Monday numbers: Our concrete jungles harm vulnerable people and contribute to climate change

A city block can make all the difference. On a sunny day last summer, the temperature in Nash Square, an urban oasis in Raleigh shaded by magnolia and oak trees, was two degrees cooler than the concrete jungle a block away.

The Urban Heat Island Mapping Project released its first round of results earlier this month, which illustrated the stark differences in how land use affects not only the temperature, but people.

July 23, 2021, was a typical summer day in North Carolina, except that smoke from West Coast wildfires kept the temperatures down. (The wildfires themselves were a result of a persistent drought induced by climate change.)

It was still plenty hot, with temperatures in the upper 80s and heat indices in the low 90s. During three periods — morning, afternoon and evening — citizen scientists roamed the streets in cars, on bikes and on foot, recording air temperature and the humidity.

In Raleigh, the largest temperature difference between shaded and unshaded neighborhoods occurred between 7 and 8 p.m., when buildings offload the heat they’ve gathered all day: 9.6 degrees. 

In Durham, the difference was even greater — 10.6 degrees — between the hottest and coolest parts of the city.

These disparities have significant consequences for people in those neighborhoods who live without air conditioning, who work outside, and who wait for the bus at stops without shelters. Higher nighttime temperatures also can cause health problems for people who can’t get cool. Their bodies never recover from extreme daytime temperatures, making them more vulnerable to heat exhaustion, dehydration, even heat stroke.

Many of these neighborhoods with a scarcity of street trees are historically marginalized, the product of racist housing and zoning policies that pushed Black residents into the least-desirable areas — without trees, in flood plains, near landfills and industry.

While the project measured city heat, temperature differences depend less on whether an area is urban, suburban or rural, and more on how the land is used, said Myleigh Neill of the State Climate Office, during an online presentation.

In Durham, this includes predominantly Black area near NC Central University, dismantled as part of “urban renewal” in the 1950s when NC 147 carved up the historic Hayti neighborhood. Any place dominated by parking lots and highways — southwest Durham, where car dealerships flank U.S. 15-501, and in west Raleigh, near the State Fairgrounds, is bound to be hotter. (In this very heat dome is where the State Fair clearcut 19 acres of temperature-cooling trees for a gravel parking lot.)

North Carolina does love its parking lots. 

A few days before Urban Heat Mapping Project leaders released its initial results, the state Department of Environmental Quality issued its biennial Greenhouse Gas Inventory. That report shows the state’s progress toward meeting its greenhouse gas emissions goals.

One of the key takeaways from the GHG inventory was the role of transportation in inducing climate change. The transportation sector, especially cars and trucks, account for more than a third of the state’s greenhouse gas emissions.

Not only do cars and trucks emit greenhouse gases while in motion, they contribute to the existential problem while standing still — in parking lots. Even electric vehicles won’t wean us off our love of asphalt.

Again, this problem is a result of policy decisions: too little investment in public transportation, and too much emphasis on road widening and road building. 

In Durham, the Urban Forestry Department is planting trees in historically redlined neighborhoods. City leaders could also consider an ordinance requiring landlords to provide air conditioning, not just heating, in their rental properties, said Tobin Freid, city sustainability manager.

In Raleigh, Sustainability Manager Megan Anderson said the city is installing splash playgrounds in historically underserved neighborhoods and experimenting with a “cool pavement project” to reduce urban temperatures. That project coats pavement with titanium dioxide, which decreases radiant heat from asphalt by 37%. (Titanium dioxide, though, could have toxic properties when inhaled; research is ongoing.)

It’s difficult to envision, but Nash Square used to be barren. In 1872, when the City of Raleigh took control of the land, the park had few trees because it had been used for cattle grazing. Now, in the heat of the summer it’s a refuge for everyone trying to find a cool place to rest.

(Sources: Urban Heat Mapping Project, whose partners included the State Climate Office and the Museum of Life and Science; North Carolina Greenhouse Gas Inventory; U.S. Census American Community Survey, 2019)

On July 23, 2021, readings were taken in the morning (6-7 a.m.), afternoon (3-4 p.m.), and evening (7-8 p.m.) These readings are for bicycling and driving routes only; data from walking routes are still being processed.

165 — Number of volunteers
19 — Number of routes
99,275 — Number of measurements

RALEIGH
88.8 degrees  — Maximum daily temperature

Temperature differences between the coolest and hottest locations

6.6 degrees — morning
8.7 degrees — afternoon
9.6 degrees — evening

DURHAM

88.6 degrees  — Maximum daily temperature

Temperature differences between the coolest and hottest locations

6.3 degrees — morning
8.5 degrees — afternoon
10.4 degrees — evening

Greenhouse gas inventory

23% — Reduction in net greenhouse emissions in 2018, compared with 2005 levels
30% — Projected reduction in net GHG by 2025
40% — Original goal for 2025 set in Executive Order 80, in 2018
39% — Projected reduction by 2030, based on energy legislation passed last year
36% — Percentage of state’s greenhouse gas emissions attributed to transportation

Statewide transportation statistics, 2019 (pre-pandemic)

4.75 million — North Carolinians ages 16 and older who commute to work
3.85 million — Commuters who drive alone, equivalent to 80%
436,089 — Commuters who carpool, or 9.2%
48,284 — Commuters who take public transportation, or 1%
276,146 —Worked from home, or 5.8%

Wake County transportation statistics, 2019

519,440 — Commuters by car
5,438 — Who ride a bus
1,473 — Who bike
6,832 — Who walk

Durham County transportation statistics, 2019

184, 978 — Commuters by car
5,732 — Who ride a bus
995 — Who bike
4,150 — Who walk