Overall confidence in attributing biological changes to climate change can be increased in multiple ways , four of which we list here. First, confidence rises when the time span of biological records is long, such that decadal trends in climate can be compared with decadal trends in biological response, and long-term trends can be statistically distinguished from natural variability. Second, confidence can be increased by examining a large geographic area, which tends to diminish the effects of local confounding factors . Third, confidence is increased when there is experimental or empirical evidence of a mechanistic link between particular climate metrics and a biological response. Fourth, confidence is increased when particular fingerprints of climate change are documented that uniquely implicate climate change as the causal driver of the biological change . These conditions constitute multiple lines of evidence, which, when they converge, can provide very high confidence that climate change is the causal driver of an observed change in a particular biological species or system .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report