Climate change will increase aflatoxin presence in US Corn

Abstract

AbstractThe impacts of climate change on agricultural production are a global concern and have already begun to occur (Kawasaki 2018Am. J. Agric. Econ.101172–92; Ortiz-Bobeaet al2021Nat. Clim. Change11306–12), with major drivers including warmer temperatures and the occurrence of extreme weather events (Lobell and Field 2007Environ. Res. Lett.2014002; Challinoret al2014Nat. Clim. Change4287; Rosenzweiget al2001Glob. Change Hum. Health290–104; Schlenker and Roberts 2009Proc. Natl Acad. Sci. USA10615594–8; Lobellet al2014Science344516–9; Ortiz-Bobeaet al2019Environ. Res. Lett.14064003). An important dimension of the climate change-crop yield relationship that has often been overlooked in the empirical literature is the influence that warming temperatures can have on plant damage arriving through biotic channels, such as pest infestation or fungal infection (Rosenzweiget al2001Glob. Change Hum. Health290–104). Aflatoxins are carcinogenic chemicals produced by the fungiAspergillus flavusandA. parasiticus,which commonly infect food crops. Currently, in the United States, aflatoxin is a perennial contaminant in corn grown in the South, but rare in the Corn Belt and northern states. Climate change may expand aflatoxin’s geographical prevalence, however; because hot, dry summers promote aflatoxin accumulation. Here we model aflatoxin risk as a function of corn plant growth stages and weather to predict US regions with high aflatoxin risk in 2031–2040, based on 16 climate change models. Our results suggest that over 89.5% of corn-growing counties in 15 states, including the Corn Belt, will experience increased aflatoxin contamination in 2031–2040 compared to 2011–2020. Interestingly, the results are spatially heterogeneous and include several southern counties expected to have lower aflatoxin risk, because the causative fungi become inactivated at very high temperatures.