Water and Climate Change
Climate change may well be humankind’s greatest self-induced challenge. The impacts of climate change severely affect the water cycle: They aggravate existing water scarcity in many regions and also increase the frequency and intensity of extreme meteorological and hydrological events.
Recent scientific studies and projections published by the Intergovernmental Panel on Climate Change (IPCC) suggest, for example, that South Asia will be exposed to more rain during monsoon. Presumably, both the rates of average rainfall and the frequency of extreme rainfall will rise, leading to an increasing risk of flooding.
Climate change also causes sea level rise, due to melting glaciers and the higher volume of warmer water. Low-lying islands, coastlines and estuaries are especially vulnerable to these changes. Kiribati is a striking example: The country consists almost completely of atoll islands and the larger part of these is believed to be engulfed by the sea before the end of the century. Kiribati’s citizens will have no other choice than to relocate to other countries.
Global warming has been ongoing for decades and cannot be reversed. Truly committed action today might however prevent the most severe impacts. Yet, not all impacts of climate change can be predicted reliably. Dealing with these uncertainties requires adaptive management approaches, in particular in the water sector. And as water knows no boundaries, international and transboundary cooperation is imperative.
Water and the hydrological cycle sustain many ecosystems, such as rivers, lakes, and wetlands. All these ecosystems have many functions that provide invaluable direct and indirect benefits to human well-being: these functions are called ecosystem services. They include providing water for consumption and also recreational activities, regulating flood flows as well as supporting the nutrient cycle.
Since water provides so many services, in case of scarcity or reduced quality trade-offs between the interests of various water users emerge. The more water is drawn out for consumption purposes, the less remains in the ecosystem for other services. Another threat to ecosystem services is the degradation of water quality. Pollution damages ecosystem health and thereby reduces the amount of water available for use even further.
Decisions on trade-offs can be facilitated by economic incentives. The case of the Catskills watershed in the United States is an often cited example: To preserve the quality of drinking water in the city of New York the city council decided to invest 1 billion dollar into catchment conservation measures. Building a water treatment plant would have cost up to six times as much.
Good governance is another key to balancing trade-offs. The concept of environmental flows can be useful in this context. It specifies those water volumes which aquatic ecosystems require to preserve their functioning and services for competing water uses. It is thus a management tool helping to allocate water and to build consensus among stakeholders.
Protecting Water Bodies
The need for protecting water bodies is undeniable, both in terms of water quantity and water quality. According to the 2016 World Water Development Report of the UNESCO, 20 – 50% of the mean annual flow of any river is needed to satisfy the water requirements of its ecosystems, also for them to provide ecosystem services.
Maintaining the quality of water bodies is equally important. Particularly in Latin America, Africa and Asia, water quality is rapidly deteriorating as a result of population growth, industrialization and intensive agriculture, compounded by discharging untreated wastewater into surface waters. However, the majority of rivers on these continents is still in a good condition and preventing further pollution should consequently take precedence.
The quality of water bodies has been significantly improved in many industrial countries over the last decades. Germany represents a success story as the amount of pollutants has been reduced dramatically since the 1970s. The water quality of the river Rhine, for instance, has progressed from foul, oxygen-poor water to water that is almost of drinking quality.
German experiences and knowledge as well as engineering solutions are shared worldwide through the German Water Partnership (GWP) a network of water experts from the German public and private sectors whose members engage in international cooperation. The Federal Foreign Office supports this initiative together with four other federal ministries.