Identifying Potentially Vulnerable Species in Philadelphia to Climate Change​

Climate Change & Philadelphia

Climate change and global warming are arguably the greatest environmental crisis of the twenty-first century, affecting humans and the planet like never seen before. However, global warming and climate change impact urban areas at a higher rate than seen in rural areas. Global urbanization is increasing, and these areas are going to be disproportionately affected by global warming trends. In urban areas there is decreased evaporation, greater and more frequent rain events, increased rainwater surface runoff, and the development of urban heat islands (UHI) which are only going to be amplified in the coming years due to climate change

Green Spaces & Biodiversity 

Looking at Philadelphia specifically, 13% of the land use in the city is made up of green spaces and natural areas, such as Wissahickon Valley Park, Pennypack Park, Fairmount Park, and a variety of neighborhood gardens and community centers (Wallace and Todd, 2010). Within these areas and Philadelphia as a whole, there are an estimated 2.9 million trees with a tree canopy that covers 20% of the city (The urban forests of Philadelphia, 2016). Philadelphia is also home to a variety of animals and over one-hundred insect species. One may be surprised to learn that within the city there are coyotes, peregrine falcons, brown snakes, redback salamanders, star nosed moles, and even the occasional flying squirrel (Brown 2015).

Impacts on Ecosystems

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The extreme weather events mentioned above will create sudden or abrupt changes in habitat conditions and quality which could lead to the rise of invasive species, diseases, and parasites (Solecki and Marcotullio, 2013). Prolonged disturbances and changes in seasonal climate could lead to invasive species outcompeting native species, as well as increased pests and diseases that are well adapted to temperature changes. These changes in species biodiversity have the potential to disrupt ecological niches and ecosystems already in place in Philadelphia. Climate shifts and global warming will change the distribution of resources available for birds, insects, and larger animals which will lead to disruptions in species competition. In the future, cities will likely see changes in the presence of biodiversity and previously identifiable species such as certain trees, birds, fish, and even rare or endangered animals due to competition changes and invasive species (Solecki and Marcotullio, 2013).

Determining At-risk Species

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To determine future changes in species biodiversity for Philly, my research used a Climate Vulnerability Index. The Index includes three categories to help assess a species’ exposure to climate change which are as follows: exposure to local climate change, indirect exposure to climate change, and sensitivity and adaptive capacity. Exposure to climate change is measured by examining the magnitude of predicted temperature and moisture change across the range of the species within the assessment area. In order to determine temperature change, The Climate wizard was used, as well as data from NOAA. Moisture change was calculated using the Hamon AET:PET moisture metric which integrates temperature and precipitation through a ratio of actual evapotranspiration (AET) to potential evapotranspiration (PET), with consideration of total daylight hours and saturated vapor pressure (Young et al, 2016). Species sensitivity is assessed by scoring species against twenty-three factors divided into two categories: indirect exposure to climate change and species-specific sensitivity. Species are also scored against eight ​other factors to help determine adaptive capacity. For each factor, species are scored on  a scale from greatly increasing to having no effect on vulnerability. After all known data is input, the six possible scores are extremely vulnerable, highly vulnerable, moderately vulnerable, less vulnerable, and insufficient evidence.

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