Colin J Carlson 

Climate change can cause outbreaks of infectious diseases in unfamiliar locations — but how do we know which unusual outbreaks are the result of climate change? Scientists often hesitate to guess, leaving the task to journalists or the public. All of these audiences would benefit from a clear and consistent framework for thinking about causality, especially in situations where outbreaks are too small for modeling to provide useful insights. This review provides a guide to different ways that climate change may be involved in an outbreak, with an eye towards the often-overlooked effects of climate change on “source” populations with endemic disease. By considering the full set of possible influences – including everything from pathogen ecology to civil conflict – I suggest that scientists and science communicators can make reasonably robust statements about the evidence for climate change involvement in specific unusual outbreaks.