Warming Effects of Spring Rainfall Increase Methane Emissions From Thawing Permafrost

Geophysical Research Letters, Journal Year: 2019, Volume and Issue: 46(3), P. 1393 - 1401

Published: Jan. 3, 2019

Abstract Methane emissions regulate the near‐term global warming potential of permafrost thaw, particularly where loss ice‐rich converts forest and tundra into wetlands. Northern latitudes are expected to get warmer wetter, while there is consensus that will increase thaw methane emissions, effects increased precipitation uncertain. At a thawing wetland complex in Interior Alaska, we found interactions between rain deep soil temperatures controlled emissions. In rainy years, recharge from watershed rapidly altered temperatures, top ~80 cm spring summer cooling it autumn. When soils were warmed by rainfall, ~30%. The warm, early growing season likely supported both microbial plant processes enhanced Our study identifies an important unconsidered role governing radiative forcing landscapes.

Language: Английский

---

Shallow groundwater thermal sensitivity to climate change and land cover disturbances: derivation of analytical expressions and implications for stream temperature modeling

Hydrology and earth system sciences, Journal Year: 2015, Volume and Issue: 19(5), P. 2469 - 2489

Published: May 26, 2015

Abstract. Climate change is expected to increase stream temperatures and the projected warming may alter spatial extent of habitat for cold-water fish other aquatic taxa. Recent studies have proposed that thermal sensitivities, derived from short-term air temperature variations, can be employed infer future due long-term climate change. However, this approach does not consider potential streambed heat fluxes gradual shallow subsurface. The groundwater particularly important regimes groundwater-dominated streams rivers. Also, recent investigated how land surface perturbations, such as wildfires or timber harvesting, influence by changing fluxes, but these typically considered disturbances also fluxes. In study, several analytical solutions one-dimensional unsteady advection–diffusion equation subsurface transport are estimate timing magnitude changes seasonal variability in temperatures. Groundwater sensitivity formulae accommodate different scenarios. suggest will warm response depends on rate warming, properties, bulk aquifer depth, velocity. results emphasize difference between (e.g., seasonal) multi-decadal) surface-temperature variability, thus demonstrate limitations using water records project warming. Suggestions provided implementing models

Language: Английский

---

Development of a land surface model with coupled snow and frozen soil physics

Water Resources Research, Journal Year: 2017, Volume and Issue: 53(6), P. 5085 - 5103

Published: June 1, 2017

Abstract Snow and frozen soil are important factors that influence terrestrial water energy balances through snowpack accumulation melt freeze‐thaw. In this study, a new land surface model (LSM) with coupled snow physics was developed based on hydrologically improved LSM (HydroSiB2). First, an energy‐balance‐based three‐layer incorporated into HydroSiB2 (hereafter HydroSiB2‐S) to provide description of the internal processes pack. Second, universal simplified HydroSiB2‐S depict freezing thawing HydroSiB2‐SF). order avoid instability caused by uncertainty in estimating phase changes, enthalpy adopted as prognostic variable instead snow/soil temperature balance equation snow/frozen module. The newly models were then carefully evaluated at two typical sites Tibetan Plateau (TP) (one covered other free, both underlying soil). At snow‐covered site northeastern TP (DY), HydroSiB2‐SF demonstrated significant improvements over HydroSiB2‐F (same but using original single‐layer module HydroSiB2), showing importance parameterization. snow‐free southwestern (Ngari), reasonably simulated changes while did not, indicating crucial role parameterization depicting thermal dynamics. Finally, proved be capable simulating upward moisture fluxes toward front from layers winter.

Language: Английский

---

Analysis of groundwater flow in mountainous, headwater catchments with permafrost

Water Resources Research, Journal Year: 2015, Volume and Issue: 51(12), P. 9564 - 9576

Published: Nov. 14, 2015

Abstract Headwater catchments have a direct impact on the water resources of downstream lowland regions as they supply freshwater in form surface runoff and discharging groundwater. Often, these mountainous contain expansive permafrost that may alter natural topographically controlled groundwater flow system. As could degrade with climate change, it is imperative to understand effect headwater catchments. This study characterizes evaluates context change movement using three‐dimensional, finite element, hydrogeologic model. The model applied representative catchment Qinghai‐Tibet Plateau, China. Results from simulations indicate contributes significantly streams baseflow majority shallow aquifer above permafrost, disrupting typical pattern observed most permafrost‐free Under warming scenario where mean annual temperature increased by 2°C, reducing areal extent catchment, contribution streamflow increase three‐fold. These findings suggest that, catchments, has large influence stream discharge. Increased air temperatures discharge streams, which implications for ecosystem health long‐term availability regions.

Language: Английский

---

Climate change effects on groundwater recharge and temperatures in Swiss alluvial aquifers

Journal of Hydrology X, Journal Year: 2020, Volume and Issue: 11, P. 100071 - 100071

Published: Dec. 28, 2020

Climate change will have both quantitative and qualitative effects on groundwater resources. These impacts differ for aquifers in solid unconsolidated rock, urban or rural locations, the principal processes of recharge. Having knowledge about intrinsic key parameters (aquifer geometries, storage properties, renewal rates, residence times, etc.), recharge processes, temperature imprinting makes it possible to compare forecast sensitivity individual climate change. The future development selected projections was qualitatively investigated representative Swiss rock resources Central Plateau as well Jura Alpine region. For non-urban areas, is expected a strong overall impact temperatures. In however, direct anthropogenic influences are likely dominate. Increased thermal subsurface use waste heat from underground structures, adaptation strategies mitigate global warming, increase Likewise, measurements city Basel show that temperatures increased by an average 3.0 ± 0.7 °C period 1993 2016, they can exceed 18 °C, especially densely urbanized areas. Similarly, regarding shallow with low saturated zone thicknesses, such Davos (Canton Grisons), strongly be influenced changes regimes. contrast, within deep large Biel/Bienne Bern), some cases distances land surface table extended unsaturated zones, Winterthur Zurich), attenuated only over long time periods. context presented research we hypothesized associated primarily determined infiltrating waters (i.e. "river-fed aquifers"). We seasonal shifts could important factor affecting Moreover, interaction during high runoff periods influence Accordingly, "business usual" scenario end century, shift precipitation river flood events summer winter months accompanied comparatively cool seasons, which would tendency "cool down"

Language: Английский

---