservice.
As for the books that are the subject of this post, I have only read Flannery and parts of Kolbert as they appeared in the NYer. I would like to add my voice to those who viewed the Weather Makers favorably.
But first, I do think that Flannery overstepped on occassion, not just in terms of his over-reliance on single scientific sources that fit his thesis, but perhaps most grievously in his reductive analysis of the genocide in Sudan. I don’t mean to dismiss the Malthusian premise entirely — no doubt it’s part of the picture — but rather to suggest that he got carried away in claiming that anthropocentric warming caused the killings directly and that the industrialized nations are culpable. All that said, his is a strong book — ambitious, concisely and passionatley argued, … a good synthesis. A polemic, yes, but he is open about that from the outset.
Next up? Anyone at RC care to weigh in on James Lovelock’s The Revenge of Gaia?
Apropos the Wunsch abstract:
It’s worth emphasizing that there are a number of levels of “causation” for a climate flip.
1. Rearranaging the winds and water vapor distribution strikes me as a good candidate for effecting a flip on the time scale of a few years, with water vapor content resetting the thermostat.
2. And what usually rearranges the winds? Likely changes in SST, sea-land differences etc.
3. Changes in SST distribution is what one gets from starting/stopping North Atlantic Current components in Labrador and Greenland Seas, capping with sea ice, etc.
4. Among the setups for that are changes in surface salinity.
But you can’t lose sight of how “excitable” this system is (I’m a neurophysiologist, and excitability — decision-making episodes of positive feedback usually called impulses or action potentials — are what make nerve and muscle so different from most other cell types). There is surely more than one way to trip it, even though freshening in glacial times is the easiest way to study it. In Stocker’s 100 runs of threshold straddling for 2xCO2, it suffices to just crank up the sun rather than actually modeling the greenhouse more explicitly.
So I’d be cautious about assuming that modern episodes would require the big meltwater lakes of last time. In my biological analogy, there are probably a dozen ways of tripping the flip, each associated with a separate use or pathology. The fact that it’s excitable means that the route last time is not the only way.