Over the next 25 years, Philadelphia is expected to experience more heat waves and the Delaware River is projected to rise by at least a foot.

The Delaware River could rise more than a foot by mid-century, and temperatures could rise nearly 6 degrees, accompanied by a rise on sweltering heat days, according to a new report that uses local data to create a snapshot of local climate change in Philadelphia.

The report came from a coalition formed in response to rallies and a petition from Drexel University students in 2019 calling for the school to take action on climate change.

Following the student work, representatives from the City of Philadelphia, Drexel University, the Delaware Valley Regional Planning Commission, and Drexel University’s Academy of Natural Sciences put together a climate resilience research agenda. The group released a report on the potential impacts of climate change on Wednesday during Green Building United’s annual sustainability symposium, which was held this year at Drexel.

Some areas will be affected more than others, said Franco Montalto, an engineering professor at Drexel who was involved in the report. For example, communities like the Eastwick section of Philadelphia are already prone to flooding. Other parts of the city are hardest hit by the heatwaves.

Montalto said the changing patterns could also affect urban forests, wetlands and floodplains.

“The groups raised a range of questions about the built environment, about transportation systems, about energy systems, about buildings, and what we need to know to make those systems continue to function despite climate change,” he said.

The report noted that the city is already experiencing an increase in precipitation, and that six of the 10 wettest years on record have occurred since 1990. Average annual precipitation has increased over the past century, and the fluctuation in amounts has become more pronounced.

For the report, the Urban Northeast Climate Risk Consortium extrapolated climate modeling data collected by the Intergovernmental Panel on Climate Change to form local models. The UN panel has been compiling climate change data for more than 30 years. It issued its sixth assessment last year with updated data.

Projections indicate a 5% to 12% increase in precipitation by the 2050s, using the baseline period of 1981 to 2010. An 8% to 16% increase in precipitation is projected by 2080. Rangers could be higher or lower Depending on whether carbon emissions increase, decrease or remain the same.

The report acknowledges that the frequency and intensity of rainstorms is difficult to predict. But they did note the heavy impact of Hurricane Isaias that swept southwest Philadelphia in August 2020 and the remnants of Hurricane Ida that flooded the Vine Street Expressway when the Schuylkill River burst its banks in September 2021.

The Delaware River’s tides, which reach Trenton, have risen at a rate of about 1.2 inches per decade over the past century. This trend is expected to continue with sea level rise in Philadelphia projected to be anywhere in the low to high range of 7 to 11 inches by 2030, 14 to 19 inches by 2050, and 24 to 38 inches by 2080.

The increases are likely to cause more tidal flooding even when there is no rain.

According to the report, the high estimate for sea level rise by 2080 is 45 inches, and by 2100, it could rise by 64 inches.

“As sea level continues to rise in the mouth of the Delaware River, it will also push brackish and brackish water upriver causing impacts on ecosystems and water treatment facilities designed to hold only fresh water,” the report states.

Philadelphia draws all of its drinking water from two freshwater rivers: the Schuylkill and the Delaware. The Baxter Processing Plant is located on the Delaware River in Philly’s Torresdale section. The current salt front lies below Wilmington. The highest on record occurred during a drought in the 1960s when the salt line crossed parallel to Camden.

Using weather observed at Philadelphia International Airport, 8 of the 10 hottest years on record have occurred since 2000, according to the report.

Moreover, average annual temperatures in the mid-range are expected to increase by 4.1 to 5.8 degrees by the 2050s, and from 5.5 to 9.4 degrees by 2080.

During the same period, the frequency and intensity of hot days and heat waves are also expected to increase. For example, by the 1950s, the number of days with maximum temperatures of 95 or higher, which currently occurs about 6 per year, is expected to increase from 21 to 34 by the 2050s.

The frequency of heat waves, defined as three or more consecutive days with maximum temperatures of 90 degrees or higher, may triple by the end of the century. There is currently an average of three heat waves per year. It can grow to nine.

The Climate Resilience Research Agenda team is made up of 100 people, Montalto said, half of whom are academics and others from government, nonprofits and community groups.

“We asked them to discuss the knowledge gaps that prevent this region from thriving with climate change,” Montalto said. “The idea was that it wasn’t just about how we reduce emissions or deal with sea level rise. It was about a broader set of things coming together.”

Subgroups began to ask questions including the impact on water, air quality, human health and the environment. Montalto said the groups have also looked at how climate change is affecting buildings, transportation systems and infrastructure.

Montalto said the report was “only a first step”.

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