Bishop Hill Stern's wheat graph redux
Apr 23, 2012 Climate: WG2 An anonymous commenter has posted an interesting observation about Lord Stern's graph of wheat yields, which was the subject of a posting a couple of days ago. For convenience, here's the graph as it appeared in the Stern report once again.
;)
And here's how it appeared in the original paper by Wheeler et al.
There's a great deal of interest. For example, the dog-leg interpretation of the data is not part of the original paper, but instead appears to be a bit of spin added by the noble lord. Notice also that an inconvenient data point (indicated by my red arrow) has been deleted in the Stern graph. After Climategate, readers will of course be familiar with the idea that deleting inconvenient data is a technique that is widely accepted, and indeed one that has been endorsed by many at the top of the scientific establishment, including the president of the Royal Society.
Perhaps the most important difference between the two graphs is the inclusion of a second set of data points in the Wheeler graph. These show the effects of raised temperatures on wheat maintained at elevated CO2 levels. As is plain to see, the effect of temperature seems to be more than compensated for by the enriched atmosphere. In other words the conditions we are alleged to be subject to in future are actually beneficial for wheat.
It seems surprising to me that Lord Stern should have failed to notice this good news.
Bishop Hill
Peter O'Neill in the comments notes that Wheeler published a later paper on temperature-only effects on crops. This included what appears to be Stern's graph, although without the dog-leg. Being a temp-only paper, it didn't consider CO2 mitigation of the yield losses. I therefore think think Stern is not excused - the whole story includes consideration of CO2 fertilisation.
Reader Comments (74)
An additional point regarding the effects of CO2 on plants, not mentioned in this discussion so far, is that agriculture is not natural vegetation. When assessing the effect of warming or CO2 on a natural ecosystem, the only thing that matters is the response of vegetation to the new conditions (at most, one may think of including natural selection of plants, and then ultimately change in the ecosystem vegetation composition, due to changing climate). Agriculture, instead, is not a natural process but the result of an interaction of human agents with Nature.
The experiments usually done do not consider that. They simply take one crop under present cultivation at a certain location, and attempt to grow the the same variety and cultivar of the crop under changed environmental conditions. As every variety of every crop grows optimally within a narrow range of soil, rainfall and temperature conditions, it is obvious that a sharp change in any of those conditions would probably cause a decrease in yields, but would not motivate farmers to keep planting that variety, with the same farming practices, under the new environmental conditions.
For wheat to show a reduced yield in a certain location once CO2 concentration reaches, say, 720 ppm in 2100, it would be necessary that farmers in 2100 at that very location still decide to sow wheat, and moreover, the same variety and cultivar of wheat, with the same technology used today (same fertilizer, same plant protection, same date of planting and so on). In the hypothetical event that such variety of wheat, cultivated in such fashion, fails to perform in that location in 2100, one may be pretty sure that farmers would rather choose another crop, or another variety or cultivar of wheat, or change their farming practices at the very least, to suit the new climatic conditions (which would not appear overnight but gradually during a century or so).
Agriculture is in itself a form of adaptation of farmers to prevailing natural conditions (soils, rainfall, temperatures), and the idea of "potential" impacts of climate change (as defined by the IPCC) on agriculture does very little sense, even theoretically. Such "potential" impacts are defined as the impacts that would occur without any adaptation, but this is practically impossible in the case of agriculture.
To use a more mundane example: after observing throngs of people sunbathing and swimming in Brighton, England during the summer, it would be absurd to predict that thousands of scantily clad people will perish from exposure in Brighton beaches during next winter: one can be pretty sure that much before the dead of winter such sun-loving people will have withdrawn from the beaches or would only venture there fully clad in woolly clothes. Sun bathing, like agriculture, are forms of adaptation to the prevailing conditions, and one should not "project" the "potential impact" of climatic (or weather) change "all other things remaining unchanged", or "without adaptation". The concept of potential impact may be useful for totally natural processes, where human intervention (if any) is exogenous, but it is not applicable to processes like agriculture (or sun-bathing) that are the result of human adaptive behaviour in the presence of certain natural conditions, especially when the "projected" change in natural conditions would occur gradually along a hundred years (involving three or four generations of farmers).
Apr 23, 2012 at 1:48 PMkim
Richard Betts, I love you too, but you must publicly damn this Stern stuff. Are you too busy to shore up your own credibility?
No No No NNNNOOOO!!!
We sceptics should abhor any scientist with an agenda, either sceptic or warmist.
We should abhor any scientists who goes beyond what the facts support ... even in the face of the most blatant lies and deceit. They must be better than the warmists.
We should ask those scientists who support us to reframe from making the same absurd unsubstantiated politically motivated assertions of the warmists, even when it helps us. They must stick only to what the facts support .... even if it hurts our cause.
Because a sceptic scientist, is a good scientist, and a good scientists is not partisan ... they do not indulge their own agenda for anyone, and it is wrong for any to do so whether sceptic or warmists.
Re: Apr 23, 2012 at 3:04 PM | Mike Haseler
"We sceptics should abhor any scientist with an agenda, either sceptic or warmist.
We should abhor any scientists who goes beyond what the facts support ... even in the face of the most blatant lies and deceit... "
You mean like those scientists who signed the infamous petition created by Julia Slingo of the Met Office,
The one that said ....
"We, members of the UK science community, have the utmost confidence in the observational evidence for global warming and the scientific basis for concluding that it is due primarily to human activities. The evidence and the science are deep and extensive. They come from decades of painstaking and meticulous research. That research has been subject to peer review and publication, providing traceability of the evidence and support for the scientific method. The science of climate change draws on fundamental research from an increasing number of disciplines, many of which are represented here. As professional scientists, from students to senior professors, we uphold the findings of the IPCC Fourth Assessment Report, which concludes that Warming of the climate system is unequivocal and that Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations."
The 'painstaking and meticulous research, by many thousands of scientists across the world who adhere to the highest levels of professional integrity' exposed for what it really was by Climategates 1&2.
Disappointing that ANY scientist could sign such a document but more so that the signators included both Richard Betts and Tamsin Edwards.
Heh, I love you, too, Mike. Would you say 'indeed disapprove' is going a little too far?
==================
kim
"Would you say 'indeed disapprove' is going a little too far?"
Well it would be a pleasant surprise if it went further than this blog.
The truncated dataset plotted in the Stern report, without the fitted dog-leg, can in fact be found in a later paper co-authored by T.R. Wheeler [Fig. 3 in Timothy R Wheeler, Peter Q Craufurd, Richard H Ellis, John R Porter, P.V Vara Prasad, Temperature variability and the yield of annual crops, Agriculture, Ecosystems & Environment, Volume 82, Issues 1–3, December 2000, Pages 159-167, ISSN 0167-8809, 10.1016/S0167-8809(00)00224-3. (http://www.sciencedirect.com/science/article/pii/S0167880900002243)]
But in this case the figure caption ["Effects of differences in the maximum temperature (Tmax) in the 5-day period ending at 50% anthesis on the number of grains per year at harvest maturity of winter wheat cv. Hereward grown at 350 ppm CO2 within two temperature-gradient chambers (redrawn from Wheeler et al., 1996a)."] makes clear that the data plotted is for wheat grown at 350 ppm CO2, and that it is redrawn, not reproduced, from Wheeler et al 1996a, both qualifications unfortunately lost by (upon?) Stern.
great comment Hector. Alarmists regularly forget that adaptation is a net-positive. Mistakes are not repeated second-time around, good ideas are.
So for example if another summer like 2003 were to happen, I'm sure France would see far fewer dead among the elderly. But after vaccinations came about, only a few crazy people campaigned to have them removed.
Bar a nuclear war, the varieties of 2100 will be better than today's, and surely either the IPCC manages to demonstrate that it is impossible for anything edible to grow under higher-CO2, warmer conditions, or there is little to worry about.
@Richard.
I am pleased to hear that there are others working on the responses of plants to increased CO2 in AR5.
However I have to wonder why they would want input from someone whose expertise is in modelling?
I ask this because there is a large body of evidence obtained from actual experiments- some of which have been running for years.
I also trust that you will be noting in your AR5 submission the misuse of experimental data in the Stern report?
Omnologos: So for example if another summer like 2003 were to happen, I'm sure France would see far fewer dead among the elderly.
That's exactly what happened in the 2006 French heatwave. There were far fewer deaths than expected and this was put down to people having learned lessons from 2003.
Experimental evidence of significant elevated CO2 crop yield enhancement was clearly inconvenient for climate policymaking and messaging on CO2. To attempt to put a dampener on this the Royal Society convened a special meeting in 2005 called ‘Food crops in a changing climate’ organized by T. R. Wheeler, A. J. Challinor, J. M. Slingo and B. J. Hoskins, which appears to be themed in the vein of 'crop enhancement less than previously thought'. One of the main papers was by Long et al. (see below) along with modelling related papers by many familiar individuals, see
http://rstb.royalsocietypublishing.org/content/360/1463.toc
The following year, an international team of ten specialists in the field published a comprehensive and persuasive debunking of all of Long et. al.'s negative contentions about non-FACE experiments (Tubiello et. al., 2006). The summary of this is given in
http://www.co2science.org/articles/V9/N52/EDIT.php
Have I just spotted a spafty croonerism?
if anything the true data shows that you cannot take gambles with modifying the present fossil fuels economy. It looks like if we would reduce CO2 and it would still be warm for one of the myriad reasons there might be warming apart from anthropogenic, then there will be hunger?
can we risk this
Anonymous --
Thanks, and yes it is a hassle for those sans subscriptions to obtain the Wheeler original paper. £20 worth of hassle, to be precise, although one can have a one-day's peek for only £4. Many other papers are available with a little Internet trawling, such as Semenov's which I cited in the other post.
But I was quite wrong to guess in my earlier post at what the filled triangles mean, and now that I am aware of their significance, I agree that you are quite correct that it is a travesty to misrepresent Wheeler's results by selecting those points which correspond to low CO2 and high temperatures. It is another case of attempting to tell a "nice tidy story", and damn the facts.
Richard Betts proverbial challenge-
The fifth Labour of Heracles was to clean the Augean stables.This assignment was intended to be both humiliating (rather than impressive, as had the previous labours) and impossible, since the livestock were divinely healthy (immortal) and therefore produced an enormous quantity of dung. These stables had not been cleaned in over 30 years, and over 1,000 cattle lived there. However, Heracles succeeded by rerouting the rivers Alpheus and Peneus to wash out the filth.
Note the fifth labour.
HaroldW - quite right. Peter O'Neil and Pharos, thanks for the references, I will chase them up. Perhaps Wheeler was willing to recast the data in a form more amenable for the narrative in a later paper. But if Stern cited the original paper (and especially if he didn't cite the later papers too) then there remains no possible excuse for the graph in his report.
To this point, this new revelation of Stern's dishonesty is as depressing as it is unsurprising. As a child, I was reared on fables of good and evil; it seems that the battle between those two protagonists is eternal and wherever any evidence in any field of science that has been in any way touched by the UK Establishment is examined, it seems the likelihood of more dishonesty and corruption being uncovered is high. I once thought, like many with a sceptical view of the question of AGW, that people such as Stern were not evil, just wrong; current evidence would suggest that I and others of a like mind were far too generous in that assessment.
mmm...seems as if the CACC crew (bitthings etc) have no idea what to say about this....perhpas they can ask their freinds for ideas...no doubt Mr Connolley with his heavily subsidised (because he is a public-spirited chap and he knows you want to help him enjoy cheaper power) solar panels, busily making zero electricity, will be able to help you...
Figure 3 in the Wheeler et al. 2000 paper, mentioned by Peter O'Neill above, omits the unusual data point highlighted in the original post. No comment is made about the omission, leaving one to wonder if that experimental run was later found to be in error, incorrectly plotted, or simply omitted as an outlier. I looked for a Correction or other update in the Journal of Agricultural Science (where the original 1996 article was published) to no avail; however, such a small change might well not merit a published correction.
The Stern report contains no reference to Wheeler et al. 2000; only to Wheeler et al. 1996.
We have two main discussions here.
The first is about Stern's partial presentation of data in favour of his biased hypothesis. I don't think that that can be cleared even by a full flood of the Alpheus and Peneus rivers.
The second is about Wheeler's experiments. I have tried hard, but I fail to see how these experiments can say anything about crop yields in a hypothetical warmer climate, even assuming dumb farmers.
What Wheelers et al show is that wheat respond badly when their flowers are cooked. Every other phenology study shows that plant's flowering and crops have seasonal fluctuations in respond to climate variations, and if the trend is warming the crops compensate by advancing their cycles in the season. If you subject a mature plant to an extreme, short and unnatural heat shock at flowering time (anthesis), it is hardly a surprise than the plant is a bit unhappy about it. Still it only reduces yield, you subject it to the same amount of cooling and the harvest is lost.
Note the caption in the debated figure:
"Effects of differences in the maximum temperature (Tmax) in the 5-day period ending at 50% anthesis"
And note the axis: from 20°C to 45°C, when the mean outside temperature should be around 16°C
Note also that inside the controlled CO2 and temperature tunnels "mean transmission of solar radiation from sowing to maturity was about 65%" so there is only two thirds of energy available for photosynthesis compared with a normal crop. They mention photoperiod sensitivity, but they neglect to establish whether there is any link to these forced environmental variables.
The increase in temperature to offset CO2 gains is 1.8°C according to Wheeler 1996 but 4.5°C according to Goudriaan and Unsworth, 1990, so nothing conclusive yet, even neglecting the caveats above.
In Wheeler 2000 we read: "Of more importance for the yield of annual seed crops may be changes in the frequency of hot (or cold)
temperatures which are associated with warmer mean climates." There is no convincing evidence about this supposed variability.
Wheeler also gives modelling results, for a mean temperature increase of 4°C and a doubling of variability!
It is fine to speculate wildly in scientific hypothesis and it is fine asking as many what ifs as you like, but I doubt that in any other field of science you will see those wild speculations translated into economic and policy documents so easily.
Have you seen this research?
Xiao, G. Q. Zhang, Y. Li, R. Wang, Y. Yao, H. Zhao, and H. Bai. 2010. Impact of temperature increase on the yield of winter wheat at low and high altitudes in semiarid northwestern China. Agricultural Water Management, 97, 1360–1364.
Zeng, Q., B. Liu, B. Gilna, Y. Zhang, C. Zhu, H. Ma, J. Pang, G. Chen, and J. Zhu. 2011. Elevated CO2 effects on nutrient competition between a C3 crop (Oryza sativa L.) and a C4 weed (Echinochloa crusgalli L.). Nutrient Cycling in Agroecosystems, 89, 93–104.
Both featured by Pat Michaels on his blog http://www.worldclimatereport.com/index.php/2012/04/20/for-wheat-and-rice-co2-is-nice/
For Wheat and Rice, CO2 is Nice!
@Patagon
"What Wheelers et al show is that wheat respond badly when their flowers are cooked" - Spot on.
"If you subject a mature plant to an extreme, short and unnatural heat shock at flowering time (anthesis), it is hardly a surprise than the plant is a bit unhappy about it."
The only feature of the Wheeler et al research threads that I find perplexing is that they find early grain mortality at such relatively low temperature. I have spent hundreds of hours in polytunnels and glasshouses, interfering with the sex lives of barley and wheat. Whereas the heat was often an issue of personal discomfort, never did it appear to affect the success of seed set on the female parent plants - which means that pollen from the donors was fertile, stigmas receptive, grain set successful - almost certainly at temperatures in excess of 31°C for considerable periods.
Filbert
“I have spent hundreds of hours in polytunnels and glasshouses”
As an aside, did you notice any variance in the ‘greenhouse effect’ between them? I’ve spent some time in commercial glasshouses, but the temperatures there were often lowered by the transpiration of the plants, encouraged by hydroponic feeding and lots of extra CO2!
@James P
The noticable difference was humidity. At the time I am referring to, polytunnels were relatively crude and the only ventilation was provided by the doors. The tunnels had earth floors, the glasshouses were paved. The tunnels were often unbearbly "muggy", glasshouses more comfortable, with roof vents.
I was in a polytunnel during the (UK) summer, when a squall blew up, with rain, and the inside of the tunnel fogged. It took about two seconds - a weird experience.