Grant: Discovery Grants Program - Individual

Organic matter (OM) is central to the function of waters and soils that support life on Earth. Although it is synonymous with carbon, OM is much more than a single element. OM consists of tens of thousands of unique molecules of varying origin and composition, making it one of the most complex mixtures in nature. This variety of molecules has been termed "chemodiversity" to mirror the term biodiversity. Despite widespread surveys of OM in waters and soils enabled by technological advances over the past 30 years, there has been no systematic attempt to ask how changes in chemodiversity associated with climate warming will impact nature and human well-being. The impacts of climate change on chemodiversity may be greatest at high latitudes, where some of the largest OM stores on Earth are experiencing the fastest rates of warming. Many of these stores were frozen for millennia in ground known as permafrost alongside their resident microorganisms. Release of these "ancient" metabolites and microbiota into present-day microbiomes because of warming-driven permafrost thaw may create novel ecological and evolutionary interactions with no analogue in the past or present. Microbes are the main consumers of OM, so changes in their diversity and metabolism will have far-reaching consequences for the functioning of entire ecosystems. This research programme aims to discover how climate warming will change the molecular composition of OM and its role in supporting ecosystem function. I hypothesise OM will become more available for microbial processing with climate warming and release more greenhouse gases from soils and freshwaters. To test this hypothesis, I will (1) identify the processes by which climate changes the molecular composition of OM; (2) predict how ecosystem function responds to climate-driven shifts in OM composition; and (3) identify if no-analogue microbiomes (microbiota, metabolomes, and functions) emerge from climate change. I will combine large-scale field surveys of soils and freshwaters spanning temperate-boreal-tundra ecotones with controlled lab experiments using real-world microbial communities and OM. The outcomes of this research will transform how we think about the carbon cycle from one element to distinct communities of organic molecules. This paradigm shift will help spur a new interdisciplinary field in the "ecology of molecules" studying interactions between organic molecules and biotic systems in an environmental context. This new paradigm, along with a better understanding of the interactions between microbes and OM, will help resolve uncertainties relevant to Earth system models that guide climate policy. By engaging with diverse research users, my research will also help climate-proof the design of carbon capture and land management strategies. Training of a diverse HQP team across career stages will enrich the legacy of this project and ensure maximum impact is transferred to wider society.