2 Peter Huybers

Crops

How are crops and climate connected?
  • Although obvious that moisture availability is critical to crop yields, this intuitive fact has been surprisingly difficult to quantify. For example, empirical models generally fail to significantly improve yield predictions when accounting for rainfall. In a pair of papers, Angela Rigden shows that observations from the Soil Moisture Active Passive (SMAP) satellite changes this situation both for corn yield in the US Midwest 2020a and Tea Yield in Kenya 2020b. SMAP observations allow for significantly improved yield predictions. Moreover, Angela is able to quantify the nonlinear interactions between demand for moisture (indicated either by temperature of vapor pressure deficit) and supply of moisture (root-zone moisture levels estimated from SMAP observations), and that oversupply and undersupply of moisture both have major consequences for yield outcomes. A Nature News and Views piece by Michelle Tigchelaar (here) gives a good summary of the US Midwestern work.
  • 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). Ethan Butler showed that this suppression of high-temperature extremes, along with a longer growing season, 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 and colleagues also showed that this cooling phenomena occurs in regions across the globe coincident with agricultural intensification, with the curious exception of Western Europe (2015). The degree to which global agricultural may have been boosted by local climate modifcation remains to be determined.
  • 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).

References

  • Rigden, Mueller, Holbrook, Pillai, and Huybers , Combined influence of soil moisture and atmospheric evaporative demand is important for accurately predicting US maize yields, Nature Food, 2020. link.
  • Rigden, Ongoma, and Huybers, Kenyan tea is made with heat and water: how will climate change influence its yield?, Envrionmental Reseeach Letters, 2020. link.
  • 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

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