Building things in cities accounts for 10-20% of global greenhouse gas emissions, according to a new study, and could soon gobble up the entire remaining carbon budget available to keep global warming within 2° C.
“Construction emissions are an important but often-overlooked part of the climate change picture,” says study team member Keagan Rankin, a graduate student at the University of Toronto. “Cities have a lot of control over what gets built in the future, so they are in a good position to reduce construction emissions, but they have historically overlooked construction emissions in their decarbonization plans.”
The researchers quantified emissions across the entire supply chain for construction and maintenance of housing, non-residential buildings, streets, sidewalks, utilities, and other urban infrastructure in more than 1,000 cities around the world. The data encompass cities in 40 high- and middle-income countries across 6 continents, with populations ranging from 50,000 to 10 million and a total population of 1.2 billion, or 15% of the global population.
Construction emissions range from 0.1 to 6 metric tons of carbon dioxide per person per year, with most cities clustering around 1 to 3 metric tons per person per year, the researchers found.
The construction sector hasn’t seen the “decoupling” between investment and emissions that has happened in other parts of the economy. In cities in high-income countries, construction emissions have held steady since 2000 at about 1 metric ton of carbon dioxide per person per year.
The stark reality: Emissions from all sources must be reduced to about 2.3 metric tons per person per year by 2030 to stay within the 2° C warming limit. And when it comes to construction emissions specifically, most cities will have to reach net-zero within 20-40 years to reach that global goal. For many high-income cities, that means “historically unprecedented” rates of emissions reductions, Rankin says.
The good news is that the way out of this bind does not require building less, but instead building better. “We were surprised that many cities could meet both their housing and climate goals into the 2030s within existing building designs (no technology changes needed),” says Rankin.
Promising strategies include choosing designs that make the most efficient use of materials; building more multi-unit apartments and fewer single-family homes; and, in rapidly growing cities, working extra hard and fast to green transport and energy in order to free up more emissions budget for the more difficult to decarbonize construction sector.
The researchers built an open-access dashboard so that citizens, planners, and politicians alike can see how their own city is doing and come up with science-based solutions.
The study, while massive, is not the last word on urban construction emissions. “There is still a big question mark around construction emissions in low-income countries. The data needed to estimate their emissions is hard to collect, or a lot of the time doesn’t exist,” Rankin says. “Determining what the impacts of growing cities in these countries—and how to make construction there sustainable—is an important lane for future research.”
Source: Rankin K.H. et al. “The climate limits of construction in over 1,000 cities.” Nature Cities 2026.
Photo by Josh Olalde on Unsplash
