# 5.2.Climate impacts

Climate change is considered to be a major challenge for agricultural production. The potential impacts on productivity of crops under heat and water stress can be simulated using globally gridded crop models (GGCM) that simulate the effects of increased radiative forcing from general circulation models (GCMs) on temperature, precipitation, and nutrient requirement. Changes in precipitation due to changes in radiative forcing also impact future annual and monthly stream flows which in turn impact water available for irrigation.

Climate change impacts are modeled using the bias‐corrected climate datasets produced by the five general circulation models (GCMs) (Table 5) (HadGEM2‐ES, IPSL‐CM5A‐LR, GFDL‐ESM2M, MIROC‐ ESM‐CHEM, NorESM1‐M) available from the Inter‐Sectoral Impact Model Intercomparison Project (ISI‐ MIP)<sup>7</sup> and used in also used in Phase 5 of the Coupled Model Intercomparison Project (CMIP5),<sup>8</sup> which offers a framework to compare climate impact projections in different sectors and at different scales (Warszawski et al., 2014). The GCMs are combined with different levels of atmospheric CO2 concentrations as prescribed by the RCPs (RCP 8.5 and RCP 2.6) to reveal the impact of climate change on global changes in temperature and precipitation. Although, the scientific community has yet to reach an agreement on whether the potential benefits from increased CO2 can be taken up and used by crops, especially if temperature and precipitation reduce crop yields, the impacts of CO2 fertilization on crop yields can be modeled with the globally gridded crop model EPIC (Environmental Policy Integrated Climate model). EPIC uses these changes in temperature, precipitation, and atmospheric CO2 concentration to model the impacts on crop yields, nutrient and water requirement for each to the GCMs and RCPs. The impacts of carbon fertilization are also excluded from the crop yield impacts for one of the GCMs (HadGEM2‐ES). These data sets are provided by the fifth phase of the Coupled Model Intercomparison Project (CMIP5) (Taylor et al., 2011).

Table 5. General Circulation Models (GCMs) used to project climate change

|GCM|Modeling group|Country|
|---|---|---|
|GFDL‐|NOAA Geophysical Fluid Dynamics Laboratory|USA|
|ESM2M|||
|HadGEM2‐<br>ES|Met Office Hadley Centre|UK|
|IPSL‐|Institut Pierre‐Simon Laplace|France|
|CM5A‐LR|||
|MIROC‐<br>ESM‐|Japan Agency for Marine‐Earth Science and Technology,<br>Atmosphere and Ocean Research Institute (The|Japan|
|CHEM|University of Tokyo), and National Institute for<br>Environmental Studies||
|NorESM1‐|Norwegian Climate Centre|Norway|
|M|||
|Source: Coupled|Model Intercomparison Project Phase 5 (https://cmip.llnl.gov/cmi|p5)|

GLOBIOM has been used for assessments of agriculture under future climate change that considered impacts of alternative adaptation strategies (Leclère et al., 2014) and the role of trade (Mosnier et al., 2014) to mitigate the impacts of climate. While the climate effects on grassland productivity are less studied than those effects on crop productivity, GLOBIOM has included these impacts to understand the economic and land use implications (Wheeler and Reynolds, 2012; Havlík et al., 2015).

For this sensitivity analysis, we have used the crop modeling simulations produced with EPIC and considered the most extreme radiative forcing (RCP 8.5), general circulation model (HadGEM GCM),

> 7 <u>https://www.isimip.org</u>

> 8 <u>https://cmip.llnl.gov/cmip5</u>

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