Epigenetics co-evolved with deoxyribonucleic acid sequence as the molecular mechanism to regulate gene expression and chromatin structure and provide the conduit for the environment to influence biology and evolution. All organisms respond to environmental factors through an alteration in epigenetic processes to alter gene expression to facilitate the cellular and organism response. Therefore, environmental epigenetics is the key molecular process involved in how the environment impacts biology. This has been shown now in all organisms from plants to humans, as well as microbes to insects. Therefore, in considering how climate change impacts biology of any organism, environmental epigenetics provides the molecular mechanism to alter gene expression, physiology and phenotypic variation of the organism.