AGU Advances最新文献

Freeze-thaw (FT) is a key hillslope weathering process in cold regions, influencing hillslope stability and sediment delivery to rivers. To understand how climate change will impact FT, we conducted field monitoring in the Pekerebetsu River basin, Hokkaido, Japan, and calibrated a numerical model to predict FT changes. Field measurements show that erosion and deposition of colluvium depends on local snow cover, because snow insulates the ground when present and greatly reduces FT cycles. We then generalize our results using a calibrated soil temperature equation and climate model scenarios to predict how FT may change under future climate. When snow cover is ignored, FT is predicted to decrease in the study area due to future warming. However, when insulating effects of snow cover are included, the area is predicted to have little change in FT in some places, and potentially large FT increases in other locations. The impact of decreased snow cover tends to be greater than that of increased temperature.

Spaceborne CO₂ observations can now resolve monthly anomalies in Earth's carbon cycle, pinpointing the impact of regional extreme events like drought and fire in near real time. Monthly atmospheric CO₂ growth rates from NASA's Orbiting Carbon Observatory-2 (OCO-2) provide an early warning system for how the carbon cycle responds to extreme events, and lay a foundation for continuous, satellite-based monitoring of carbon cycle changes. However, NASA FY 2026 President's Budget Request omits OCO-2 funding after FY 2025, risking a gap in this monitoring capability as climate hazards intensify.

Freshwater wetlands are major sources of global methane emissions through biogenic methanogenesis, a process increasingly influenced by climate change. High latitude wetlands are subject to uniquely altered biogeochemical inputs due to disproportionate warming. For example, glacial meltwater delivers metal-rich sediments that are easily reducible. Additionally, if the wetland is located upon a subduction zone, periodic and dynamic geological forces, such as megathrust earthquakes, can disrupt these systems further. To explore these interactions, we analyzed the genomic potential of microbial communities across a glaciated wetland located in an active forearc region subject to repeated megathrust ruptures. We found that sediment microbial communities contained the complete potential for methanogenesis and iron cycling, yet the relative abundance of key methanogenic genes was reduced in recently deposited freshwater sediments despite high levels of organic matter and iron. These findings suggest that megathrust fault activity and associated uplift exerts broad, abrupt change on microbial metabolic potential, and that overlying sediments reflect modern glacial input which modify the development of metabolic potential. Glacial influence likely disrupts methanogenesis by supporting communities capable of dissimilatory iron reduction, which may increase metal-dependent methanotrophy. As climate change accelerates glacial melt, extant and newly developing microbial communities will likely respond rapidly to shifting carbon and mineral inputs, altering carbon cycling dynamics in these sensitive ecosystems. Our work links small scale microbial metabolic potential with some of the largest processes on our planet, revealing how cyclical tectonic events can overprint broad scale biogeochemistry by homogenizing microbial metabolisms and disrupting elemental cycling.

Venus' thick atmosphere rotates in the same direction as the solid body, but ∼60 times faster. This atmospheric superrotation has produced dozens of windblown ejecta deposits (“parabolas”) on the surface of Venus. The formation and modification of parabolas is an interplay between impacts, aeolian modification, and atmospheric dynamics. We conducted a survey to explore the nature of these sedimentary surface features. First, we observe trends in parabolas' morphology that shed light on how they are deposited and gradated. Changes in the size and radar albedo of parabolas are likely linked to the height and density (respectively) of ejecta plumes at time of formation. Next, we discovered that parabolas show orientations inconsistent with present atmospheric dynamics. This discrepancy may record a change in these dynamics or geologically recent true polar wander at a rate of ∼1° Myr⁻¹, which is similar to that observed on Earth over the past century. These results highlight how overlapping observations at different radar wavelengths provide important insights into the history and character of geologic processes on Venus. Overall, atmospheric superrotation has probably persisted for at least the age of Venus' surface.

NASA’s FY2026 President’s Budget Request omits continued funding for the Orbiting Carbon Observatory missions (OCO-2 and OCO-3) beyond FY2025, ending September 30, 2025. The unexpected but scientifically transformative observations of solar induced chlorophyll fluorescence (SIF) - originally not part of the missions' design—have opened new opportunities for detecting photosynthesis from space and monitoring the health of the planet's natural resources. Thanks to their high spectral and spatial resolution and over a decade of experience from the project and the science teams, these missions have set a gold standard for space-based retrievals of SIF. Both instruments remain healthy and continue to produce high-quality data that offer great potential to continue transforming our fundamental understanding of terrestrial ecology and to provide actionable information to manage risks associated with extreme weather events such as droughts, floods and wildfires. In this commentary, we outline how OCO-2 and OCO-3 SIF data support crop-yield forecasting, drought early warning, forest and rangeland management, and discuss why keeping these satellites operational is essential for U.S. agriculture, national interests, and global food security.

Earth's mid-latitudes host synoptic scale corridors of intense horizontal moisture transport called atmospheric rivers (ARs). These storms are responsible for substantial heat transport across the mid-latitudes and deliver large amounts of precipitation to impacted locations. ARs occasionally penetrate the Northern Hemisphere high latitudes, resulting in elevated temperatures and anomalous precipitation, which can have a major influence on the Greenland Ice Sheet (GrIS), yet the impact ARs may have had on the GrIS in past climates remains unexplored. The Last Interglacial (LIG; 130,000–115,000 years before present) featured a warmer Arctic than present and a smaller GrIS configuration, providing an ideal time period for characterizing how AR impacts on the GrIS respond to orbital forcing and GrIS topography. Here, we use existing simulations spanning the LIG with a dynamic GrIS to study AR behavior around the GrIS. Results show that there are two mechanisms for AR migration through the LIG. There is a dynamical control across the mid-latitudes through orbitally induced migrations of the prevailing winds and a thermodynamic control at high latitudes due to changes in atmospheric moisture. This results in more warm season ARs at high latitudes early in the LIG which drive substantial melt around the margins of the GrIS and accumulation on the ice sheet interior. Future AR impacts on the GrIS are shown to be similar to the early LIG where an increase in high latitude moisture increases summertime ARs and thus ice sheet ablation around the GrIS margins.

Synchronous streamflow droughts across multiple river basins can lead to large-scale water scarcity and disruptions in food and water security. However, the drivers and changes in drought synchronicity across Indian rivers remain unexplored due to the limited length of instrumental records. Using streamflow observations and paleohydrological records, we reconstructed streamflow for 45 gauge stations on major Indian rivers, spanning 1200–2012 C.E., to examine the changes and drivers of streamflow drought synchronicity. Our reconstructed streamflow record for the past ∼800 years shows that streamflow drought frequency and synchronicity have increased during the recent period (1850–2012). While past major synchronous droughts in Indian rivers were associated with El Niño and positive Indian Ocean Dipole (IOD) conditions, the recent increase in streamflow drought synchronicity is linked with anthropogenic climate warming. Simulations of the Paleo Model Intercomparison Project Phase 4 (PMIP4-CMIP6) that include both natural and anthropogenic forcings confirm the role of anthropogenic warming in enhancing drought synchronicity. Our findings provide critical insights into the long-term variability of droughts in Indian rivers and underscore the growing risk of large-scale water scarcity.

The evolution of the spatial pattern of ocean surface warming affects global radiative feedback, yet different climate models provide varying estimates of future patterns. Paleoclimate data, especially from past warm periods, can help constrain future equilibrium warming patterns. By analyzing marine temperature records spanning the past 10 million years with a regression-based technique that removes temporal dimensions, we extract long-term ocean warming patterns and quantify relative sea surface temperature changes across the global ocean. This analysis revealed a distinct pattern of amplified warming that aligns with equilibrated model simulations under high CO₂ conditions, yet differs from the transient warming pattern observed over the past 160 years. This paleodata-model comparison allows us to identify models that better capture fundamental aspects of Earth's warming response, while suggesting how ocean heat uptake and circulation changes modify the development of warming patterns over time. By combining this paleo-ocean warming pattern with equilibrated model simulations, we characterized the likely evolution of global ocean warming as the climate system approaches equilibrium.

Terrestrial ecosystems annually absorb $��\sim �30�$% of anthropogenic C emissions. The degrees to which contemporary $��{\text{CO}}_2�$ and climate trends drive this absorption are uncertain, as are the governing mechanisms. To reduce uncertainty, we use Bayesian model-data integration (CARbon DAta MOdel fraMework) to retrieve a terrestrial biosphere reanalysis where Earth Observations optimally inform mechanistic model processes: observations include satellite- and inventory-based constraints on distributions and change in terrestrial C (including live biomass, dead organic C, and land-atmosphere $��{\text{CO}}_2�$ exchanges) and underlying mechanisms (including photosynthesis, deforestation, water storage anomalies, and fire). We find that the impact of 2001–2021's atmospheric $��{\text{CO}}_2�$ increase on terrestrial C (+39.4 PgC) opposes and far outweighs the impact of climate trends over this period ($��-�$10.5 PgC). Globally, C gains are mostly attributable to live biomass growth (+31.2 PgC), while $��{\text{CO}}_2�$-induced dead organic C gains (+7.8 PgC) are compensated by climate-induced losses ($��-�$

Coccolithophores are a group of marine phytoplankton precipitating about 50% of total calcite carbonate in the surface ocean. During the Pleistocene, coccolithophores experienced several periodic high-abundance and dominance intervals (acmes) that significantly altered the ocean carbon cycle by increasing the production of carbonate in the ocean. However, the reason for these episodes of enhanced calcification is still unclear. Here, we focus on one of the most significant dominance intervals, the Gephyrocapsa caribbeanica acme event, that lasted between ∼500 and 300 thousand years ago. We find that the variations of seawater alkalinity made only a minor contribution to the increased calcification rates during coccolithophore blooms. Rather, coccolithophore carbon isotopic fractionation indicates that coccolithophores employed a stronger bicarbonate pumping to increase intracellular carbon availability. Greater nutrient availability and shallower living depth likely facilitated higher bicarbonate pumping rates. The upregulation of bicarbonate pumping indicates the vital role of nutrients and light, and not only the ocean carbonate system, in the evolution of marine phytoplankton. Models of future coccolithophore calcification response to changing ocean carbon chemistry would, therefore, benefit from a more comprehensive consideration of how light and nutrient availability affect cellular energy budgets and drive carbon uptake.