The United States and Canada are already extracting fossil fuels from shale formations by fracking, and the industry is expanding rapidly into Australia, Asia, South America and Europe. Whereas conventional energy-production sites tend to cause mainly local impacts, the wide spatial footprint of shale-energy extraction means that many more people will be affected as such sites are established.

Credit: Data Sources: naturalearthdata.com/EIA

We estimate that around 300 million people across 6 continents occupy land overlying shale-energy reservoirs (see 'Socio-economic impacts of shale energy'). This figure is based on shale gas and oil basins identified by the US Energy Information Administration (see go.nature.com/tgsmsv) and on settlement data. Large-scale industrial extraction sites are likely to have socio-economic consequences for all these people.

These effects could be benefits or costs, depending on how they play out. Examples include positive or negative changes to income, employment and housing costs for individuals. For communities, there could be impacts on population growth, youth migration, income distribution, the aesthetic appeal of the landscape and service provision. Extraction sites could also alter the economic productivity of host areas, for example because of competition for land use or the energy sector's high wages.

Tackling these factors fairly will be a challenge to policy-makers, who need to realize the benefits of shale-energy technology to communities. They also have to offset potential losses, including setting appropriate compensation.