Climate change is the greatest threat facing global natural and cultural heritage. All World Heritage (WH) properties will be impacted over the coming century, and our ability to adapt will often be limited. Yet climate change was a threat never envisioned by the drafters of the World Heritage Convention (WHC). This chapter considers how concepts central to the WHC may need to adapt to a rapidly changing world, to reflect three uncomfortable realities of the climate crisis and its impacts on heritage sites. Firstly, climate change is and will continue threatening and invalidating the Outstanding Universal Value (OUV) of many properties, and there may be little we can do to stop this. Secondly, climate change knows no borders and existing mechanisms may need to be rethought to reflect this. Thirdly, these challenges will, like climate change, disproportionately impact marginalised and indigenous communities in the Global South. It is suggested here that more precise and explicit guidance, which considers local climate modelling and an inclusive approach to values, within the existing proactive mechanisms of the WHC Operational Guidelines would result in a more consistent consideration of climate change impacts at WH properties, that reflects the spirit of the WHC.