How Climate Change Affects the Water Cycle
Did you know that water in Pennsylvania's lakes, reservoirs, and underground aquifers is not a renewable resource? In fact, the water we use is a finite resource. The amount of fresh water on Earth today is essentially the same as it was 1,000 or 1 million years ago. The water cycle only recycles water—it does not regenerate it or add to it.
When we use water, we need to understand how our actions affect the water cycle and, ultimately, the availability and quality of water to people around us and downstream.
Our water supply behaves like a finite resource and can be depleted at alarming rates during periods of peak usage or drought.
Under natural circumstances, the water cycle recharges the mountain streams and underground aquifers that feed our water needs…eventually. Weather patterns are the fuel for the water cycle. Even minor climate changes can disrupt weather patterns and the current balance of water resources available for use. Unfortunately, all water supply systems are designed and operated on the assumption that a climate scenario would not change over time.
- The Intergovernmental Panel on Climate Change published Climate Change and Water (PDF) in 2008.
- The Pacific Institute published Threats to the World's Freshwater Resources (PDF) in 2001, and Water: The Potential Consequences of Climate Variability and Change for the Water Resources of the United States in 2000.
- U.S.Global Change Research Program published the report Global Climate Change Impacts in the United States in 2009.
How Climate Change Affects Pennsylvania's Water Supply System
Changes to the amount or frequency of rain, the amount of winter snows, or the average temperature would all likely disrupt the amount of water available for Pennsylvanians to use.
If increases in temperature and evaporation rate stress sources of supply, such as impoundments, aquifers, and rivers, demand for water—both residential and agricultural irrigation—could also increase, exacerbating the effects of climate change on the water supply. Pennsylvania's water managers already face the challenge of determining when to store water in reservoirs for dry periods and when to reduce reservoir levels to prepare for the onset of high water from the spring thaw. If regularities in the water cycle become harder to predict in the future, it could become more difficult to meet the demand for water during extended dry periods without also increasing the risk of flooding during extreme precipitation events.
Conserving water through efficient water use in the home and at work is not only beneficial, but necessary to withstand the potential effects of climate change.
- The U.S. Environmental Protection Agency published the National Water Program Strategy: Response to Climate Change in 2008.
- The National Oceanic and Atmospheric Administration, Coastal Services Center published Local Strategies for Addressing Climate Change (PDF) in 2009.
- The Pew Center on Global Climate Change published Water and Global Climate Change: Potential Impact on U.S. Water Sources which discusses impacts of climate variations and possible adaptations to mitigate changes in average climate.