Almost half of the world’s population lives in regions with severe water stress and climate change will worsen the situation. However, nature-based solutions, such as reforestation, the protection of wetlands or water-efficient agricultural practices, can improve the supply and quality of water and reduce the impact of natural disasters. This is the message of the UN World Water Development Report 2018. Currently, an estimated 3.6 billion people live in areas that are potentially water-scarce at least one month per year, and this number could increase to some 5.7 billion by 2050. Climate change will put further pressure on the global water cycle, with wetter regions generally becoming wetter and drier regions becoming even drier. Urbanisation, deforestation and the intensification of agriculture will add to these challenges. The global demand for water has been increasing at a rate of about 1% per year over the past decades due to population growth, economic development and changing consumption patterns. The report projects that demand will continue to grow. Industrial and domestic demand for water will increase much faster than agricultural demand, although agriculture will remain the largest user.

The report says that the challenge is to meet this demand in a way that does not exacerbate negative impacts on ecosystems. Ecosystem degradation is already a major problem. Although about 30% of the global land remains under forest cover, at least two thirds of this area are in a degraded state. Most of the world’s soil resources, notably farmland, are in only fair, poor or very poor condition. This has serious impacts on water cycling due to higher evaporation rates, lower soil water storage and more surface runoff accompanied by increased erosion. Since the year 1900, an estimated 64–71% of the natural wetland area worldwide has been lost due to human activity. This ecosystem degradation is negatively affecting hydrology. But nature-based solutions in agriculture could make a difference.

The report argues that agriculture needs to use resources, including water, more efficiently and reduce its external footprint. It calls for sustainable food production, which enhances ecosystem services in agricultural landscapes, for example through improved soil and vegetation management as well as farming practices that minimise soil disturbance, maintain soil cover and ensure crop rotation. The authors stress that “agricultural systems that conserve ecosystem services by using practices such as conservation tillage, crop diversification, legume intensification and biological pest control perform as well as intensive, high-input systems”. They cite a study that assessed agricultural development projects in 57 low-income countries and found that using water more efficiently combined with reductions in the use of pesticides and better soil cover increased average crop yields by 79%.

The report gives further examples for nature-based solutions in agriculture: Following a severe drought in the Indian state of Rajasthan in 1986, NGOs worked alongside local communities to set up water harvesting structures and regenerate soils and forests in the region. This led to a 30% increase in forest cover, groundwater levels rose by several metres and cropland productivity improved. Another solution is the System of Rice Intensification that enables savings of 25 to 50% in water requirements and 80 to 90% in seeds while raising paddy output by 25 to 50%, depending on the region. The UN sees a huge potential in rain-fed systems that account for the bulk of current production and family farming and hence provide the greatest livelihood and poverty reduction benefits. “The theoretical gains that could be achievable at a global scale exceed the projected increases in global demand for water, thereby potentially reducing conflicts among competing uses,” the report reads.

However, the use of nature-based solutions remains marginal due to the lack of enabling conditions. The report argues that payment for environmental services schemes would provide monetary and non-monetary incentives to communities, farmers and land owners to protect, restore and conserve natural ecosystems and to adopt sustainable agricultural and other land use practices. It calls for a shift in agricultural policy to finance the further uptake of nature-based solutions. “This requires overcoming the fact that the vast majority of agricultural subsidies, and probably the majority of public funding and almost all private sector investment in agricultural research and development, support the intensification of conventional agricultural, which increases water insecurity,” the authors write. (ab)