Abstract
Climate change is the greatest global threat to ecosystems on the Earth. Previous studies assessed the impacts of climate change on sensitive tropical coral reefs, extreme environments in European Alps and the Arctic with a focus on snow and permafrost. This article reflects on the past developments and future challenges for scientific research and policy response relating to these topics from a peer's perspective. This leads to the identification of several warning signs for potentially dangerous developments in these sensitive system and extreme environments as well as opportunities for research and policy in the future. While urgent actions are required to limit global warming, science-based policy can provide needed guidance.