Several lines of evidence suggest the evolution of melanism in response to climate change , with colour changes associated with thermoregulation being demonstrated in butterflies , beetles , dragonflies  and phasmids . Such changes may represent decreased phenotypic diversity and, potentially, genetic diversity , but the consequences of climate change for the genetic structure and diversity of populations have not been widely assessed . Simplistically, the thermal melanism hypothesis suggests that lighter  individuals should be fitter and therefore be selected for in a warmer climate . However, several biotic  and abiotic  factors interact to influence changes in colour, making attribution to climate change across species and broad geographic regions difficult .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report