Impact of Climate Change on Water Bodies and water insecurity

Climate change is expected to exacerbate current stresses on water resources. By 2020, between 75 and 250 million people are projected to be exposed to increased water stress due to climate change.

• Warming has resulted in decline in mountain glaciers and snow cover in both hemispheres and this is projected to accelerate throughout the 21st century.
  • This will in turn lead to reducing water availability, hydropower potential, and would change the seasonal flow of rivers in regions supplied by meltwater from major mountain ranges (e.g. Hindu-Kush, Himalaya, Andes).
• By 2050s freshwater availability in Central South, East and South-East Asia, particularly in large river basins, is projected to decrease.
• A warmer climate will accelerate the hydrologic cycle, altering rainfall, magnitude and timing of runoff.
• The IPCC Report 2007 states that the availability of fresh water in India is expected to drop in response to the combined effects of population growth and climate change.
• The IPCC (2007) also suggests that two main drivers of climate change, higher water temperature and variations in runoff– are likely to produce adverse changes in water quality affecting human health, ecosystems, and water use.
• Increase in sea-level has serious implications for both human security (increased flood-risks, degraded groundwater quality, etc.) and ecosystems (impact on mangrove forests and coral reefs, etc.), especially so in coastal regions.
• Reduced precipitation and increased evapotranspiration- will reduce recharge and possibly increase groundwater withdrawal rates.
• In coastal areas, sea level rise will exacerbate water resource constraints due to increased salinization of groundwater supplies.
• Available records suggest that the Gangotri glacier is retreating about 28 m per year. Glacial melt is expected to increase under changed climate conditions, which would lead to increased summer flows in some river systems
• In the Indo-Gangetic Plain Region in the past whereby different rivers (including Kosi, Ganga, Ghaghara, Son, Indus and its tributaries and Yamuna) changed their course a number of times. => devastating floods in Nepal and Bihar.