I started on this yesterday, had to put it aside for work, and I’m hugely busy today. Then I thought, you know, I have a whole army of people that can crowdsource an article, so why not ask them to help?
OK the premise starts with this press release:
Higher temperatures to slow Asian rice production
Production of rice will be thwarted as temperatures increase in rice-growing areas with continued climate change
Production of rice—the world’s most important crop for ensuring food security and addressing poverty—will be thwarted as temperatures increase in rice-growing areas with continued climate change, according to a new study by an international team of scientists.
The research team found evidence that the net impact of projected temperature increases will be to slow the growth of rice production in Asia. Rising temperatures during the past 25 years have already cut the yield growth rate by 10-20 percent in several locations.
Published in the online early edition the week of Aug. 9, 2010 in Proceedings of the National Academy of Sciences —a peer-reviewed, scientific journal from the United States—the report analyzed six years of data from 227 irrigated rice farms in six major rice-growing countries in Asia, which produces more than 90 percent of the world’s rice.
“We found that as the daily minimum temperature increases, or as nights get hotter, rice yields drop,” said Jarrod Welch, lead author of the report and graduate student of economics at the University of California, San Diego.
…
more here:
http://www.eurekalert.org/pub_releases/2010-08/uoc–htt080610.php
Problem is, I don’t quite believe this study, especially since the INTERNATIONAL RICE RESEARCH INSTITUTE shows this graph:
Average rice yield in the Philippines and a selection of
other rice-growing countries (tons per hectare) (Source: FAOstats)
Source: http://beta.irri.org/test/j15/index.php?option=com_content&view=article&id=393&Itemid=100104
I don’t know a thing about rice growing, but I figure some readers do. How can we have a temperature rise and CO2 rise in the past century and have 50 year increasing rice yields in the same Asian countries as the study?
Some other data:
http://asiapacific.anu.edu.au/newmandala/2009/09/10/more-on-thailands-low-agricultural-productivity/
http://beta.irri.org/test/j15/index.php?option=com_content&view=article&id=710&Itemid=100111
I can compile what readers find and post in comments and present it as a new article. Thanks for your consideration – Anthony
“I can compile what readers find and post in comments and present it as a new article. Thanks for your consideration – Anthony”
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I have a feeling that you won’t need to. But, it occured to me that someone can get a lot out of this piece and the comments you’ve generated and run with it as a rebuttal to the original. Only problem is, non-believers (infidels) don’t go far in psyence today; especially in the Coliseum of “Climate Warming Maximus” –too many lions and tigers and bears ripping you to shreds– as Mann-kind fiddles away the day.
Rice yields Indies.
http://i599.photobucket.com/albums/tt74/MartinGAtkins/Rice-Yield-Indies.jpg
It will be interesting to see what Willis Eschenbach has to say about the paper but it seems to me that any decline in rice yield growth is confined to local areas and is spasmodic. This indicates that local conditions prevail and any crop variance cannot be attributed to global warming. Indeed the exact opposite would seem to be true.
The paper is just speculating on future conditions based on the phony science of the IPCC.
What a great idea for a “science” blog – have your readers comment about the reliability of a paper that few, if any, have read because it is behind a pay wall! Sounds a little too Mannian for me – he didn’t need to read M&M to know they were wrong.
Sarcasm aside, an obvious first question is: What is the effect of minimum temperature on rice growing in a greenhouse where all variables except temperature are completely controlled? The introduction or discussion sections of Welch at al should inform you of the results of such studies. If increasing Tmin or at least Tmean isn’t already proven to have a negative effect in the relevant temperature range on the growth and yield of rice in the lab, it certainly doesn’t make scientific sense to look for effects in uncontrolled fields. However, there are plenty of studies that show that crops including rice have an optimum growth temperature, but I didn’t find any that distinguished Tmin from Tmax from Tmean. These papers also try to determine the mechanisms by which non-optimal temperature reduces growth.
An earlier study (not behind a pay wall) that reached the same conclusion as Welch et al can be found at: http://www.pnas.org/content/101/27/9971.full = PNAS (2004) 101, 9971-9975. From my perspective, their conclusion is flawed because the three years (of 11) with the highest Tmin and lowest productivity were also 3 of 4 years with the lowest sunlight. That paper provides some of limited references to laboratory studies where all variables except temperature are properly controlled.
From the supplemental data at http://www.pnas.org/content/suppl/2010/07/27/1001222107.DCSupplemental/pnas.201001222SI.pdf, Welch et al is clearly a far more serious attempt to resolve the contributions of various parameters that influence yields on real farms.
The results of Welch et al will mean little in the long run if rice strains with better tolerance of high Tmin already exist or can be easily developed. The differing strains of rice used on the farms studied by Welch may already vary in their tolerance to high Tmin.
Dave F says: August 10, 2010 at 8:07 pm
“If daily maxima/minima are so important, why do they not run the simulations this way instead of averaging?”
They do, but for some reason forget to emphasise that the models themselves are predict most of the ‘average’ increase is due to higher minimum temperatures at high latitudes.
Common sense suggests it is pretty hard to increase the temperature significantly in the high humidity tropics anyway. And predicting 3 degrees C nighttime temperatures rather than 2 degrees for the typical UK winter evening isn’t very scary.
E.M.Smith says:
August 10, 2010 at 10:22 pm
>Steve in SC says:
>> Economists have no knowledge of agriculture.
>Can we lose the “economist bashing”? I am a California Economist
One thing that’s gone downhill on WUWT since the readership surge after Climategate is there seems to me a greater percentage of expert bashing and piling on to people others disagree with. The former comments are disrespectful, the latter are nearly content free.
Climate Science is too large a field for anyone to understand, but that’s also one of its attractions – Anyone can learn more about some niche than Nobel Laurate scientist (science prize, not just peace prize). Scientists focused on some small niche or a more general view will have gaps in their knowledge but still may have much to offer.
Blanket statements like yours with nothing to back it up don’t advance the discussion. Also, the readership at WUWT is large enough so that there’s like an existence proof that falsifies your hypothesis.
BTW, I suspect that given Chicago is home to both the Univ. of Chicago and the major commodities exchange, there are probably a lot of existence proofs there….
PhilJourdan says:
August 11, 2010 at 5:24 am
Randy, I was just going on the state’s claim. Which goes to show never trust a government claim. (No I do not live there either, but it is a nice place to visit).
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I thought you might have been quick on the trigger. I have experience doing that. No big deal. What is remarkable to me is the self-correcting ability of this forum. Sort of like science with looser hypotheses, instant publication (and criticism), and no funding. It’s not perfect here but it does work. Hats off to Anthony and crew.
There is several points to consider :
– how was built the set of 227 rice farm ? from statistical analysis of the population of each country or because IRRI or FAO follow them and have the data set from an another programm (including meteo datas) ?
– is this set representative of the whole farm of the area ? ( cultivated areas, technical practices, used varieties, climate, parasites, markets for farmers, costs for chemicals, …)
– other thing is to check how meteo datas were collected ? ( Anthony, you’re the specialist, 😉 )
http://www.pnas.org/content/suppl/2010/07/27/1001222107.DCSupplemental/pnas.201001222SI.pdf
Sure, a lot of things to check but whitout the whole paper … (model …) …
Good luck !