by Gavin Schmidt and Stefan Rahmstorf
Many readers will be aware that three scientists (two of which are contributors to this site, Michael Mann and Ray Bradley) have received letters from Representative Joe Barton (Texas), Chairman of the House Energy and Commerce Committee specifically requesting information about their work on the ‘hockey stick’ papers (Mann et al (1998) and Mann et al (1999)) as well as an enormous amount of irrelevant material not connected to these studies.
Many in the scientific community would welcome any genuine interest in climate change from the committee, but the tone and content of these letters have alarmed many scientists and their professional organisations. In the words of Alan Leshner, CEO of the American Association for the Advancement of Science, the Barton letters “give the impression of a search for some basis on which to discredit these particular scientists and findings, rather than a search for understanding.” Other organisations and individual scientists have also expressed strong concerns:
- A statement from the EGU
- The American Association for the Advancement of Science (AAAS)
- A Nature editorial
- A letter from US scientists (including leading members of the NAS, a Nobel Prize winner and two of us (ES, GS))
- A letter from the head of the National Academy of Sciences, and
- A commentary from Tom Crowley in EOS
- Other politicians, the House Committee on Science and Henry Waxman.
The individual responses have now been delivered (and you can read them here):
These responses emphasise two main points that we have explained in great detail in earlier postings on this site:
- There is no case for casting doubt on the scientific value and integrity of the studies by Mann et al. – they have been replicated by other scientists, the data and the computer code are available in the public domain (including the actual fortran program used to implement the MBH98 procedure), and many other studies with different data and methods have confirmed the prime conclusion: that it is likely that the late 20th Century is the warmest period of at least the past one thousand years.
- The above studies are just one small piece of evidence in a very solid scientific case that humans are now altering the climate – and with or without this piece of evidence, this case is firm (see our post “What if the Hockey Stick were wrong?” or the commentary on Prometheus).
The real question we are faced with is not whether humans are changing climate. The science on this is clear, and decades of research have culminated in a scientific consensus on this point. The real question now is what we need to do about it. A Congressional committee concerned with energy could be – and indeed should be – a key player in exploring policy options to deal with the global warming threat. We hope that after studying the responses by the scientists, they will make a start.
Re#99
In improving the climate reconstructions do we not face the same problem as drug trials and other contentious research? In both cases it is reasonable to assume that the people doing the work will have personal views that could lead to bias. Peer review may well be a necessary process but is it sufficient? Isnâ??t independent or even hostile verification at least as important?
There are some few things known in economics — not many. For example Gresham’s law (bad money replaces good money) and the fact that printing paper money and distributing it causes price inflation.
My guess is that climate science is working with comparably basic observations — greenhouse gases function to capture heat; gas hydrates when warmed sufficiently release methane. That sort of thing.
In economics, there are some few things it’s known to be really stupid to do. Reduce the percentage of gold in the coinage — people hoard the coins with more gold and spend those with less. Print lots and lots of paper money — undermine an economy.
In climate science, there are some few things it’s looking very likely would be really stupid to do, too.
In economics, “in the long run we are all dead.” That’s the people, real and corporate, participating in the economy (it remains to be proved that all corporations die, but we can hope none is immortal).
In climate science, “we” is the biosphere. So far, it hasn’t quite died even in the worst events. We can hope that remains true.
Re 101: If you want an analogy, the IPCC is the equivalent of an NIH or FDC (US example) panel of experts who recommend for or against a drug. They examine all the studies. The IPCC has clearly said there is a problem. Why don;t you accept that and let us move on?
If you want an analogy, this is like the situation with the morning after pill in the US. The FDA board of experts (science) has recommended that the pill be allowed on general sale, but the FDA (policy) is resisting and trying all sorts of yes but gambits. If the foo….
I think the comparison of predicting the economy vs predicting the climate is an interesting one.
People who think these fields are on comparable intellectual footing are incorrect. Climatology is a physical science, and is limited by very specific constraints. There are many trajectories that we know without any doubt that the climate cannot and will not take. They are not actually of much scientific interest, but when comparing to the state of the art in economics it’s important to consider the fact that the vast majority of conceivable climate outcomes simply can’t happen. Energy conservation, angular momentum conservation, mass conservation, etc. will not be violated.
This is a very different sort of confidence than “most of the time, historically, the stock market goes up in ten year intervals”.
We don’t know *exactly* what the climate will do in response to the anthropogenic carbon forcing but we know a *great* deal about what it *won’t* do. It won’t, for instance, stay substantially the same, because to do so would violate fundamental physical laws.
This is not an “eight times out of ten, barring unusual circumstances, all things more or less on an even keel” sort of certainty. It is simply a fact.
Back on the topic of “Science Under Seige,” Rachel’s Environment & Health News ( http://www.rachel.org/bulletin/index.cfm?St=1 ) has an article this week by that same title; they cover a wide range of environmental science topics under seige. An excellent book covering similar ground is, TOXIC DECEPTION: HOW THE CHEMICAL INDUSTRY MANIPULATES SCIENCE, BENDS THE LAW, AND ENGANGERS YOUR HEALTH, by Dan Fagin, et al (1996).
Although these 2 sources do not cover climate change, they put the Barton case in a broader perspective and reveal how widespread the attack on science is.
It just occurred to me that Ray Bradley of this blogpage is the lead author of the article that gave me the initial impetus to reduce my GHGs (Bradley, R. S., H. F. Diaz, J. K. Eischeid, P. D. Jones, P. M. Kelly, and C. M. Goodess. 1987. “Precipitation Fluctuations over Northern Hemisphere Land Areas Since the Mid-19th Century.” Science 237:171-175). It was actually the film, HOT ENOUGH FOR YOU, showing how the precipitation belt was shifting from the Sahel in Africa (causing droughts) to Europe (causing floods), and that this might be due to GW, if and when it was proved (which it was in 1995). I contacted Mick Kelly (who was in the film) & he sent me the article.
Now there is a very bad drought in Niger; looks like millions are going to die, because the world has ignored them. Can it be partly attributed to GW??
I do know (from a 1992 article I read) that uranium mining is harming the land of subsistent farmers and pastoralists in Niger, who don’t even use fossil fuel or nuclear energy. And now they have this drought, possibly enhanced by by GW.
I just wanted to say thank you to Ray Bradley & the other climate scientists.
Re #102 “in the long run we are all dead.”
Quoted from John Maynard Keynes. If I remember correctly, he used to say that to underline that, being mortal should not prevent us to act now with long term persectives in mind.
I’m not so convinced by Michael Tobis’s argument. Sure, there are physical laws that are not in dispute. But at the sharp and interesting end, there are lots of uncertainties, and the fact that there is a (“hard”?) physical as opposed to (“soft”?) socioeconomic truth underlying it all is of little help when trying to predict the future. The truth is not accessible to us, and probabilistic estimation of future climate is a statement of our current ignorance rather than any fundamental randomness or unknowability. To the extent that we understand the physics “better” than the socioeconomics, we can forecast climate “better” than the economy (or vice-versa – how can we compare skill usefully between the two?). But this is a quantitative and not qualitative difference.
RE#103, interesting analogy there. Don’t forget about the products which are FDA-approved and get banned after use by the general public because problems show-up that the FDA missed.
Re 108/109 Both posts talks about differences on the margin. WRT the FDA one must ask what percentage of treatment that were approved worked. Not bad odds and certainly orders of magnitude better than the previous system where any shaman could set herself up as a purveyor of cures and kill you. WRT physical laws, as Michael Tobis points out, they strongly limit the list of probabilities. Compare the how known physics, chemistry and biology limit climate change outcomes to the 10^500 possible realities of string theory and you begin to get the idea.
A couple of observations:
Re #108:
I don’t disagree with the observation that economic modelling and climate modelling are different only in the degree of complexity. But I would add a couple of thoughts:
It has been observed (by someone very wise – don’t remember who) that all quantitive changes eventually become qualitative changes. And I’m inclined to think that the difference in complexity between climate modelling and economic modelling is so great that, in effect, they are qualitatively different. After all, modelling what the economy will be in 10 years really means modelling human behavior in the next ten years -wars, politics, birthrates, crime rates, religious upheavals, changes in work-ethic, death-rates, etc. In effect – predicting history. We will never be able to do this by looking at each human actor (or even each group of human actors) in time-slices of an hour or a day or a week at a time, forecasting its behavior, and modelling forward.
Re #88
Thanks for the link to the Pew study. Honestly, I found it frustrating in that it provided no explanation of its logic or assumptions. We are told that GW will eventually lead to much higher agricultural costs…but there is no discussion of how or why, so I don’t know what to make of the conclusions.
Re #93 –
X-rapt, I’m not a climate scientist, and don’t have access to these papers. Sorry.
Re #92 and others:
I agree, it is misleading to look at the cost of GW using ANY economic measure – wealth, GDP, consumption or whatever. Consider the possibility that coral will not be able to adapt to warmer ocean temperatures and 95% of it will die. This is not a measurable impact in terms of decrease in wealth. But, as it is a source of beauty and aesthetic pleasure to millions of people, losing it would surely, in some way, make the world poorer.
Yet while we may agree that justifying GHG reduction in economic terms alone is oversimplifying, there is no doubt that much of the future debate will focus on this issue – defined precisely in economic terms. So it would be nice if there was something concrete and defendable in this area that demonstrated economic costs.
Thanks all for your interesting posts.
– Dan
Re: #102,
“In economics, “in the long run we are all dead.” That’s the people, real and corporate, participating in the economy (it remains to be proved that all corporations die, but we can hope none is immortal).”
Forgive me for citing a non-scholarly movie quote in response to this. In “Star Wars IV” of all things, Han Solo said: “What good is money if you’re not around to use it?”
This quote should apply to the current debate, as well. If fossil fuel industries continue to pour out the GHGs and pollutants, it will lead to increased rates of cancer as well as increasing numbers of people dying as a result of famine-causing drought, from tropical cyclones and other storms, and from flooding, just to name a few.
Far too many people (especially those in business and politics) think only in the short-term. They rarely, if ever, consider the consequences of their decisions, some of which could end up making life unbearable or even unliveable in many parts of the world.
Even those in politics and in business will likely be in some sort of danger as a result of climate change. Those who live in gated communities and on the hills will not be completely immune to these effects.
RE #92 & economics, Adam Smith’s classical economics that privileges exchange value over use value (which I believe Nordhaus & nearly all economists follow) is not the only economic approach to environmental problems. There is talk of “green GDP” (I think by Michael Porter) and “quality of life” measures, including health (r/t mere quantity of money), putting value on “free” ecoservices (like bees that pollinate or the air we breathe), and distinguishing between “bads” and “goods.” “Bads” would include having to spend money (which increases the GDP) to correct (environmental) harms, such as medical bills and rebuilding after floods & hurricanes.
One problem with classical economics in which everything is reduced to monetary value, is that the lives of the poor (as in Niger) lost to GW are probably only valued at 2 cents each, if anything — so GW costs seem very low. It is the very old, the very young, the very ill, and the very poor (all virtually worthless in economic terms) that are the most vulnerable to GW harm. Fetuses “naturally” aborted by air pollution don’t even get a bleep. And, as mentioned by others here, things not of immediate economic interest are not valued at all, such as coral reefs — which not only give us beauty but are key to ocean ecosystems, supporting ocean life, fish, etc. in those areas.
Another problem with economics is that unlike the usual laws of supply & demand setting “correct” prices, the price of wood, say, goes sky high when only a few trees are left & the forest is in a state of collapse. I think I read that in Blueprint for a Green Economy, which gives the logic behind that. Thus in many cases, only when we have nearly destroyed life-supports and are gasping for air, metaphorically speaking, do such supports, such as air, suddenly gain economic value. But it may be too late. By then the life-support systems may be in irreversible states of collapse.
Finally, how can reducing GHGs, such as turning off lights not it use, “cost” money? Let’s give energy/resource conservation/efficiency a try for a year, then if we’re not satisfied, we can always go back to inefficiency and wastefulness.
BTW, the FDA has a dual mandate to protect business AND consumers, and who do you think comes first? They have allowed MSG (under 50+ different names) to poison our food supply without adequate labeling & cause neurological harm to many Americans (migraines for me). Buyer beware, as Adam Smith might say.
Re#106,
Just from a quick google search, because I recall that Sahel droughts are always serious yet relativley commonplace http://www.unu.edu/unupress/unupbooks/80422e/80422E02.htm . It’s a tad out-of-date, but still a good read. A few highlights:
“In the oral tradition of Niger, drought and hunger are familiar topics. Before foreign conquest there were the periods known as Ize Mere, “the sale of children”; Goosi Borgo, “grinding up the water gourd”; and Yollo Moron, “sit and stroke your plaits”-for there was nothing more that could be done…”
“…One of the primary characteristics of arid and semi-arid zones is extreme variability in rainfall, and the Sahel is no exception…”
“…Climatic change is another popular incantation that is brought forward to “explain” the recent droughts in the Sahel, but this carries little validity except over the very long term…”
“…With a standard deviation of 57.2 mm, in any given year the chance are one out the three that rainfall will exceed 215 mm or fall below 101 mm…”
“This variability also makes it mathematically impossible to make any claims of short-term climatic change. In all likelihood any past climatic change took place over hundreds of years, so the change over a period as short as 50 years would be at most a few millimetres of rainfall…”
Another google tidbit, from July http://www.dawn.com/2005/07/01/int11.htm . Here the UN is blaming African droughts on global warming (including a ridiculous statement about how the frequency of droughts has increased greatly “in the past few years”). It concurrently mentions that, “In Europe, one of the worst droughts on record has hit Spain and Portugal” and that, “Researchers are reporting a general drying of the land and growth of desertification in the Mediterranean region.” This would seem to conflict with the idea of climate change causing a shift of precipitation from Africa (drought) to Europe (flooding).
I acknowledge James Annan’s point that in practice the uncertainties of climate prediction and the uncertainties of economic prediction are substantially at play in the, alas hypothetical, project of designing and implementing sensible climate change policy. I will stick to my guns in asserting that nevertheless the fields are qualititatively different.
Economics is the study of a social construction and climate is the study of a natural system. Climate is very strictly constrained by physics and by the mathematics that describes it. While economists like to do some mathematics, those mathematics describe very crude approximations of human society compared to the precision of the ways in which mathematics describes physical systems.
Does it matter? In my opinion it does. I think wealth is well-defined over a short time periods, say a decade, but to say that thus-and-such a policy will cost so many billions of dollars over a century has dramatically less precision than it pretends to. A thousand dollars will buy me many fewer acres and many more books than it would have a century ago, and try as you might you cannot convince me that these goods can be substituted for each other. So is a dollar worth more or less? As a person who prefers information to real estate, I perceive deflation, but the person who prefers real estate will see the opposite. How does the concept of a “dollar” capture these opposing trends?
On the other hand, a degree celsius a millenium from today will mean exactly what it does today, and exactly what it “meant” (in a very real sense) a billion years ago.
Physical scientists are used to theories which apply well at certain scales and not at others. As fluid dynamicists, for example, we abstract away atoms. Economists seem to think that a dollar is a dollar, and come up with a “discount rate” that automatically and with a dubious claim on cold objectivitiy trivializes our moral obligation to subsequent generations. The discount rate, a meaningful and useful measure on short time scales, is abused. The resulting decision process, though brilliantly effective on short time scales, is stunningly perverse and arrogant on longer ones. Fluid dynamicists might see a rough analogy to applying an approximation outside its regime of validity.
Furthermore, in climate modeling, our prediction becomes fuzzier as we go deeper into time, but the validity of the theory on which the models are based remains constant. In economic modeling, the validity of the theory itself degrades over time becuase economics is a mathematical theory of a social and historical artifact, one whose nature changes gradually over time. This is a very fundamental difference between physical and economic models, and one which has practical implications for thinking rationally about global change policy.
Does this mean we should forego economic thinking entirely? I think not. On the other hand, the longer out in time we look, the less guidance conventional economic thinking offers.
Whatever happened to the board’s stated policy: “…The discussion here is restricted to scientific topics and will not get involved in any political or economic implications of the science.”?
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More trivia perhaps, but it is good to get trivia as accurate as possible. In posting #51, I said “CGX Energy Inc. occupy the same Canadian address given for McIntyre in McIntyre and McKitrick (2003), an address which is also occupied by Northwest Exploration Company, another business which apparently engages in oil and gas exploration (or at least a company with the same name does)”. Steve McIntyre now informs me that there ARE two different companies called “Northwest Exploration Company” and that his company has “no oil and gas reserves or production” and is “nothing to do with a company with a similar name with oil and gas production in Nevada”. This does not of course change the main point of posting #51, which was that “around the time of the writing of McIntyre and McKitrick (2003 ….. ) and of the ….. biography, McIntyre was actually a `Strategic Adviser’ to CGX Energy Inc. who describe their `principal business activity’ as `petroleum and natural gas exploration'”.
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Michael (#113) – I take it you are aware of the butterfly effect?
Regarding 116:
When a Congressman with strong links to oil and gas energy interests decides he needs to investigate scientists, I think that discussion of the item about that investigation will necessarily involve politics and the economy. However, I would be interested in more science — perhaps next week Dr. Archer can comment on interesting aspects of the Chapman Conference which took place this week, for which he was one of the co-conveners?
Chapman Conference on
the Role of Marine Organic Carbon and Calcite Fluxes
in Driving Global Climate Change, Past and Future
http://www.agu.org/meetings/cc05fcall.html
http://www.agu.org/meetings/cc05f_Preliminary_Scientific_Schedule.pdf
re #114 : ” This would seem to conflict with the idea of climate change causing a shift of precipitation from Africa (drought) to Europe (flooding). ”
I would be surprised to see any climate scientist making such an assertion. Do you have any indication that any science is suggesting “a shift of precipitation fomr Africa to Europe”?
This appears to be a straw man. The coupling between subtropical and middle latitude precipitation at a particular longitude is essentially nonexistent – the dominant rainfall mechanisms are very different and very weakly coupled through the global circulation.
Local humidity in subtropical desert regions is of course very low, which makes evaporation efficient. If these regions heat up, evaporation becomes more efficient. To avoid a decrease in soil moisture, there has to be an increase in local precipitation to balance it. In the African subtropics, this essentially amounts to wider latitude excursions of the intertropical convergence zone or increased intensity of equatorial convection. If we don’t have a strong reason to expect either of those, we would conclude that the African desert would expand. Apparently this drying is indeed what the models are indicating.
IPCC TAR (WG2) says: “Africa is the continent with the lowest conversion factor of precipitation to runoff, averaging 15%. Although the equatorial region and coastal areas of eastern and southern Africa are humid, the rest of the continent is dry subhumid to arid. The dominant impact of global warming is predicted to be a reduction in soil moisture in subhumid zones and a reduction in runoff. Current trends in major river basins indicate a decrease in runoff of about 17% over the past decade. Reservoir storage shows marked sensitivity to variations in runoff and periods of drought. Lake storage and major dams have reached critically low levels, threatening industrial activity. Model results indicate that global warming will increase the frequency of such low storage episodes.”
( http://www.grida.no/climate/ipcc_tar/wg2/378.htm )
regarding this quote:
“This variability also makes it mathematically impossible to make any claims of short-term climatic change. In all likelihood any past climatic change took place over hundreds of years, so the change over a period as short as 50 years would be at most a few millimetres of rainfall…”
I will note that your source (http://www.unu.edu/unupress/unupbooks/80422e/80422E00.htm#Contents) is a natural resource management specialist and the date is 1986. With all due respect to the author the claim of “mathematical impossibility” is obviously excessive and is almost certainly predicated on an implicit idea that global forcings will not change on the decadal time scale.
He just wasn’t considering anthropogenic climate change when it made the rather overstated assertion. probably in reaction to some statistically naive extrapolations that others were making at the time. This hardly constitutes any significant input into a serious review of our current understanding. We aren’t just indulging in weekend curve-fitting; a large group of smart people is trying very hard to anticipate what is going to happen as a result of human forcing of climate.
The result as embodied by the IPCC reports, especially regarding regional trends, may be wrong but it is reasonable at this point to have confidence that it isn’t stupidly wrong. A monograph from twenty years ago by someone who is not a physical climatologist is very unlikely to add to our understanding.
#74 – It doesn’t look like anyone answered you.
If we did reduce CO2 emissions to zero today then the difference it would make would still be fairly small in 20 years time, but would be noticeable in 50 years.
This is because the climate system takes a long time to respond to forcings on it [mostly because of the large heat capacity of the oceans] and so takes a long tim e to reach a new equilibrium. I believe that our committment to future climate change is generally though to be of the order of 0.5 degrees C [ie about the same as occured during the 20th century].
Re #46
Recall that there was a large volcanic eruption in August 1883, the Krakatoa eruption, the largest volcanic eruption in the past several hundred years, which affected global climate for years, therefore “the sudden sharp upwards inflection just after 1900” is most simply interperted as the rebound from an earlier abrupt increase in volcanic activity.
#114; Re “climate change causing a shift of precipitation from Africa (drought) to Europe (flooding).”
Although not directly related to what you are saying I came across an interesting tidbit using results from an EU-funded project involving many regional climate models over Europe [the names of these EU projects are always hard to remember].
Anyway, the upshot of it was that the models were predicting mean summer rainfall to decrease over most of the European continent [ie more drought], but that the incidence of extreme rainfall events [above a certain threshold in mm/day] would also increase over much of Europe [ie more floods].
If you visualise a pdf of rainfall you can see that whilst the total amount of rain can decrease [ie the area under the curve], if the shape of the curve changes [in this case flattens] then you can get more extreme events at the same time.
Anyway, I found it quite interesting.
RE climate v. economic uncertainties, we are really missing the big picture that the environment is FUNDAMENTAL, the economy CONTINGENT. And that uncertainties go in both directions. If the environment is greatly harmed from GW — either worst case scenario of the scientists, or even worse than that due to current uncertainties — the economy collapses, along with lots of human & nonhuman life. If, on the other hand, the environment is in good shape to support life, and the economy collapses (as it slightly did during the great depression), people can at least forage for themselves & survive, as animals (which do not have economies) do. For instance, my parents & grandparents went & picked their own produce during the Depression. I take Economy to mean the production (esp division of labor, work groups), distribution (incl exchange), and consumption of goods & services — money & the market type economy being very recent new-comers in human history/prehistory. Thus the economy is largely about social relations, but is dependent on and constrained by environmental factors. Now “subsistence patterns” and “technology” (how we eke a living out of the environment) are more fundamental than the economy; subsistence patterns include methods from hunting/gathering (food foraging) with stone tools to horticulture to industrialization — with its downside of causing GW, which is/will boomarang back on the economy, subsistence patterns, and all else.
RE #114 & 120, the article/film I cited (#106) do say the the Sahel is drought-prone, but point out the precip had been decreasing even further over seveal decades. In a drought-prone area, even a very slight decrease in precip (due to GW or other factors) could mean the difference between survival & millions starving; just as in a flood-prone area that few extra inches (due to GW or other factors) could mean breaching the levy & flooding a big metro area & billions in damages & some loss of life.
In other words, although GW & GHGs increase slowly & incrementally — sort of linearly (after that bend in the hockey stick) — the harms they cause might not follow a linear function, but go haywire, as in mathematics catatrophe theory. Thus when I hear “only slight changes in temp or precip” I think this might entail a big leap in harm. You know, the straw that breaks the camel’s back.
Re: #124
I would disagree with your assertion that if “…the economy collapses (as it slightly did during the great depression), people can at least forage for themselves & survive, as animals (which do not have economies) do.” Hunter-gatherers (human foragers) have dramatically lower population densities than do agriculturalists. Better suggestions of what true economic collapse in the modern era might do are the Stalinist destruction of Ukrainian agriculture in the early ’30s and the Great Leap Forward in China (late ’50s), which resulted in mass famines totalling something like 40-50 million victims.
Given today’s higher population densities, reduced proportion of farmers, and the dependence of modern farming on manufactured inputs such as fertilizer, fuel, & machinery, I would expect that a true economic collapse today would result in greater famines.
So, we clearly need to avoid both major economic and environmental harm. The tricky part is getting to agreement on what “major” means…
Pe#118-Certainly.
Re#120-“I would be surprised to see any climate scientist making such an assertion. Do you have any indication that any science is suggesting “a shift of precipitation fomr Africa to Europe”?”
I was responding to #114 – “It was actually the film, HOT ENOUGH FOR YOU, showing how the precipitation belt was shifting from the Sahel in Africa (causing droughts) to Europe (causing floods), and that this might be due to GW, if and when it was proved (which it was in 1995).” I have no idea if the film is based on climate scientist assertions.
“I will note that your source…is a natural resource management specialist and the date is 1986.”
I acknowledged that it was old, and no, it is not purely a climate study. It was the first hit I looked at from a quick google search. But it was an interesting read nonetheless.
RE#125-Int’l Journal of Climatology, 2004, “The Recent Sahel Drought is Real” by A.Dai, P.Lamb, K.Trenberth, M.Hulme, P.Jones, and P.Xie
http://www.cgd.ucar.edu/cas/trenberth.papers/Comment_CA04.pdf
Under “Concluding remarks” (my caps): “Using station rainfall data extracted from the GHCN2 and CAM, we show that large decreasing rainfall trends were widespread in the Sahel from the late 1950s to the late 1980s; THEREAFTER, SAHEL RAINFALL HAS RECOVERED SOMEWHAT THROUGH 2003, even though drought conditions have not ended in the region. THESE RESULTS ARE CONSISTENT WITH MANY PREVIOUS STUDIES.” So the drought severity increased greatly even during a period of global cooling, and rainfall began to recover during some of the hottest decades in history. So at first glance, it might be complicated to blame things on GW.
Granted, they also conclude that, “large multi-year oscillations appear to be more frequent since the late 1980s than previously.” I’m not sure if 15 yrs of data is enough to make a substantial conclusion, but lets accept it. Nevertheless, GW doesn’t get mentioned, only this: “This might suggest that the region’s climate has become more unstable and prone to droughts after the prolonged severe droughts from the early 1970s to late 1980s due to, for example, reduced water-holding capacity by soils and vegetation that would normally provide some smoothing or stabilizing effects (e.g. Charney, 1975; Trenberth and Guillemot, 1996).” Also of note: “As shown previously (e.g. Folland et al., 1986; Dai et al., 1997; Ward, 1998; Dai and Widley, 2000), Sahel rainfall is significantly affected by ENSO.” They also say in the introduction: “Several possible causes or mechanisms, including local land-atmosphere interations (e.g. Charney, 1975; Nicholson, 2000), tropical Atlantic and global sea-surface temperature influences (e.g. Folland et al., 1986; Lamb and Peppler, 1992; Ward, 1998; Giannini et al., 2003) and atmospheric wave disturbances (Druyan and Hall, 1996), have been identified and investigated.”
One could argue, of course, that ENSO or other factors are enhanced in magnitude/frequency by GW. Nevertheless, I found it interesting that the only possible link suggested that could possibly be directly tied to GW was sea-surface temp influences, and one would have to go through the listed references to identify links to GW. Keep in mind that co-author Trenberth is the IPCC member who has tied hurricane frequency to GW and whose remarks helped produce the resignation of Chris Landsea from the IPCC. Jones has numerous studies concerning climate change and human influences. Dai has said he thinks the risks of drought increase with GW. The other authors have done climate change work, too. We’re not talking about a group that wouldn’t consider GW effects, so I found it particularly interesting GW got no mention, not even in passing.
RE #127, anyway, the article & film (#106), both from the late 1980s, did give me impetus to reduce my GHGs, even if they are not as valid by today’s standards (science does change). And I don’t regret reducing because I’ve only saved money (without lowering living standard), and I have many other reasons now to abate GW – just read Mark Lynas’s book HIGH TIDE to get a picture of GW victims today & tomorrow.
#118: Actually an interesting question here (there are many in other parts of this thread). Does the butterfly effect have any relevance to climate? I actually doubt it has any for weather.
FWIW do trivially minor differences in initial conditions for weather models make significant differences in outcomes and the same for climate models.
The professional “skeptics” are now starting to defend Barton, and attack Mann. This, from Steven Milloy, is typical; Barton is simply trying to research global warming, while his critics are part of the climate change “lobby”.
http://www.foxnews.com/story/0,2933,163999,00.html
Eli (#129): Trivially different initial conditions certainly lead to widely divergent weather, although a randomly-imposed perturbation (as distinct from a dynamically-relevant one) is likely to stay small (shrink, even) for some initial interval. In real applications, weather forecasters are quite some way from trivially small uncertainties in initial conditions, and in any case the models are imperfect enough that forecasts would degrade over a few days/week even with perfect initialisation, so the point is rather moot.
As for climate, so long as one averages over a long enough time scale (such that external forcing is large compared to internal variability), the initial conditions generally don’t matter too much. This pic gives a typical example.
re #129, #131:
Climate being not very well-defined as a mathematical construct, the question as to whether it is chaotic is also ill-defined. In defining the system, are we including the hydrosphere? the cryosphere? the carbon cycle? the tectonics?
Climate change is even more problematic. What constitutes an event and what constitutes a shift in statistical properties? Is El Nino a climate shift? What about decadal variability in tropical storms? There is signal at all frequencies so a formal definition climate change is somewhat elusive.
You can specify formal defnitions of the climate system in some specific way, and then, at least in principle, argue that the physical system so defined does or does not have certain statistical properties. Whether this is fruitful or not depends on what actual question you are considering.
Regarding the century scale climate predictions, the matter of whether the system is chaotic is rather unimportant. Chaos is a property that describes the predictability of an unforced system. What we see in Hansen’s plots that James Annan links is primarily the behavior of multiple realizations of a strongly forced system. The chaos part is qualitiatively the bumps and wiggles superimposed on the forced part, which is quite predictable.
It’s hard to predict the swirls of cream in your coffee cup, but if you push the cup off the edge of the table it will surely fall to the floor.
RE # 130, somebody forgot to throw the kitchen sink at Barton. Looks like people concerned about GW need to get some professional lobbyists to keep up with those slick oil guys, who really know how to toss the kitchen sink.
Before we move to another topic, I just wanted to say how depressed and demoralized I am by the Barton witch hunt.
As a social scientist, I think it (along with all the other attacks on science, see http://www.rachel.org/bulletin/index.cfm?St=1 ) tears at the fabric of society and demoralizes it. Laura Nader (legal anthropologist) did a film, “Little Injustices,” about people in the U.S. who buy lemons (bad appliances, cars, etc), and cannot get them fixed or get their money back. Since they have no recourse, they just “lump it,” but the overall effect is growing cynicism & apathy, which harm society. This is unlike traditional societies where informal justice fora resolve conflicts quickly and with the idea of reestablishing social harmony (an area my husband & I also specialize in).
I think the whole contrarian attack on science (beyond typical skepticism) is really harmful. The general public hears GW is happening one day, and it’s just a hoax the next. We hear that a study has shown chocolate to be good for the health, and I think, “Yeah, right, who did that study, the Chocolate Institute?” And apparently the CI did do the study, and maybe they’re even on to something, but we just can’t trust anyone anymore….
OK, I admit I’m all over the map on this thread, but I can’t resist commenting on Milloy’s efforts on the Fox website. Note the following:
Truly nasty business, calling the AAAS an alarmist group and calling the IPCC a political organization.
I like to think that people who act so effectively against the interests of all of us are honestly fooling themselves, but it’s hard to see something like that as other than maliciously misleading. I really can’t fathom this behavior. It sometimes seems like some of these guys are actively promoting as much climate disruption as they can get.
Re #133: Lynn, I think the Barton situation is showing all the signs of working out very well in the end. The scientific organizations and (for the most part) the media are stacking up very nicely on the proper side, and should Barton try to hold rigged hearings Boehlert is in a position to at least neutralize them. In the end, all Barton will succeed in doing is bringing more needed attention to the issue. I’ll go out on a limb here and predict that he will try to find a way to just let the whole thing drop, but even still the whole incident will be a net plus.
Re#128,
Have you considered the “clean drinking water” crusade? There are a number of organizations who do their part to improve sanitary conditions and improve water infrastructure in 3rd world countries (eg, Water for People). With preventable water-borne illnesses annually ranking at the top of the list of deaths world-wide, how long will it take the theoretical AGW sufferage to match? And many predict that water resources will start wars in the next 10, 25, or 50 yrs…maybe we’ll all be wiped clean before we can even see how right the IPCC models are.
FYI, a non-GW story about the woes in Niger. As is the case with most famine issues, a lot of the blame goes to politics http://biz.yahoo.com/ap/050730/why_africa_goes_hungry.html?.v=3
Re #135. You hope!
Re #130. Is true that only a single tree is used for the reconstruction of part of the 15th century in study under discussion? This sort of question and any answer would seem to be to do with the real science of climate change. So would the question as to whether the answer to Barton’s question 7C concerning R2 is yes or no. It is wishful thinking to suggest these basic questions will go unanswered.
[Response: The comment in the Fox news piece is incorrect. As I understand it, over the whole period from 1450 back (including the section 1400-1421) the first 3 PCs from the N. American network are used along with 9 over proxys as described in MBH99. The N. American PCs are the summaries of 70 tree-ring series (of which one is the Gaspe series) . The removal of the Gaspe series, or indeed of all the Bristlecone pine trees as well, has a minimal effect ( ~0.05 deg C) on the reconstruction as long as you include consistent numbers of PCs as described in the Dummies Guide. This is most clearly seen in the upcoming W&A paper in Climatic Change where they specifically go into these details (sorry I can’t post the figure). Including the Gaspe series does however improve the RE scores over the validation period, and so can be justified on those grounds. The reasons why RE is the preferred statistic rather than R2 is explained in Mann’s response above. It is important to note that while choosing the proxies to be used in a reconstruction is a valid test of the robustness of the result, it is not a criticism of the MBH methodology which is what the principle advance was in those papers. – gavin]
What’s wrong with requesting info? It happens all the time. Why be so defensive about it? If your study is correct it will be proven for the public once the complete record is brought forward in the manner requested. What better way to prove the WSJ article wrong?!
RE #135, I’m a firm believer that good comes from bad, new life from the humus of trials and tribulations, and from the long-suffering struggle against wrong. And I hope much good comes from this bad. But that doesn’t make the wrong right. It’s one thing for the people and private businesses to retreat into a shell of denial in the face of a serious problem or threat, such as GW, and work on reinforcing that shell, but when our leaders do that, risking putting the people in harms way, this is a serious matter and it de-legitimizes that leader and even the institution of governance itself, and it demoralizes the people.
A comparison was made earlier to McCarthyism, but I think this Barton witch hunt is worse than that. I remember the times. Many were afraid of communism, which was spreading around the world, and the bomb threat only heightened that fear. While McCarthyism was a misguided, excessive response to that fear, the thrust was to save the American way of life. I think McCarthy was sincerely in his own mind doing what he thought was right, and he was being bold and brave about it.
Here we have a leader in Barton who refuses to face up to the serious problem of GW facing our nation and world, but is doing all he can to strengthen denial, instead of taking the bold and brave action of confronting the problem and searching for creative ways of abating it that will not harm our American way of life. Okay, abating the problem (reducing GHGs) is itself a bit fearful and I understand how some could construe it as threatening the American way of life (even though I think they are dead wrong). Okay, it is even more scary for the oil companies that back Barton – but they should be trying to diversify into non-fossil fuel energy, as some are. A patient facing surgery may be more afraid of the surgery than the life-threatening disease. But that is no justification for ignoring GW and seeking to deny it (especially under the pretext of trying to understand it), and seeking to discredit the messengers that are bringing us the information about it. That is not leadership. That is the king running and hiding, clinging to his treasure chest, while letting the beast harm the kingdom and the people.
Until Barton does an “about face” to face the problem of GW or is removed from his post, I cannot give full respect to our government.
#129, #131, 132 seems to have reached a sensible consensus that the butterfly effect is not an issue with respect to climate. A couple of caveats and points:
– the stronger the forcing, the less important the butterfly effect even over shorter periods, for example, large volcanic forcings overcome chaotic behavior easily. The greenhouse gas forcing is now exceeds that scale
– chaotic (butterfly) effects average out over the 20-30 year time scale if there is no forcing, so on average they have no effect on climate viewed over any appropriately long time scale. This means that if we “de-force” the observed climate, we get a measure of the frequency spectrum of the chaotic component. The fact that noise in climate observations is not white shows that even the chaotic component is bound.
– (My original point, although perhaps not explicitly made) There is no way to see if climate, or even weather, is effected by butterflies without models. Ensemble forcasting shows that any effect averaged over time and/or space is at best small. In other words, it may or may not rain today over Joe Btfsplk’s head (fat chance), but the chaotic component of the forecast for greater Dogpatch is much smaller.
In the nice version one would say that the butterfly effect is not relevant to climate, in the not nice, that it is a red herring. Some will raise the issue that near a bifurcation this is not so, extremely small changes in some parameter can result in a large change in outcome. However, since all climate parameters have both inertia and fluctuations, once you approach a bifurcation, you are all but certain to cross, the only question is when. If you doubt this run Monte Carlo trajectories on an appropriate surface.
Re: #136,
“FYI, a non-GW story about the woes in Niger. As is the case with most famine issues, a lot of the blame goes to politics”
I disagree. Famines are caused primarily by adverse meteorological or climatological conditions (droughts or flooding, reducing the ability of land to grow crops and feed livestock).
Sure, in this day and age of globalisation (not true globalisation, though), there are political aspects of famine, etc. However, Niger was suffering through severe drought conditions (before some flooding rains occurred around a week ago).
Political inactivity is a problem today. I agree. However, had Niger received a fairly normal quantity of rain, they would not be suffering through the current famine. Climate change is likely, in part, a contributing factor to this, since climate change is likely enhancing climatic variability. AGW will only exacerbate such problems in the future.
Re: #141
Stephen, if famines (as opposed to instances of crop failure) were really caused primarily by adverse meteorological or climatological conditions, then you would expect them to hit all countries affected by those conditions, not chiefly ones with bad governments. For a recent example, compare the mass famine in North Korea with the opposite in South Korea.
You would also not expect them to occur in the absence of such adverse conditions (as did the mass famines in 1920s Ukraine and 1950s China, and [perhaps in the near future?] the current situation in Zimbabwe).
Re: #142,
How about the famines that struck India and China in the 1870s? The El Nino event of 1877-78 resulted in monsoon failures in India and drought in China from which tens of millions died. This famine was due primarily to adverse climatological conditions and not politics (though Mike Davis attempts to blame the British provisional government in India, perhaps, a bit more than he should in his otherwise excellent examination “Late Victorian Holocausts”).
Governments can try to safeguard their populations from starvation by stockpiling food supplies. However, this can only happen in rich nations where governments can purchase grain and produce in bulk. Poor nations, such as Niger, can ill afford to do this since every last grain must be put into the food supply to allow as many people as possible to be sufficiently nourished (or just nourished enough to survive) until the next crop comes in. This makes it tougher for them, however, since they cannot save grain for the next season to seed more crops. (Agricultural subsidies in the US, Europe, and to a small extent in Canada have made the situation worse.)
Lynn, I find the perspectives you have provided in #133 and #138 both large-minded and very valuable to a rational – and therefore scientific – understanding of the communication and decision-influencing processes currently going on.
RE crop failures & famine, if the world food production on the whole is decreasing (as apparently it is) then eventually there will be famine, even if food is distributed equitably & governments are all helpful. GW is expected to decrease global food production (though some areas may increase), and certainly those areas dependent on the glacial cycle for irrigation, once their glaciers are all melted, will be very severely hit, not to mention the drought areas, and flood areas; even heat can stunt & kill crops.
I thought #123 pointed to something important re increased drought AND flooding in Europe – due to a lot of precip coming down in a short time alt w/ long drought periods. I would guess that GW by holding more water vapor in the atmosphere (not allowing it to precipitate as much) would tend to lead to greater droughts in general. I remember the early computer models (around 1990) showing a GW world with greater droughts closer to the equator & mid-latitudes, & great precip closer to the poles, with a net greater precip, but in a smaller area. Are these models still basically valid?
I do agree with #136 that there are other problems besides GW that need attention, but we shouldn’t forget that (1) we hold the keys to reducing GHG in our daily lives, while we may not be able to help much with 3rd world water problems, aside from donating money (which we can raise by saving money by reducing our GHGs); (2) the GHGs we cause to be emitted today will be harming the world in the future, perhaps up to 1/4 of our emissions lasting up to 100,000 years (as David Archer on this site suggested); and (3) a lot of water problems are linked to GW in various ways – GW causing drought & glacier melt & sea rise (entailing salinization of coastal ag lands & drinking water supplies), as well as water conservation (which entails energy conservation) helping reduce GW.
My tiny church environmental group in my previous town was able to limp along only because we addressed everyone’s environmental concern, and I was amazed to find so many other problems related to GW in various ways – even nuclear power causing cancer to uranium miner, etc (since our electricity was 70% nuke & 30 coal – so reducing electricity helped reduce both problems). One member a geologist was even dead set against accepting that GW was a problem (I think she does now), but we found common ground by having a water conservation campaign (our area had water depletion problems). We either pull together or hang on separate gibbets. Now in my new town the church didn’t even have a “peace & justice” committee, so we started one, and the environment has taken a back seat to our anti-drug & family violence campaign, though I plan to bring in GW & environmental problems when we do “Souper Sunday” about world hunger.
Barton has an op-ed in the Dallas Morning News: http://www.dallasnews.com/sharedcontent/dws/dn/opinion/viewpoints/stories/080105dnedibarton.7b0a5fb.html