Global warming relates to the growing average temperature of Earth ‘s atmospheric state and seas and its planned sequel. A rise in global temperature will making sea levels to increase and will alter the amount and form of downfall water, and a likely enlargement of semitropic deserts. Heating is expected to be strongest in the Arctic and would be linked with going forward draw back of glaciers, permafrost and sea ice. Weather change will have a substantial affect on the sustainability of water supplies in the coming decades. A new research were conducted by Natural Resources Defense Council and studied the consequences of global warming on water supply and demand in the contiguous United States. The study found that more than 1,100 counties will face higher risks of water shortages by mid-century as the result of global warming. All this is due to cutting forests and finishing natural lakes by human being. We should think about our climate changes and try to reduce pollution and plantation of trees.