When countries worldwide signed the Paris Agreement in 2016, they agreed to hold the increase in global average temperature to well below 2 degrees Celsius.
When a city or country has reduced its greenhouse gas emissions by at least 10% for five years or more, they are described as having "peaked," according to a definition by C40, a global network of 94 cities working to address climate change.
Although the news hasn't always been hopeful, there's good progress to report: Four more cities have hit their peak greenhouse gas emissions. Austin, Texas; Athens, Greece; Venice, Italy; and Lisbon, Portugal (shown above) are the latest to reduce their carbon emissions.
According to an analysis published by C40, 30 of the world's largest cities have now reached this landmark. That represents areas where more than 58 million people live.
The other cities are: Barcelona, Spain; Berlin; Boston; Chicago; Copenhagen, Denmark; Heidelberg, Germany; London; Los Angeles; Madrid; Melbourne, Australia; Milan; Montréal; New Orleans; New York City; Oslo, Norway; Paris; Philadelphia; Portland, Oregon; Rome; San Francisco; Stockholm; Sydney; Toronto; Vancouver, Canada; Warsaw, Poland; and Washington, D.C.
'A very encouraging signal'
"The fact that 30 of the world's largest and most influential cities have already peaked greenhouse gas emissions demonstrates that a rapid, equitable low-carbon transition is possible, and is already well underway," the group said in a statement during the C40 World Mayors Summit, which runs through Saturday. "C40 analysis shows that, since reaching peak emissions levels, these 30 cities have reduced greenhouse gas emissions by an average of 22 percent. Copenhagen, the host city for this year’s C40 World Mayors Summit, has reduced emissions by up to 61 percent."
Michael Doust, C40's program director of measure and planning, tells CityLab that investments in transit, building energy efficiency, and switching fuel to zero-carbon energy sources are some of the main factors influencing cities.
Although the news is good, it's still possible that emissions could grow again in any of these cities, Doust says. But it's still worth celebrating, albeit cautiously.
"It is expected that these cities should peak before 2020, and the fact that they're doing so is encouraging," he says.
"Overall, it's a very encouraging signal that yes you can still grow your economy, you can still grow your cities in size and still peak."