While the major climate hazards at the global level are generally well described with high confidence, there is less understanding about the importance of hazards on ecosystems when they are superimposed , and the outcomes are difficult to quantify in future projections . Simultaneous or sequential events  can lead to an extreme event or impact, even if each event is not in themselves extreme . For example, the compounding effects of SLR, extreme coastal high tide, storm surge, and river flow can substantially increase flooding hazard and impacts on freshwater systems . On land, changing rainfall patterns and repeated heat waves may interact with biological factors such as altered plant growth and nutrient allocation under elevated CO2, affecting herbivore rates and insect outbreaks leading to the widespread dieback of some forests  . Risk assessments typically only consider a single climate hazard with no changing variability, thereby potentially underestimating the actual risk .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report