How might climate change affect Pennsylvania?

Average Temperature Plot

Pennsylvania or "Penn's Woods" has long been identified by its forests. When Europeans first encountered the Native Americans here, 90 % of the land was forested. Despite the decimation of Pennsylvania forests by the logging industry in the late 1890's, the conversion of large tracts of land to agricultural use, and the growth of major cities and their suburbs, Pennsylvania continues to be one of the most forested states in the nation. It also contains 83,000 miles of streams. Dynamic communities of plants and animals are supported by Pennsylvania's natural resources, which is home to more than 21,000 species of organisms including vertebrates, invertebrates, plants and algae, fungi and lichens. A changing climate is likely to impact the abundance and distribution of organisms in the state.

According to the Pennsylvania Climate Impact Assessment Report to the Department of Environmental Protection (2009), it is very likely that Pennsylvania will warm throughout the 21st century. Pennsylvania can expect to see warming of on average 2.5 degrees Fahrenheit over historic levels in the coming decades (Union of Concerned Scientists).

Annual precipitation is also likely to increase overall. However, the precipitation events will likely be more extreme, with heavy, intense rains and longer dry periods. These and other changes related to climate are likely to lead to many changes to Pennsylvania's forests. Some northern tree species, such as Paper birch and Quaking aspen may disappear altogether in the state. Many other species, including Black cherry, Sugar maple, and Eastern white pine are likely to decline as areas of suitable habitat decrease. Some of the species that do remain in PA are likely to be increasingly stressed by the changes in climate and this stress will make them more vulnerable to damage from insects and diseases. Changes in forest habitats may also impact many of the bird species that nest in Pennsylvania forests, such as scarlet tanager and wood thrushes.

Along with the changes to the forests, streams and wetland communities in Pennsylvania will also be significantly impacted by climate change. The average temperature of some water bodies is expected to rise and the increased variability of precipitation is likely to cause changes in the typical water levels and flood patterns of aquatic ecosystems. Reduced biodiversity of plant and animal life can be expected. Cool-water species such as the eastern brook trout expected to decline.

Human communities in Pennsylvania will not be spared the impact of climate change. Declines in agricultural yields, such as reduced milk supply in cows or reduced apple production may occur. Some recreation opportunities such as snowboarding and skiing may begin to disappear in the state as snowpack decreases. The increased heat could also cause a decrease in air quality, especially in cities, leading to increases in allergies, asthma and other respiratory problems.

What does this mean for Silver Lake Nature Center?

Playing in Rain

Silver Lake Nature Center, with its location in the small strip of coastal plain in southeastern Pennsylvania already experiences longer and hotter summers than the rest of the state. By the later part of the century, the number of days per year over 90°F are likely to at least double and may be as high as 70 days per year (Union of Concerned Scientists). Periods of high precipitation may cause problems with flooding and stormwater management. Periods of drought may dry out our wetlands to a degree that threatens the survival of some of our plant and animal species.

Silver Lake Park is essentially an island located in the middle of a sea of development. Very few pathways or corridors are open to promote species dispersal or seed exchange beyond the constant barrage of non-native species typically found in suburbia. Located in the Coastal Plain of Pennsylvania, the Center is home for 43 plant species and two plant communities considered rare, threatened or endangered in Pennsylvania. Climate change is likely to alter plant communities as certain plants struggle to survive. At the same time the location inhibits many opportunities for seed dispersal from outside of the park, reducing opportunities for natural successional changes. Monitoring the species mix and change over time will guide future managers in ways they may enhance species diversity appropriate to any new climatic conditions.

The staff of Silver Lake Nature Center is beginning to take active steps to monitor the overall health and stability of our local environment. Through our watershed monitoring program, we are collecting data to monitor the ongoing health of our streams. With Project BudBurst, we will begin to monitor the populations and phenophases of our plant communities. With the help of volunteer "citizen scientists", we will be able to collect significant and timely data that will assist us in developing appropriate management strategies and educational programs to help us all adapt to our changing climate.


Photo courtesy of Silver Lake Nature Center

Temperature data from The Weather Channel website for Bristol, PA:

Union of Concerned Scientists. Climate Change in Pennsylvania: Impacts and Solutions for the Keystone State. 2008. Union of Concerned Scientists. Cambridge, MA 53pp.

Shortle, James, David Abler, Seth Blumsack, Robert Crane, Zachary Kaufman, Marc McDill, Raymond Najjar, Richard Ready, Thorsten Wagener, and Denice Wardrop. June 2009. Pennsylvania Climate Impact Assessment: Report to the Department of Environmental Protection. Environmental & Natural Resources Institute.

Furedi, M., B. Leppo, M. Kowalski, T. Davis, and B. Eichelberger. 2011. Identifying species in Pennsylvania potentially vulnerable to climate change. Pennsylvania Natural Heritage Program, Western Pennsylvania Conservancy, Pittsburgh, PA.

Price, Will, Eric Sprague, January 2012. Pennsylvania's Forests. How They are changing and Why We Should Care. Pinocot Institute for Conservation. Washington DC.