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Climate At A Glance Factchecks–Crop Production

March 23, 2020

By Paul Homewood



Second in the Climate Glance series.

There have been comments about the lack of detail and references, but there is a balance that needs to be struck between detail and readability to the wider public, who have no interest in the detail.

As Heartland note:

Climate At A Glance puts frequently argued climate issues into short, concise, summaries that provide the most important, accurate, powerful information.  The summaries are designed to provide a library of solid yet simple rebuttals so that legislators, teachers, students, and laymen can easily refute the exaggerations of the so-called “climate crisis.”

Facts, data, and perspectives are presented that put media scares in proper perspective

Today’s topic tackles the common misconception that global warming is reducing crop yields, and includes full references to the data quoted.

There is also a video link to the Heartland conference, where this topic is explored in more detail.


Bullet Point Summary:

  • As our planet gradually warms, global crop yields and crop yields across the planet are setting new records almost every year.
  • U.S. crop yields continue to grow, setting new records nearly every year.
  • Longer growing seasons, higher temperatures, and more atmospheric carbon dioxide are creating ideal crop conditions.

Short Summary: As global climate modestly warms, U.S. and global crop yields are setting new records almost every year. The same is true for nearly all other nations, too. Thanks in large part to longer growing seasons, fewer frost events, more precipitation, and the fertilization effect of atmospheric carbon dioxide, farmers are producing more food on less land, allowing them to feed a growing global population.

Crop Production Facts: The 2019 global crop year brought record production of the important cereal crops; corn, wheat, and rice. This builds on previous records set nearly every year during the past decade. Almost every important U.S. crop has set record yields per acre during the past three years (latest data for when this summary went to press in February 2020), with most of the top 10 years in yields-per-acre occurring during the past decade. For example, each of the three record-high corn yields have occurred during the past three years. Each of the five record-high rice yields have occurred during the past five years. Each of the past nine years have produced top-10 all-time wheat yields.

How Global Warming Benefits Crop Production: Global warming lengthens growing seasons, reduces frost events, and makes more land conducive for crop production. Global soil moisture has maintained pace or modestly improved as global temperatures have risen modestly, with greater oceanic evaporation leading to more global precipitation, especially during summer and fall crop seasons. Further, carbon dioxide greatly benefits crop production, as atmospheric carbon dioxide works as aerial fertilizer. Higher atmospheric carbon dioxide levels assist plant growth and resistance to drought and heat. It is for this reason that greenhouses often pump in elevated amounts of carbon dioxide.

Source: U.N. Food and Agriculture Organization:

More Information: Crop yields in
nearly every country
are growing, with many frequently
setting new records.



See the 19min mark and onward in the video linked above. The video is The Heartland Institute’s rebuttal to the United Nations’ 2019 Civil Society Conference.

  1. Immune to propaganda permalink
    March 23, 2020 11:29 am

    The whole climate crisis fakery has done so much damage and wasted so much time and money that when a ‘real’ crisis like Coronavirus comes along the western governments who have been tackling a non- problem are completely unprepared and the economy gets shut down. For me it highlights the madness of our political classes and the eco religion creating false gods.

  2. March 23, 2020 1:10 pm

    All life depends on plants. What temperature is best for plants?
    Greer and Weedon (2012) investigated the response of Semillon grown in conditions typical of the irrigated areas in inland Australia. Temperatures exceeded 35°C on at least 33% of the days peaking at 43°C. High transpiration rates required irrigation at up to 120 litres per vine per week. The authors found that the efficiency of photosynthesis in low light conditions was not related to temperature. As more light is available higher temperatures enable increased photosynthetic output. Simple enough. Light is required for photosynthesis, as is carbon dioxide and chemical reactions are temperature dependent. Under what circumstances does the plant perform best?
    1. The optimum temperature for photosynthesis of the Semillon leaves in the field was 25°C.
    2. At light saturation, the photosynthetic optimum increased to 30°C.
    3. CO2‐saturated photosynthetic rates were optimal between 35 and 40°C, as with olive trees.
    Greer. D.H. and Weedon. M.M., Modelling photosynthetic responses to temperature of grapevine (Vitis vinifera cv. Semillon) leaves on vines grown in a hot climate. Plant Cell and Environment, Volume35, Issue 6 June 2012 Pages 1050-1064.¬

  3. StephenP permalink
    March 23, 2020 1:27 pm

    When I started in agriculture back in the 1960s a good wheat field in the UK was 5 tonnes per hectare, now a good yield is 10 tonnes per hectare.
    The main reasons:
    Improved cereal varieties brought about by plant breeding
    Nitrogen fertilisers, and we now have to use added sulphur because the fallout of sulphur has declined so much
    Herbicides and fungicides
    However there is pressure on farmers to become more sustainable which in effect would mean stopping the inputs have increased yields and going back to the level of yields of the 1960s.
    The world relies on a rolling harvest around the world and on the whole a poor yield in one hemisphere is compensated by a good yield in the other.
    If both hemispheres have poor harvests then it makes large inroads into any carry-over stocks.
    A couple of months ago a think tank report suggested that the UK didn’t need a farming industry as we could import all the food we needed!
    That suggestion has been blown out of the water by recent events. Look at the speed the supermarket shelves have emptied.
    It is said that 3 days of empty shelves would lead to civil unrest.
    Water, food, sewerage, electricity/fuel and a good health service are the important factors in life, anything further is icing on the cake.
    These are certainly interesting times.

  4. Thomas Carr permalink
    March 23, 2020 6:56 pm

    The crop production statistic published by The Global Economy cited by Heartlands rebuttal seem so complete that any arguments put forward about crop reduction being attributed to global warming seem farcical. One can understand why the US had been getting so tired of funding the UN’s position on climate change.
    You will recall, Paul , when the most disastrous experiment in collectivisation ( a.k.a. socialisation) starved so many people. We were reminded recently that Singapore is said to have the cheapest food and has no agricultural industry wheres the supposedly self sufficient-in-food North Korea has the greatest food poverty.

  5. Joe Public permalink
    March 23, 2020 8:56 pm

    For those looking for a negative angle from that good news, here’s a clickbait headline I made earlier:-

    “Climate change linked to obesity increases.”

    Worldwide obesity has nearly tripled since 1975.

    In 2016, more than 1.9 billion adults, 18 years and older, were overweight. Of these over 650 million were obese.

    39% of adults aged 18 years and over were overweight in 2016, and 13% were obese.

    Most of the world’s population live in countries where overweight and obesity kills more people than underweight.

    40 million children under the age of 5 were overweight or obese in 2018.

    Over 340 million children and adolescents aged 5-19 were overweight or obese in 2016.

    If only there wasn’t so much food for them to stuff their faces with!

    • David virgo permalink
      March 24, 2020 12:23 pm

      Now I understand – it’s all a plan to reduce obesity: less CO2 means sicker plants, less food and therefore less obesity…

  6. March 24, 2020 4:08 am

    Another fact check
    Ocean acidification

  7. paul weldon permalink
    March 24, 2020 7:39 am

    Odd that one of the reasons given for increased crop production is more precipitation. Paul has posted many times showing that precipitation has not increased, and given data to support his statement. There are many arguments as to why rising temperatures are not increasing rainfall, one of the obvious and simple to comprehend ones being that if this is true, why do we have more rain in winter than in summer?
    The other obvious flaw in the summary is that most increase in yields is due to changes in farming practices rather than climate.
    I still believe that it is more convincing, even to the uninformed, to give reasons for assertions – they do not have to be complex or scientific. But just to make a contrary statement does nothing to convince the reader to change his/her mind.

    • March 24, 2020 10:11 am

      It’s certainly wetter in the US, which naturally they focus heavily on.

      Put another way, droughts used to be far more severe and extensive there

      • paul weldon permalink
        March 24, 2020 2:37 pm

        The USA and according to this reference, the rest of the world too. But not overall, some parts even with a falling trend. But a small fraction of an inch per decade? That is hardly going to make a difference! Do take a look at the drought graph, forget the trend and see the fluctuation. We seem to be around normal at present. Can one really say that this data backs up what is being stated?

      • paul weldon permalink
        March 24, 2020 6:53 pm

        Paul, try this one – the one I posted was for drought index.

        There are similarities. But you can get a different trend depending on where you start/finish. What is more relevant is the fluctuation. As you say, there are periods of higher rainfall, periods of less. My point was that these differences are going to have little or no influence on the increased crop figures. Neither do they support the opposite, that a changing g climate will decrease yields. Averages throughout the year will also be meaningless – the extremes will disappear and the drought after seeding or the heavy rainfall at harvest time will both have negative effects.

      • March 24, 2020 8:00 pm

        The difference is obvious. It was much drier pre 1970s, with many extreme drought years

        Also there is no evidence of rainfall being too extreme at harvest times.

      • paul weldon permalink
        March 24, 2020 10:22 pm

        I think you mean pre-1950s. My reference to harvest time is from personal experience. But USA is a large country – averages do not tell the whole story. Again the important point I was trying to make – has this increase in rainfall actually improved the yields (post 1950s)?

      • March 25, 2020 9:46 am

        No, the 1950s were probably even worse for drought than the 30s

        You are right about averages, BTW. It is something I have analysed in the past.

      • paul weldon permalink
        March 25, 2020 11:39 am

        This might demonstrate better the point I am trying to make:

  8. jack broughton permalink
    March 24, 2020 8:06 pm

    Looked at the EPA site mentioned by Paul Weldon. It is a typically obfuscating piece of work to make points that are almost entirely based on model predictions mixed with sense.

    Trends in anomolies are a particularly disingenuous device: as usual, the base point and error in the mean that is used are not mentioned, nor is the actual value of the mean in most cases. This is because the changes are such a small percentage of the mean that they would not be noticeable and would obviously be insignificant.

    These zealots also make statements such as the 10 hottest years have occurred in the last 20: absolutely obvious when the world is recovering from the LIA minimum, but part of the deliberate propaganda.

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