Claim: Crop harvests in the US to suffer from climate change

So far, “global warming” has just devastated crop yields.

More modeling nonsense. CO2 is good for plants. The rest depends largely on technology.

The media release is below.

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Harvests in the US to suffer from climate change
POTSDAM INSTITUTE FOR CLIMATE IMPACT RESEARCH (PIK)

Some of the most important crops risk substantial damage from rising temperatures. To better assess how climate change caused by human greenhouse gas emissions will likely impact wheat, maize and soybean, an international team of scientists now ran an unprecedentedly comprehensive set of computer simulations of US crop yields. The simulations were shown to reproduce the observed strong reduction in past crop yields induced by high temperatures, thereby confirming that they capture one main mechanism for future projections. Importantly, the scientists find that increased irrigation can help to reduce the negative effects of global warming on crops – but this is possible only in regions where sufficient water is available. Eventually limiting global warming is needed to keep crop losses in check.

“We know from observations that high temperatures can harm crops, but now we have a much better understanding of the processes,” says Bernhard Schauberger from the Potsdam Institute for Climate Impact Research, lead author of the study. “The computer simulations that we do are based on robust knowledge from physics, chemistry, biology; on a lot of data and elaborate algorithms. But they of course cannot represent the entire complexity of the crop system, hence we call them models. In our study they have passed a critical test.” The scientists compare the model results to data from actual observations. This way, they can find out if they include the critical factors into their calculations, from temperature to CO2, from irrigation to fertilization.

Without efficient emission reductions, yield losses of 20 percent for wheat are possible by 2100

For every single day above 30°C, maize and soybean plants can lose about 5 percent of their harvest. The simulations have shown that the models capture how rather small heat increases beyond this threshold can result in abrupt and substantial yield losses. Such temperatures will be more frequent under unabated climate change and can severely harm agricultural productivity. Harvest losses from elevated temperatures of 20 percent for wheat, 40 percent for soybean and almost 50 percent for maize, relative to non-elevated temperatures, can be expected at the end of our century without efficient emission reductions. These losses do not even consider extremely high temperatures above 36°C, which are expected to lower yields further.

The effects go far beyond the US, one of the largest crop exporters: world market crop prices might increase, which is an issue for food security in poor countries.

Irrigation could be a means for adaptation – yet only in regions where there’s sufficient water

“The losses got substantially reduced when we increased irrigation of fields in the simulation, so water stress resulting from temperature increase seems to be a bigger factor than the heat itself,” says co-author Joshua Elliott from the University of Chicago. When water supply from the soil to the plant decreases, the small openings in the leaves gradually close to prevent water loss. They thereby preclude the diffusion of CO2 into the cells, which is an essential building material for the plants. Additionally, crops respond to water stress by increasing root growth at the expense of above-ground biomass and, eventually, yields. “Irrigation therefore could be an important means of adaptation to dampen the most severe effects of warming,” says Elliott. “However, this is of course limited by the lack of water resources in some regions.”

Burning fossil fuels elevates the amount of CO2 in the air. This usually increases the water use efficiency of plants since they lose less water for each unit of CO2 taken up from the air. However, this cannot be confirmed as a safeguard of yields under high temperatures, the scientists argue. The additional CO2 fertilization in the simulations does not alleviate the drop in yields associated with high temperatures above about 30°C.

The comparison of different computer simulations of climate change impacts is at the heart of the ISIMIP project (Inter-Sectoral Impacts Modelling Intercomparison Project) comprising about 100 modelling groups worldwide. The simulations are generated in cooperation with AgMIP, the international Agricultural Model Intercomparison and Improvement Project.

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9 thoughts on “Claim: Crop harvests in the US to suffer from climate change”

  1. Is it not true that the carbon dioxide hypothesis says that average night time temperatures will increase but average daytime temperatures will not be elevated significantly? I just looked up the average temperature for July and August in Lincoln, Neb and found that the average daily maximum was about 88 degrees F (31 C), but the average daily average was about 24 degrees C. It seems unlikely that any average daily temperature in the corn belt will exceed 30 degrees C even if the worst of the alarmist forecasts are true.

  2. Mike, Nice list but may I suggest alternative crops which do better when it gets hot. Also, thousands of commercially viable plants found in the world, and in your back yard, can be tapped as an alternative crop. It is what the pioneers and farmers did. The days of monoculture and GMOs may not help us through a warming trend, but man and nature always adapt.

    People have starved to death with plants which were edible next to them. I eat “weeds” which is nothing more than a neglected food source. When I was a kid, my grandmother made poke and dandelion salad, even though she had a farm growing corn, raising chickens, etc. They knew how to survive well. The wild greens were just adding to the table.

    1) plant earlier
    2) hybridize
    3) wheat, corn & soy bean are grown from Mexico to Canada
    4) not mentioned is sorghum
    5) curb food crop ethanol production
    add…
    6) Grow alternative crops & tap overlooked food crops
    7) Change the crop for the modified weather patterns

    Did this study take into account the types of crops, GMO v Non-GMO, native species, hybrids, etc. If not, then the study is flawed. We know from history that men adapted and found other crops. Sever freezes and droughts were the exception.

  3. Warmer climates have always produced more crops than cold ones. The real threat to agricultural production is land seizure for “recreation” or “environmental” or “historical” purposes. Our grassy steppes which constitute a lot of the world’s land surface are not prolific at producing food for humans and carnivores. Ruminants can convert grasses, which cannot feed people, into meat which is high in protein. In my lifetime, almost all of the famines where people died were man made famines, not climate caused.

  4. It is called extrapolating. For example : 59 years ago I weighed only about 10 pounds. Now I weigh 170 . Therefore by the year 2076 , I will weigh about 330 pounds and by 2135 I will weigh 660. Scientists could project that I will need to go on a diet……..

  5. I’m surprised they included maize (corn) in their list. Corn is a tropical plant that loves heat. If your growing season doesn’t have enough heat (measured in heat days) your crop will suffer.

  6. They claim: “The simulations were shown to reproduce the observed strong reduction in past crop yields induced by high temperatures,…”

    Reproduce what reductions? The same people claim the world has gotten hotter over the last several decades and crop production has quadrupled – not been reduced.

    They don’t expect anyone to really read their nonsense, as the MSM and politicians look at their headlines and summaries (all of which include the words “may” and “might” all over the place.)

  7. The real problem with this is one that besets much of alarmist forecast modeling: take a narrowly valid (if even that) fact and apply universally. Gives you an impressive result for news releases that have all the appearance to the science-challenged ignorant media and its audience of impending catastrophe.

  8. 1) plant earlier
    2) hybridize
    3) wheat, corn & soy bean are grown from Mexico to Canada
    4) not mentioned is sorghum
    5) curb food crop ethanol production

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