As water scarcity is aggravated by climate change impacts, inaction, and inefficient use of water, it will have severe costs that involve steeper trade-offs. Since the beginning of industrialisation, there has been a surge in greenhouse gas concentrations in the atmosphere. This has resulted in positive radiative forcing, which causes more energy from the sun to be retained and reflected to the Earth’s surface, thus intensifying overall temperatures and leading to global warming. Intergovernmental Panel on Climate Change (IPCC) reports (2007 and 2018) have projected a temperature increase of 1.8–4°C by 2100 in global latitudes, especially in seasonally dry and tropical regions. Additionally, dryness and wetness are increasing in parts of the world that earlier saw moderate climates.

About 80 percent of the world’s cultivated land is rainfed and contributes to about 60% of global food production. The remaining 20%, constituting about 275 million hectares, is irrigated and accounts for 40% of global food production. Globally, irrigated agriculture is by far the main consumer of water, accounting for almost 70% of all freshwater withdrawals. Among the G20 countries, there is a clear divide between developed and developing economies in terms of agriculture water efficiencies. Agriculture accounts for about 44% of the total water withdrawals in the United States, France, and Australia, but in countries like Brazil, Russia, India, and China, it accounts for 70% on average; for instance, in China it is 60% and in India 80%. In India, South Africa, and China, the number of rainy days during the season has decreased and rainfall intensities have increased, resulting in frequent occurrences of dry spells during the crop growth period.

The water cycle is a fundamental part of the climate system. Several effects of climate change manifest through the water cycle, such as changing precipitation patterns and increased intensity and frequency of floods and droughts. By 2050, over half of the world’s population is projected to live in water-stressed regions and 1.6 billion people are projected to live with the risk of floods. The climate crisis has triggered widespread shifts in the cryosphere (which includes snow, glaciers, permafrost, and lake and river ice) and is leading to a sharp reduction in global snow and ice cover. With glaciers melting faster, the amount and seasonality of runoffs in glacier-fed river basins have been impacted which, in turn, is affecting farming communities downstream. For example, in China, water issues are especially pronounced in the more arid, northern parts of the country, where the average water availability is 760 cubic metres per year—well below the internationally agreed threshold for water scarcity. Similarly, environmental and socio-economic factors in South Africa’s agricultural system have been affected by droughts, creating cascading pressures on the nation’s agro-economic and water-supply systems. These shifts will worsen water stress, which is a critical issue in the 21st century, especially in Asian and African nations.

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This paper has been authored by Prashant Pastore and others.