Here’s how city networks can help American cities reduce their carbon footprint

Trump world, at a climate protest in Berlin in June 2017. Image: Getty.

Over the last three years, US mayors have become increasingly convinced that cities should play a strong role in reducing the effects of climate change. Today, two thirds of mayors are willing to expend resources to take action on climate. If the political will exists, the question then becomes: who is offering a roadmap to get there – and what are the next steps?

On top of many head-scratching policy reversals over the past three years, the new presidential administration has refused to take over the baton when it comes to following up on commitments made in international climate negotiations. In the absence of federal leadership and momentum, cities – and especially networks of cities – have entered the race more energetically and are working to close the gap between promised and actual greenhouse gas reductions.

In the report “Cities Joining Ranks” by the Boston University Initiative on Cities we trace the emergence of city networks, systematically review which cities join which networks and take stock of what networks have to offer to their members.

Five out of the ten city-to-city environmental networks we looked at – including C40, Climate Mayors, ICLEI USA, and We Are Still In – were formed since 2014. And the media has caught on to this burst of activity. We find that the number of articles referencing any of the ten networks has increased by 60 per cent in between 2017 and 2016 alone.

When talking about how climate networks can help cities decarbonise, it is important to keep cities’ big picture challenge in mind. Scientists calculated that, in order to have a reasonable chance to keep average global warming under 2 degrees without needing to resort to geoengineering, global GHG emissions need to be halved in every single decade, starting now. This means cities in high-income countries like the US or UK should be carbon neutral by mid-century the latest. It is an extremely ambitious agenda, but the straw to cling to requires especially wealthy and carbon-intensive cities to act fast.

Small and mid-sized cities in particular need assistance in building capacity to dramatically reduce their carbon emissions. This is where city networks come in providing technical assistance and facilitating best practice exchange.

Mayors confided that the abundance of environmental networks was at times overwhelming as they consider possible memberships. In charting the network landscape, we found encouraging news. By and large, environmental city networks complement each other and allow cities with different levels of ambition and capacity to find peer cities and access tailored assistance. Moreover, the networks are interconnected not only by overlapping memberships, but via joint events and collective advocacy.

Cities which have set their sights high and formulated ambitious decarbonisation plans can use their different network memberships like rungs on a ladder towards achieving their goals. By climbing from one network to another, they can take advantage of the different combinations of technical assistance and membership obligations. My analysis of cities’ joining behavior over time shows that cities appear to follow a very similar pattern that is consistent with gradually ramping up ambition levels.

Close to 80 per cent of American cities with up to one million residents and which have joined at least five environmental networks first became part of ICLEI USA, a network that provides a broad range of technical tools to engage in climate planning. Then they signed on to the tiered commitment process of the US Compact of Mayors, which requires cities to do a GHG inventory, set GHG reduction targets and devise an implementation plan. Thereafter, they joined Climate Mayors, which provided them a national advocacy platform and closer peer-to-peer coordination.

Most recently these cities all committed to uphold the Paris Agreement in their jurisdiction through the “We are still in” movement. The majority have pledged through the Sierra Club Mayors for 100 per cent Clean Energy Initiative to work towards realizing 100 per cent clean and renewable energy in their city.

It is an exciting area for future research to probe deeper into how this joining trajectory has helped cities in practice. For now, it presents a possible roadmap for other ambitious cities to orient themselves as they climb up the ladder of decarbonisation.

Nicolas Gunkel is a research fellow at the Boston University Initiative on Cities and co-author of the “Cities Joining Ranks” report. Previously, he has worked with cities and towns to better collaborate on climate adaptation and he has written about the difficult path for solar in the “sunshine state” Florida.  


To beat rising temperatures, Vienna launches a network of 'Cool Streets'

A Vienna resident cools off at one of the city's new Cool Streets installations. (Courtesy Christian Fürthner/Mobilitätsagentur Wien)

Over the past several months, Austria has recorded its highest unemployment rate since World War II, thanks to the economic aftermath of the Covid-19 pandemic. With no job or a suddenly smaller income – not to mention the continued threat of the virus – many Viennese will opt for a staycation this summer.  

At the same time, last year, Austria’s capital experienced 39 days with temperatures of over 30°C (86°F), one of its hottest summers in history according to the Central Institute for Meteorology and Geodynamics.

Climate experts expect a similarly sizzling 2020 season, and city officials are now doubling down on efforts to combat the heat by launching a “Cool Streets” initiative as well as a new, state-of-the-art cooling park.

“As the city councilwoman in charge of climate, it is my job to ensure local cooling,” Vienna’s deputy mayor Birgit Hebein proclaimed at the opening of one of 22 new “Cool Streets” on 22 June.

“In Austria, there are already more heat deaths than traffic fatalities,” she added.

Hebein was referring to the 766 people the Austrian Agency for Health and Food Security included in its 2018 heat-associated mortality statistics. The number was up by 31% compared to 2017, and in contrast to the 409 people who died in traffic collisions the same year.

The project includes 18 temporary Cool Streets located across the city, plus four roads that will be redesigned permanently and designated as “Cool Streets Plus”.

“The Plus version includes the planting of trees. Brighter surfaces, which reflect less heat, replace asphalt in addition to the installation of shadow or water elements,” said Kathrin Ivancsits, spokeswoman for the city-owned bureau Mobilitätsagentur, which is coordinating the project.

Vienna's seasonal Cool Streets provide shady places to rest and are closed to cars. (Petra Loho for CityMetric)

In addition to mobile shade dispensers and seating possibilities amid more greenery provided by potted plants, each street features a steel column offering drinking water and spray cooling. The temporary Cool Streets will also remain car-free until 20 September.

A sensor in the granite base releases drinking water and pushes it through 34 nozzles whenever the outside temperature reaches 25°C (77°F) . As soon as the ambient temperature drops to 23°C (73°F), the sensor, which operates from 10 a.m. to 8 p.m., turns off the water supply.

The sensors were included in part to allay concerns about legionella, a pathogenic bacteria that can reproduce in water.  

“When the spray stops, the system drains, and therefore no microbial contamination can develop,” said Dr. Hans-Peter Hutter, deputy head of the Department of Environmental Health at the Center for Public Health at Medical University Vienna, in a televised interview.

Hutter also assured the public that there is no increased risk of a Covid-19 infection from the spray as long as people adhere to the one-meter social distance requirement.

But Samer Bagaeen of the University of Kent's School of Architecture and Planning notes that air cooling systems, like the ones used in Germany at abattoirs, have been found recently to be a risk factor for Covid-19 outbreaks.

“The same could be said for spay devices,” he warned.

Vienna’s district councils selected the 22 Cool Street locations with the help of the city’s Urban Heat Vulnerability Index. The map shows where most people suffer from heat by evaluating temperature data, green and water-related infrastructure, and demographic data.

“Urban heat islands can occur when cities replace the natural land cover with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat,” as the US Environmental Protection Agency states.

A rendering of Vienna's planned park featuring a Coolspot, which is scheduled to open in August. Click to expand.
(Courtesy Carla Lo Landscape Architecture)

Vienna’s sixth district, Mariahilf, is such an area. The construction of the capital’s first “Cooling Park”, a €1 million project covering the 10,600 square-metre Esterházypark, is designed to provide relief. 

Green4Cities, a centre of excellence for green infrastructure in urban areas, designed the park’s main attraction, the “Coolspot”. The nearly 3.40-metre high steel trellis holds three rings equipped with spray nozzles. Textile shading slats, tensioned with steel cables, cover them.

The effects of evaporation and evapotranspiration create a cooler microclimate around the 30 square-metre seating area, alongside other spray spots selectively scattered across the park.

The high-pressure spray also deposits tiny droplets on plant and tree leaves, which stimulates them to sweat even more. All together, these collective measures help to cool their surroundings by up to six degrees.

The landscape architect Carla Lo and her team planned what she calls the “low-tech” park components. “Plants are an essential design element of the Cooling Park,” Lo says. “By unsealing the [soil], we can add new grass, herbaceous beds, and more climate-resistant trees to the existing cultivation”.

Light-coloured, natural stone punctuated by grass seams replaces the old concrete surfaces, and wooden benches meander throughout the park.

Living near the park and yearning for an urban escape close by, Lo says she’s motivated to ensure the park is completed by mid-August.

“If we don't do anything, Vienna will be another eight degrees Celsius hotter in 2050 than it already is,” Hebein said.

Vienna recently came in first in the World's 10 Greenest Cities Index by the consulting agency Resonance.

“There is no one size fits all on how cities respond to urban heat,” says the University of Kent’s Bagaeen, who points out that Vienna was one of the first European cities to set up an Urban Heat Islands Strategic Plan in 2015.

In the short term, prognoses on the city’s future development may be more difficult: Vienna votes this autumn.

Petra Loho is a journalist and photographer based in Austria.