This Working Group focuses on the planetary boundaries of Biosphere Integrity and Biogeochemical Flows.
The group is currently working to expand the below statement, which summarises the two boundaries and their relationship with AMR, into a longer policy brief.
This Working Group is open to new members – please email CLIMAR.Network@exeter.ac.uk to join.
The Triple Planetary Crisis refers to three primary interlinked issues that humanity currently faces: climate change, pollution and biodiversity loss [1] [2]. These challenges are included within the Planetary Boundaries framework. Biodiversity encompasses microbial diversity, that which both underpins ecosystem function and includes microorganisms that produce the antibiotics harnessed to treat infection. Microbial biodiversity also includes reservoirs of antibiotic resistance mechanisms that are continually emerging in human pathogens. Direct climate change impacts will be largely felt by environmental microbiomes, with direct effects of temperature, precipitation, UV exposure, salinity and pH and indirect effects of CC including human population perturbations, changes in wild animal migration patterns, animal trade routes and agricultural practice etc [3][4]. It’s therefore critical to understand the intersection of human induced climate change, pollution and changes in biodiversity within the context of the AMR pandemic. AMR is not a simple phenomenon. Resistance can be acquired through mutation, many of which occur in pathogens during antibiotic chemotherapy in humans and/or animals and potentially in antibiotic polluted environments. However, much resistance occurs through acquisition of antimicrobial resistance genes through horizontal gene transfer. Current understanding concludes that the majority of these genes have origins in nature predating antibiotic use, the existence of humans and perhaps, for some, even the existence of multicellular life. To some it might seem surprising that resistance predates use of antibiotics, but we need to emphasise that most of our antibiotics are products that are produced naturally by bacteria and fungi and resistance to these antibiotics has evolved over evolutionary time. Therefore, this critical component of the AMR pandemic is rooted in microbial biodiversity. Climate change, environmental pollution and other anthropogenic outcomes effect microbial diversity in the same way that human activity impacts plant and animal biodiversity [5].
Management of agricultural land includes application of agricultural fertilisers, manures and biosolids, associated with biogeochemical flows of nitrogen and phosphorus. Bacteria are involved in both nitrogen and phosphorus cycles and are also involved in carbon and sulphur cycling. “The synthetic production of nitrogen entering ecosystems through fertilizers is now greater than all forms of natural production combined, and phosphorus levels in bodies of water due to the runoff from agricultural and mining activities are dangerously high, though underreported” [6]. We can think about biogeochemical flows in the context of manure and biosolids specifically, how these practices designed to enrich nitrogen and phosphorus in soils for plant growth also leads to the introduction of both exogenous bacteria from humans and animals that include pathogens and AMR mechanisms, and antimicrobial residues that have the capacity to drive further evolution of resistance [7,8]. Urban geochemical flows are also worth thinking about: cleaning products and air pollution from traffic also cause challenges, and more environmental investigation is needed. We can also think about biogeochemical flows from a climate change perspective. We know that nitrous oxide and methane are potent greenhouse gases and that microbial activity is responsible for production of both. However, the impact of antibiotics on microbial community function is poorly understood, particularly at the concentrations found in agricultural soils [9,10]. Carbon cycling is also heavily impacted by microbial respiration, with CO2 production being a function of bacterial metabolism. We know that respiration rates can increase with temperature, but it is unclear how antibiotic stress may impact soil and aquatic microbial communities.