Philly to experience frequent heat waves, flooding, says Drexel report

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Increasing heat waves and floods. Rising tides in the Delaware River. These are just some of the concerning projections about the future of climate change in the Philadelphia region. The predictions were highlighted in a new report from Drexel University that evaluates climate change impacts, as well as hopeful pathways for climate resiliency.

The frequency of heat waves, which are three or more consecutive days with temperatures at or above 90 degrees, may triple by the end of the century.

The prevalence and intensity of precipitation events such as hurricanes and nor’easters are also increasing — and causing more flooding.

“The projections in terms of climate change are sobering,” said Franco Montalto, a Drexel engineering professor who helped lead the research. “We’ll have increases in temperature, we’ll have increases in extreme precipitation, we’ll have elevated sea levels. And all of those changes pose significant challenges for our city.”

The report was gathered by a coalition of environmental scientists who came together after students at Drexel University petitioned the institution in 2019 to take action on climate change.

The group is made up of scientists from Drexel University, the city of Philadelphia, and the Delaware Valley Regional Planning Commission.

The report finds that over the past 82 years, precipitation in Philadelphia has continued to increase, with six of the 10 wettest years on record occurring after 1990. Precipitation is estimated to increase 5 to 12% by the 2050s, and 8 to 16% by the 2080s, according to the report.

Though harder to predict, major storm events are impacting the region at an increasing rate. In 2020, Tropical Storm Isaias enveloped large portions of the Eastwick community with as much as 4  feet of water in a matter of minutes. In 2021, water from the Schuylkill River flooded the Vine Street Expressway following Hurricane Ida.

“As the decades progress, portions of Eastwick get inundated more and more frequently due to just regular monthly high tides than they are today,” Montalto said.

The report also indicates that the Delaware River is rising about an inch per decade. It projects that sea level rise in Philadelphia will increase by 7 to 11 inches by the 2030s, 14 to 19 inches by the 2050s, and 24 to 38 inches by the 2080s. Flooding due to tide levels alone is also becoming a threat, the report states.

Scientists say sea level rise is a concern, because as it pushes salty and brackish water upriver, it could impact drinking water quality.

Temperatures have risen over the past 82 years, with eight of the 10 hottest years on record occurring since 2000. Temperatures could increase by 4.1 to 5.8 degrees by the 2050s, and by 5.5 to 9.4 by the 2080s.

The frequency and intensity of hot days and heat waves is also projected to increase —  from 21 to 34 days per year by the 2050s and from 34 to 72 days per year in the 2080s.

“There are neighborhoods that are already heat vulnerable because of historic disinvestment, because of a lack of tree canopy and a variety of other reasons,” Montalto said. “People with respiratory problems, people with heart problems, all kinds of health vulnerabilities to temperature — those people are experiencing worse conditions.”

The researchers teamed up with community leaders to come up with about 200 recommendations. Community leaders helped scientists understand how the climate change projections will impact specific neighborhoods, particularly marginalized communities, Montalto said.

“Floods, for example, make it harder for people to get to work. Heat makes it more difficult to do outdoor work,” he said. “So there’s a whole bunch of cascading effects that we need to think about. Those questions are best understood with the input of folks in specific communities.”

Some of those include implementing long-term monitoring for climate scenarios, studying the health impacts of flooding and how improving building codes could prepare, educating the community on climate resilience, and exploring whether changes to physical building designs  can offset stormwater runoff.

Montalto said federal dollars should be used to help communities become resilient to climate change.

“The opportunity is now to start the right conversations, so that we can best use those funds to have benefits that impact people in meaningful ways, and specifically in communities that are most vulnerable to the types of changes that we expect to come,” he said.