Climate model predictions are telling a consistent (if wrong) story

From AARHUS UNIVERSITY and the department of shredded wheat, comes this story. Maybe they should get out more.

Climate model predictions are telling a consistent story

Three independent methods of modelling climate change impact on yield display the same bleak tendency: When global temperature increases, wheat yield will decline. This is demonstrated in a study carried out by an international group scientists, including Professor Joergen E. Olesen and Postdoc Mohamed Jabloun from the Department of Agroecology at Aarhus University.

The good news is that the comparison of the three very different climate models allowed the scientists to be even more precise in their projections and enabled them to put more accurate figures on the relation between global warming and declining yields. The models unanimously demonstrate that for each 1°C that the global temperature increases, the global wheat production is projected to decline by an average of 5.7 percent.

Evidence-based action is necessary

The world population continues to grow and the standard of living continues improving. These two factors result in an increasing demand for food production. However, due to global warming we run the risk that food production decreases. Wheat is one of the world’s most important food crops and we face an important problem if yields fall concurrently with an increasing demand.

– When talking about global food security it is important to understand how climate change will impact crop production at a global level in order for us to develop fact-based mitigation and adaptation strategies, says Joergen E. Olesen.

Three ways to predict the future

The scientists compared three very different crop model types: grid-based, point-based and regression-based. The two first were simulation models while the third was based on statistical data analyses. Each type included a series of different models and thus included actual implementation of the model types.

A simulation model creates a model of reality based on the existing knowledge of reality. The model makes it possible to predict what will happen if some of the conditions/parameters are changed. Examples of input include facts on how crop growth periods and productivity react to temperature, precipitation and CO2 levels, and how evapotranspiration depends on temperature and atmospheric CO2 concentration. In such models you can tweak the temperature and find an answer to the question “What will happen if the global temperature increases by 5°C?”

Regression models use a statistical process for estimating the relationship between data. For instance, observed crop yield is statistically related to temperature and precipitation during the growing season. This estimated relationship can then be used to predict crop yield when temperature increases.

Grids, points and numbers

The grid-based model used by the scientists was based on the division of the world into geographical grid cells according to longitudes and latitudes. Together with climate and crop system data this division was used to estimate yields and production across the world in present production areas.

The point-based model applied data from 30 different locations (points) representing two thirds of the global wheat production. Results from these 30 locations were up-scaled to cover geographical areas with similar conditions.

The regression-based model was based on global and country-level data. This type allows for indirect effects such the impact of climate variation on crop pests and diseases, or crop adaptation to climate change.

Warmer regions suffer the most

Depending on the model in question, the expected wheat yield will decline between 4.1 and 6.4 percent with each 1°C global temperature increase. Warmer regions are most likely to experience the greatest decline in wheat yield.

This projected impact was similar for major wheat-producing countries such as China, India, USA and France but less so for Russia due to the generally cooler conditions of Russia’s wheat-producing areas.

– By combining several models we were able to improve the confidence of the estimates in relation to climate change impact on global food security, says Professor Joergen E. Olesen.

Read the scientific article “Similar estimates of temperature impacts on global wheat yield by three independent models” in Nature Climate Change here.


The models unanimously demonstrate that for each 1°C that the global temperature increases, the global wheat production is projected to decline by an average of 5.7 percent.

Perhaps these guys should look at some “evidence based action”, such as crop yields in the “hottest year ever”.


Meanwhile, there’s so much wheat, that prices have been dropping sharply:


The long term trend seems to favor warmer temperatures and more CO2. But what do I know, I’ve only got some graphs of actual data, while these guys have a unanimous consensus of three computer models.



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Hmmm, maybe they are holding their graphs upside down again ? Or they just need to come back down to real world once in a while…


When global temperature increases, wheat yield will decline.
Then hold them to that….
Since it ‘s obvious wheat yields have increased…..
…then it’s obvious they have been lying about temperature increase

Reasonable Skeptic

I like the way your think!

Bryan A

Here is one way to physically check if this is the case.
install 10 rows of greenhouses with ceiling irrigation sprays.
Increase enrich their environments with elevated CO2 levels.
Increase their temperature by single degree respectively so that greenhouse #1 is 50ppm above ambient levels and temperature is +1d above external levels through Greenhouse 10 that is 500ppm above ambient levels and temterature is maintained at + 10d above external temperature.
Plant the area in wheat and allow it to grow for a season then measure results.
This would give you the proposed Doubing of CO2 at worst case scenereo temperatures.
Unless this sounds too much like actual science and not enough like Climate Science


Testing has been done under differing CO2 and temperature regimes. Back in 1995, 700 ppm was found to increase winter wheat yield over then ambient CO2 concentration by 39%. Raising temperature by four degrees C over ambient lowered yield by 35%, but water was held steady, so no surprise there.
Of course, if average temperature increased that much, wheat could be grown a lot farther north.


Increased yield during a period of warming does not imply that warming is beneficial. Other factors can drive wheat yield up (technological advancements in harvest, better pest and disease management, genetic improvements, etc). The paper accounts for these factors, and still finds a negative effect of temperature on wheat yield, controlling for these other factors. So as long as the positive effects outpace the negative effects of climate change, then sure, nothing to worry about… but I wouldn’t count on it.


“Increased yield during a period of warming does not imply that warming is beneficial.”
Yes. As we all know, when the data doesn’t match the model, the data is wrong. You should simply ‘adjust’ the wheat yield data down to prove the model is correct.

george e. smith

What is the correct Temperature to set the globe to, to get maximum wheat. izzit the same temperature for most rice ??

Bill Treuren

There are a lot of places on earth still to cold for wheat.
Are these folks completely stupid or do they think we all are.

“Are these folks completely stupid or do they think we all are.”
I don’t know. How about we ask Obama and Jon Gruber.
I believe they believe they know the answer.

Once again they ignore history while trusting climate model predictions. From actual studies of NA wheat and grain production, researchers concluded:
“The historical record offers insight into the capability of agriculture to adapt to climatic challenges. Using a new county-level dataset on wheat production and climate norms, we show that during the 19th and 20th centuries North American grain farmers pushed wheat production into environments once considered too arid, too variable, and too harsh to cultivate. As summary measures, the median annual precipitation norm of the 2007 distribution of North American wheat production was one-half that of the 1839 distribution, and the median annual temperature norm was 3.7 °C lower.”
“The currently predicted changes during the next century will, in a sense, reverse the predominant historical path of the past two centuries by creating a warmer and wetter environment in the Plains and Prairies that will partially approach the conditions that existed in the Middle Atlantic region when it constituted the North American wheat belt.”

Under semi-official terminology those “predictions” are “projections.”

Bloke down the pub

I made a model once, it was by Airfix.

Pop Piasa

Ironic, but I used to assemble Revell brand models as an adolescent in the 60s. Not the same spelling but does remind me of Roger Revelle nowadays.

I made a bunch of model airplanes when I was airplanes kid. They looked liked they were flying. Then reality hit…none of them could fly.


Those pictures on the box were false advertising.

Pop Piasa

But model rockets (Estes) really did fly. They had to be too dangerous for 9-year-olds but we mowed enough lawns to go to the hobby shop and get some for July 4th. We had a blast chasing the parachutes. That was the space age at its best.
Oh, forgot about 5-cent balsa gliders with bottle-rockets taped to the fuselage launched off a 70-ft. cliff at the river’s edge.


I made a number of models, then strapped a Jetex motor to the bottom/top and boy did they fly.
Strapped them to Dinky/Matchbox cars and they flew as well.
Didnt work so well on the skateboard though

george e. smith

I wonder, is it that the Antarctic highlands are getting warmer than -94 deg. C , or is it that the sand in the north African Deserts is getting hotter than +60 deg. C
Because the global average doesn’t seem to be doing much of anything, and hasn’t done so for almost a couple of decades.

Bryan A

I made a model once too…Not sure what she is up to today though

Mark from the Midwest

In Sterling Colorado they had combines sitting idle for 15-20 minutes at a stretch because the equipment could not keep up with the off-loading. This from, July 22
“Colorado Wheat staff out in the eastern part of the state today saw lots of wheat piled on the ground. Elevators are reporting record production everywhere”


Piling on the ground is now often preferred to storage in elevators. If the wheat is to be stored long-term, it’s wrapped in plastic.
Apparently the modelers forgot to factor in that more CO2 means more wheat, it being a C3 plant.

Steve Lohr

Both wheat and corn is being stored on the ground as storage has fallen behind production. It is happening all over. That is good for about a year but that will change. Next year’s wheat production will be very low, if all stays as it is. Commodities prices are down. Acreage in wheat next year will probably break a record for lowest ever. All is not well on the farm. With less than 3 percent of our population producing food, it is a tenuous situation. Green meddling isn’t helping, as they all are experts with no contact with reality (as noted above). Every producer, from cattle to chickens, to wheat beans and corn, has some sort of “environmental” issue. Don’t need no stinkin’ issues, but that is the world we live in.


Ah, yes–models. Here’s what Patrick Frank, PhD thinks about “models” (he destroys GCM’s) :

george e. smith

One question about your model (GCMs) all 97 of them, or izzat 57 ??
Does your earthen planet rotate once in 24 hours, like ours does.
Question two/ why not and why would you expect your model to work then ??

Why isn’t the below enough to dissuade any reliance on climate models for economic disruptions to the current energy sector? Why did a large group of people in Australia recently suffer a monster blackout because of the implementation of “Green” energy solutions, if they did suffer it because of “Green” energy solutions, in light of the below? What am I missing?
In sum, a strategy must recognise what is possible. In climate research and modelling, we should recognise that we are dealing with a coupled non-linear chaotic system, and therefore that the long-term prediction of future climate states is not possible. The most we can expect to achieve is the prediction of the probability distribution of the system’s future possible states by the generation of ensembles of model solutions. This reduces climate change to the discernment of significant differences in the statistics of such ensembles. The generation of such model ensembles will require the dedication of greatly increased computer resources and the application of new methods of model diagnosis. Addressing adequately the statistical nature of climate is computationally intensive, but such statistical information is essential.


Hello Paul Ehrlich!


Probably the only read on Wired worth a revisit – Doomslayer vs Doomsayer!

Chris Wright

Thanks, that was very interesting.
Simon was actually slightly criticised in the piece by claiming that there were just ten extinctions per year (the doom mongers were claiming tens of thousands of extinctions per year).
Correct me if I’m wrong, but Willis (Where are the bodies?) came to the conclusion that (possibly for mammals and birds) the extinction rate peaked around 1900 and today the rate is – drum roll please – just one extinction per decade.
I also loved the bit about the bet between Simon and Paul Ehrlich. Needless to say, the doom monger massively lost the bet and he did pay up around $500.

Keith J

And Thomas Malthus 😉


Examples of input include facts on how crop growth periods and productivity react to temperature, precipitation and CO2 levels, and how evapotranspiration depends on temperature and atmospheric CO2 concentration. In such models you can tweak the temperature and find an answer to the question “What will happen if the global temperature increases by 5°C?”

They are getting precipitation levels from models. There’s a problem with that.
Back before they started adjusting the temperature record like crazy, the 1930s were hot and there wasn’t much precipitation on the Great Plains. It was reasonable to expect that more heat would lead to decreased precipitation. Now that the temperatures have been adjusted, and 2016 is the warmest year on record, there seems to be no correlation between temperature and precipitation. If the temperature goes up 5 deg. it could rain lots and transpiration would not be a problem. ROTFL


Yeah, when it is extremely hot, it is also extremely dry. What happened to 2016?


This year it’s been some of the best crops I’ve ever seen. Some parts have had some trouble getting them off because of a wet cool fall, and even early snow. However, for the most part it’s been good.

1) I doubt they factored in co2 because yields of crops for a 0.6C rise In temps has been +20-30% net improvement in yield since 1945 from co2 alone. It is hard to imagine that a 1C change which might come from another 100-200ppm of CO2 in the atmosphere would result in a DROP in yields. Greenhouses show crop yield improvements up to 1400 ppm for most agriculture.
2) as the Illinois data shows it’s just hard to beleive that temp increase will decrease productivity unless it is severe. 1C isn’t severe.
3) recent article showed contradicting the study above that all losses of yield due to heat is mitigated by plants increasing drought tolerance as co2 rises.
4) assuming we would grow in the same areas is stupid. If crop yields fell much we would be negligent not to use land farther north. Failing to do this would not be a negative of climate change but a negative of political stupidity. There is no shortage of land in cooler areas as most of the globe is covered in ice and snow and freezing.
5) of wheat is a problem for some reason economist discovered this idea of “substitution”. When something goes up in price or becomes more scarce we have an uncanny ability to find substitutions.
6) by the time we get another 1C of temp change which is going to take 140 years at current rates we will have so much food we likely will have an excess that we won’t even notice this decline. Even if it only takes 50 years we are on a path of growing food productivity from standard and other technical innovations that a 5% reduction would be negligible.
7) food production In developed countries is 2% of GDP. If wheat production dropped we could spend another 0.1% of GDP abd double it. This is simply NOT A PROBLEM. SORRY.


Quite right.
But the good Perfesser Olesen needs to stay employed until he is 65 or so [so much food, people are living longer!]. I have to goo 65 plus three months.
So, the good Perfesser – ignoring US [and UK, I hope] politics – looks to bolster his watermelon-friendly credentials.
Might a publication date before the US elections be tentatively surmised?

I have an uncle that used to work for Agriculture Canada breeding crops. They grew two seed crops per year at Indian Head, Saskatchewan, and two crops a year at the research station south of the Salton Sea in California. Two completely different climate zones. They grew many varieties of wheat and other cereal grains including small amounts of Teff, native to Ethiopia and Eritrea.
Somehow I can’t imagine that an “average” temperature change of a degree or so is going to make much difference in crop production given our adaptability. In fact, typically, we often have several degrees difference in the average year over year, month over month. Averages are meaningless in a lot of cases. Did the lows stay higher (beneficial to plants) or did the highs go really high and burn the crop … or???? What did they actually model?
Seems like a controlled experiment or “model” is very different from my snow covered fields in the real world of today.

Svend Ferdinandsen

Models and assumptions all over.
“and how evapotranspiration depends on temperature and atmospheric CO2 concentration.”
I believe evapotranspiration depends on temperature and humidity. I have never heard it depends on CO2, but i am not a climateer.


..IIRC, the more CO2 a plant has access to, the LESS water it needs for optimum growth…


More specifically, with higher CO2 concentration the stomata (tiny openings on plants used for gas exchange) do not have to open as wide to bring enough CO2 in. Smaller stomata (or fewer) means less water loss.

george e. smith

How’s the icebergs in Greenland, Svend, or did you move out of there to some warmer place ??


“…enabled them to put more accurate figures on the relation between global warming and declining yields.”
“Accurate” in what sense? Just because models may agree doesn’t mean they are accurate. Just because they can push nonsense numbers out to multiple decimal points doesn’t mean they are real.
Very intelligent people can be mind-numbingly stupid at times.


“Very intelligent people can be mind-numbingly stupid at times.”
Not “can be” : they are “bound to be”. Very intelligent people tend to be unhappy with reality and to have rather live in their own brain-construct fantasy-land, where they have complete control, escape ugliness, and indeed perform very well. Just fine as long as they either remember that it’s just fantasy-land (math, theoretical physics, …), or keep in touch with reality by engineering to real life the things they envisioned (inventions, show-business…). Too many of them forget these prerequisite and mistake their fantasy-land for reality, hence, turn stupid.


Hey, are you calling me stupid?

george e. smith

Define intelligent; if different from dumbass !


My brother has an IQ that puts him in the top 1%. On other hand, I’ve learned not to leave him alone with power tools.

george e. smith

He should take the test more often, then he would get into the top 0.1%
It’s a very stupid test anyway. Often the questions have more than one correct answer, and the examination writers don’t know that.

Accurate? I would think they developed very “precise” models but they may not even have been close to the target.

Bob boder

Funny when I look at a globe I see an awful lot of northern land mass, since will happen more towards the poles wouldn’t this add a lot of farmable land to the mix, so even if these models where correct (which actual evidence refutes) actual production because added aecrage would sky rocket.


Bolder Bob,
Remember it is a political land-grab by the watermelons.
Mitigation is explicitly ruled out of their belief system, I understand.

michael hart

How many different varieties of wheat are grown between the southern limit near Mexico and the northern limit in Canada? A poster here at WUWT gave the number a while ago. 11, or 17, or something like? Anyway, they are all chosen for their suitability for the local climate, hot to cold.
This is just another non-existent climate problem. Humans have already adapted.


There are more than 10,000 varieties of wheat in the world, with more released every year. Were GM wheat accepted, the number could soar.

In such models you can tweak the temperature and find an answer to the question “What will happen if the global temperature increases by 5°C?”
Well, this is called an invalid situational assumption – that those temps will be raised to that extent only as a result of increases in carbon emissions. Note that if carbon emissions can only account for 1 degree of warming (the more likely event) then there is no point to this study.
Also unlikely is that they can predict future precipitation any better than they can predict future anything. We know higher CO2 produces more crops, and warmer temps means a longer growing season, so apparently their entire conclusion is based upon their ability to predict all important precipitation. To my knowledge , no models have been able to do that.


The really stupid thing about such studies is that they assume that farmers will make no changes as temperatures rise. In reality, if temperatures did actually start to rise, farmers would grow different varieties of wheat, or change to other crops altogether.
Mexico can grow enough food to feed itself, and it’s noticeably closer to the equator than the US is.

The models unanimously demonstrate that for each 1°C that the global temperature increases, the global wheat production is projected to decline by an average of 5.7 percent.
“unanimously demonstrate that…production is projected to decline”
Can a model demonstrate a projection? It seems to me only time can do that.

My original draft asked what it means to say that a model has demonstrated a projection. I took it out, but I’d put it back in if I could.

Another case of computer models (and GIGO) all the way down.


If it keeps warming up, all us farmers will be broke raising these “invisible” bushels.
Wonder if the CBOT will take these fellers study seriously? The price of wheat should be $20.00 a bushel, don’t ya know? There is NO WHEAT to be had!!!
(Aw shucks, the reality of those invisible bushels feeding millions of invisible folks)

Mark Luhman

No model can project anything, it can only project the assumptions of the modeler nothing else! The question always remains is the modeler guesses any good? Too bad our educated idiots and the educated idiots in the media don’t understand this! My father axiom in life was “do you understand all that you know about this,”my axiom in life is, “if you ask the wrong question you will always get the wrong answer,” too bad most people ask neither question!

Hank Kimball

“When talking about global food security…”
Whenever I hear the term “food security”, I know I’m getting politics rather than science.

Dave Fair

Hank, as is for the word “sustainable” followed by any other word, such as: energy, farming, growth, etc.

Joel Winter

Whaddayaknow?! Our three Powerpoints turned out the same. Great minds really do think alike.
I built a lot of models when I was young. And most of the them turned out just like the picture on the box. These guys get to use super (expensive) computers to build theirs. All using the same plans it seems.

Peta in Cumbria

Pete puts on his Devil’s Advocado hat and, 2 points.
1. If a Warmist arrived here and pointed to a graph that ramped ever upward – I don’t need to say do I?
2. The Human Animal is not evolved to eat this stuff – we are fat eaters. Saturated fat.
Mother Nature tried to give us a clue about that by covering these vegetable seeds in an indigestible husk. But oh no, we humans are sooooo clever and invented processing (removal of the husk and grinding trhe grains) and also cooking, which turns indigestible starch into water soluble sugar.
Sugar is great because it releases Dopamine and makes us feel good. That’s for an hour or so till we fall asleep – our body’s protection system to stop us eating more of this nutrient free gunk.
And now in these modern times, we are all getting fat & flatulent, diabetic & stupid, lazy & argumentative while our immune systems are driven crazy by all these weird plant proteins and our own immune systems attack ourselves. Any proteins not thus attacked/cleared away clump together around our brain neurons and strangle them – thus driving us completely nuts.
Meanwhile unsaturated vegetable oils float around our bodies with their double bonds snapping open in all sorts of delicate places setting off cancers.
And The Solution to all our problems (Global Warming esp) is Eat More Vegetables.
Just as drunks support each other with the eternal refrain ‘Oh go on have another drink, it’ll make you feel better’
yeah right


As to the claim that we are designed to eat only meat. Compare our teeth to a dog or cats.


Auto, happy to eat pork, pasta, peas, parsnips, puddings and even pizza [and probably alternative alliterative alimentation].

This modelling buffoonery is seriously discrediting science. Models have their place, such as in trying to understand the complex dynamics of stellar atmospheres, and the game is to encode what you think you know and see how that works out against observation. Everyone understands that such things are massively non-linear and so you don’t expect to get it right but, who knows, perhaps there are islands of stability embedded within the chaos or some harmonic component which you might detect or whatever. As such it’s a worthwhile exercise and worth employing a few dedicated people to work on.
What you don’t do is claim that the models represent some sort of reality independent of the observational data and employ thousands working on them under the erroneous assumption that more = better. That part of the game has gone horribly, horribly wrong and for anyone who’s ever worked in coupled field non-linear modelling it is truly and buttock-clenchingly embarrassing to watch these halfwits take a wrecking ball to the scientific method.


Models are useful in that they can help you figure out what it is that you don’t know.

Dave Fair

Related: Why do we need 20-plus modeling groups worldwide if “it’s just physics?”

Declining wheat yields are idiocy beyond belief.
If it really gets warmer yields will increase. Every biologist knows that warmth, irrespective of more sunshine, helps plants grow faster, provided water and nutrients are not limiting factors. Unsurprising, because, as I learnt in high school, an extra 10°C will approximately double the rate at which a chemical reaction proceeds. Did these guys never study Chemistry 101?
With GMOs, yields will double, quadruple or more. Within 30 years we will be able to green nearly all the world’s deserts. Researchers have already designed a new metabolic pathway for synthetic life which has the potential to increase the photosynthetic rate by an order of magnitude and more. Current plant photosynthesis is actually very slow. Each RuBisCO reactive site does about 5 to 10 CO₂ molecule conversions per second. Snooze. Partly because binding site selectivity for CO₂ over O₂ is too low. So plants keep stomata open for long (to get more CO₂), so respiring too much water. A typical food plant needs 1 tonne of water per 1 kg plant weight. Add on nitrogen fixation for domesticated plants to this, and our grandchildren will witness blooming plant life in all earth’s arid regions. Imagine plants with nitrogen fixation, requiring only 100 kg of water per 1 kg of plant weight, doing photosynthesis ten times faster. This is my prediction, I’ll put money on this.
Their climate science is wrong too. I’m not surprised they blunder in their predictions.
Example GMOs of the future
1. Photosynthesis improved by 15% in Tobacco by accelerating recovery from photoprotection. Technique generally applicable to most, if not all, domesticated plants: Improving photosynthesis and crop productivity by accelerating recovery from photoprotection
2. Superwheat with yields boosted by 20% or more set to begin field trials: Do GMOs boost yields? ‘Superwheat’ set for field trials boosts harvests by 20%
3. New synthetic metabolic pathway invented using enzymes from all walks of life. Enzymes were often tweaked: A synthetic pathway for the fixation of carbon dioxide in vitro
4. Plant bacteria breakthrough enables crops worldwide to take nitrogen from the air


And what about warmer temperatures allowing two wheat crops per year (can you say, “winter wheat”) instead of one in colder climes? Not saying this is happening, but anyone grounded in the real world should consider the possible benefits of increased temps.

Not to mention opening vast stretches of currently useless tundra in Canada and Russia to cultivation. The shame is that CAGW is almost surely wrong. It would be a boon for humanity if it were true.

Keith J

Hypothesis valid as wheat is a C3 plant but ignores the disjunct nature of precipitation and average temperature with respect to soil temperature and planting date.
Here again, single factor ANOVA fails when it intersects chaos. Planting date and precipitation are far more important than air temperature. Look at the latitude range of wheat. Lower lats plant in the fall for winter wheat where higher plants in the spring.

Dodgy Geezer

….When global temperature increases, wheat yield will decline….
Yes. And when global temperature decreases, wheat yield will decline as well. That’s called ‘optimising your agriculture for the growing season. The assumption is that we have the optimum strategy at teh moment, and ANY change will diminish yield.
Of course, once we get a new temperature, we will re-optimise. And then yield will be better than before…


I love how they say “based on models” and follow it up with “evidence-based action” – as though the models are evidence!

Yes it’s funny but also deeply disturbing. The current trajectory of politicised science is to employ thousands of people creating and running models written expressly to support whatever the agenda du jour happens to be and it’s almost impossible to deflect simply because of the sheer volume of garbage output. The invariable defense from the establishment is of course that they have ‘overwhelming evidence’ but all of it is in the form of model output. This idea that output from unvalidated and unfalsifiable models coding untested assumptions represent evidence MUST be nipped off and buried forever in the ocean abyss where all of the global warming hides.

David S

Historical Wheat yields From the USDA:
Year Yield
Bushels / acre
1950 16.5
1960 26.1
1970 31
1980 33.5
1990 39.5
2000 42
2010 46.1
Data extracted from
So while temperatures and Co2 levels have been rising, the yields have also been rising.


Of course, CO2 is plant food !

Dr. S. Jeevananda Reddy

This is the Technology contribution.
At what costs?
Harm it created to environment!!!
If we account all these, then the best yield is 1950 yield only.
Dr. S. Jeevananda Reddy


For the global temperature to rise by 5º something globally incredible has to happen. Something so incredible that humans haven’t the capacity to cause it or prevent it. If something that incredible happens wheat will be the least of our worries. The premise of this study requires a world that is inconsistent with life as we know it and there would be so many challenges to focus on that picking out wheat yield from the full scope of things that would change is silly and borders on fear mongering.

Steve Case

…When global temperature increases, wheat yield will decline. …
Probably not true, but it doesn’t matter, at least for the United States, because:
Maximum summer temperatures have been declining for 80 years. For most states east of the Rockies the decline extends back to the 19th century.
The increase is in the minimum temperatures. The climate is getting milder. When our friends on the left tell us that extreme weather will be the new norm, they will have to talk about extreme mildness (-:

Clyde Spencer

It looks to me that the maximum Summer temperatures have been increasing since about 1965. As much as I’d like to believe your claim, cherry picking end-points opens you to criticism from alarmists AND those who are objective.

Steve Fraser

If all the data are shown, it is not cherry picking. Multiple analyses can be performed, for longer and shorter periods, as the analyst may desire. A curiosity would be to see if US wheat yields vary in parallel with the chart such as it is.

Steve Case

The data for each state was downloaded from NOAA’s Climate At A Glance and analysed to see how far back in time you could go and still find a negative trend for the Maximum temperature. Try it yourself, go to Climate at a glance and pick any one of those states in the Mississippi or Ohio River valley and select the Max Temp, 4 months ending in September and display trend. Nearly all of them trend negative since 1895. There isn’t any cherry picking here.


Clyde, did you not notice that it goes UP, then DOWN, then UP…? What comes next, UP or DOWN ?

Read Bob Tisdale’s book “Who Turned Down the Heat?”. He has examples of what the minimums (and extremes) have done. I see that in a number of places in Environment Canada Data also.
I have a little different take, the extremes are not as extreme (UHI, GW, Clouds – who knows?):
Just one example of many but 125 years of EC data on this location.

Pop Piasa

Well, of course the models are consistent, they all contain the same gross exaggeration CO2’s net forcing effect. Water vapor is the Elephant and the remaining GHGs are ants trying to steer it.

Caligula Jones

If you ate today, thank a farmer.
If cried yourself to sleep because you think that the world is going to end because of climate change, thank a computer modeller, a well-funded greenscare campaign and politicians who think you are as stupid as you appear to be.

Pop Piasa

A year of summer would be highly preferable to a year without summer from my view. Heres hoping that history doesn’t repeat itself soon.

Bruce Cobb

Let’s see; models based on flawed models, or reality. Which to choose? Life is full of difficult decisions.

Reasonable Skeptic

“When global temperature increases, wheat yield will decline. ”
Cool, so obviously models show that global cooling increases wheat yield right?

Ian Magness

“Arse University”
’nuff said.

James in Philly

I am not sure if scientists are not taught the meaning of words, but the better word choice would be as follows:
“The models unanimously PREDICT that for each 1°C that the global temperature increases, the global wheat production is projected to decline by an average of 5.7 percent.”
It would be even better yet if the scientists got the science right!

Robert from oz

Going by the logic we should get greater yields the colder it gets !

Clyde Spencer

A significant weakness in the statistical analysis (and probably the other models as well) by the authors is in using average temperatures. A single-killing frost arriving prematurely can decrease the yield, yet not show on the temperature average. The theory of AGW predicts that most of the warming should be occurring at night and in the Winter. I demonstrate that in my article: A slight increase in night-time temperatures will be benign, if not helpful, and crops (except Winter wheat) don’t grow in Winter. So, the mastication of the data by the authors simply confirms the old admonition — Garbage In, Garbage Out.


Practical farmers obviously know the extremes are bad, drought, early frost, hail, etc.
Here is a plot of extreme drought in the US.
The 1930s were by far the worst decade for extreme drought.


“The 1930s were by far the worst decade for extreme drought.”
And the 1930’s were by far the hottest decade from that time to today.
It’s ridiculous for the climate alarmists to claim the 21st century was as hot or as dry as the 1930’s.


I live in an ag area. The grain elevators are full. The farmer’s bins are full. They are piling the grain on the ground. They are filling these giant white Ag-Flex bags to store even more. This is true for corn, wheat, millet, sorghums, and oats. I heard today that there is a 4 year supply of wheat in the world.

Steve Fraser

Time to brew beer, anyone?




The Arctic is greening along with the rest of the planet. Greenies hate that.


I guess every unforseeable Arctic greening has its silver lining for these people. Ever more grants to study the looming whale/seal/polar bear obesity problem.


On the bright side, the “work” was done at a Danish university so probably I didn’t pay for any of it.


Sorry..That darn foreseeable climate change….


“Evidence-based action is necessary”
True but where is the evidence again? Oh your computer models? Forgive me but I though those were theoretical simulations. Dang!

Rhoda R

Why won’t people just farm in higher latitudes? Why won’t people change from wheat to corn or some other warm weather crop?


Agricultural field corn needs more water. Most crops are limited by growing season and water.


The Church of CACA claims, when it suits its adherents, that a warmer world will be and must be a wetter world, contrary to the evidence.
They can’t gin up Catastrophic Anthropogenic Climate Alarmism without the positive feedback effect of more water vapor in the air, hence presumably more rain.


Do they put the correct amount of dust in their models?
To reduce, yet more ,uncertainties!!! Clouds! Dust!
“The modeling showed that if dust had even relatively small impacts on sea surface temperatures, this could have pronounced impacts on precipitation and winds both in the north Atlantic and over North Africa,” McGee says. Noting that the next key step is to reduce uncertainties in the modeling of dust’s climate impacts, he adds: “We’re not saying, the expansion of monsoon rains into the Sahara was caused solely by dust impacts. We’re saying we need to figure out how big those dust impacts are, to understand both past and future climates.”
Read more at:


“We’re not saying, the expansion of monsoon rains into the Sahara was caused solely by dust impacts. We’re saying we need to figure out how big those dust impacts are, to understand both past and future climates.”
Someone has to break it gently to these guys that the science is settled.

The models unanimously demonstrate that for each 1°C that the global temperature increases, the global wheat production is projected to decline by an average of 5.7 percent
So why has that not happened over the past 150 years, while temperatures have gone up 1C?
Oh yes, our models cannot predict the past, but they for sure can predict the future.


Please don’t confuse polemicists with facts. If the facts disagree with the models, the models are right. Because otherwise, no money.
Global wheat production and yield have increased so spectacularly in the past 150 years in part because of warmer weather. Even limiting it just to areas already producing wheat then.


Chimp, you were almost right.
It should read ” if the facts contradict the models, then the facts must be disposed of”
Seems to be the way of the Global Warmist Religion.


I stand corrected.
Post-modern science, in which inconvenient truths must be disposed of.

So because all the other models have been BANG ON, we need to give credence to this?
Stealing money I say, stealing money…

Lil Fella from OZ

Food production and development never remains static. It improves. Don’t think they put that in their fractured models.

Where does the best wheat in the world grow? What is the climate like there?

Gareth–the best wheat for what? Hard wheat makes good pasta and bread, but lousy cake, which requires soft wheat. I think the growing requirements are different between the two types, too.


Not all wheat is created equal.
There are three basic types, to wit, hard, soft and durum. Do you want bread or pastry? Cakes or ale?
But the best wheat of all types is grown in the USA. We export wheat for spaghetti to Italy, because ours is better. We export wheat to Asia for noodles, because ours is better. Unfortunately for US growers, the strong dollar prices our varieties out of international markets.


The best wheat of all types is grown on “Chernozem” (see wikipedia), a byproduct of “extreme” climate (quite hot in summer, pretty cold in winter –killing pest and preventing quick rot, so roots turn into humus and fertilize following year crop). Found in USA, true, but also Canada, Ukraine, Russia, etc.

Derek Colman

I don’t believe it for a moment. Crop yields have continued to grow as the planet got warmer and CO2 higher. However should these scientists be right, maybe we should stop using 40% of the American grain crops to make biofuels to run our cars on.