From shutting down coal-fired power plants to changing how they handle waste, cities around the world are taking bold actions to address global climate change.

They’re doing so even as their counterparts at the national level are not expected to act on commitments they made last year under the Paris Agreement until 2020. Meanwhile, the dedication of the U.S. government to the climate fight has been thrown into doubt by the election of Donald Trump.

A united front

Against this backdrop, 11 cities received global recognition for their efforts Dec. 1 at the fourth annual C40 Cities Awards in Mexico City. The awards were handed out on the sidelines of a summit of mayors whose cities are among the 90 members of the C40 Cities Climate Leadership Group. At the mayoral confab, it was widely acknowledged that cities increasingly will need to shoulder the burden of both mitigating the causes of climate change and adapting to its impacts in this uncertain era.

"C40 cities around the world are setting a strong example for others — and the summit is a great chance for cities to share their progress, learn from one another and help the world reach the goals that were set in Paris," said Michael Bloomberg, the former mayor of New York City who is also the president of C40’s board.

Meeting those goals will require global action. But not all countries are created equal when it comes to greenhouse-gas emissions. The world’s "big four" emitters — China, the European Union, Russia and the U.S. — are considered crucial to the success of the Paris Agreement, alongside rising industrial powers such as India and Brazil. Over half of the C40 Awards winners come from the ranks of these big emitters, where city-to-city idea sharing at the national level potentially could have huge benefits for meeting national targets.

A prime example is Shenzhen, China, one of the world’s fastest growing cities with 15 million people and an annual GDP growth rate of 10 percent. Shenzhen is a heavily industrialized city, the locus of a "special economic zone" just across the border from Hong Kong. To rein in emissions, the city implemented an emissions trading scheme. 

In the past three years, 636 companies have joined the effort, which caps overall emissions allowed and sets emissions allowances that companies can buy from each other.

In the past three years, 636 companies have joined the effort, which caps overall emissions allowed and sets emissions allowances that companies can buy from each other. Collectively, they have reduced their emissions by 17 percent since 2010 while still increasing their contribution to overall GDP by 55 percent. National emissions-reductions targets are delegated to the local level in China, which provides a strong incentive for cities such as Shenzhen to act.

Although Africa’s overall contribution to global warming is comparatively low, the continent is the world’s fastest urbanizing region — which means cities have the opportunity to act before locking in future emissions. Addis Ababa took that step with a 34-kilometer light-rail system that opened last year, the first in sub-Saharan Africa outside of South Africa. The new transit option has proven immensely popular in the fast-growing Ethiopian capital. Daily ridership is at full capacity of 60,000 passengers per hour.

"The award means a lot," said Yehualaeshet Jemere, who managed the project for the Ethiopian Railway Corporation. The light rail "passed through so many challenges and proved that a project like this can be done in sub-Saharan Africa." Already, delegations from Kenya, Tanzania and Uganda have visited the Addis light rail in hopes of learning from the city’s experience. Jemere said the award could help Addis in applying for other international financing for low-carbon projects; the $475-million light rail was built and financed by the Chinese government.

Innovative cities

Innovative uses of green space are a trend throughout the award winners. Curitiba, Brazil, was honored for its urban agriculture program, which reaches 20,000 citizens, while Paris plans to set aside 82 acres for food cultivation by 2020.

The City of Light won for its overall climate adaptation strategy, which will embark on a greening program of planting 20,000 trees, adding 1 million square meters of green roofs and walls and creating large amounts of new green space to reduce urban heat-island effect. In 2003, a nationwide heat wave killed 11,000 people in France. (Paris Mayor Anne Hidalgo is the incoming chair of C40.)

Parks are at the core of Copenhagen’s approach to deal with 100-year rain events that, in an era of global climate change, are coming more often. Heavy rains quickly can shut down streets in the seaside city and the textbook response would be to build more underground pipes to accommodate the stormwater.

Innovative uses of green space are a trend throughout the award winners.

Jesper Nygard, CEO of Realdania, a Danish foundation focused on the built environment, called this approach the "old-fashioned engineering solution." He told Citiscope: "This investment is only paying back the seven days a year when we have a lot of rain. The rest of the 358 days it’s not an investment that creates quality of life."

To that end, with Realdania’s support, the Danish capital has created flexible public spaces, such as a skateboard park that can double as a stormwater reservoir. This approach to managing cloudbursts is now de rigueur in some 20 Danish cities. The parks and green spaces double as bulwarks against urban heat-island effect and carbon sinks to suck CO2 out of the atmosphere. Across the Atlantic, Philadelphia pursued a similar approach with its award-winning "Green City Clean Waters" plan.

To Nygard, the rapid spread of the idea is just how it should be. "When a screenwriter writes a play or a photographer takes a photograph, it’s illegal to copy," he said. "But what cities are doing, it’s stupid not to copy."

The full list of winners of the 2016 C40 Awards are:

• Addis Ababa (Transportation)
• Copenhagen (Adaptation in Action)
• Curitiba (Sustainable Communities)
• Kolkata (Solid Waste)
• Sydney & Melbourne (Building Energy Efficiency)
• Paris (Adaptation Plans & Assessments)
• Portland (Climate Action Plans & Inventories)
• Seoul (Social Equity & Climate Change)
• Shenzhen (Finance & Economic Development)
• Yokohama (Clean Energy)

Citiscope is a nonprofit news outlet that covers innovations in cities around the world. More at Citiscope. org.