Regarding food, you suggest that due to climate change, soil erosion, water scarcity, and phosphorus depletion, there are risks to the global food supply that could constitute a global catastrophe. What do you think is the probability of this occurring in the next 30 or 80 years?
I am sceptical of this. Crop yields for almost all crops have increased by 200% since 1980, despite warming of about 0.8 degrees since then. The crop effects of climate change you outline, which are typically on the order of up to 20% losses for major food crops at 5 degrees, should be set in this context. Various studies suggest that yield will increase by 25% to 150% by 2050. e.g UN FAO; Wiebe. The yield damage estimates you cite seem like they will be outpaced by technological progress unless there is a massive trend break in agricultural productivity progress.
On phosphorous, according to a report by the IFDC funded by USAID, global phosphorous reserves (those which can be currently economically extracted, so this is a dynamic figure) will last for 300-400 years. “Based on the data gathered, collated and analyzed for this report, there is no indication that a “peak phosphorus” event will occur in 20-25 years. IFDC estimates of world phosphate rock reserves and resources indicate that phosphate rock of suitable quality to produce phosphoric acid will be available far into the future. Based on the data reviewed, and assuming current rates of production, phosphate rock concentrate reserves to produce fertilizer will be available for the next 300-400 years.” The US geological survey says “World resources of phosphate rock are more than 300 billion tons. There are no imminent shortages of phosphate rock.”
On water scarcity, agriculture is about 4% of global GDP and declining. If water became enough of a constraint on agriculture to threaten a global catastrophe, why would we not throw some money or wisdom at the problem for example by spending more money on water, desalination, or stopping subsidising agricultural uses of water? Have any middle or high income countries ever failed to produce more than enough food because of lack of water?
On soil erosion, the UN report on soil says “A synthesis of meta-analyses on the soil erosion-productivity relationship suggests that a global median loss of 0.3 percent of annual crop yield due to erosion occurs.7 If this rate of loss continues unchanged into the future, a total reduction of 10 percent of potential annual yield by 2050 would occur”. again, this is in the context of otherwise increasing yields. Soil erosion rates are also declining in various regions.
I was researching the food security—climate link a couple of years ago for German policy-makers. Two findings stood out:
1. While climate has an effect on agricultural productivity, the effects of increasing yields and a decreasing rate of population growth will very likely lead to a less food-insecure future in terms of global food supply (in line with Halstead’s comment).
2. Obviously, this does not mean that climate change will not lead to famines in some places, but this will not be an issue of global insufficiency, but of unequal vulnerability and access.
I am very worried about the destabilizing effects of climate change because of mechanisms related to 2 and other indirect effects—the risk for civil strife, political instability, migration, knock-on effects etc.
But it seems very unlikely that climate change will cause a collapse of the global food system constituting a global catastrophe as a direct effect.
I would agree with that—climate change seems like it could have very bad humanitarian costs for poor agrarian societies that look set to experience low economic growth this century. I do though find it very difficult to see how it could lead to a collapse of the global food system
Thanks for the comment and these very useful links—will check with our food expert colleague and get back to you, especially on the probability question.
Just personally, however, let me note that we say that those four factors you mention are current ‘sources of significant stress’ for systems for the production and allocation of food—and we note that while ‘global food productivity and production has increased dramatically’ we are concerned about the ‘vulnerability of our global food supply to rapid and global disruptions’ and shocks. The three ways we describe climate change further reducing food security are growing conditions, agricultural pests and diseases, and the occurrence of extreme weather events.
Note also that the global catastrophe is the shock (hazard) plus how it cascades through interconnected systems with feedback. We’re explicitly suggesting that the field move beyond ‘is x a catastrophe?’ to ‘how does x effect critical systems, which can feed into one another, and may act more on our vulnerability and exposure than as a direct, single hazard’.
Note also that the global catastrophe is the shock (hazard) plus how it cascades through interconnected systems with feedback. We’re explicitly suggesting that the field move beyond ‘is x a catastrophe?’ to ‘how does x effect critical systems, which can feed into one another, and may act more on our vulnerability and exposure than as a direct, single hazard’.
My understanding is that we all agree on that (I certainly do). It just seems that the direct risk to food security is overstated in the article.
Thanks for sharing this.
Regarding food, you suggest that due to climate change, soil erosion, water scarcity, and phosphorus depletion, there are risks to the global food supply that could constitute a global catastrophe. What do you think is the probability of this occurring in the next 30 or 80 years?
I am sceptical of this. Crop yields for almost all crops have increased by 200% since 1980, despite warming of about 0.8 degrees since then. The crop effects of climate change you outline, which are typically on the order of up to 20% losses for major food crops at 5 degrees, should be set in this context. Various studies suggest that yield will increase by 25% to 150% by 2050. e.g UN FAO; Wiebe. The yield damage estimates you cite seem like they will be outpaced by technological progress unless there is a massive trend break in agricultural productivity progress.
On phosphorous, according to a report by the IFDC funded by USAID, global phosphorous reserves (those which can be currently economically extracted, so this is a dynamic figure) will last for 300-400 years. “Based on the data gathered, collated and analyzed for this report, there is no indication that a “peak phosphorus” event will occur in 20-25 years. IFDC estimates of world phosphate rock reserves and resources indicate that phosphate rock of suitable quality to produce phosphoric acid will be available far into the future. Based on the data reviewed, and assuming current rates of production, phosphate rock concentrate reserves to produce fertilizer will be available for the next 300-400 years.” The US geological survey says “World resources of phosphate rock are more than 300 billion tons. There are no imminent shortages of phosphate rock.”
On water scarcity, agriculture is about 4% of global GDP and declining. If water became enough of a constraint on agriculture to threaten a global catastrophe, why would we not throw some money or wisdom at the problem for example by spending more money on water, desalination, or stopping subsidising agricultural uses of water? Have any middle or high income countries ever failed to produce more than enough food because of lack of water?
On soil erosion, the UN report on soil says “A synthesis of meta-analyses on the soil erosion-productivity relationship suggests that a global median loss of 0.3 percent of annual crop yield due to erosion occurs.7 If this rate of loss continues unchanged into the future, a total reduction of 10 percent of potential annual yield by 2050 would occur”. again, this is in the context of otherwise increasing yields. Soil erosion rates are also declining in various regions.
I was researching the food security—climate link a couple of years ago for German policy-makers. Two findings stood out:
1. While climate has an effect on agricultural productivity, the effects of increasing yields and a decreasing rate of population growth will very likely lead to a less food-insecure future in terms of global food supply (in line with Halstead’s comment).
2. Obviously, this does not mean that climate change will not lead to famines in some places, but this will not be an issue of global insufficiency, but of unequal vulnerability and access.
I am very worried about the destabilizing effects of climate change because of mechanisms related to 2 and other indirect effects—the risk for civil strife, political instability, migration, knock-on effects etc.
But it seems very unlikely that climate change will cause a collapse of the global food system constituting a global catastrophe as a direct effect.
I would agree with that—climate change seems like it could have very bad humanitarian costs for poor agrarian societies that look set to experience low economic growth this century. I do though find it very difficult to see how it could lead to a collapse of the global food system
Thanks for the comment and these very useful links—will check with our food expert colleague and get back to you, especially on the probability question.
Just personally, however, let me note that we say that those four factors you mention are current ‘sources of significant stress’ for systems for the production and allocation of food—and we note that while ‘global food productivity and production has increased dramatically’ we are concerned about the ‘vulnerability of our global food supply to rapid and global disruptions’ and shocks. The three ways we describe climate change further reducing food security are growing conditions, agricultural pests and diseases, and the occurrence of extreme weather events.
Note also that the global catastrophe is the shock (hazard) plus how it cascades through interconnected systems with feedback. We’re explicitly suggesting that the field move beyond ‘is x a catastrophe?’ to ‘how does x effect critical systems, which can feed into one another, and may act more on our vulnerability and exposure than as a direct, single hazard’.
My understanding is that we all agree on that (I certainly do).
It just seems that the direct risk to food security is overstated in the article.
The factors you mention therefore seem to increase vulnerability, but merely in the following sense
Some of the factors don’t seem relevant at all (phosphorous depletion)
The food system will be much less vulnerable in the future vs today despite these factors.
Some other event would have to do 99% of the work in bringing about a global food catastrophe
Sorry its taking a while to get back to you!
In the meantime, you might be interested in this from our Catherine Richards: https://www.cser.ac.uk/resources/reframing-threat-global-warming/