Crop yields expected to decline earlier than previously thought

For me, the security of our food supply is one of the most significant of all the climate change impacts. Food shortages lead to famine which leads to mass migration and conflict. It is therefore important to predict how the warming planet will affect the yields of crops that we eat.

A paper published this week in Nature Climate Change finds that without adaptation, crop yields for wheat, rice and maize will start to decline from the 2030s onwards with the greatest impact in the second half of the century. This is much earlier than previously thought.

With adaptation however, these losses can be mitigated, particularly for rice and wheat, less so for maize. Adaption refers to changing farming practices to suit the new climate. This includes things like using different plant varieties, changing planting times, irrigation and also by changing crops altogether.

I’ve taken the following image from the paper. It shows crop yields for maize, wheat and rice in both tropical and temperate regions and the impact of temperature up to 5°C, with and without adaptation (click to view a larger version).

crops

What does this mean? The yields of all three crops decline as the temperature increases. With adaptation, though, these losses can be mitigated and in some cases reversed. Wheat performs best with adaptation in temperate regions and rice does best with adaptation in tropical regions. Adaptation seems to make little difference for maize in both temperate and tropical regions.

The Working Group II IPCC assessment is due to be released at the end of this month and its focus is on impacts, adaptation and vulnerability. The last Working Group II assessment was in 2007 and the outlook for crop yields has worsened since that report. The results of this paper will be a part of this next assessment.

What this paper highlights for me is how increasing temperatures are not necessarily good for the plants we eat and also how important adaptation is going to be.

5 thoughts on “Crop yields expected to decline earlier than previously thought

  1. There is already some impact. That is, the price of food is increasing, epecialy bread (in the UK anyway). Add fuel prices and life is going to become increasingly expensive. Rural land more expensive etc. Foreknowledge is a great boon.

    1. I thought the price of bread in Britain was extraordinarily cheap; at least compared to New Zealand it is very cheap. But I can remember people in the UK complaining about how the cost of groceries had risen in recent years and this is true also in Australia and New Zealand.

  2. Thanks for the article and the graphs. My Congressman, Frank Lucas, is now chairman of the House Agriculture Committee. He does not believe in climate change and voted not to investigate the influence of climate change on our food supply. We are already seeing the effects of climate change on food prices.

    Droughts in the Midwest and recently in California have damaged crops and forced ranchers to reduce their cattle herds. The droughts in Oklahoma and Texas were shown to have a link to climate change, and it is likely that the droughts in California are also linked. I once wrote an article about whether more CO2 was better for plants, and the conclusion is that any small gain from increased CO2 will be far outweighed by other factors. http://jcmooreonline.com/2011/01/10/is-more-co2-better-for-plants/

    1. JCMoore,

      It is very unwise for policy makers to ignore the projected future impacts of climate change on our food source. I am shocked to hear about your Congressman, Frank Lucas. Does he take out fire insurance for his house? I’m sure he does. This is no different and the consequences are worse.

      I liked reading your post about co2 and plants. I wrote a post about this topic too – Is global warming good for plants?.

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