There is evidence that the global climate is changing. A global temperature increase of 3-4°C could cause changed run-off patterns and glacial melt will force an additional 1.8 billion people to live in a water scarce environment by 2080.
Source: UNDP: Human Development Report, 2007/2008

Climate change is predicted to have a whole range of impacts on water resources. Variation in temperature and rainfall may affect water availability, increase the frequency and severity of floods and droughts, and disrupt ecosystems that maintain water quality.
Source: Intergovernmental Panel on Climate Change (IPCC)

By 2050, rising populations in flood-prone lands, climate change, deforestation, loss of wetlands and rising sea levels are expected to increase the number of people vulnerable to flood disaster to 2 billion.
Source: WWDR, 2012

The cost of adapting to the impacts of a 2°C rise in global average temperature could range from US$70 to $100 billion per year between 2020 and 2050, according to the World Bank.
Source: WWDR, 2012

Water is a primary medium through which changes in human activity and the climate impact with the earth’s surface, its ecosystems, and its people. It is through water and its quality that people will feel the impact of change most strongly.
Source: WWDR, 2012

Collecting water is expected to become increasingly burdensome with global warming. More regions will experience water shortages, as rainfall becomes erratic, glaciers melt and seas rise. People living within 60 miles of a shoreline — a full third of the world's population — will be hit especially hard, as they are most susceptible to increased salinity of coastal potable water sources. As it takes more time to gather water and fuel, the available time for education or other economic and political activities decreases. Already, the majority of children worldwide who do not attend school are girls.
Source: UN Women

Climate variability, water resource management and economic development are intricately linked. Vulnerability to natural disasters affecting the water supply hampers economic performance and undermines poverty reduction goals and achievement of the MDGs.
Source: WWAP