Freshwater wetland soils have a disproportionately large impact on global carbon cycling, playing key roles in regulating climate. These soils hold upwards of 30% of carbon on Earth despite occupying less than a tenth of the land surface, making these habitats critical atmospheric carbon dioxide sinks. Yet, this carbon is not completely protected or guaranteed to be stored in soils. In fact, much of it is destabilized by microorganisms. Soil microorganisms decompose this stored carbon, breaking it down for energy and releasing carbon dioxide, methane, and nitrous oxide. When these greenhouse gases are released from wetland soils, they further exacerbate climate warming. In fact, freshwater wetlands are recognized as the largest natural source of global methane. Ultimately, the development of climate smart soil strategies that manage soil carbon gain from sequestration and loss through greenhouse gas emissions, will require enhanced knowledge of soil microbiology in freshwater wetlands. It is surprising given their importance to climate that we know so little about the microorganisms or the microbial enzymes that control the conversion of soil carbon into methane. Fortunately, advances in genomic sciences have cracked the window on soil carbon cycle, offering some of the first insights into microorganisms that contribute to and even those that can reduce soil methane emissions. While a promising start, these observations have been derived from site specific studies and thus any generalizable rules or understanding about the fundamental microbial controls on soil carbon cycling in freshwater wetlands are lacking. This knowledge gap hinders accurate predictions of greenhouse gases emissions from these climatically important soils. To address this knowledge deficit, we designed this research project to sample over ten wetlands in the continental United States with varying methane emissions from low to some of the highest globally. We seek to identify the chemical and biological rules that explain why some wetlands emit high amounts of methane and others do not, despite close geographic and climatic similarity. We use high resolution methods for uncovering the molecular attributes of soil carbon and pair this to a first of its kind microbial genome catalog, providing a blueprint for the cycling of carbon across and unique to different wetlands. Together, this project will reveal the soil attributes that are conserved across high methane emitting wetlands, allowing us to build a new era of climate models that are microbiologically informed.  Key deliverables from our proposed research efforts will have value to scientific communities and more generally to society. Scientists will benefit from our soil microorganism genome catalog, a community resource which inventories and describes the reactions catalyzed by hundreds of thousands of previously enigmatic soil microbes. Our highly collaborative and multidisciplinary team will offer direction for increased realism in predictive process-oriented models of soil methane flux. Beyond identifying climate-smart solutions, our microbial collection and models can be mined for new enzymes for biofuels or to guide precision therapeutics for enhanced bioremediation or carbon sequestration in soil.