Skip to main content
USGS - science for a changing world
Advanced Search

Filters: Tags: Glaciers and Permafrost (X)

60 results (11ms)   

Filters
Date Range
Extensions
Types
Contacts
Categories
Tag Types
Tag Schemes
View Results as: JSON ATOM CSV
Abstract: P-band interferometric synthetic aperture radar (InSAR) data at 5 m resolution from Kahiltna Glacier, the largest glacier in the Alaska Range, Alaska, USA, show pronounced spatial variation in penetration depth, δ P. We obtained δ P by differencing X- and P-band digital elevation models. δ P varied significantly over the glacier, but it was possible to distinguish representative zones. In the accumulation area, δ P decreased with decreasing elevation from 18±3 m in the percolation zone to 10±4 m in the wet snow zone. In the central portion of the ablation area, a location free of debris and crevasses, we identified a zone of very high δ P (34±4 m) which decreased at lower elevations (23±3 m in bare ice...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/2016EF000479/full): Glacier hypsometry provides a first-order approach for assessing a glacier's response to climate forcings. We couple the Randolph Glacier Inventory to a suite of in situ observations and climate model output to examine potential change for the ∼27,000 glaciers in Alaska and northwest Canada through the end of the 21st century. By 2100, based on Representative Concentration Pathways (RCPs) 4.5–8.5 forcings, summer temperatures are predicted to increase between +2.1 and +4.6°C, while solid precipitation (snow) is predicted to decrease by −6 to −11%, despite a +9 to +21% increase in total precipitation. Snow is predicted to undergo a pronounced...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/2014GL060199/abstract): While recent work demonstrates that glacial meltwater provides a substantial and relatively labile flux of the micronutrient iron to oceans, the role of high-latitude estuary environments as a potential sink of glacial iron is unknown. Here we present the first quantitative description of iron removal in a meltwater-dominated estuary. We find that 85% of “dissolved” Fe is removed in the low-salinity region of the estuary along with 41% of “total dissolvable” iron associated with glacial flour. We couple these findings with hydrologic and geochemical data from Gulf of Alaska (GoA) glacierized catchments to calculate meltwater-derived...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/2016GB005493/abstract): Phytoplankton growth in the Gulf of Alaska (GoA) is limited by iron (Fe), yet Fe sources are poorly constrained. We examine the temporal and spatial distributions of Fe, and its sources in the GoA, based on data from three cruises carried out in 2010 from the Copper River (AK) mouth to beyond the shelf break. April data are the first to describe late winter Fe behavior before surface water nitrate depletion began. Sediment resuspension during winter and spring storms generated high “total dissolvable Fe” (TDFe) concentrations of ~1000 nmol kg−1 along the entire continental shelf, which decreased beyond the shelf break. In July, high...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1111/gcb.12875/abstract): Permafrost thaw can alter the soil environment through changes in soil moisture, frequently resulting in soil saturation, a shift to anaerobic decomposition, and changes in the plant community. These changes, along with thawing of previously frozen organic material, can alter the form and magnitude of greenhouse gas production from permafrost ecosystems. We synthesized existing methane (CH 4) and carbon dioxide (CO 2) production measurements from anaerobic incubations of boreal and tundra soils from the geographic permafrost region to evaluate large-scale controls of anaerobic CO 2 and CH 4 production and compare the relative importance...
thumbnail
The Gulf of Alaska is one of the most productive marine ecosystems on Earth, supporting salmon fisheries that alone provide nearly $1 billion per year in economic benefits to Southeast Alaska. Glaciers are central to many of the area’s natural processes and economic activities, but the rates of glacier loss in Alaska are among the highest on Earth, with a 26-36 percent reduction in total volume expected by the end of the century. This project brought together scientists and managers at a workshop to synthesize the impacts of glacier change on the region’s coastal ecosystems and to determine related research and monitoring needs. Collected knowledge shows that melting glaciers are expected to have cascading effects...
thumbnail
The Jago, Okpilak, and Hulahula rivers in the Arctic are heavily glaciated waterways that are important for fish and wildlife as well as human activities including the provision of food, recreation, and, potentially, resource extraction on the coastal plain. If current glacial melting trends continue, most of the ice in these rivers will disappear in the next 50-100 years. Because of their importance to human and natural communities, it is critical to understand how these rivers and their surrounding environments will be affected by climate change and glacier loss. The overarching goal of this project is to research (1) the amount of river water, sediment, nutrients, and organic matter in the Jago, Okpilak, and...
Abstract (from http://bioscience.oxfordjournals.org/content/65/5/499): Rates of glacier mass loss in the northern Pacific coastal temperate rainforest (PCTR) are among the highest on Earth, and changes in glacier volume and extent will affect the flow regime and chemistry of coastal rivers, as well as the nearshore marine ecosystem of the Gulf of Alaska. Here we synthesize physical, chemical and biological linkages that characterize the northern PCTR ecosystem, with particular emphasis on the potential impacts of glacier change in the coastal mountain ranges on the surface–water hydrology, biogeochemistry, coastal oceanography and aquatic ecology. We also evaluate the relative importance and interplay between interannual...
This 4-page publication was produced from the March 2013 Juneau Glacier Workshop. The publication describes the current understanding of the interconnected icefield, stream, and ocean systems that are such a dominant feature of coastal Alaska. The publication describes the state of research on glaciers and icefields, glacier ecology, and the role that glaciers play in ocean processes.
Abstract (from http://link.springer.com/article/10.1007/s10236-013-0684-3): A three-level nested Regional Ocean Modeling System was used to examine the seasonal evolution of the Copper River (CR) plume and how it influences the along- and across-shore transport in the northern Gulf of Alaska (NGoA). A passive tracer was introduced in the model to delineate the growth and decay of the plume and to diagnose the spread of the CR discharge in the shelf, into Prince William Sound (PWS) and offshore. Furthermore, a model experiment with doubled discharge was conducted to investigate potential impacts of accelerated glacier melt in future climate scenarios. The 2010 and 2011 simulation revealed that the upstream (eastward)...
Abstract (from: http://www.igsoc.org/journal/60/221/j13J176.html): The Randolph Glacier Inventory (RGI) is a globally complete collection of digital outlines of glaciers, excluding the ice sheets, developed to meet the needs of the Fifth Assessment of the Intergovernmental Panel on Climate Change for estimates of past and future mass balance. The RGI was created with limited resources in a short period. Priority was given to completeness of coverage, but a limited, uniform set of attributes is attached to each of the ~198 000 glaciers in its latest version, 3.2. Satellite imagery from 1999–2010 provided most of the outlines. Their total extent is estimated as 726 800 +/- 34 000 km2. The uncertainty, about +/-...
Abstract: To test the effects of altered hydrology on organic soil decomposition, we investigated CO2 and CH4 production potential of rich-fen peat (mean surface pH = 6.3) collected from a field water table manipulation experiment including control, raised and lowered water table treatments. Mean anaerobic CO2 production potential at 10 cm depth (14.1 ± 0.9 μmol C g-1 d-1) was as high as aerobic CO2 production potential (10.6 ± 1.5 μmol C g-1 d-1), while CH4 production was low (mean of 7.8 ± 1.5 nmol C g-1 d-1). Denitrification enzyme activity indicated a very high denitrification potential (197 ± 23 μg N g-1 d-1), but net reduction suggested this was a relatively minor pathway for anaerobic CO2 production. Abundances...
thumbnail
Suicide Basin is a glacier-fed lake that branches off Mendenhall Glacier in Juneau, Alaska. Since 2011, Suicide Basin has been collecting melt- and rainwater each summer, creating a temporary glacier-dammed lake. Water that accumulates typically gets released through channels that run beneath the glacier. These channels are normally blocked by ice, but if the water pressure gets too high the channel breaks open, rapidly draining the basin in what is known as an “outburst flood”. In past years, these events have led to flooding along Mendenhall Lake and Mendenhall River in the most heavily populated neighborhood of Juneau. Because of the threats posed to infrastructure in the Mendenhall Valley, it is critical that...
Streamwater dissolved oxygen (DO) concentrations are driven by interacting physical and biotic parameters. Future DO depletion events in small, coastal salmon streams are therefore likely to be driven by changes in hydrology in addition to atmospheric warming. We measured DO, temperature, discharge and spawning salmon abundance in upstream (reference reach) and downstream salmon bearing reaches of four streams in southeast Alaska to determine how multiple physical and biotic factors interact to control streamwater DO. Stream temperature ranged from 5.1 to 15.8 °C and fell within the optimum range that is considered favorable for salmon physiology. Concentrations of DO ranged from 2.8 to 12.3 mg/L, with concentrations...
thumbnail
Rates of glacier loss in the northern Pacific coastal temperate rainforest (PCTR) are among the highest on Earth. These changes in glacier volume and extent will affect the flow and chemistry of coastal rivers, as well as the nearshore marine ecosystem of the Gulf of Alaska (GOA). Runoff from glaciers accounts for about half of the land-to-ocean movement of freshwater into the GOA, strongly influencing the freshwater and marine ecosystems along the coast. Runoff from glaciers, for example, significantly impacts the water temperature and clarity of aquatic habitats, which are important conditions for salmon reproduction. Moreover, runoff from glaciers along the GOA is an important factor in the structure of the...
thumbnail
Ongoing climate change has the potential to negatively impact Alaska’s ecosystems and the critical services that they provide. These ecosystem services include supplying food and fiber for Alaskan communities, offering opportunities for recreational, cultural, and spiritual activities, and regulating temperature and water flow (runoff, flooding, etc.). Scientists build models to better understand processes and interactions in the natural environment and to use what we know to predict what will happen in the future, so that we can plan for it. Researchers from multiple institutions and disciplines developed an Integrated Ecosystem Model (IEM) for Alaska and Northwest Canada. The model helps forecast how climate...
Abstract (from The Cryosphere): There is significant uncertainty regarding the spatiotemporal distribution of seasonal snow on glaciers, despite being a fundamental component of glacier mass balance. To address this knowledge gap, we collected repeat, spatially extensive high-frequency ground-penetrating radar (GPR) observations on two glaciers in Alaska during the spring of 5 consecutive years. GPR measurements showed steep snow water equivalent (SWE) elevation gradients at both sites; continental Gulkana Glacier's SWE gradient averaged 115 mm 100 m−1 and maritime Wolverine Glacier's gradient averaged 440 mm 100 m−1 (over > 1000 m). We extrapolated GPR point observations across the glacier surface using terrain...
thumbnail
As glaciers melt from climate change, their contents – namely, large quantities of freshwater, sediment, and nutrients – are slowly released into coastal ecosystems. This project addressed the impacts of melting glaciers on coastal ecosystems in the Copper River region of the Gulf of Alaska, which is home to several commercially important fisheries. Researchers examined how glacial melting is altering the amount and timing of freshwater that enters the Gulf of Alaska from the Copper River. They also investigated the source and amount of two nutrients, iron and nitrate, dissolved in the water. As a complementary piece of the study, researchers tested the relationship between nutrient levels, plankton populations,...


map background search result map search result map Impacts of Climate Change and Melting Glaciers on Coastal Ecosystems in the Gulf of Alaska Understanding the Impacts of Permafrost Change: Providing Input into the Alaska Integrated Ecosystem Model The Impacts of Glacier Change on the Jago, Okpilak, and Hulahula Rivers in the Arctic From Icefield to Ocean: Glacier Change Impacts to Alaska’s Coastal Ecosystems Assessing Links between Glaciers and the Northern Pacific Coastal Temperate Rainforest Ecosystem Improving Forecasts of Glacier Outburst Flood Events Improving Forecasts of Glacier Outburst Flood Events The Impacts of Glacier Change on the Jago, Okpilak, and Hulahula Rivers in the Arctic Impacts of Climate Change and Melting Glaciers on Coastal Ecosystems in the Gulf of Alaska From Icefield to Ocean: Glacier Change Impacts to Alaska’s Coastal Ecosystems Assessing Links between Glaciers and the Northern Pacific Coastal Temperate Rainforest Ecosystem Understanding the Impacts of Permafrost Change: Providing Input into the Alaska Integrated Ecosystem Model