Summer in Savannah has always been a beast.
In 1758, the governor of the colony of Georgia, Henry Ellis, complained about Savannah's swelter in a letter the Savannah Morning News published centuries later. Ellis, whose namesake downtown square includes a cooling splash pad, claimed the temperature was 102 degrees as he wrote.
“Twice it has risen this summer to the same height, viz, on the 28th of June, and the 11th of July. Several times it has been at 100, and for many days successively at 98; and did not in the nights sink below 89…. The greatest heat we had last year was but 92, and that but once; from 84 to 90 were the usual variations; but this is reckoned an extraordinary hot summer.”
Wonder what Ellis would write about today with the last week averaging highs of 88, lows of 77, and a relative humidity registering above 80%? At least we have air conditioning.
If you think Savannah is getting hotter by the season, you'd be correct. A city-by-city analysis by the nonprofit Climate Central indicates the average temperature of a Savannah summer day has increased by 2 degrees Fahrenheit since 1970. Overnight lows have warmed by 2.1 degrees. And the average number of days each year over 95 degrees has increased by 12 days. Climate change, driven by human activities such as development, deforestation and the burning of fossil fuels, has slowly made the extraordinary of Ellis's more ordinary in ours.
From hot to hotter
Residents here may not have noticed the change from hot to even hotter. Rita DeLorme, in her 80s, grew up in Savannah and raised seven children in her tidy two-story home in Parkside. She's always hated the heat.
"Summer here was always hot as a rule," she said, sitting in her living room cooled with a window unit. "By the time you hit July and August you're suffering if you don't have air conditioning."
Unlike most of her neighbors, she's never had central air but makes do with several window units.
Other Georgia cities have experienced similar heat increases since 1970. In Augusta, the increase is 2.4 degrees on average and a 2-degree higher overnight low, with 26 extra days — almost a full month — of days topping 95 degrees in a typical summer compared to 1970. Atlanta has increased even more, a full 3 degrees for summer average temperature, 3.7 degrees higher for the overnight low and five more days above 95 degrees.
Urban heat islands
Cities are growing hotter even more rapidly than their suburbs because of the heat island effect. Urban heat islands are city areas where heat is intensified by the heat-trapping ability of roads and buildings, the heat production of engines and air conditioning, plus the loss of the cooling power of trees and other plants, according to Climate Central.
Researchers at Climate Central created an index to evaluate the intensity of urban heat islands and applied it to 159 cities across the U.S. Savannah received a score of 5.8 degrees, meaning it's on average that much warmer in Savannah than in the surrounding suburbs. Augusta scored the same, while Atlanta scored 6 degrees.
And that's just the average, said Kim Cobb, Georgia Power Chair, ADVANCE Professor, and Director, Global Change Program, Georgia Tech.
"It's certainly not pegged to the most extreme differentials that we see, for example, during the very hottest days of the year," said Cobb, who was not involved in producing the Climate Central rankings but who does study climate change. "And so those in Atlanta, you know, are pressing up into the 10 degrees Fahrenheit area, if not more. This is just the kind of differential of heat, that can put the entire metro area under heat alert, not just for a couple hours for one day, but pretty much for potentially days on end."
Urban heat islands are influenced by albedo, which measures whether a surface reflects sunlight or absorbs and retains the sun’s heat. Think a white roof versus a black one. Other factors include the amount of impermeable surface, such as roads and parking lots. Hard, dry surfaces provide less shade and moisture than natural landscapes and contribute to higher temperatures, Climate Central reports. Other components include a lack of greenery and trees, the area and heights of buildings, and heat created by human activities like running engines and air conditioners.
The Smart Sea Level Sensor project (https://www.sealevelsensors.org), which already tracks flooding vulnerability around Chatham County, is aiming to expand to include an urban heat component with internet-linked thermometers in the near future, Cobb said.
"So they'll be likely installed on street(light) poles, you know, that kind of person height. And they'll they'll be deployed across what we know to be the most vulnerable areas of Savannah," Cobb said.
Reducing heat islands
Short-term solutions to heat problems focus on getting people out of sweltering temperatures and making sure they're hydrated. But for the long term, Climate Central suggests these ways to reduce urban heat island effects:
• Planting trees, particularly along paved streets.
• A green roof, or rooftop garden, is a vegetative layer grown on a rooftop and can provide shade and lower temperatures of the roof surface and surrounding air.
• Cool roofs are made of highly reflective and emissive materials that remain cooler than traditional materials, and help to reduce energy use.
• Cool pavements, or whitewashing roads and sidewalks, is more complicated than roofs. In cities with urban canyons, the sunlight may not even reach the street level long enough to make a significant difference. In places like Los Angeles, a cool pavement study showed that heat was reflected off the white surface and onto pedestrians, which made people feel hotter.
Mary Landers is the environment and health reporter at the Savannah Morning News. Contact her at 912-655-8295. Twitter: @MaryLandersSMN
This article originally appeared on Savannah Morning News: Savannah goes from hot to hotter as climate warms
