Warming-driven erosion and sediment transport in cold regions

Abstract

Rapid atmospheric warming since the mid-20th century has increased temperature-dependent erosion and sediment transport processes in cold environments, impacting food, energy and water security. In this Review, we summarize landscape changes in cold environments and provide a global inventory of cryosphere degradation-driven increases in erosion and sediment yield. Anthropogenic climate change, deglaciation, and thermokarst disturbances are causing increased sediment mobilization and transport processes in glacierized and peri-glacierized basins. With continuous cryosphere degradation, sediment transport will continue to increase until reaching a maximum (peak sediment). Thereafter, transport will likely shift from a temperaturedependent regime toward a rainfall-dependent regime roughly between 2100-2200. The timing of the regime shift would be regulated by changes in meltwater, erosive rainfall and landscape erodibility, and complicated by geomorphic feedbacks and connectivity. Further progress in integrating multi-source sediment observations, developing physics-based sediment transport models, and enhancing interdisciplinary and international scientific collaboration are needed to predict sediment dynamics in a warming world. Key points1. A global inventory of cryosphere degradation-driven increases in erosion and sediment yield is presented, with 76 locations from the high Arctic, European mountains, High Mountain Asia and Andes, and 18 Arctic permafrost-coastal sites.2. Sediment mobilization from glacierized basins is dominated by glacial and paraglacial erosion; transport efficiency is controlled by glacio-hydrology and modulated by sub-, pro-, supra-glacial storage and release but is interrupted by glacial lakes and moraines.3. Degraded permafrost mainly mobilizes sediment by eroding thermokarst landscapes in high-latitude terrain and unstable rocky slopes in high-altitude terrain, which is sustained by exposing and melting ground ice and sufficient water supply; transport efficiency is enhanced by hillslope-channel connectivity.4. The sediment transport regime will shift in three stages, from a thermal-controlled regime to one jointly control by thermal and pluvial processes, and finally to a regime controlled by pluvial processes. 5. Peak sediment yield will be reached with or after peak meltwater.2 / 37 6. Between the 1950s and 2010s, sediment fluxes have increased by 2-8 folds in many cold regions and coastal erosion rates have more than doubled along many parts of Arctic permafrost coastlines.

Scale-dependent influence of permafrost on riverbank erosion rates

“…The geomechanical strength imparted to bank materials is lost upon thawing and riverbanks erode by a combination of thaw and physical transport of thawed material (thermal abrasion) Cooper & Hollingshead, 1973;Costard et al, 2003;Lawson, 1983;Leffingwell, 1919;Miles, 1976;Scott, 1978;Walker et al, 1987;Walker & Arnborg, 1963;Zhang et al, 2022). Therefore, the rate of bank erosion may be set by the combined effects of thermal and physical processes.…”

“…We do not have enough confidence in the rate or magnitude of changes in future sediment fluxes to speculate how important these changes will be to riverbank erosion. In a recent review, Zhang et al (2022) highlight that changes in sediment loading to rivers may vary greatly in space and time depending on the drivers of sediment production.…”

Hydroclimate Drives Seasonal Riverine Export Across a Gradient of Glacierized High‐Latitude Coastal Catchments

“…Globally, glaciers are losing mass at an accelerated rate leading to changes in the flux of freshwater, solutes, and sediment (Anderson, 2005; Beamer et al., 2017; Hood et al., 2020; Neal et al., 2010; Zhang et al., 2022). Sediment fluxes have increased in the past several decades in many high latitude, high altitude, and cold regions driven by the deterioration of the cryosphere (Li et al., 2021; Zhang et al., 2022). Glacierized watersheds are extremely important in moderating hydrologic and biogeochemical cycles globally (Milner et al., 2017).…”

Peak Cenozoic warmth enabled deep-sea sand deposition

“…Our results and model invite compilations for other hothouse and warm periods, as in the Cretaceous 49,50 or Paleozoic 51,52 , to further query the potential for widespread sandy, deep-marine systems during eustatic highs, as well as compilations for periods of falling or low sea level (e.g., cooling or cold climates) to further test our conceptual model. Furthermore, in light of anthropogenic climate change, our work invites investigation into the ramifications of present-day climate warming and warming-driven increases in sediment supply 41,53,54 on deep-sea sedimentary systems.…”

“…Alongside widespread evidence for active margin deposition during a eustatic high (e.g., as in Quaternary-age examples from California and Chile 12,14 and as previously discussed from a process standpoint 36 ), widespread distribution of early Paleogene turbidite systems suggests that in passive margin settings during eustatic highs, an integrated drainage system may be a prerequisite for substantial sand-rich deep-sea deposition 37 . Activity of such drainages may have been magnified by increasingly episodic, intense precipitation events in the early Eocene [30][31][32] , while sediment transport along drainages may have been magnified by intensified weathering and erosion [2][3][4][5]33,34 , both of which would act to increase sediment supply, and both of which could in turn drive further integration of drainages [38][39][40][41] . Increased sediment supply as a means to overwhelm shelf accommodation even during a highstand is consistent with work on high-supply and supply-dominated systems, whereby significant deep-marine turbidite deposition occurs despite eustatic highs (e.g., modern river estimates 17 ; Maastrichtian shelf of Wyoming 18 ; modeling work 15 ), and may be consistent with work suggesting sediment supply as the dominant control-beyond frequency and amplitude of sea-level fluctuations-on deep-sea fan size 42,43 .…”