Global crop exposure to critical high temperatures in the reproductive period: historical trends and future projections

By S. Gourdji, A. Sibley, David B. Lobell. 2013

474 citations recorded by the source corpus.

Long-term warming trends across the globe have shifted the distribution of temperature variability, such that what was once classified as extreme heat relative to local mean conditions has become more common. This is also true for agricultural regions, where exposure to extreme heat, particularly during key growth phases such as the reproductive period, can severely damage crop production in ways that are not captured by most crop models. Here, we analyze exposure of crops to physiologically critical temperatures in the reproductive stage (Tcrit), across the global harvested areas of maize, rice, soybean and wheat. Trends for the 1980–2011 period show a relatively weak correspondence (r = 0.19) between mean growing season temperature and Tcrit exposure trends, emphasizing the importance of separate analyses for Tcrit. Increasing Tcrit exposure in the past few decades is apparent for wheat in Central and South Asia and South America, and for maize in many diverse locations across the globe. Maize had the highest percentage (15%) of global harvested area exposed to at least five reproductive days over Tcrit in the 2000s, although this value is somewhat sensitive to the exact temperature used for the threshold. While there was relatively little sustained exposure to reproductive days over Tcrit for the other crops in the past few decades, all show increases with future warming. Using projections from climate models we estimate that by the 2030s, 31, 16, and 11% respectively of maize, rice, and wheat global harvested area will be exposed to at least five reproductive days over Tcrit in a typical year, with soybean much less affected. Both maize and rice exhibit non-linear increases with time, with total area exposed for rice projected to grow from 8% in the 2000s to 27% by the 2050s, and maize from 15 to 44% over the same period. While faster development should lead to earlier flowering, which would reduce reproductive extreme heat exposure for wheat on a global basis, this would have little impact for the other crops. Therefore, regardless of the impact of other global change factors (such as increasing atmospheric CO2), reproductive extreme heat exposure will pose risks for global crop production without adaptive measures such as changes in sowing dates, crop and variety switching, expansion of irrigation, and agricultural expansion into cooler areas.

Subfields: Ecology, Evolution, Behavior and Systematics, Global and Planetary Change, Plant Science

View Paper: https://www.semanticscholar.org/paper/e86eac0fb0e474eda69c90566601958ce31969ad

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Citations in the corpus

Crop modelling for integrated assessment of risk to food production from climate change (2015, background): “variability (Lobell et al., 2011a; Gourdji et al., 2013; Lobell et al., 2013) and increases in mean temperatures for crops now grown”
Climate change impacts on agriculture in 2050 under a range of plausible socioeconomic and emissions scenarios (2015, methodology): “These models represent three of the five ISI-MIP GCMs that were selected byfirst availability (Hempel et al2013).”
Climate Change, Global Food Security, and the U.S. Food System (2015, background): “Hotter average temperatures affect crops by accelerating rates of crop development and evapotranspiration, but extreme temperatures can cause damage that is not typically captured by models, particularly during flowering and the reproduction phase (Gourdji et al. 2013).”
Climate Change and Global Food Systems: Potential Impacts on Food Security and Undernutrition. (2017, background): “Exposure to damaging temperatures will generally increase as global temperatures rise (60), although these trends will vary regionally and can be locally tempered by irrigation or other changes in agricultural practices (20, 40, 106).”
The effect of high temperature stress on male and female reproduction in plants (2015, background): “Temperatures >30 ◦C reduce stigmatic receptivity and stigmatic pollen germination (Gross and Kigel, 1994; Harsant et al., 2013), and subsequent growth within the stigma and style (Saini et al., 1983; Snider et al., 2011; Song et al., 2015) and ovule penetration (Saini et al., 1983).”
Wheat yield loss attributable to heat waves, drought and water excess at the global, national and subnational scales (2017, background): “However, increasing unfavorable conditions under observed and projected climate change conditions will probably impact wheat production variability (Gourdji et al 2013, Deryng et al 2014, Siebert and Ewert 2014, Asseng et al 2015, Ray et al 2015), especially because of the exacerbated effects of…”