The AAAS heard how cities with lower carbon emissions could be built. More than half the world’s population dwell in cities, and by 2050 the un expects that proportion to reach 68%. This means more homes, roads and other infrastructure. In India alone, the equivalent of a city the size of Chicago will have to be developed every year to meet demand for housing. Such a construction boom does, though, bode ill for tackling climate change, because making steel and concrete, two of the most common building materials, generates around 8% of the world’s anthropogenic carbon-dioxide emissions. If cities are to expand and become greener at the same time, they will have to be made from something else...

The Economist: Building sustainable cities with wooden skyscrapers