The weakening of the Walker circulation in the tropical Pacific is a robust response to global warming in climate models. This can have a global impact on climate, because the convection in the ascending branch of the Walker circulation triggers planetary scale waves that radiate to higher latitudes. In a recent article in the Journal of Atmospheric Sciences (Wills et al. 2017), we study the physical mechanisms responsible for the Walker circulation weakening in an idealized model. Here, we discuss how this work applies to the real-world climate system and how Walker circulation changes are related to tropical Pacific sea-surface temperature changes.