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Abstract The evolution of modern academic practices, analogous to the evolution of biological systems, reflects the influence of both contingency and determinism. From a theoretical perspective, how then could academic practices differ from those that were inherited? Would any alternative outcomes be more just, equitable, diverse, or inclusive? Here we present 14 alternative academic practices that might be attained upon replaying the tape of academia and evaluate their benefits and drawbacks. Oriented primarily around the physical sciences within the United States, these alternative practices reconsider common activities within the broad categories of the graduate student experience, faculty careers, evaluation methods, peer review and publication, and conference norms. Consideration of these alternative practices can guide within‐system change and large‐scale restructuring of academia to address the myriad challenges facing researchers and students. Conversely, alternative practices may introduce new issues or exacerbate existing problems. These alternative practices are meant to be imaginative, not prescriptive, and we hope their underlying ideas spur reflection and conversation on the existing practices embedded within academic culture. Readers are encouraged to complete a brief survey regarding their impressions of the alternative practices, available at the following link:rebrand.ly/AlternativePractices2024. 

Biogeochemical reactions modulate the chemical composition of the oceans and atmosphere, providing feedbacks that sustain planetary habitability over geological time. Here, we mathematically evaluate a suite of biogeochemical processes to identify combinations of reactions that stabilize atmospheric carbon dioxide by balancing fluxes of chemical species among the ocean, atmosphere, and geosphere. Unlike prior modeling efforts, this approach does not prescribe functional relationships between the rates of biogeochemical processes and environmental conditions. Our agnostic framework generates three types of stable reaction combinations: closed sets, where sources and sinks mutually cancel for all chemical reservoirs; exchange sets, where constant ocean–atmosphere conditions are maintained through the growth or destruction of crustal reservoirs; and open sets, where balance in alkalinity and carbon fluxes is accommodated by changes in other chemical components of seawater or the atmosphere. These three modes of operation have different characteristic timescales and may leave distinct evidence in the rock record. To provide a practical example of this theoretical framework, we applied the model to recast existing hypotheses for Cenozoic climate change based on feedbacks or shared forcing mechanisms. Overall, this work provides a systematic and simplified conceptual framework for understanding the function and evolution of global biogeochemical cycles. 

Silicate weathering and organic carbon (OC) burial in soil regulate atmospheric CO2, but their influence on each other remains unclear. Generally, OC oxidation can generate acids that drive silicate weathering, yet clay minerals that form during weathering can protect OC and limit oxidation. This poses a conundrum where clay formation and OC preservation either compete or cooperate. Debate remains about their relative contributions because quantitative tools to simultaneously probe these processes are lacking while those that exist are often not measured in concert. Here we demonstrate that Li isotope ratios of sediment, commonly used to trace clay formation, can help constrain OC cycling. Measurements of river suspended sediment from two watersheds of varying physiography and analysis of published data from Hawaii soil profiles show negative correlations between solid-phase d7Li values and OC content, indicating the association of clay mineral formation with OC accumulation. Yet, the localities differ in their ranges of d7Li values and OC contents, which we interpret with a model of soil formation. We find that temporal trends of Li isotopes and OC are most sensitive to mineral dissolution/clay formation rates, where higher rates yield greater OC stocks and lower d7Li values. Whereas OC-enhanced dissolution primarily dictates turnover times of OC and silicate minerals, clay protection distinctly modifies soil formation pathways and is likely required to explain the range of observations. These findings underscore clay mineral formation, driven primarily by bedrock chemistry and secondarily by climate, as a principal modulator of weathering fluxes and OC accumulation in soil. 

Abstract Permafrost degradation is altering biogeochemical processes throughout the Arctic. Thaw‐induced changes in organic matter transformations and mineral weathering reactions are impacting fluxes of inorganic carbon (IC) and alkalinity (ALK) in Arctic rivers. However, the net impact of these changing fluxes on the concentration of carbon dioxide in the atmosphere (pCO₂) is relatively unconstrained. Resolving this uncertainty is important as thaw‐driven changes in the fluxes of IC and ALK could produce feedbacks in the global carbon cycle. Enhanced production of sulfuric acid through sulfide oxidation is particularly poorly quantified despite its potential to remove ALK from the ocean‐atmosphere system and increasepCO₂, producing a positive feedback leading to more warming and permafrost degradation. In this work, we quantified weathering in the Koyukuk River, a major tributary of the Yukon River draining discontinuous permafrost in central Alaska, based on water and sediment samples collected near the village of Huslia in summer 2018. Using measurements of major ion abundances and sulfate () sulfur (³⁴S/³²S) and oxygen (¹⁸O/¹⁶O) isotope ratios, we employed the MEANDIR inversion model to quantify the relative importance of a suite of weathering processes and their net impact onpCO₂. Calculations found that approximately 80% of in mainstem samples derived from sulfide oxidation with the remainder from evaporite dissolution. Moreover,³⁴S/³²S ratios,¹³C/¹²C ratios of dissolved IC, and sulfur X‐ray absorption spectra of mainstem, secondary channel, and floodplain pore fluid and sediment samples revealed modest degrees of microbial sulfate reduction within the floodplain. Weathering fluxes of ALK and IC result in lower values ofpCO₂over timescales shorter than carbonate compensation (∼10⁴ yr) and, for mainstem samples, higher values ofpCO₂over timescales longer than carbonate compensation but shorter than the residence time of marine (∼10⁷ yr). Furthermore, the absolute concentrations of and Mg²⁺in the Koyukuk River, as well as the ratios of and Mg²⁺to other dissolved weathering products, have increased over the past 50 years. Through analogy to similar trends in the Yukon River, we interpret these changes as reflecting enhanced sulfide oxidation due to ongoing exposure of previously frozen sediment and changes in the contributions of shallow and deep flow paths to the active channel. Overall, these findings confirm that sulfide oxidation is a substantial outcome of permafrost degradation and that the sulfur cycle responds to permafrost thaw with a timescale‐dependent feedback on warming.