Changes in Climate Vulnerability and Projected Water Stress of The Gambia's Food Supply Between 1988 and 2018: Trading With Trade-Offs

Abstract

Background: The coexistence of under- and overnutrition is of increasing public health concern in The Gambia. Fruits, vegetables and pulses are essential to healthy and sustainable diets, preventing micronutrient deficiencies and non-communicable diseases, while cereals significantly contribute to energy intake. However, environmental changes are predicted to intensify, reducing future yields of these crops if agricultural productivity and resilience are not improved. The Gambia is highly climate-vulnerable and import-dependent, but the extent of its reliance on other climate-vulnerable countries for its supply of nutritionally important crops is currently unknown.

Methods: We used United Nations Food and Agriculture Organization data, with novel origin-tracing algorithms applied, to analyse The Gambia's supply of cereals, fruits, vegetables and pulses between 1988 and 2018. The climate vulnerability of countries was assessed using Notre Dame Global Adaptation Initiative (ND-GAIN) index scores, and projected water stress (2040) assessed using World Resources Institute (WRI) scores. Multilevel generalized linear mixed-effects models were used to identify changes in the overall climate vulnerability and projected water stress of supply.

Results: Between 1988 and 2018, The Gambia's supply of cereals, fruits, vegetables and pulses diversified, with the proportion domestically produced falling (Cereals: 61.4%-27.7%; Fruits: 93.0%-55.7%; Vegetables: 24.6%-16.3%; Pulses: 100.0%-76.0%). The weighted-average ND-GAIN scores improved (indicating less climate vulnerability) for supply of all crops except cereals, but the weighted-average WRI score for supply deteriorated (indicating increased projected water stress) for all crops except vegetables. When just considering imports, weighted-average ND-GAIN scores deteriorated for fruits and cereals while showing no significant change for other food groups, and the WRI score deteriorated for cereals only.

Conclusions: Despite some notable improvements in the environmental vulnerability of The Gambia's supply of nutritionally important crops (particularly vegetables), considerable, and in some cases increasing, proportions of their supply are produced in countries that are vulnerable to climate change and future water stress. This may have implications for the availability, affordability, and hence consumption of these crops in The Gambia, ultimately exacerbating existing nutritional challenges. Exploring the options to strengthen supply resilience-such as altering trade patterns, agricultural techniques and diets-should be prioritized.

Keywords: adaptation; climate change; climate vulnerability; environmental change; food security; food system resilience; trade; water stress.

Figure 1

Changing total supply (g/capita/day) of (A) cereals, (B) fruits, (C) vegetables, and (D) pulses, split by imports (light) and domestic production (dark), between 1988 and 2018. Import dependency ratio (IDR) shown by black dashed line. Total supply uses the FAO food balance data, but the overlaid proportions of imports and exports, and hence IDRs, are 3-year rolling averages from the Kastner et al bilateral trade data (1987–2019).

Figure 2

ND-GAIN vulnerability index of country of origin of cereals, fruits, vegetables and pulses supplied to The Gambia. The proportion of supply, within a given crop group and for a given year (1988, 1998, 2008 or 2018), originating in countries characterized by a given climate vulnerability status ([1–dark red] Extreme; [2–red] High; [3–orange] Intermediate to high; [4–yellow] Intermediate; [5–green] Low; or [*-blue] Unknown). Domestic production is shown with diagonal stripes and falls into the Extreme vulnerability (1) category, with the ND-GAIN country index score (2019) of The Gambia being 39.2. This figure also shows the weighted average ND-GAIN score of total supply (black dashed line) and of imports (gray dashed line). All data are 3-year rolling averages. All data between the years of 1988, and 2018 were analyzed, but we present 1988, 1998, 2008, and 2019 as evenly spaced time intervals for figure readability. Data for all years can be found in the supplementary materials (Supplementary Figure 4).

Figure 3

Climate vulnerability of trade partners (ND-GAIN index) contributing ≥1% of supply of (A) cereals (B) fruits (C) vegetables, (D) pulses, in 1988, 1998, 2008, and 2018. Amount the imported crop contributes to supply is represented by arrow thickness (not to scale) and numbers (%). There are five climate vulnerability categories: [1–dark red] Extreme; [2–red] High; [3–orange] Intermediate to high; [4–yellow] Intermediate; [5–green] Low.

Figure 4

Projected water stress (WRI score) of country of origin of cereals, fruits, vegetables and pulses supplied to The Gambia. The proportion of supply, within a given crop group and for a given year (1988, 1998, 2008 or 2018), originating in countries of varying projected 2040 water stress levels (ratio of total water withdrawals to total renewable supply, WRI Aquaduct). There are five levels of water stress: [1] Low (<10%); [2] Low to medium (10–20%); [3] Medium to high (20–40%); [4] High (40–80%); [5] Extreme (>80%); plus those that are unknown [*-gray]. Projected water stress increases as colors move from light to dark blue. Domestic production is shown with diagonal stripes and falls into the low stress [1] category. This figure also shows the weighted average WRI score of total supply (black dashed line) and of imports (gray dashed line). All data are 3-year rolling averages. Analysis of 2040 projections based on a business-as-usual scenario. All data between the years of 1988 and 2018 were analyzed, but we present 1988, 1998, 2008, and 2019 as evenly spaced time intervals for figure readability. Data for all years can be found in the supplementary materials (Supplementary Figure 5).

Figure 5

The projected water stress of trade partners (ratio of total water withdrawals to total renewable supply, WRI Aquaduct) contributing ≥1% of supply of (A) cereals (B) fruits (C) vegetables (D) pulses, in 1988, 1998, 2008, and 2018. Amount the imported crop contributes to supply is represented by arrow thickness (not to scale) and numbers (%). There are five water stress severity categories: [1] Low (<10%); [2] Low to medium (10–20%); [3] Medium to high (20–40%); [4] High (40–80%); [5] Extreme (>80%). The darker the color, the more water stressed a country is projected to be in 2040, in a business-as-usual scenario.