Home to more than half of the planet’s 7 billion people and a large portion of its 1.2bn cars, cities face a huge challenge as the world strives to meet the Paris climate goal of limiting global warming to 1.5C above pre-industrial levels. Cutting emissions in cities is critical: they make up only 2% of the world’s total land area, but produce up to 70% of its climate emissions from human activity, according to a 2011 United Nations report.

As they work to reduce emissions, governments and public agencies – which often lack the resources to tackle the weighty global warming problem alone – are increasingly looking to the private sector for help, says Robert Puentes, a senior fellow at the Brookings Institution’s Metropolitan Policy Program thinktank.

“Tackling climate change – particularly from a transportation perspective – will require these kinds of partnerships largely because traditional governments and public agencies are underperforming,” Puentes said. “The public sector often does not have the capacity or expertise to design, finance, execute and sustain policies that work, so these partnerships are helping fill the vacuum with a new kind of problem solving.”

In one of the most recent examples, the C40 Cities Climate Leadership Group, a consortium of the world’s largest cities, has enlisted an unusual partner to help reduce tailpipe emissions: MasterCard. It’s one of the largest public-private partnerships aimed at fighting climate change so far.

The consortium – which includes more than 80 cities around the world, including London, Bangkok, Cape Town, New York and San Francisco – says its members collectively emit over 300m tons of carbon dioxide per year from transportation alone, or close to Poland’s total emissions from fossil fuels.

The partnership, announced last month, will set up what’s called a mobility management network, which will connect city staff members to each other and to experts to come up with ideas to nudge people to use public transportation more often.

“These types of measures are all relatively low-cost, compared to investing in a new transport infrastructure, and are therefore of interest to a number of cities,” says Gunjan Parik, director of C40’s Transportation Initiative. “They also allow money to flow back into city coffers to deliver further improvements to public transit.”

Through face-to-face workshops and other events, as well as virtually through webinars, phone calls and a private online forum, cities and transportation experts will have ample opportunities to share their knowledge and brainstorm for answers on topics including parking, ticketing, congestion and integrating different modes of transportation.

MasterCard is working with cities to enable commuters to pay for bus and subway fares more easily, instead of needing to buy tickets in a separate step or having to carry cash or exact change. In London, for example, the company has helped create a system in which riders can use contactless bank cards or mobile phones to pay for fares.

“Around 85% of the world’s transactions are still done in cash, which not only weighs as an inconvenience and a cost on our economies, but also facilitates crime,” says Hany Fam, president of MasterCard Enterprise Partnerships. A study by Tuft University found that using cash costs American society about $200bn per year, from fees paid for using ATMs to lost tax revenues from unreported transactions.

C40 officials said their approach to solving transportation problems has achieved success in other initiatives. San Francisco created SFpark programme, which adjusts meter and garage pricing according to demand, helps drivers find available parking spaces quickly and reduces air pollution and congestion in the process. Milan’s Area C programme, which requires each vehicle that enters the city center on weekdays to pay a roughly €5 ($5.46) congestion charge, reduced the number of cars entering the restricted area by nearly one third this year compared to 2011, before the program was launched.

According to Fam, the success of the initiative with MasterCard will be measured over the next three years by looking at the number of lessons shared and adopted between cities and assessing how much these sustainable transportation projects contribute to the reduction of carbon emissions in cities.

“The biggest thing we can do to truly make a difference in terms of emissions is to get people out of single occupancy vehicles and using whatever combination of bike sharing, walking, shuttles and so on,” said Sharon Feigon, executive director of the Shared Use Mobility Center, a national, public interest organization which advocates for car- and bike-sharing. “All of these modes together are enormously more efficient than the private automobile.”

While new payment systems can greatly improve the public transportation system, they alone aren’t enough to nudge people to forego driving or owning cars. Finding the right strategies to encourage people to take buses and trains is a big challenge. It remains to be seen whether simpler payments and better communication will make a significant difference.

“Information and technology transfer is very important in the adoption of shared mobility concepts,” said Susan Shaheen, adjunct professor and co-director of the Transportation Sustainability Research Center at the University of California, Berkeley.

“It’s going to take many different strategies to accomplish these goals, and we need a vast set of transportation options.”