I just submitted my MSc thesis studying crop treatments for drought resilience. Plant breeding for drought tolerance has been hit or miss. Some real success in barley (deeper, stronger root systems), but in general, plants need an irreducibly similar amount of water in their growth phase, and the optimal breeding strategy has been to optimize for yield in well-watered conditions, because this also increases yield under water stress. A lot of things that you think would improve drought tolerance actually decrease yield because they accelerate lifecycle or divert growth at the expense of yield. Transgenic approaches have been a notable failure, even Monsanto Droughtgard for Maize - which appears to only protect against water stress during a very specific part of the Maize lifecycle. Its an extremely complex problem and there doesn't seem to be any popular science content that explains it well - I had to read like 300 papers to get the landscape.
That makes sense, relentlessly selecting or engineering strains solely on yield for current climate in current markets is likely to decrease performance in other dimensions.
I wonder what new things could be done to boost yields in Africa. With the exception of South Africa and Egypt,
Farm yields for most cereals on the continent are terrible.
Vast majority of African farmers are subistent farmers with low fertilizer use, irrigation systems, or mechanization. We have seen USAID, African VC backed agri firms and government led domestic policies try to improve yields but average yields per hectare is still abysmal. I wonder if it is a soil quality issue..
It is a soil quality issue - tropical temperatures result in very active soil microbial communities who convert organic matter very rapidly. This reduces the "cation exchange capacity" of the soil which means that N fertilizer tends to leach out quickly when it rains. Or due to the higher temperatures, it volatilizes much more easily into ammonia - leaving much less for crops.
Would you know how India, Indonesia, Bangladesh, Sri Lanka, and Vietnam managed? Their yields are much higher per hectare. Indonesia's average is over 5T per hectare and Sri Lanka is 4.5T
I'm not an expert on tropical soils, but I think only Indonesia is a tropical (as opposed to sub-tropical) soil and many of the soils there have the same problem as African soils and require a lot of fertilizer and calcium amendment to be productive. On the other hand there are some volcanic soils that have better levels of cation exchange capacity: https://www.jircas.go.jp/sites/default/files/publication/tars/tars24-_69-78.pdf
That’s interesting, but what explains the 3-5 x higher cereal yields in Mexico, India and Brazil compared to Nigeria, which have similar tropical temperatures?
For India and Brazil you have to look at the cereal growing regions for both - those are in Southern Brazil and Northern India - again much different temperature range than Nigeria.
When I was in the tropical parts of Africa where there's plenty rain, much of the calories for poor people came not from cereals but from plantain, either steamed or deep-fried in palm oil - was really good too!! Eaten with beans, was nutritionally excellent too.
I would guess there's decent investment in improving yields for palm oil (which is already very high), though perhaps more for the varieties that grow in Indonesia, and less sure for plantain, kassava, sorghum and other crop that do well there. Also not sure those are still popular foods.
Yes, there is some palm oil investment, but most palm oil in Africa is imported from Malaysia or Indonesia.
I'm Ghanaian, and yes we make palm oil and have palm nut soups and plantain dishes with palm oil (one is called red-red), but most of the palm oil we get comes from those South Asian countries because we don't produce enough. When Ghana faced a foreign currency shortage last year (and this year), palm oil prices exploded through the roof since we couldn't import palm oil from abroad, and there isn't enough domestic producers.
Very cool data source, thanks! I am shocked that Cameroon is not a large exporter, much of the northern coast there is basically an endless sea of oil palm.
Oooh! Red-red was good!! Thanks for making me remember.
Do rising CO2 levels increase agricultural output measurably? They certainly do in greenhouse experiments, but can this be a counterweight to production decreases from other climate change effects?
The interactions of temperature, soil moisture and CO2 levels make forecasting future crop yield responses under climate change technically challenging and results from experimental simulation and statistical modeling vary widely. For example, in a well-controlled growth chamber study of wheat response under Representative Concentration Pathway (RCP) 8.5 temperature and CO2 levels, crop lifecycle shortened appreciably but yields were not affected, and one of the study’s cultivars had approximately 25% higher yield under simulated climate change (Sabella et al., 2020). Conversely, a meta-analysis of 91 statistical studies of crop response after adaption, found a mildly negative mean yield response for most crops to climate change, but the variance of response across studies was extremely high. Yield responses for combinations of crop and region, ranged from more than 40% yield loss to over 40% yield gain under mean temperature increases of 1 oC to 5oC. (Challinor et al. 2014).
As ever a brilliant analysis. A factor which is also worth consideration when looking forwards is soil degradation from intensive farming. This may reduce the availability or productivity of land. This further increases the need for better varieties with higher yields.
Good point, though perhaps better agricultural practice for soil conservation, and legislation where business can increase profit not too long term by doing so, are just as important.
I appreciate your focus on resilience. The vast majority of the focus in climate change discussion is on the increased hazard risk of rising CO2. But historically resilience to weather-related events is what has saved lives.
I believe that as long as we keep innovating new agricultural technologies, the world will be able to keep increasing agricultural production on fewer acres of land regardless of future temperatures.
In particular, we need to innovate new agricultural technologies that work in Sub-Saharan Africa, which got passed up by the first Green Revolution.
Thanks as usual for your insightful analysis. However, I’m struck by your choice of crops to use as examples in the the data on increasing yields of most crops; although giving a nod to the risk of land expansion and deforestation as a potential method for increased supply, the example crops - rice, wheat, and to a somewhat lesser extent corn - are not known to be the most at risk for land use expansion. I’d love to see the same data for crops widely associated with deforestation such as palm oil, cocoa, coffee and soy to see yield improvements of those crops as I am not aware of great improvements for those crops. I suspect the potential for yield improvements as the explanation for increased supply varies between crops and the connection between rising supply and deforestation also varies.
Isn't "modern agriculture" more or less equivalent to "nearly exclusive use of Roundup Ready crops"? Monsanto/ Bayer held the line for awhile by funding scientists but now the bill is coming due via the court system, where alleged cancer may make it harder for this model to continue. Will an alternative to that cropping system be found or society come to accept the increasingly common cancer associated with glyphosate poisoning?
The US EPA says there is no link between glyphosate and cancer in humans. Lawsuits decided by non scientific juries with sympathetic cancer patients and highly paid professional expert testimonies are not scientific proof of anything. Other studies show effects in animals only at extremely high unnatural levels of glyphosate. In any case, new technologies that use robotic sprayers to directly hit weeds with small doses of glyphosate will significantly reduce its use, as will laser based weed removal.
Agriculture is a sector of the economy where Green policies are very destructive. They still have not accepted the technologies of the Green revolution that dramatically increased global food production and virtually eliminated famines. And they are opposed to most new agricultural technologies.
How ironic that Greens oppose the Green revolution!
I see mainstream politics handing the climate issue to Greens - "you care so much, you fix it" - as a serious dereliction and failure of mainstream politics. It wasn't and isn't up to environmentalists but I think their influence over agricultural policies and direction - over any policies - is much less pivotal than the opponents of environmental policies, especially of climate action would have us believe.
Making what activists say or do that is wrong or gets up people's noses to justify and win support for passing over or denying what everything science based expert advice gets right has been an effective tactic; certainly easier to muster derisive opposition to extremists than opposition our leading science agencies.
"We want to produce more food with less land, which means higher yields." --> Not only. This could simply mean less meat. Don't forget that 3/4 of agricultural land is dedicated to the production of animal products, which only represent 18% of the calorie intake around the world. I know that you know that, Hannah, since you produced most of the OWID graphs related to that, I'm just a bit disappointed that you don't raise this key (and extremely straightforward solution) in this article, and that you prefer to insist on science or innovation. Also, you say that "Yields across the world have doubled, tripled, or more over the last 50 years". This is true, but mainly because of chemicals products and mechanization, which are at the centre of land erosion and the pollution of water sources. Overall, my impression is that your conclusion is that more engineering and technology is going to be the key, when in fact we just need more subsidies to encourage more people to manage smaller, less chemically dependent farms, (a lot) less meat, and farms that are oriented towards regenerating the land by planting trees, hedges, and working with nature, not against it via technology...
I would think crop yields are increasing due to economies of scale, polytunnels and to the use petrochemical fertilisers, pesticides and herbicides. I think that the nutritional content and healthy outcomes are probably inversely proportional to the increase in yield.
The graph from one world data excludes pasture for livestock; what would the increase in global increase in agricultural land look like with it? Over half of habitable land is used for agriculture and 77%. of that for animal agriculture. A conversion to plant based eating would free up 2/3rds of the land currently used for agriculture which could be forested. https://georgiedonny.substack.com/p/yet-another-unsuccessful-attempt Yes crop yields for some plants are increasing and others decreasing but the increase in drought, flood and high temperatures doesn't bode well.
I looked up some papers on CEC levels in African soils just for reference. In 5 Nigerian samples, CEC was between 2 and 4. By contrast, Irish (my home) soils - some of which are not so great - are an average of about 18 - and the best soils for arable farming (Rendzinas) are ~42 average.
Thanks for sharing these (conditionally) good news Hannah.
One big cushion we have I think is that most of these calories are lost in heating the bodies of cattle, right? I would like to hope if there's any large scale famine, people would be willing to swap their steaks for pork, chicken, or beans - although, come to think of, not so sure...
It would be really nice to visualise this issue in your bar graph of global food production, where the bars for each year of e.g. corn would stack-up direct human consumption colour-filled, edges and no fill for what goes to make beef, and within the latter the small part of calories from beef that human consume filled in blue.
It would clearly illustrate that risk of famine is more a question of food choices than increased yields.
I just submitted my MSc thesis studying crop treatments for drought resilience. Plant breeding for drought tolerance has been hit or miss. Some real success in barley (deeper, stronger root systems), but in general, plants need an irreducibly similar amount of water in their growth phase, and the optimal breeding strategy has been to optimize for yield in well-watered conditions, because this also increases yield under water stress. A lot of things that you think would improve drought tolerance actually decrease yield because they accelerate lifecycle or divert growth at the expense of yield. Transgenic approaches have been a notable failure, even Monsanto Droughtgard for Maize - which appears to only protect against water stress during a very specific part of the Maize lifecycle. Its an extremely complex problem and there doesn't seem to be any popular science content that explains it well - I had to read like 300 papers to get the landscape.
That makes sense, relentlessly selecting or engineering strains solely on yield for current climate in current markets is likely to decrease performance in other dimensions.
I wonder what new things could be done to boost yields in Africa. With the exception of South Africa and Egypt,
Farm yields for most cereals on the continent are terrible.
Vast majority of African farmers are subistent farmers with low fertilizer use, irrigation systems, or mechanization. We have seen USAID, African VC backed agri firms and government led domestic policies try to improve yields but average yields per hectare is still abysmal. I wonder if it is a soil quality issue..
https://ourworldindata.org/grapher/cereal-yield
https://open.substack.com/pub/yawboadu/p/east-asia-vs-african-development-05a?r=garki&utm_campaign=post&utm_medium=web
It is a soil quality issue - tropical temperatures result in very active soil microbial communities who convert organic matter very rapidly. This reduces the "cation exchange capacity" of the soil which means that N fertilizer tends to leach out quickly when it rains. Or due to the higher temperatures, it volatilizes much more easily into ammonia - leaving much less for crops.
Would you know how India, Indonesia, Bangladesh, Sri Lanka, and Vietnam managed? Their yields are much higher per hectare. Indonesia's average is over 5T per hectare and Sri Lanka is 4.5T
I'm not an expert on tropical soils, but I think only Indonesia is a tropical (as opposed to sub-tropical) soil and many of the soils there have the same problem as African soils and require a lot of fertilizer and calcium amendment to be productive. On the other hand there are some volcanic soils that have better levels of cation exchange capacity: https://www.jircas.go.jp/sites/default/files/publication/tars/tars24-_69-78.pdf
Thank you so much for this explanation!
That’s interesting, but what explains the 3-5 x higher cereal yields in Mexico, India and Brazil compared to Nigeria, which have similar tropical temperatures?
https://ourworldindata.org/explorers/crop-yields?facet=none&country=IND~NGA~BRA~MEX&hideControls=false&Crop=Cereals&Metric=Actual+yield
Mexico doesn't really have similar tropical temperatures as Nigeria - take a look at the annual temperature ranges:
https://climateknowledgeportal.worldbank.org/country/nigeria/climate-data-historical
https://climateknowledgeportal.worldbank.org/country/mexico/climate-data-historical
For India and Brazil you have to look at the cereal growing regions for both - those are in Southern Brazil and Northern India - again much different temperature range than Nigeria.
When I was in the tropical parts of Africa where there's plenty rain, much of the calories for poor people came not from cereals but from plantain, either steamed or deep-fried in palm oil - was really good too!! Eaten with beans, was nutritionally excellent too.
I would guess there's decent investment in improving yields for palm oil (which is already very high), though perhaps more for the varieties that grow in Indonesia, and less sure for plantain, kassava, sorghum and other crop that do well there. Also not sure those are still popular foods.
Yes, there is some palm oil investment, but most palm oil in Africa is imported from Malaysia or Indonesia.
I'm Ghanaian, and yes we make palm oil and have palm nut soups and plantain dishes with palm oil (one is called red-red), but most of the palm oil we get comes from those South Asian countries because we don't produce enough. When Ghana faced a foreign currency shortage last year (and this year), palm oil prices exploded through the roof since we couldn't import palm oil from abroad, and there isn't enough domestic producers.
If you look at this chart here:
https://oec.world/en/profile/hs/palm-oil
Ghana imports $290M, exports $78.9M
Togo imports $330M, exports $46M
Nigeria imports $570M , exports $1M
Kenya imports $1.3B, exports $130M
Other cereals that Africans don't make enough, but are staples include rice and couscous.
Very cool data source, thanks! I am shocked that Cameroon is not a large exporter, much of the northern coast there is basically an endless sea of oil palm.
Oooh! Red-red was good!! Thanks for making me remember.
Do rising CO2 levels increase agricultural output measurably? They certainly do in greenhouse experiments, but can this be a counterweight to production decreases from other climate change effects?
The interactions of temperature, soil moisture and CO2 levels make forecasting future crop yield responses under climate change technically challenging and results from experimental simulation and statistical modeling vary widely. For example, in a well-controlled growth chamber study of wheat response under Representative Concentration Pathway (RCP) 8.5 temperature and CO2 levels, crop lifecycle shortened appreciably but yields were not affected, and one of the study’s cultivars had approximately 25% higher yield under simulated climate change (Sabella et al., 2020). Conversely, a meta-analysis of 91 statistical studies of crop response after adaption, found a mildly negative mean yield response for most crops to climate change, but the variance of response across studies was extremely high. Yield responses for combinations of crop and region, ranged from more than 40% yield loss to over 40% yield gain under mean temperature increases of 1 oC to 5oC. (Challinor et al. 2014).
As ever a brilliant analysis. A factor which is also worth consideration when looking forwards is soil degradation from intensive farming. This may reduce the availability or productivity of land. This further increases the need for better varieties with higher yields.
Good point, though perhaps better agricultural practice for soil conservation, and legislation where business can increase profit not too long term by doing so, are just as important.
I appreciate your focus on resilience. The vast majority of the focus in climate change discussion is on the increased hazard risk of rising CO2. But historically resilience to weather-related events is what has saved lives.
I believe that as long as we keep innovating new agricultural technologies, the world will be able to keep increasing agricultural production on fewer acres of land regardless of future temperatures.
In particular, we need to innovate new agricultural technologies that work in Sub-Saharan Africa, which got passed up by the first Green Revolution.
Thanks as usual for your insightful analysis. However, I’m struck by your choice of crops to use as examples in the the data on increasing yields of most crops; although giving a nod to the risk of land expansion and deforestation as a potential method for increased supply, the example crops - rice, wheat, and to a somewhat lesser extent corn - are not known to be the most at risk for land use expansion. I’d love to see the same data for crops widely associated with deforestation such as palm oil, cocoa, coffee and soy to see yield improvements of those crops as I am not aware of great improvements for those crops. I suspect the potential for yield improvements as the explanation for increased supply varies between crops and the connection between rising supply and deforestation also varies.
Ourworldindata has these, and yields are increasing in most locations.
https://ourworldindata.org/crop-yields
Isn't "modern agriculture" more or less equivalent to "nearly exclusive use of Roundup Ready crops"? Monsanto/ Bayer held the line for awhile by funding scientists but now the bill is coming due via the court system, where alleged cancer may make it harder for this model to continue. Will an alternative to that cropping system be found or society come to accept the increasingly common cancer associated with glyphosate poisoning?
The US EPA says there is no link between glyphosate and cancer in humans. Lawsuits decided by non scientific juries with sympathetic cancer patients and highly paid professional expert testimonies are not scientific proof of anything. Other studies show effects in animals only at extremely high unnatural levels of glyphosate. In any case, new technologies that use robotic sprayers to directly hit weeds with small doses of glyphosate will significantly reduce its use, as will laser based weed removal.
https://www.epa.gov/ingredients-used-pesticide-products/glyphosate
Agriculture is a sector of the economy where Green policies are very destructive. They still have not accepted the technologies of the Green revolution that dramatically increased global food production and virtually eliminated famines. And they are opposed to most new agricultural technologies.
How ironic that Greens oppose the Green revolution!
Not all “greens” are opposed to climate- and ag-tech. There’s much nuance to the conversations about trade offs in agriculture.
1) No, not all of them, but the vast majority are.
I am happy to agree with the very few who are and would encourage them to drop out of the Green movement.
2) Those that do are often attacked by more ideologically pure Greens.
3) The primary opposition to the Green Revolution comes from the Greens.
4) No other major political group consistently organizes against the extension of the Green Revolution
5) There is very little nuance in the agricultural policy when it comes to Greens (that goes for energy policy as well).
I see mainstream politics handing the climate issue to Greens - "you care so much, you fix it" - as a serious dereliction and failure of mainstream politics. It wasn't and isn't up to environmentalists but I think their influence over agricultural policies and direction - over any policies - is much less pivotal than the opponents of environmental policies, especially of climate action would have us believe.
Making what activists say or do that is wrong or gets up people's noses to justify and win support for passing over or denying what everything science based expert advice gets right has been an effective tactic; certainly easier to muster derisive opposition to extremists than opposition our leading science agencies.
I have no idea what your point is, or how it relates to my comment…
Brilliant, as always, Hannah. I await the Climate Doomers to descend and attack you for defaming their dogma.
BTW, have you seen: https://www.politybooks.com/blog-detail/climate-change-isnt-everything-liberating-climate-politics-from-alarmism
"We want to produce more food with less land, which means higher yields." --> Not only. This could simply mean less meat. Don't forget that 3/4 of agricultural land is dedicated to the production of animal products, which only represent 18% of the calorie intake around the world. I know that you know that, Hannah, since you produced most of the OWID graphs related to that, I'm just a bit disappointed that you don't raise this key (and extremely straightforward solution) in this article, and that you prefer to insist on science or innovation. Also, you say that "Yields across the world have doubled, tripled, or more over the last 50 years". This is true, but mainly because of chemicals products and mechanization, which are at the centre of land erosion and the pollution of water sources. Overall, my impression is that your conclusion is that more engineering and technology is going to be the key, when in fact we just need more subsidies to encourage more people to manage smaller, less chemically dependent farms, (a lot) less meat, and farms that are oriented towards regenerating the land by planting trees, hedges, and working with nature, not against it via technology...
I would think crop yields are increasing due to economies of scale, polytunnels and to the use petrochemical fertilisers, pesticides and herbicides. I think that the nutritional content and healthy outcomes are probably inversely proportional to the increase in yield.
The graph from one world data excludes pasture for livestock; what would the increase in global increase in agricultural land look like with it? Over half of habitable land is used for agriculture and 77%. of that for animal agriculture. A conversion to plant based eating would free up 2/3rds of the land currently used for agriculture which could be forested. https://georgiedonny.substack.com/p/yet-another-unsuccessful-attempt Yes crop yields for some plants are increasing and others decreasing but the increase in drought, flood and high temperatures doesn't bode well.
The answer is not another green revolution which steals tomorrows genetic potential for today https://georgiedonny.substack.com/p/what-were-the-results-of-the-green
We need to eat less meat and dairy
I looked up some papers on CEC levels in African soils just for reference. In 5 Nigerian samples, CEC was between 2 and 4. By contrast, Irish (my home) soils - some of which are not so great - are an average of about 18 - and the best soils for arable farming (Rendzinas) are ~42 average.
Thanks for sharing these (conditionally) good news Hannah.
One big cushion we have I think is that most of these calories are lost in heating the bodies of cattle, right? I would like to hope if there's any large scale famine, people would be willing to swap their steaks for pork, chicken, or beans - although, come to think of, not so sure...
It would be really nice to visualise this issue in your bar graph of global food production, where the bars for each year of e.g. corn would stack-up direct human consumption colour-filled, edges and no fill for what goes to make beef, and within the latter the small part of calories from beef that human consume filled in blue.
It would clearly illustrate that risk of famine is more a question of food choices than increased yields.