Abstract The 2025–26 late‐fall and winter climate pattern featured an extreme upper‐tropospheric zonal geopotential height gradient across North America, consisting of an amplified west ridge and an east trough, which produced record warmth and low snowpack across the western United States alongside severe cold and winter storms in the east. The dynamical origins of such extreme ridge‐trough patterns and whether their underlying circulation configurations are becoming more or less frequent under anthropogenic warming remain unresolved. Using ERA5 reanalysis and the CESM2 Large Ensemble, we find that the extreme ridge‐trough pattern was associated with convective suppression in the eastern tropical Pacific, consistent with a Gill‐type upper‐tropospheric response and a poleward‐propagating Rossby wave train that manifests as a zonal geopotential height gradient. We train a self‐organizing map on the joint 250 hPa streamfunction and outgoing longwave radiation anomalies and find that the convective‐circulation pattern over the eastern Pacific and North America sector, reminiscent of the 2025–26 extreme ridge‐trough pattern, increases in frequency by the end of the 21st century, despite a decrease in amplitude of the composite scalar defining the ridge‐trough pattern. The covariance between eastern tropical Pacific convection and the upper‐tropospheric circulation over the western United States also strengthens. This study suggests that the background state under anthropogenic warming increasingly favors the convective‐circulation pattern associated with the 2025–26 extreme ridge‐trough pattern.
Abstract Illegal coca cultivation in Colombia sustains one of the largest global illicit economies and drives substantial carbon emissions and biodiversity loss. Repurposing these plantations offers opportunities to align climate mitigation, rural development, and anti‐drug policies. Yet, the climate impacts of the cocaine value chain and the mitigation potential of alternative land uses remain poorly quantified. This study combines spatially explicit land cover data sets and emission data to estimate life‐cycle greenhouse gas emissions of coca cultivation, processing, and distribution and the mitigation potential of repurposing coca‐occupied land. Colombia's 2022 cocaine production generated 3.1 MtCO 2 ‐eq., with about 50% of emissions arising from land use change. Restoring the 0.2% of Colombian land under coca through natural forest regrowth or options such as agroforestry or bioenergy crops could mitigate 2.5–3.6 MtCO 2 ‐eq.yr −1 (equivalent to national aviation and shipping emissions). Unlocking this potential requires overcoming socio‐economic barriers, ideally through targeted international investments supported by counternarcotics budgets to secure legal livelihoods while advancing environmental and anti‐trafficking goals.
Abstract Extreme floods rank among the most destructive natural hazards, disrupting economic development, societal stability, and river ecosystems. Although macro‐scale flood risk disparities across poverty‐classified regions have drawn increasing attention, they remain critically underexplored in China, the world's most flood‐vulnerable country, where flood‐induced human displacement accounts for one‐third of the global total. Here, we develop a rigorously validated, macro‐scale framework to estimate flood‐induced economic losses across China and to quantify the disparity of these impacts across distinct poverty strata. We find that impoverished regions experience disproportionately severe relative impacts, with their flood losses escalating by at least 22% for each 0.5°C of global warming, outpacing non‐poor regions by up to seven percentage points. Furthermore, economic growth within projected flood‐prone areas markedly exacerbates these losses. Although enhancing flood‐defense standards can mitigate damages, maintaining historical loss levels requires ambitious defense standard upgrades of 80% (under 1.5°C of warming) and 95% (under 2.0°C), corresponding to an average 16‐percentage‐point improvement per 0.5°C of warming. Our findings reveal the accelerating flood risk and macro‐scale disparity faced by impoverished regions in China, a dynamic long overlooked, and challenge the adequacy of historical flood risk management strategies. As nations work toward the United Nations Sustainable Development Goals (SDGs), particularly SDG 10 (Reduced Inequalities), which intrinsically requires a foundational understanding of risk disparities, our study provides critical baseline evidence for national adaptation planning and offers globally transferable methodologies.
Abstract Soil organic carbon (SOC) sequestration represents a critical nature‐based strategy for atmospheric CO 2 mitigation. Yet, the magnitudes and dynamics of SOC accrual following bare land restoration have not been rigorously quantified at a large scale. By integrating field‐based observations with a spatially explicit machine learning framework, this study systematically evaluated the drivers, optimization pathways and SOC sequestration potential of bare land restoration across China. Results reveal that SOC accrual follows a distinct three‐stage pattern: rapid accumulation (0–17 years), a restoration bottleneck (17–30 years), and slow accumulation toward SOC saturation (>30 years). This process is primarily driven by baseline SOC, with greater accrual in low initial SOC regions. Projections indicate a nonlinear trajectory, reaching a plateau around 2,080 (approximately 55 years post‐restoration). By 2,100, cumulative SOC sequestration in the top 30 cm is projected at 6.1 ± 0.9 Pg C, concentrated in humid regions. Notably, the 0–5 cm layer responds rapidly, whereas the 15–30 cm horizon exhibits a temporal lag but sustained growth. Uncertainty analysis indicates that spatial heterogeneity dominates total variance (79.5%–87.8%), whereas climate scenario uncertainty is comparatively limited. These findings demonstrate that SOC sequestration is a spatially heterogeneous and saturation‐constrained process, emphasizing the importance of site‐specific restoration strategies for effective climate mitigation.
Abstract Despite the scientific and economic importance of hydrogen and helium, their crustal budgets remain poorly quantified. This study systematically assesses the accumulation of natural hydrogen and helium in global sedimentary basins by integrating predictive models for both gases with H 2 /He ratios. The predictive model infers natural hydrogen resources in global sedimentary basins of 10 0 –10 6 Mt (megatons), with a most probable estimate of 1.7 × 10 3 Mt, and subsurface helium resources of 17.9 Mt. Water–rock reactions and the decay of radioactive elements within crystalline basement rocks generate natural hydrogen and helium, respectively, supplying background gas fluxes to overlying sedimentary basins. Mantle degassing and source rocks within sedimentary sequences provide supplementary gas contributions, resulting in an underestimation of these resources. This study reveals that global sedimentary basins host significant accumulations of natural hydrogen and helium resources—a finding that warrants increased attention.
