Follow the authors on Twitter: @danpulido and @IrenePortabales   A branded metro station in Madrid Most metro systems around the world are unable to cover their operating costs with fare box…

Daniel Pulido, Irene Portabales González |

Also available in Français | Español | 中文 In January, World Bank Group President Jim Yong Kim urged the audience at the World Economic Forum in Davos to look closely at a young, promising form of…

Heike Reichelt, Alexandra Klöpfer |

In September, the world’s top scientists said the human influence on climate was clear. Last month, they warned of increased risks of a rapidly warming planet to our economies, environment, food…

Rachel Kyte |