CropsHow are crops and climate connected?
- Surface temperature in the U.S. Midwest has changed over the last several decades so as to increase the length of the growing season and, rather surprisingly, decrease exposure to damagingly high temperatures. Ethan Butler and Nathan Mueller estimated that these changes, along with farmers planting earlier, account for about a quarter of the trend in maize yields since 1981 (2018). Whether such peculiarly pleasant changes will continue, however, is far from certain.
- Nathan Mueller showed that the hottest summer temperatures in the U.S. Midwest have been cooling over the last century because of increasing agricultural intensification and associated increases in transpiration (2015). Temperatures return to historically high values during drought, however, because of limitations upon evapotranspiration. In a follow-up paper, Nathan showed that this cooling phenomena occurs in regions across the globe coincident with agricultural intensification, with the curious exception of Western Europe (2015).
- Ethan Butler demonstrated that sensitivity of maize yield to high temperatures varies according to climatology across the U.S. (2013). Using this spatial adaptation as a proxy for adaptability to future warming suggests substantial scope for mitigating damage from climate change, though changes in temperature variance and rainfall are still wild cards. More recently, Ethan showed that maize cultivars adapted to hotter climate tend to increase time spent in the grain-filling stage of development in response to high temperatures, whereas cultivars that are more sensitive to high temperatures tend to shorten this stage of development (2015).
- Sam Myers led a team in exploring whether nutrient contents of major crops change when grown at high atmospheric CO2 concentrations. Concentrations of a number of micronutrients decline, especially zinc (2014).
- Marena Lin showed that historical trends toward increasing wheat yields show signs of having leveled off. The pattern of leveling is consistent with local socio-economic factors (2012), except that India appears to have increased fertilizer use without realizing increased yield.
- Butler, Mueller, and Huybers, Peculiarly pleasant weather for US maize , Proceedings of the National Academy of Sciences, 2018. link, pdf
- Mueller, Rhines, Butler, Ray, Siebert, Holbrook, and Huybers Global Relationships Between Cropland Intensification and Summer Temperature Extremes Over the Last 50 Years, Journal of Climate, 2017. link, pdf
- Mueller, Butler, McKinnon, Rhines, Tingley, Holbrook, and Huybers Cooling of US Midwest summer temperature extremes from cropland intensification, Nature Climate Change, 2015. pdf
- Butler and Huybers Variations in the sensitivity of US maize yield to extreme temperatures by region and growth phase, Environmental Research Letters, 2015. pdf
- Myers et al. Increasing CO2 threatens human nutrition, Nature, 2014. pdf
- Butler and Huybers Adaptation of US maize to temperature variations, Nature Climate Change, 2013. pdf
- Lin and Huybers Reckoning wheat yield trends, Environmental Research Letters, 2012. pdf and supplemental material