On Aug. 17 of an unusually hot Pittsburgh summer, environmental and community groups held a press conference on Brightridge Street, on the North Side. Standing on a street of red-brick rowhouses, they raised an alarm: Unless we seriously begin fighting climate change, summers like this could become the norm -- making things especially hot, and even dangerous, for low-income folks like residents of Brightridge, few of whom have air-conditioning.
Three weeks later, city councilors Bill Peduto and Natalia Rudiak joined another set of environmental activists Downtown, at PPG Plaza, to issue this warning: Climate change will mean more big snowstorms like the one that stymied city snowplows in February.
The two predictions might sound contradictory: Climate change breeds hotter summers and snowier winters?
Yet such forecasts echo what scientists have said for years: Climate change doesn't just mean higher mercury readings. And its effects go beyond drowning polar bears and islands swamped by rising oceans.
Climate change also portends more extreme weather of all kinds, even in our own backyard. More heat waves -- and bigger snowstorms (at least in the short term). More floods and more droughts -- sometimes in the same place.
The National Wildlife Federation and Citizens for Pennsylvania's Future visited Brightridge Street because cities concentrate heat. (Summer sunlight beats down on rooftops and pavement, and in the absence of shade can heat those surfaces by 50 degrees or more.) And half of Pittsburgh's households lack air-conditioning, says the NWF, with the percentage surely higher in low-income neighborhoods.
"If it's hot outside, it's like 10 times hotter in the house," said Latasha Wharton, a Brightridge resident who watched the press event. "I have to stay under the fan because I'm pregnant and the heat makes me sick."
Infants and the elderly are especially susceptible to dehydration, fainting and heat stroke. Press-conference speaker Dr. Daniel Fine, of Physicians for Social Responsibility, said warmer air also creates more air pollution, like smog; aggravates asthma; harbors more allergenic pollens; facilitates the spread of disease; and boosts mosquito and tick populations.
"Prolonged heat waves with temperatures over 90 degrees hurt our most vulnerable populations the most," added the Rev. Sandi Strauss, of the Pennsylvania Council of Churches.
This summer was among Pittsburgh's hottest ever, with 15 days topping 90 degrees -- about twice the historic average. By 2040, according to a new NWF report, summers with up to 20 such days could be common unless emissions of heat-trapping greenhouse gasses are slowed. By 2100, that number could be 50.
Noting that fossil fuels are the major contributor to man-made climate change, Khari Mosley, of Pittsburgh-based Green Economy Initiatives, said heat risks should motivate us "to move away from a 20th-century economy to a 21st-century economy," one powered by renewable energy.
While no single weather event or season can be blamed on climate change, trends are clear. For example, six of the 10 warmest U.S. summers on record have come since 2001, according to the National Oceanic and Atmospheric Administration. (2010 ranked fourth.) And as Penn Environment's Matthew Ward put it at the Sept. 8 press conference, "global warming loads the dice" for extreme weather.
Even in winter, for example, warmer air holds more moisture. So as long as temperatures sometimes drop below freezing, we can expect more and bigger snowfalls like those from February -- the city's snowiest month on record. On Feb. 5-6 alone, 21 inches fell.
"'Snowmageddon' is just a taste of what's to come for Pittsburgh unless we tackle global warming," said Ward.
It's true that decades of greenhouse-gas buildup mean temperatures will rise no matter what we do now. It's just a question of how bad we'll let things get. The NWF estimates that reducing emissions 80 percent by 2050 could keep annual 90-degree days here under 30 (instead of 50) by 2100.
Fuel-industry lobbying and Republican opposition killed a Congressional climate bill with those emissions goals. But the longer we wait, the harder it gets. So along with pressuring Congress to revive such efforts, activists say we need to push at the state and local level.
City councilors Rudiak and Peduto, meanwhile, emphasized that local clean-energy initiatives could create jobs and make Pittsburgh a leader in the field.
For Ronell Guy, head of the Northside Coalition for Fair Housing, climate change is likewise no abstract problem: "It's about people."