Effects of warming on crop yields: A meta-analysis

Background/Question/Methods

Under current trends of population growth, food production must increase up to 70% by 2050 to feed a population exceeding 9 billion people. Any efforts to increase food production will be done in a climate with elevated temperatures and atmospheric CO2; conditions that will alter crop yield and quality. Current research has shown that higher levels of CO2 will decrease protein, zinc, and iron concentrations, exacerbating nutrient deficiencies globally, especially in disadvantaged and marginalized populations. While we know that crop yield declines with warming, we lack understanding in how nutritional quality is also affected. To address this issue, I used the Web of Science database to compile articles for a meta-analysis on the effects of warming on crop yield, harvest index, and nutritional quality. In total, 50 of the original 4,873 articles returned from the search query were assessed using a random-effects meta-analysis.

Results/Conclusions

Compared to control conditions, elevated temperatures saw significant decreases in yield (in Kg/Ha and g/m2), and thousand grain weight (grams), while no significant change was detected in harvest index. The articles compiled in the database did not return enough data to perform analysis on nutritional quality, emphasizing that our understanding of how the nutritional quality of major crops changes with warming is not well enough investigated. The results of this study show that crop yields will continue to decline with warming above optimum temperatures and that a better understanding of how nutritional quality is impacted by warming will be crucial to provide an adequate and nutritious food supply for the future population.