Respecting the boundaries: balancing climate adaptation and Earth system resilience

Abstract. Anthropogenic climate change necessitates not only rapid climate mitigation but also widespread adaptation. It is common knowledge that climate adaptation cannot replace and must not derail mitigation efforts. Yet surprisingly little is known about the existing pressures of climate adaptation on the Earth system. The Planetary Boundaries framework sets biogeophysical limits for critical Earth system processes. In an explorative analysis, existing interactions of climate adaptation with proxies for the Planetary Boundaries are investigated. Linking research from various domains into an attribution analysis, it is found climate adaptation currently contributes ~25.56 percent of annual greenhouse gas emissions and ~74.08 percent of annual human freshwater withdrawals. Climate adaptation even affects the stratosphere: the ozone hole is to a considerable degree an unintended consequence of climate adaptation. Climate change already drives some of these impacts. However, fuelled by factors such as economic and population growth, the majority of these effects would likely also have occurred under Holocene climates. This proves both the importance and the urgency of respecting safe boundaries when accelerating global climate adaptation.