Changes in the rate of global warming can be pinned to specific episodes in human history.
In a statistical analysis, a team led by Francisco Estrada of the National Autonomous University of Mexico in Mexico City looked at global mean temperatures since 1880, as well as greenhouse-gas levels and other factors that warm or cool the planet. The authors found that economic slowdowns during the two world wars and in the Great Depression temporarily slowed the planet's warming.
The analysis also suggests that the Montreal Protocol, which phased out chemicals that deplete the ozone layer and trap heat, has helped to slow warming in recent decades.
For a longer story on this research, see go.nature.com/g93gb6