Discriminating the climate impacts of half-degree warming increments is high on the post-Paris science agenda. Here the researchers argue that evidence from the observational record provides useful guidance for such assessments.

Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. The 2015 Paris Agreement includes a two-headed temperature goal: "holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C". Despite the prominence of these two temperature limits, a comprehensive overview of the differences in climate impacts at these levels is still missing.

Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. The 2015 Paris Agreement includes a two-headed temperature goal: “holding the increase in the global average temperature to well below 2 ◦C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 ◦C”. Despite the prominence of these two temperature limits, a comprehensive overview of the differences in climate impacts at these levels is still missing.