Modeling the Changing Roles of Snow and Permafrost in Mid- and High-latitude Climate Systems
Modeling the Changing Roles of Snow and Permafrost in Mid- and High-latitude Climate Systems

Author: Diana R. Gergel

Publisher:

Published: 2019

Total Pages: 150

ISBN-13:

DOWNLOAD EBOOK

The land surface plays a key role in local and regional climates at mid- and high-latitudes as well as in the global climate system. Consequently, changes in snow and permafrost affect other parts of the climate system. In this dissertation, we explore the role of the land surface in the cryosphere, with a particular focus on high latitudes, using a hierarchy of standalone land surface models (LSMs), fully-coupled regional climate models (RCMs) and global climate models (GCMs). In Chapter 2, I describe simulated changes in snowpack and fire potential in the western US using the Variable Infiltration Capacity (VIC) hydrology model under future climate projections for an ensemble of GCMs from the Coupled Model Intercomparison Project (CMIP5) archive for two Representative Concentration Pathways (RCPs), RCP4.5 and RCP 8.5. Large losses of snowpack and increases in fire potential are projected to occur in the mountainous parts of the western US in the 21st century, whereas increases in fire potential are much more uncertain in lowland regions due to large uncertainty in precipitation projections. In Chapter 3, I draw on two modeling ensembles, the Community Earth System Large Ensemble (CESM-LE) and the CESM Low Warming Ensemble (CESM-LWE), to understand projected changes in snow and how these changes will affect soil thermal regimes and permafrost in the 21st century over the circumpolar Arctic for three levels of warming: 1.5°C, 2°C and RCP 8.5. Even for the lower emissions scenarios represented by the 1.5°C and 2°C global-mean warming pathways, the majority of the Arctic is projected to experience significant decreases in Snow Water Equivalent (SWE), while parts of Eurasia will experience substantial increases. Large losses of permafrost are projected due to a significant warming of the soil column by the end of the 21st century. Soil organic carbon (SOC) stocks are highly vulnerable and loss of permafrost could result in potentially large losses of carbon to the atmosphere. In Chapter 4, I describe the process of designing a new parameter set for application over a pan-Arctic domain in version 5 of the VIC hydrology model (VIC-5) and in the Regional Arctic System Model (RASM), a fully-coupled regional climate model. Simulated streamflow in RASM simulations is significantly higher than in standalone VIC-5 simulations and much more closely matches observations, while simulated permafrost in standalone VIC-5 simulations more closely approximates observed permafrost extent, illustrating the difficulties of designing land surface parameters for application in a land surface model that is used in both standalone and fully-coupled modeling contexts.

Opportunities to Use Remote Sensing in Understanding Permafrost and Related Ecological Characteristics
Opportunities to Use Remote Sensing in Understanding Permafrost and Related Ecological Characteristics

Author: National Research Council

Publisher: National Academies Press

Published: 2014-06-04

Total Pages: 171

ISBN-13: 0309301246

DOWNLOAD EBOOK

Permafrost is a thermal condition-its formation, persistence and disappearance are highly dependent on climate. General circulation models predict that, for a doubling of atmospheric concentrations of carbon dioxide, mean annual air temperatures may rise up to several degrees over much of the Arctic. In the discontinuous permafrost region, where ground temperatures are within 1-2 degrees of thawing, permafrost will likely ultimately disappear as a result of ground thermal changes associated with global climate warming. Where ground ice contents are high, permafrost degradation will have associated physical impacts. Permafrost thaw stands to have wide-ranging impacts, such as the draining and drying of the tundra, erosion of riverbanks and coastline, and destabilization of infrastructure (roads, airports, buildings, etc.), and including potential implications for ecosystems and the carbon cycle in the high latitudes. Opportunities to Use Remote Sensing in Understanding Permafrost and Related Ecological Characteristics is the summary of a workshop convened by the National Research Council to explore opportunities for using remote sensing to advance our understanding of permafrost status and trends and the impacts of permafrost change, especially on ecosystems and the carbon cycle in the high latitudes. The workshop brought together experts from the remote sensing community with permafrost and ecosystem scientists. The workshop discussions articulated gaps in current understanding and potential opportunities to harness remote sensing techniques to better understand permafrost, permafrost change, and implications for ecosystems in permafrost areas. This report addresses questions such as how remote sensing might be used in innovative ways, how it might enhance our ability to document long-term trends, and whether it is possible to integrate remote sensing products with the ground-based observations and assimilate them into advanced Arctic system models. Additionally, the report considers the expectations of the quality and spatial and temporal resolution possible through such approaches, and the prototype sensors that are available that could be used for detailed ground calibration of permafrost/high latitude carbon cycle studies.

Modeling the Influences of Climate Change, Permafrost Dynamics, and Fire Disturbance on Carbon Dynamics of High Latitude Ecosystems
Modeling the Influences of Climate Change, Permafrost Dynamics, and Fire Disturbance on Carbon Dynamics of High Latitude Ecosystems

Author: Qianlai Zhuang

Publisher:

Published: 2001

Total Pages: 436

ISBN-13:

DOWNLOAD EBOOK

"A Soil Thermal Model (STM) with the capability to operate with a 0.5-day internal time step and to be driven with monthly input data was developed for applications with large-scale ecosystem models. The use of monthly climate inputs to drive the STM resulted in an error of less than 1C̊ in the upper organic soil layer and in an accurate simulation of seasonal active layer dynamics. Uncertainty analyses identified that soil temperature estimates of the upper organic layer were most sensitive to variability in parameters that described snow thermal conductivity, moss thickness, and moss thermal conductivity. The STM was coupled to the Terrestrial Ecosystem Model (TEM), and the performance of the STM-TEM was verified for the simulation of soil temperatures in applications to black spruce, white spruce, aspen, and tundra sites. A 1C̊ error in the temperature of the upper organic soil layer had little influence on the carbon dynamics simulated for a black spruce site. Application of the model across the range of black spruce ecosystems in North America demonstrated that the STM-TEM has the capability to operate over temporal and spatial domains that consider substantial variations in surface climate. To consider how fire disturbance interacts with climate change and permafrost dynamics, the STM was updated to more fully evaluate how these factors influence ecosystem dynamics during stand development. The ability of the model to simulate seasonal patterns of soil temperature, gross primary production, and ecosystem respiration, and the age-dependent pattern of above-ground vegetation carbon storage was verified. The model was applied to a post-fire chronosequence in interior Alaska and was validated with estimates of soil temperature, soil respiration, and soil carbon storage that were based on measurements of these variables in 1997. Sensitivity analyses indicate that the growth of moss, changes in the depth of the organic layer, and nitrogen fixation should be represented in models that simulate the effects of fire disturbance in boreal forests. Furthermore, the sensitivity analyses revealed that soil drainage and fire severity should be considered in spatial application of these models to simulate carbon dynamics at landscape to regional scales"--Leaves iii-iv.

Thawing Permafrost
Thawing Permafrost

Author: J. van Huissteden

Publisher: Springer Nature

Published: 2020-01-01

Total Pages: 508

ISBN-13: 3030313794

DOWNLOAD EBOOK

This book provides a cross-disciplinary overview of permafrost and the carbon cycle by providing an introduction into the geographical distribution of permafrost, with a focus on the distribution of permafrost and its soil carbon reservoirs. The chapters explain the basic physical properties and processes of permafrost soils: ice, mineral and organic components, and how these interact with climate, vegetation and geomorphological processes. In particular, the book covers the role of the large quantities of ice in many permafrost soils which are crucial to understanding carbon cycle processes. An explanation is given on how permafrost becomes loaded with ice and carbon. Gas hydrates are also introduced. Structures and processes formed by the intense freeze-thaw action in the active layer are considered (e.g. ice wedging, cryoturbation), and the processes that occur as the permafrost thaws, (pond and lake formation, erosion). The book introduces soil carbon accumulation and decomposition mechanisms and how these are modified in a permafrost environment. A separate chapter deals with deep permafrost carbon, gas reservoirs and recently discovered methane emission phenomena from regions such as Northwest Siberia and the Siberian yedoma permafrost.

Interactions of Water and Energy Mediate Responses of High-Latitude Terrestrial Ecosystems to Climate Change
Interactions of Water and Energy Mediate Responses of High-Latitude Terrestrial Ecosystems to Climate Change

Author: Zachary Marc Subin

Publisher:

Published: 2012

Total Pages: 380

ISBN-13:

DOWNLOAD EBOOK

Both biogeophysical and biogeochemical feedbacks to climate change from high-latitude terrestrial ecosystems may be mediated by permafrost thaw. For instance, lakes may expand as relatively intact permafrost begins to thaw but experience drainage with continued permafrost degradation; thawing permafrost also increases the vulnerability of soil carbon to decomposition. In order to quantify these feedbacks, Earth System Models (ESMs) need to adequately represent a number of sub-surface processes. I improved the lake model in the land-surface component (CLM4) of an ESM by including the physics of snow, ice, and underlying sediment, allowing shallow high-latitude lakes to be adequately simulated. After evaluating the model, I investigated the sensitivity of regional surface fluxes to included lake model processes. The inclusion of snow insulation and lake water phase change each cause 15-30 W m-2 changes in seasonal surface fluxes, altering the forcing of lakes on the atmosphere. With realistic inclusion of these processes, I predict that the presence of high-latitude lakes causes little net change in mean annual air temperature. However, due to increased sub-surface thermal inertia, lakes moderate the seasonal and diurnal cycle in regions of large lake area like the Canadian Shield. Consequently, the loss of lake area in areas of disappearing permafrost could exacerbate increases in summer daily maximum temperatures due to climate warming by up to 1 °C. Snow insulation has long been recognized as a key control on permafrost soil thermal regime. I show that the snow thermal rectifier can interact with hydrology to cause significant changes in soil temperature associated with non-thermal anthropogenic forcings. Elevated CO2 or increased summer rainfall could increase soil water-filled pore space by 0.1-0.2 in some permafrost areas, associated with 1-2 °C increases in mean soil temperature. This warming results from both the increased thermal conductivity of the soil and the increased latent heat of fusion. Because these mechanisms saturate once soils are relatively saturated, the initial soil moisture state is crucial in determining susceptibility to these warming mechanisms. In this model, these warming mechanisms were not effective in substantially increasing permafrost vulnerability to thaw in a severe 21st century transient warming scenario. In summary, I have shown that explicit representation of snow insulation and of freezing and thawing in lakes and soils can alter the predicted responses of soil and air temperatures to changes in climate.

General Geocryology
General Geocryology

Author: E. D. Yershov

Publisher: Cambridge University Press

Published: 2004-08-19

Total Pages: 612

ISBN-13: 9780521607575

DOWNLOAD EBOOK

A wide-ranging and up-to-date review of permafrost science, unique in presenting the Russian viewpoint. This English edition brings the standard Russian work on geocryology to a larger readership, allowing the value of the knowledge and concepts developed to be realised more widely.

The Ocean and Cryosphere in a Changing Climate
The Ocean and Cryosphere in a Changing Climate

Author: Intergovernmental Panel on Climate Change (IPCC)

Publisher: Cambridge University Press

Published: 2022-04-30

Total Pages: 755

ISBN-13: 9781009157971

DOWNLOAD EBOOK

The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.

Water-Carbon Dynamics in Eastern Siberia
Water-Carbon Dynamics in Eastern Siberia

Author: Takeshi Ohta

Publisher: Springer

Published: 2019-07-01

Total Pages: 309

ISBN-13: 981136317X

DOWNLOAD EBOOK

This book discusses the water and carbon cycle system in the permafrost region of eastern Siberia, Providing vitalin sights into how climate change has affected the permafrost environment in recent decades. It analyzes the relationships between precipitation and evapotranspiration, gross primary production and runoff in the permafrost regions, which differ from those intropical and temperate forests. Eastern Siberia is located in the easternmost part of the Eurasian continent, and the land surface with underlying permafrost has developed over a period of seventy thousand years. The permafrost ecosystem has specific hydrological and meteorological characteristics in terms of the water and carbon dynamics, and the current global warming and resulting changes in the permafrost environment are serious issues in the high-latitude regions. The book is a valuable resource for students, researchers and professionals interested in forest meteorology and hydrology, forest ecology, and boreal vegetation, as well as the impact of climate change and water-carbon cycles in permafrost and non-permafrost regions.

Simulating the Present-day and Future Distribution of Permafrost in the UVic Earth System Climate Model
Simulating the Present-day and Future Distribution of Permafrost in the UVic Earth System Climate Model

Author: Christopher Alexander Avis

Publisher:

Published: 2012

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

Warming over the past century has been greatest in high-latitudes over land and a number of environmental indicators suggest that the Arctic climate system is in the process of a major transition. Given the magnitude of observed and projected changes in the Arctic, it is essential that a better understanding of the characteristics of the Arctic climate system be achieved. In this work, I report on modifications to the UVic Earth System Climate model to allow it to represent regions of perennially-frozen ground, or permafrost. I examine the model's representation of the Arctic climate during the 20th Century and show that it capably represents the distribution and thermal state of permafrost in the present-day climate system. I use Representative Concentration Pathways to examine a range of possible future permafrost states to the year 2500. A suite of sensitivity experiments is used to better understand controls on permafrost. I demonstrate the potential for radical environmental changes in the Arctic over the 21st Century including continued warming, enhanced precipitation and a reduction of between 29 and 54 % of the present-day permafrost area by 2100. Model projections show that widespread loss of high-latitude wetlands may accompany the loss of near surface permafrost.