Peatlands are major global mercury (Hg) reservoirs and are highly sensitive to warming, yet climate effects on microbial controls of neurotoxic methylmercury (MeHg) formation remain unclear. Here, we combined global synthesis with new measurements to assess climate-associated variation in net MeHg production. Metagenomes from 144 peat soils revealed higher relative abundance of the Hg-methylation gene hgcA but lower relative abundance of the demethylation gene merB at high latitudes, consistent with their opposing correlations with mean annual temperature. The ratio of nitrogen-fixation to denitrification genes (nifH/nosZ) covaried with hgcA and merB, suggesting links between nitrogen cycling and Hg transformation. Genome-resolved analyses further showed expanded denitrification pathways in hgcA-bearing taxa from warmer peatlands. Together, these findings indicate that warmer climates may be associated with microbial community restructuring and lower net MeHg production. A space-for-time framework therefore suggests reduced MeHg yields under future warming, informing Hg-risk assessment under the Minamata Convention. Metagenomes from 144 peat soils revealed higher relative abundance of the mercury-methylation gene but lower abundance of the demethylation gene at high latitudes, consistent with their opposing correlations with mean annual temperature, based on metagenomes from subtropical and temperate-boreal regions in China and metagenomes spanning tropical to Arctic regions.
Over the past two decades, there has been a staggering increase in greenhouse gas emissions, particularly carbon dioxide (CO2) from unrestrained anthropogenic activities, leading to notable environmental shifts. Despite continuous efforts to reduce emissions, the world is not making satisfactory progress, which calls for immediate action to implement alternative strategies to enhance environmental sustainability. The Earth naturally absorbs and stores carbon through various processes, but merely keeping pace with ongoing human activities is no longer sufficient. Land plants and marine prokaryotes absorb CO2 during photosynthesis and store carbon as biomass. Eukaryotic organisms also represent a valuable resource that can provide insights into the biological fixation and removal of atmospheric CO2. Expanding the capacities of Earth’s natural systems offers enormous potential for enhancing carbon sinks and promoting environmental resilience. Although extensive synthetic engineering of plant systems has been conducted to enhance their native carbon fixation pathways, research on microorganisms, especially fungi, has been limited. In this review, we specifically explore the role of soil-borne fungi in carbon management, elucidating their responses to environmental shifts and their potential for climate change mitigation. We place particular emphasis on the role of various fungal guilds in this process, highlighting those that should be prioritized for future synthetic biology applications. We then engage with previous endeavors to address primary challenges in advancing genetic tools for these understudied fungi. Lastly, we discuss how integrating synthetic biology practices into the field of soil-associated fungi can drive advances in long-term carbon storage, enhance degradation of environmental pollutants, and improve nutrient exchange and soil health, contributing to more resilient soil ecosystems and sustainable environmental interventions. Rising carbon dioxide emissions from human activities are driving environmental change and increasing the need for strategies that strengthen natural carbon sinks and ecosystem resilience. While plants and microorganisms play important roles in carbon capture and storage, the potential of soil-associated fungi remains comparatively underexplored, particularly from a synthetic biology perspective. In this Review, we examine the roles of soil-borne fungi in carbon management, their responses to environmental change, and their potential contributions to climate change mitigation. We highlight key fungal guilds that could be prioritized for future synthetic biology applications and discuss current challenges in developing genetic tools for understudied fungi. Finally, we explore how engineering soil-associated fungi could support long-term carbon storage while providing broader environmental benefits, including pollutant degradation, nutrient exchange, and improved soil health. Together, these opportunities position fungal synthetic biology as a promising approach for developing more resilient soil ecosystems and sustainable environmental interventions. Soil fungi are an underexplored tool for climate mitigation, as discussed in this synthesis, which examines how synthetic biology could enhance their contributions to carbon sequestration as well as nutrient cycling, soil health, pollutant degradation, and ecosystem resilience.
Extreme precipitation on the central Tibetan Plateau, particularly outside the summer monsoon season, strongly affects glacier mass balance and downstream water availability, yet the moisture transport mechanisms remain poorly understood. This study combines high-resolution measurements of the isotopic composition of atmospheric water vapour at Nam Co Lake with isotope-enabled climate model simulations to investigate an extreme snowfall event on 25 October 2022. We show that the event was triggered by a cyclonic disturbance over the northern Bay of Bengal, reinforced by the western Pacific subtropical high, which channelled moisture into the plateau interior. We identify a growing class of similar cyclone-driven extreme precipitation events before and after the monsoon season from 1990 to 2022. Climate projections indicate that such events will become more frequent under moderate and high emissions. These findings identify a robust isotopic fingerprint of cyclone–orography interactions and highlight the growing role of Bay of Bengal moisture in Tibetan Plateau water security in a warming climate. Extreme precipitation events on the central Tibetan Plateau outside the monsoon season have been increasingly linked to cyclones in the Bay of Bengal and is projected to occur more frequently under global warming, as suggested by observations and model experiments.
Sediment respiration in streams/rivers impacts global biogeochemical cycles, yet is mostly studied under perennially-inundated conditions despite all river corridors having variably inundated areas and most streams going dry each year. Previous experiments observed sediment rewetting to cause elevated or suppressed aerobic respiration, indicating variation across studies. To deepen understanding, we conducted 21-day wet/dry experiments with sediments from 64 streams spread across the contiguous United States. Here we show that drying and rewetting sediments from perennial and non-perennial streams had near-neutral effects or suppressed O2 consumption rates. These biogeochemical cold moments contrast previous studies that observed hot moments. Sediment texture and microbial activity explained variation in responses to rewetting, but this did not reveal why some studies observed cold moments while others observed hot moments. To solve this we propose a unifying conceptual model whereby hot and cold moments exist simultaneously upon rewetting by considering both dry-state and perennially-inundated reference points. Drying and rewetting sediments caused near-neutral or extreme cold moments with suppressed oxygen consumption in perennial and non-perennial streams, with no meaningful hot moments observed, based on wet/dry experiments with sediments from 64 streams across the Continental United States.
The temporal stability of plant net primary productivity (NPP), defined as the ratio of temporal mean productivity to its standard deviation, is crucial for sustaining ecosystem services. Yet, little is known about whether the effects of nitrogen deposition on aboveground NPP (ANPP) stability are coupled with corresponding changes in belowground systems. Here we conducted a global meta-analysis based on 542 multi-year observations from 111 studies to assess the impacts of nitrogen deposition on the stability of ANPP and belowground NPP (BNPP). Nitrogen addition significantly decreased the stability of both ANPP and BNPP in a synchronized manner, reflecting a coupled response resulting from the allocation trade-off between mean ANPP and BNPP and their synchronized increase in variability. Further analysis showed that the declines in both ANPP and BNPP stability were associated with decreased plant species richness under nitrogen addition. Moreover, the negative responses intensified with longer treatment durations and higher nitrogen addition intensity. These findings highlight the importance of considering above- and below-ground interactions in future ecosystem management strategies under global change scenarios. Nitrogen deposition synchronously reduces above- and belowground plant productivity stability via an allocation trade-off between mean productivity and variability, with stronger declines under longer or more intensive treatments, based on a meta-analysis.
