Fleeing the sweltering, cement jungles of many urban centers during the dog days of summer is going to become even more critical in coming years as temperatures continue to rise.
According to a new report from the Urban Climate Change Research Network, based at Columbia University, average annual temperatures in 100 cities around the world are projected to increase by 0.7 degrees Celsius (1.3 degrees Fahrenheit) to 1.5 degrees Celsius (2.7 degrees Fahrenheit) by the 2020s from their 1971-2000 average. Thirteen of these cities could exceed 2 degrees Celsius (3.6 degrees Fahrenheit) warming over the next decade or so, thus easily breaching the goal of the Paris Agreement less than a decade after its signing. These cities include Seattle; Leipzig, Germany; Moscow, Russia; Ottawa, Canada, and other cities in higher-latitude regions.
According to the report, temperatures are already rising in cities around the world, due to both climate change and the urban heat island effect. Mean annual temperatures in 39 cities of the cities included in the Second Assessment Report on Climate Change and Cities (ARC3.2)—released on Tuesday at the Cities IPCC Conference—increased at a rate of 0.12 to 0.45 degrees Celsius per decade from 1961 to 2010.
“The report released today presents massive evidence that cities and city leaders can and are playing a central role in the global climate change challenge,” William Solecki, co-director of UCCRN said in a statement with the release. “The need for small incremental actions is rapidly being superseded by demands for larger-scale transformative action.”
The report, which was years in the making, recommends five key “urban transformation pathways” to confronting climate change, focusing on making sure the process is as inclusive as possible. This means taking actions that both reduce global greenhouse gas emissions and have local benefits, such as increasing natural disaster resilience. It means involving all stakeholders in formulating climate plans, including scientists, and making an extra effort to address the needs of the most disadvantaged and vulnerable citizens. And it means starting now.
The urgency and importance of meeting urban climate challenges will only increase over the decades as climate change worsens and more people move to urban areas. According to the U.N., the percentage of people living in urban areas is expected to rise from just over half to around two-thirds by 2050.
The report projects that temperatures in the 100 cities analyzed could increase by 1.7 degrees Celsius (3.1 degrees Fahrenheit) to 4.9 degrees Celsius (8.8 degrees Fahrenheit) by the 2080s compared to their late 20th century averages.
Aside from temperature increases, sea level rise is also expected to hit cities especially hard. Sea levels in just over half the cities assessed are projected to rise four to 19 centimeters by the 2020s, and 22 to 124 centimeters by the 2080s. According to the report, over half the global population with be living in coastal-zone cities by mid-century, and annual flooding losses cold reach $71 billion by 2100.
In the U.S., cities have stepped up their efforts to fight climate change since President Trump reached office, especially after Trump announced his intention to withdraw the U.S. from the Paris Agreement last June. That unilateral action gave rise to the #WeAreStillIn movement a few days later. Over the ensuing nine months, dozens of cities, along with states, businesses, universities, and nonprofits, have signed up to remain committed to the Paris Agreement’s targets even if the Trump administration pulls out.
In December, more than two dozen mayors, including Chicago Mayor Rahm Emanuel, who are part of We Are Still In signed the first-of-its kind “Chicago Charter” at the North American Climate Summit. The Charter represents more than 67 cities and commits them to achieving emissions reductions and moving forward with climate action.
Update: Due to data issue the original cities listed for 2 degree Celsius increases were incorrect. The report authors notified us with an update and the text has been corrected.