As climate changes, the environmental variables that shape soil ecosystems will change too. In the thawing permafrost, these changes will be especially dramatic. The trajectory of microbes' adaptive response will depend in part on the available mechanisms for genomic change. Mobile genetic elements (MGEs) offer multiple paths to major changes: different MGEs can introduce or excise entire genes, massively diversify existing genes, or potentially introduce mechanisms for post-transcriptional regulation of gene expression. I will discuss new developments in our understanding of the prevalence, activity, and ecological significance of integrated MGEs in Stordalen Mire, a model ecosystem in thawing permafrost.