from climaterealism
Author: H. Sterling Burnett
Our World in Data (OWID) publishes a series of articles written by Hannah Ritchie exploring the impact of climate change on crop production. Overall, these stories set the record straight, pointing to dramatic increases in yields of major crops due in large part to the fertilizing effects of carbon dioxide and modest warming; however, parts of the stories lapse into speculation that some crops are growing less than expected and they will decline in the future due to climate change. The latter claim is false and based on controversial computer model output and unreasonable beliefs about crop responses to modest temperature increases, rather than experience or data, which is what OWID should stand for.
Rich's series of articles, “Crop yields have increased dramatically in recent decades, but without climate change, yields of crops like corn would have increased even more,” “How will climate change affect future crop yields?” and “Climate Change “will impact food production, but there are steps we can take to adapt,” Overall, these are well-written, data-driven articles describing the beneficial impacts of current climate change on crop production, and modern agriculture There is huge potential for technology to penetrate more widely into developing countries. The only flaw in the article is that she cites unsubstantiated studies that rely on flawed climate model projections to speculate on what might happen to certain crops if temperatures rise, and what might happen in the future.
Rich's series starts from a solid foundation, noting the tremendous growth in cereal crops and regionally important staple crops. Rich wrote:
When considering the net impact of climate on food production, we need to consider three key factors: rising carbon dioxide concentrations, rising temperatures and changes in rainfall (which can lead to either too much or not enough water).
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Carbon dioxide helps plants grow in two ways.
First, it increases the rate of photosynthesis. Plants use sunlight to produce sugar from carbon dioxide and water. This process occurs faster when the amount of carbon dioxide in the atmosphere increases.
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Secondly, it means plants can use water more efficiently
Ritchie went on to detail how higher carbon dioxide concentrations can increase crop yields. it's a fact climate realism It has been pointed out before in over 200 articles, with some examples here , here and here . Data from the Food and Agriculture Organization of the United Nations (FAO) show that during the recent period of mild warming, yields and output of wheat, rice, corn and other top cereal crops have reached new highs.
- Cereal production increased by nearly 52%, with the latest production record set in 2022; and
- Cereal production increased by about 57%. (see picture below)
Rich expressed concern about three cereal crops, corn, millet and sorghum, claiming that without climate change their yields would increase even more, but this was a counterfactual analysis based on computer model predictions rather than data. She cites research showing that many of the areas where these crops are grown have already exceeded or are about to exceed their optimal growing temperatures, with each increase in the maximum optimal temperature range leading to lower yields. However, in the face of 1.3°C to 1.5°C warming over the past century, yields of these three crops have all experienced substantial increases in recent decades, both globally and in tropical developing countries in Asia and Africa, and she worries that Not fully benefiting from carbon dioxide fertilization.
Regarding corn, FAO data shows that between 1991 and 2022, global corn production increased by approximately 55%, and African corn production increased by approximately 49%.
FAO data for millets and sorghum are similar, with each crop showing large increases in production globally and across Africa and Asia during the past three decades of mild warming. (See picture below).
As discussed in more than 200 articles climate realismWhat is true for global cereal production also applies to most crops such as fruits, legumes, tubers and vegetables in most countries in the world. During recent climate changes, yields have reached record highs, food security has improved, and hunger and malnutrition have declined.
Ritchie cites studies that show yields of corn, millet and sorghum would be higher without climate warming, which has pushed temperatures outside of their optimal ranges in many growing areas — a problem that will only be solved in the future. will get worse if CO2 emissions are not limited – but this argument has many flaws. First, most corn, millet, and sorghum are grown across or near the equator. However, climate change theory suggests that the equatorial regions are least likely to experience significant temperature rises, and conversely, the regions closest to the poles are expected to see dramatic increases in temperatures. There was little or no increase in temperature in the relevant regions, meaning exceeding the optimal temperatures speculated by some scientists should not be a problem.
Second, Ritchie is right about precipitation changes reducing crop yields, but again, this shouldn't be an issue. Many of the areas in Africa and Asia highlighted by Ritchie experience cyclic and even seasonal droughts. As Ritchie points out, CO2 fertilization should benefit crops by allowing them to use water more efficiently and lose less water through transpiration. On the other hand, many countries in Africa and Asia rely on rainfall for crop production and have limited access to modern irrigation infrastructure. Here, climate change helps because most studies show, and the IPCC predicts, that climate change will lead to increased precipitation, which means more water is needed for crops, which can be achieved if the water is seasonal like it is in many countries. Stores more water for use when rain or snow falls.
Third, the idea that climate change is harming crops is theoretically contradictory. Climate alarmists claim that rising carbon dioxide concentrations are driving rising temperatures – and if so, then rising temperatures are a by-product of rising carbon dioxide levels, meaning that without carbon dioxide, temperatures may not be rising. However, carbon dioxide is a key factor in driving crop yield growth, so without an increase in carbon dioxide, crop yields will increase but growth will continue to slow (if at all). According to this theory, if you want CO2 fertilization to benefit, you have to accept a moderate increase in temperature. Lowering CO2 levels to avoid minimal warming is tantamount to killing the golden goose of crop yields, causing yields to fall more sharply or grow more slowly, rather than the small yield declines caused by the associated hypothetical small warming.
What are we left with. As carbon dioxide levels rise, crop yields increase, reducing hunger in the process. Furthermore, there is no reason to believe that CO2 fertilization will not continue to increase yields in the foreseeable future unless climate policies lead to lower CO2 concentrations.
On the other hand, as Ritchie points out, any foreseeable negative impact of climate change on crops, especially development China's crops will be far offset. As Rich writes:
[T]There are other steps we can take to mitigate this risk and offset some of these pressures.
Huge production gaps still exist around the world today. The “yield gap” is the difference between the yields farmers are currently getting and what they could get if they had access to the best seeds, fertilizers, pesticides, irrigation and existing practices.
Let’s take Kenya and corn as an example. Farmers currently plant about 1.4 tons per hectare. However, researchers estimate that if farmers had access to today's best technology and practices, they could achieve a yield of 4.2 tonnes. This implies a production gap of 2.8 tonnes. …
Under some of the worst climate scenarios, Kenya's corn yields could decline by 20% to 25%. If there are no other changes, the current output of 1.4 tons will be reduced to around 1.1 tons: a decrease of 0.3 tons.
However, the current production gap of 2.8 tons is much larger than the 0.3 tons production decline caused by climate change.
However, modern agriculture relies heavily on the use of fossil fuels: chemicals used to promote crop growth; chemicals used to protect crops from pests; and machinery used to plant, water, harvest, store and transport crops. Therefore, for agriculture, any possible negative impacts of climate change arising from the use of fossil fuels in agriculture are far outweighed by the huge direct benefits of fossil fuel use to food producers and consumers.
High yields would not be possible without carbon dioxide and modern fossil fuel-intensive agricultural infrastructure. This is the overall lesson readers should take away from Ritchie's “Our World in Data” series.
H. Sterling Burnett
Dr. H. Sterling Burnett is director of the Arthur Robinson Center for Climate and Environmental Policy and editor-in-chief of Environment and Climate News. In addition to directing the Heartland Institute's Arthur B. Robinson Center for Climate and Environmental Policy, Burnett brings together environment and climate news and is editor of the Heartland Climate Change Weekly email, as well as Environment and Climate Host of a news podcast.
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