Climate Change & Our Waterways

According to the U.S. Environmental Protection Agency, Pennsylvania’s climate has warmed more than half a degree farenheit in the last century and heavy rainstorms have become more frequent. The abnormal climate patterns we’ve been observing don’t happen in a vacuum, they’re affecting ecosystems across the globe. Climate change makes the Earth hotter but it also causes extreme weather events, threatens extinction, and degrades water quality and public health. Communities without a resilience plan in place and without the means to combat these effects will be hit the hardest.

The rising global temperature we’ve begun to observe is beginning to increase the evaporation of water bodies and shrink their size. With a lower volume of water, waterways will become more polluted as common pollutants are less likely to be diluted, causing a problem for wildlife, plants, and humans that rely on the water. American Rivers reports the increased temperatures will also lead to more frequent algal blooms, which reduce dissolved oxygen in the water that some aquatic organisms need to survive. Low river flows can make the nation’s rivers extremely difficult to navigate and disrupt trade patterns during drought events.

According to American Rivers, reservoirs on the Colorado River already lose around 1.8 million acre-feet of water due to evaporation annually, about 13% of the river’s annual flow, with that number rising with the threat of climate change.

Some parts of the country will see a sharp increase in precipitation whereas other parts will see a significant decrease due to varying precipitation patterns, according to the Climate Reality Project. Wet places will continue to get wetter and dry places will grow increasingly drier. In the U.S., American Rivers predicts the southwest is expected to experience the greatest decline in precipitation which will affect the size and volume of water available for use. We will also witness less snowfall because the rising global temperature will cause more precipitation to fall as rain rather than snow.

The fluctuating climate will also contribute to severe weather events such as flooding and droughts as precipitation patterns vary in certain regions. Scientists predict storms will increase in severity and frequency as the atmospheric capacity to retain moisture greatly increases in correlation with temperature. This allows a greater capacity for severe natural events. According to U.S. EPA, the precipitation from extremely heavy storms has increased 70% in the Northeast since 1958. The increased frequency of extreme storms can also escalate the contamination of water as large volumes of stormwater runoff pick up pollutants, carrying them into nearby waterways. In cities like Pittsburgh where we have increased stormwater overflow, we will see combined sewage overflow events where raw effluent to be discharged into local rivers.

Climate change has also been showing effects on the world’s oceans and total ice mass. The ocean’s surface has warmed around one degree Fahrenheit within the last 80 years, as published by the U.S. EPA. This has caused an influx of snow melt running into the oceans and raising the sea level, as well as warming glaciers and ice cover to the point of melting and decreasing ice sheet mass.

Likewise, rising temperatures cause snow to melt earlier in the spring, increasing earlier annual evaporation and drying the soil in the summer and fall. According to the U.S. EPA, this will lead to increased chances of flooding in the winter and spring and drought conditions in the summer and fall seasons.

Predicted changing weather patterns due to climate change. Graphic by the U.S. EPA.

Predicted changing weather patterns due to climate change. Graphic by the U.S. EPA.

Because of the increasing uncertainty of future water supplies due to the expected decrease in precipitation, water sources will continuously dwindle. The United Nations estimates that by 2025, 2/3 of the population will live in water scarce regions. The most important changes can come from changing how we live and reducing the emissions we are producing that speed up atmospheric warming. Climate change is expected to affect a wide range of factors in the year to come and threatens ecosystems and human health. It’s important we educate ourselves on the potential outcomes and take the necessary steps to prepare ourselves for the changes that may come sooner than we expect.


Marissa Rollman