Over the next 15 years, about $90 trillion will be invested in infrastructure in the world's cities, agriculture and energy systems. 24 leaders from government, business, finance and economics in 19 countries think it should be spent fighting climate change. One of the key challenges is to remove cars from cities.

Urban sprawl: we can't carry on like this.

There are obvious benefits, but how can city administrations transform to permit such a radical new direction?

The leaders making these recommendations are part of The Global Commission on the Economy and Climate, which includes Lord Nicholas Stern, Co-Chair and Al Gore. The latter presented the idea at the World Economic Forum at Davos last week together with the former president of Mexico, Felipe Calderon.

Calderon (above) told delegates that the cities of the world should be redesigned so that they do not need cars. "We cannot have these cities with low density, designed for the use of cars," he said. "We recommend those cities should have more density and more mass transportation."

The pair were arguing that this vast amount of money, which must be spent anyway, should be spent wisely. They are on a mission to persuade all of the mayors on earth that designing new cities this way will be much preferable in terms of efficiency and prosperity for residents. 75% of the infrastructure that will be in place by 2050 does not yet exist, and so decisions made now will have repercussions way into the future.

Above: graphic taken from the New Climate Economy report.

"The mistake we made in Mexico was to let cities develop however they want, and it's a mess," Calderon told Business Insider in an interview. "It's in their [the mayors] best interests" not to repeat that "mistake," Calderon said.

The ideas come from the Commission's New Climate Economy report initially launched last September prior to the climate change summit in New York.

Towards car-free cities

A recent conference addressing the Commission's idea of doing away with cars and creating a human-centred smart city of the future, Transforming Transportation 2015, Smart Cities for Shared Prosperity, was awash with ideas for what these cities of the feature might contain.

IBM presented its idea for semiautonomous, or highly automated systems for personal transportation, which is sent will be standard in vehicles within the next decade. Quoting respondents to a report it had commisssioned, 55 percent said highly-automated driving, where an onboard system recognises its limitations and calls the driver to take control when needed, would also be a feature of vehicles by 2025. Cars will connect to services providing information on traffic, weather and other events that might affect a journey.

Buses will be smarter as they are transforming to be in Bangalore, below.

But who needs cars anyway? Maybe you will for a while if you live in LA, since it was designed around the car and it will take a huge effort and a lot of money to re-purpose it for public transit.

But new urban areas don't have legacy problems. Instead, by instigating efficient, integrated transport systems with planning, as has been done from the start in Curitiba (above), huge savings can be made, emissions can be reduced, and streets can be safer and made for people. (Every year, more than 1.2 million people die in traffic crashes worldwide, equivalent to nearly eight Boeing 747 plane crashes every day.) And, since transport accounts for 23% of energy-related greenhouse gas emissions, these will also be reduced.

For example, Medellín's Metrocable system has transformed what was once a day-long journey from the city's mountainous slums to its urban core into a 30-minute journey.

Bus rapid transit (BRT) now serves 31 million people in over 180 cities every day. In Guadalajara, Mexico, just one lane of the Macrobús BRT corridor traveling in one direction transports 5,000 passengers per hour. Normal traffic lanes in Guadalajara can accommodate only 3,194 passengers per hour. In 2011 726 Traffic accidents occurred on these lanes while the Macrobús suffered just six over the same period.

A new report from the WRI Ross Center for Sustainable Cities' EMBARQ initiative and endorsed by the World Bank, Traffic Safety on Bus Priority Systems, shows that high-quality public transport systems can improve traffic safety, reducing injuries and fatalities by as much 50 percent, seen in cities like Guadalajara and Ahmedabad.

Tests in Rio de Janeiro, Mexico City, and Istanbul have suggested design strategies to make bus priority systems safer at intersections, transfer stations, pedestrian crossings, and more.

Designing cities to minimise car use has economic benefits as well. Traffic congestion cost Rio de Janeiro and São Paulo a combined $43 billion in 2013 alone, equivalent to 8 percent of each city's GDP. In Beijing, the costs of congestion and air pollution are estimated at 7-15 percent of GDP. Urban sprawl costs the United States alone $400 billion per year.

The first change must be in the way cities are run

This is all a challenge for planning. How should cities react? The Brookings Institution's Metropolitan Policy Program and Barcelona's ESADE Business School recently brought together officials from cities throughout Europe, Canada, and the United States. Following a two-day workshop, they emerged with several recommendations for changes in city administration:

1. Cities must have an overarching economic vision based on a true assessment of their strengths, challenges and opportunities that focus on using the best research from successful examples elsewhere and an appropriate application of technology. They should not expect national government assistance.

2. As part of the economic vision, three aspects must be taken into account:

• Resilience: there must be a sustainable built environment that is robust in the face of climate challenges;
• Inclusivity: education must apply to everyone to enable them to take their part in the economic revitalisation;
• Productivity: finally, as with New York City, technology and information industries can be harnessed in the cause of long-term economic health.

3. Cities must also reform their decision-making structure in order to integrate technology and sustainability into decision-making, especially in terms of infrastructure (climate resilience then reducing energy use) and technology (ubiquitous Wi-Fi).

4. Risk must be spread. Amsterdam was chosen as an example of utilising public-private partnerships to spread the risks and rewards of smart city technologies; and Toronto, for partnering with both state and national government to unlock $500 million in capital that will stimulate $700 million in private investment.

5. Finally there must be better communication between cities and within urban centres. The Urban Sustainability Directors Network was highlighted as an organizational model. Participants also recognized European cities have a clear advantage in this realm, as European Commission programs like Smart Cities and Communities help build networks through formal communication and grant-making authority.

Now that more people live in cities across the planet than do not, it is imperative that this revolutionary change in attitude occurs rapidly.