This analysis brings together, for the first time, detailed modeling of crop growth under climate change with insights from an extremely detailed global agriculture model, using two climate scenarios to simulate future climate. The results of the analysis suggest that agriculture and human well-being will be negatively affected by climate change:There are a lot of differences between what IFPRI did and what we did. At its core, the IFPRI uses crop simulation models developed and used by agronomists. We looked at the raw data and did everything from scratch. IFPRI also looked at the whole world where we looked at just the U.S.. IFPRI then combined the agronomics with a lot of complicated economic modeling, and went on to predict price responses an adaptation effects.
- In developing countries, climate change will cause yield declines for the most important crops. South Asia will be particularly hard hit.
- Climate change will have varying effects on irrigated yields across regions, but irrigated yields for all crops in South Asia will experience large declines.
- Climate change will result in additional price increases for the most important agricultural crops–rice, wheat, maize, and soybeans. Higher feed prices will result in higher meat prices. As a result, climate change will reduce the growth in meat consumption slightly and cause a more substantial fall in cereals consumption.
- Calorie availability in 2050 will not only be lower than in the no–climate-change scenario—it will actually decline relative to 2000 levels throughout the developing world.
- By 2050, the decline in calorie availability will increase child malnutrition by 20 percent relative to a world with no climate change. Climate change will eliminate much of the improvement in child malnourishment levels that would occur with no climate change.
- Thus, aggressive agricultural productivity investments of US$7.1–7.3 billion are needed to raise calorie consumption enough to offset the negative impacts of climate change on the health and well-being of children.
Wolfram Schlenker and I are more "raw data" kind of folks and are nowhere near ready to make these kinds of broader predictions. But I do know these guys at IFPRI have been working hard on this stuff for a long time. Awhile back I presented our work at IFPRI and for awhile they seemed interested in our statistical approach to modeling yields. But ultimately I guess they found that for many countries it's hard to get the necessary high-quality data.
I can't claim to understand the details of their model. But from what I do know, their results smell about right to me...
Funny, it wasn't that long ago everyone was saying that, for the world as a whole, climate change would be a wash and maybe even good for agriculture. What's changed? Three key things:
1) A lot less optimism about the positive effects of CO2 fertilization.
2) A greater appreciation for the detrimental effects of extreme heat.
3) Steadily worsening predictions for the amount of warming that will take place.
Excellent post, but I might add that the benefit of "complicated" economic modeling (versus a pure statistical analysis) is that you can capture the fact that economic agents will adapt in myriad ways to new circumstances -- we are not fixed in our behaviors.
ReplyDeleteFor example, farmers may adapt to climate change by switching crops and livestock species; seed producers will develop new seeds that are resistant to extreme heat and drought; consumers will switch from one product to another; trade patterns will shift as different regions will differently; the volume of trade may increase.
I don't know if the IFPRI study allows for any of these responses, but this will surely be an immensely important component of how the food/agriculture system ultimately fares. I don't wish to downplay the threat posed by climate change, but things may not turn out to be as bad as they initially appear.
I'm Jerry Nelson, lead author of the IFPRI study. Some quick responses - we allow switching of crops, but not crop varieties which could potentially be important (crop varieties can have very different response to temp and precip patterns). We allow consumers and producers to respond to market prices. And we allow the volume of trade and for that matter the direction of trade flows to change.
ReplyDeleteHere are some things we don't do. We assume gdp and population growth are not affected by what happens in agriculture. We don't take into account variability in climate. We don't factor in glaciers melting and reducing the potential for irrigated agriculture in some places, and we don't account for sea level rise.
So, I would argue our results are conservative.
And some people have mistaken our $7 billion per year number to mean total ag. productivity investments of $7 billion. In fact, to meet the 50% increase in population between now and 2050, along with higher incomes in the developing world, we will need to spend a lot more on ag. productivity.
I'm happy to answer more questions at g.nelson@cgiar.org.
Regards, Jerry
I'm trying to pick favourite AGW-resistant commodities in my mind. Obviously not feeds. But maybe can do this after the fact of a crop failure. Slaughter the animals after a drought and then plant fewer feeds from now on.
ReplyDeleteWheat is most storable but a a recent paper says rice is more extreme temperature resistant while growing. And soybeans have all essential amino acids if AGW reduces diversity of food sources, for example if meats are scaled back. Cassava can be grown on marginal land and pasture land is marginal.
Strange creatures we are who use the 200 year old industrial revolution to undo the 6000 year old agriculture revolution.