Large earthquakes in active mountain belts can trigger landslides, which mobilize large volumes of clastic sediment. Delivery of this material to river channels may result in aggradation and flooding, while sediment residing on hillslopes may increase the likelihood of subsequent landslides and debris flows. Despite recognition of these processes, the controls on the residence time of coseismic landslide sediment in river catchments remain poorly understood. Here we assess the residence time of fine-grained (5 mm day–1). Together with previous observations from the C.E. 1999 Chi-Chi earthquake in Taiwan, our results demonstrate the importance of landslide density and runoff intensity in setting the duration of earthquake-triggered landslide impacts on river systems

Moving Carbon: During the last glacial maximum, approximately 23,000 years ago, both the atmosphere and the terrestrial biosphere contained much less carbon than in the immediately preindustrial era. The carbon must have been stored in the deep ocean, and the transfer of carbon to the air and land during deglaciation must have affected the carbonate chemistry and carbon isotopic composition of the sea. Yu et al. (p. 1084 ) estimated how deep-water carbonate concentrations changed over the course of the last deglaciation and combined their results with ¹³ C/ ¹² C data to show that carbon released by the deep ocean between 17.5 and 14.5 thousand years ago mostly stayed in the atmosphere as CO ₂ , while between 14 and 10 thousand years ago, a substantial fraction was absorbed by the terrestrial biosphere.

Evaluating the influence of earthquakes on erosion, landscape evolution, and sediment‐related hazards requires understanding fluvial transport of material liberated in earthquake‐triggered landslides. The location of landslides relative to river channels is expected to play an important role in postearthquake sediment dynamics. In this study, we assess the position of landslides triggered by the M_w 7.9 Wenchuan earthquake, aiming to understand the relationship between landslides and the fluvial network of the steep Longmen Shan mountain range. Combining a landslide inventory map and geomorphic analysis, we quantify landslide‐channel connectivity in terms of the number of landslides, landslide area, and landslide volume estimated from scaling relationships. We observe a strong spatial variability in landslide‐channel connectivity, with volumetric connectivity (ξ) ranging from ~20% to ~90% for different catchments. This variability is linked to topographic effects that set local channel densities, seismic effects (including seismogenic faulting) that regulate landslide size, and substrate effects that may influence both channelization and landslide size. Altogether, we estimate that the volume of landslides connected to channels comprises 43 + 9/−7% of the total coseismic landslide volume. Following the Wenchuan earthquake, fine‐grained (<~0.25 mm) suspended sediment yield across the Longmen Shan catchments is positively correlated to catchment‐wide landslide density, but this correlation is statistically indistinguishable whether or not connectivity is considered. The weaker‐than‐expected influence of connectivity on suspended sediment yield may be related to mobilization of fine‐grained landslide material that resides in hillslope domains, i.e., not directly connected to river channels. In contrast, transport of the coarser fraction (which makes up >90% of the total landslide volume) may be more significantly affected by landslide locations.

Seawater lithium isotopes (δ⁷Li) record changes over Earth history, including a ∼9‰ increase during the Cenozoic interpreted as reflecting either a change in continental silicate weathering rate or weathering feedback strength, associated with tectonic uplift. However, mechanisms controlling the dissolved δ⁷Li remain debated. Here we report time-series δ⁷Li measurements from Tibetan and Pamir rivers, and combine them with published seasonal data, covering small (10⁶ km²). We find seasonal changes in δ⁷Li across all latitudes: dry seasons consistently have higher δ⁷Li than wet seasons, by −0.3‰ to 16.4‰ (mean 5.0 ± 2.5‰). A globally negative correlation between δ⁷Li and annual runoff reflects the hydrological intensity operating in catchments, regulating water residence time and δ⁷Li values. This hydrological control on δ⁷Li is consistent across climate events back to ~445 Ma. We propose that hydrological changes result in shifts in river δ⁷Li and urge reconsideration of its use to examine past weathering intensity and flux, opening a new window to reconstruct hydrological conditions.