To our knowledge, there has been no global study attempting to estimate the impact of salinity on crop production. The literature on this topic is composed primarily of regional estimates based on crop production models or crop specific analyses which examine sensitivity to salinity for specific crops. Recent regional estimations include Dam et al. (2019), which finds that in central Vietnam, for each 1 percent increase in EC levels, yields of paddy rice decline by 0.24 percent. Clarke et al. (2015) estimate that in coastal Bangladesh, irrigating with saline surface and groundwater will reduce crop yields by at least 25 percent by the end of the century. Similarly, Dasgupta et al. (2014) estimate that rice yields will fall by 15.6 percent in by 2050 in 9 coastal districts in Bangladesh due to climate induced increases in salinity. Genua‐Olmedo et al. (2016) find that in the Ebro Delta in Northeast Spain, rice productivity will fall by up to 50 percent by 2100 due to the effects of sea‐level rise on soil salinity.

A deep scientific literature exists on the sensitivity of specific crops to salinity. A thorough review of this literature was conducted by Tanji and Kielen (2002) where threshold and slope values for 81 crops in terms of EC are collected and listed.<sup>1</sup> Similarly, Machado and Serralheiro (2017) review the literature on salt tolerance of vegetables. In table 2 they compare soil salinity and irrigation water salinity tolerance thresholds (i.e. the EC at which yields begin to decline) for 19 common vegetables. They find that vegetables generally have a soil salinity tolerance below 250 mS/m, and that irrigation water tolerances are generally around 30‐50 percent less than soil salinity tolerances. Several more recent studies examine specific crops. For example, Rameshwaran et al. (2016) find that sweet peppers become sensitive to water salinity at levels exceeding 143 mS/m and decline by a slope of 11 percent thereafter. Arslan et al. (2015) found that yields of chickpeas, lentils, and fava beans fell by 50 percent when EC in irrigated water exceeded 420, 440, and 520 mS/m, respectively. This implies that based on the staple diet of countries, salinity may have an amplified impact on countries relying on agricultural production that is more salinity sensitive. While crop based studies are informative, they do not provide an indication of the global loss of food production due to salinity. To address this issue, this paper provides estimates of the average impacts on yields across all crops using a variety of recently available data sources and finds a remarkably stable yield response function that holds across wide geographies.

# 2. Data

To estimate the impact of water salinity on global agricultural productivity, we use several georeferenced data sets related to water quality, agricultural yields, land cover, and weather. A description of these data sets can be found below and summary statistics are provided in Table 1.

## 2.1 Water Quality

Data on electrical conductivity (EC) were used to measure salinity in water. EC measures the ability of an electrical charge to pass through water. Distilled, or deionized water is a very poor conductor of electricity and as dissolved ions in water increase, it becomes a better conductor. In surface and groundwaters, these ions are generally dissolved salts, which is why EC is a widely used indicator of water salinity (Miller, Bradford, and Peters 1988). EC as a measure of salinity has the added benefit of being easily measured at monitoring stations or with handheld monitors, making it a very widely available water quality indicator.

> 1 See Tanji and Kielen (2002) Table A1.1 for values and list of studies.

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