SHRINK – Is Global Warming Shrinking Soil Microorganisms?

Global warming affects all life on Earth, including the tiniest organisms - microorganisms. In our project (SHRINK), we study how temperature changes are affecting microbial cells and their ability to carry out different functions. Soil microorganisms, for example, are responsible for the release of billions of tons of carbon from soils to the atmosphere in the form of CO2, a potent greenhouse gas. However, they can also help to retain carbon in the soil and promote the growth of plants, which in turn can remove CO2 from the atmosphere. The SHRINK project aims to understand the consequences of warming-induced changes on microbial cells, microbial communities, and key microbial functions that have global relevance. By doing so, we hope to gain a better understanding of how soils will change in a warmer future – our future. This knowledge will help us predict and manage the effects of global warming on our planet.

Soil microorganisms are responsible for the degradation of soil organic carbon (C) and the subsequent release of billions of tons of CO2 to the atmosphere. It is of great concern that global warming is increasing microbial activities and microbial-derived CO2 emissions from soils, especially in northern regions. To meet national and global climate action plans, such as Norway’s Climate Action Plan for 2021–2030 and the UN 2030 Agenda for Sustainable Development, we urgently need to understand soil-climate feedback loops triggered by warming, including underlying microbial activities. SHRINK is based on our recent discovery that soil microorganisms exposed to warming reduce their cellular numbers of ribosomes, their “protein production factories”. Since ribosomes are universal, highly abundant, and constitute a large fraction of the cell mass, a reduction will have extensive implications. For example, microbial cells require less energy and matter to synthesize ribosomes, and consequently, less cellular space is needed to harbour them. These spared resources (energy, matter, space) can be simply saved or re-allocated, possibly leading to smaller cells, accelerating microbial activities, and increasing microbial-derived CO2 emissions. SHRINK will advance our understanding of microbial responses to soil warming and reveal the molecular basis of ribosome reduction, uncover the effect of this key physiological mechanism on microbial cells and their physiological states, and assess implications for soil ecosystems and microbial-derived CO2 emissions from soils. Furthermore, the temperature-dependent regulation of cellular ribosome contents and the subsequent cellular resource re-allocations might represent the key module to advance and refine metabolic models, ecosystem simulations, and Earth system models. Thus, SHRINK will eventually help to better understand, predict, and manage soil-climate feedbacks in a warmer future – our future.