Many researchers have sought to map vulnerability to climate change or identify climate change hotspots, all with the same basic question: who will be hit the hardest? If we could agree on an answer it could be very helpful, for example for allocating adaptation funding.

However, the results rely heavily on which metrics are used to assess climate change risk: potentially important factors range from soil moisture to safety regulations to social cohesion.

A new study, described here by Climate Central @ClimateCentral, aims to identify hotspots in Africa in terms of the risks for hydrology, ecosystems, and crop yields. Even before you start thinking about human vulnerability, there are many decisions to be made about how to quantify hydroclimatic risk. In this case the authors decide to focus only on "negative" impacts and not on potential benefits from climate change, and also use agreement between climate models to assign likelihoods. These are defensible choices, but different methods might modify their findings.

This study, and other work on hotspots, is very interesting and useful for understanding the interaction between multiple climate impacts. But could it be confusing for decision makers trying to prioritise adaptation spending?