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At least 163 records · Page 9Linked to original sources
USGS2012

Impacts of climate change on biodiversity, ecosystems, and ecosystem services: technical input to the 2013 National Climate Assessment

Ecosystems, and the biodiversity and services they support, are intrinsically dependent on climate. During the twentieth century, climate change has had documented impacts on ecological systems, and impacts are expected to increase as climate change continues and perhaps even accelerates. This technical input to the National Climate Assessment synthesizes our scientific understanding of the way climate change is affecting biodiversity, ecosystems, ecosystem services, and what strategies might be employed to decrease current and future risks. Building on past assessments of how climate change and other stressors are affecting ecosystems in the United States and around the world, we approach the subject from several different perspectives. First, we review the observed and projected impacts on biodiversity, with a focus on genes, species, and assemblages of species. Next, we examine how climate change is affecting ecosystem structural elements—such as biomass, architecture, and heterogeneity—and functions—specifically, as related to the fluxes of energy and matter. People experience climate change impacts on biodiversity and ecosystems as changes in ecosystem services; people depend on ecosystems for resources that are harvested, their role in regulating the movement of materials and disturbances, and their recreational, cultural, and aesthetic value. Thus, we review newly emerging research to determine how human activities and a changing climate are likely to alter the delivery of these ecosystem services. This technical input also examines two cross-cutting topics. First, we recognize that climate change is happening against the backdrop of a wide range of other environmental and anthropogenic stressors, many of which have caused dramatic ecosystem degradation already. This broader range of stressors interacts with climate change, and complicates our abilities to predict and manage the impacts on biodiversity, ecosystems, and the services they support. The second cross-cutting topic is the rapidly advancing field of climate adaptation, where there has been significant progress in developing the conceptual framework, planning approaches, and strategies for safeguarding biodiversity and other ecological resources. At the same time, ecosystem-based adaptation is becoming more prominent as a way to utilize ecosystem services to help human systems adapt to climate change. In this summary, we present key findings of the technical input, focusing on themes that can be found throughout the report. Thus, this summary takes a more integrated look at the question of how climate change is affecting our ecological resources, the implications for humans, and possible response strategies. This integrated approach better reflects the impacts of climate in the real world, where changes in ecosystem structure or function will alter the viability of different species and the efficacy of ecosystem services. Likewise, adaptation to climate change will simultaneously address a range of conservation goals. Case studies are used to illustrate this complete picture throughout the report; a snapshot of one case study, 2011 Las Conchas, New Mexico Fire , is included in this summary.

Report↗
USGS2008

The Importance of Uncertainty and Sensitivity Analysis in Process-based Models of Carbon and Nitrogen Cycling in Terrestrial Ecosystems with Particular Emphasis on Forest Ecosystems — Selected Papers from a Workshop Organized by the International Society for Ecological Modelling (ISEM) at the Third Biennal Meeting of the International Environmental Modelling and Software Society (IEMSS) in Burlington, Vermont, USA, August 9-13, 2006

Many process-based models of carbon (C) and nitrogen (N) cycles have been developed for terrestrial ecosystems, including forest ecosystems. They address many basic issues of ecosystems structure and functioning, such as the role of internal feedback in ecosystem dynamics. The critical factor in these phenomena is scale, as these processes operate at scales from the minute (e.g. particulate pollution impacts on trees and other organisms) to the global (e.g. climate change). Research efforts remain important to improve the capability of such models to better represent the dynamics of terrestrial ecosystems, including the C, nutrient, (e.g. N) and water cycles. Existing models are sufficiently well advanced to help decision makers develop sustainable management policies and planning of terrestrial ecosystems, as they make realistic predictions when used appropriately. However, decision makers must be aware of their limitations by having the opportunity to evaluate the uncertainty associated with process-based models ( Smith and Heath, 2001 and Allen et al., 2004 ). The variation in scale of issues currently being addressed by modelling efforts makes the evaluation of uncertainty a daunting task.

Ecological Modelling↗
USGS2011

Proceedings of the Fourth Interagency Conference on Research in the Watersheds—Observing, Studying, and Managing for Change

These proceedings contain the abstracts, manuscripts, and posters of presentations given at the Fourth Interagency Conference on Research in the Watersheds—Observing, Studying, and Managing for Change, held at the Westmark Hotel in Fairbanks, Alaska, September 26–30, 2011. The conference was jointly hosted by the Bureau of Land Management and the National Park Service. Watersheds face resource impacts driven by accelerated change related to land use, population, and climate. About every three years a conference is held to bring together watershed researchers, observers, and managers to share scientific advances and management strategies. This year, the Fourth ICRW took a wider perspective on watershed science and examined some pressing issues of watershed science and management in our largest and perhaps most vulnerable state, Alaska. The purpose of the conference was to better understand the processes driving change and help managers incorporate societal needs and scientific uncertainty in the management of natural resources. The conference echoed similar themes to the last, highlighting the challenges of managing watersheds based on available science when considerably uncertainty remains regarding the hypothesized relationships between observed environmental changes and their ultimate effects. For example, while the scientific case for anthropogenic climate change has been well presented, confirming possible cause and effect relationships between climatic change and physical and ecological impacts in highly variable, natural systems continues to represent a scientific challenge. This goal becomes even more difficult when superimposed upon a long history of natural resource and land management practices that have fundamentally changed the physical, chemical and biological processes important in maintaining naturally functioning ecosystems. Designing and implementing studies to better understand watersheds and clearly communicating the findings to decisionmakers will be the primary challenge for natural resource scientists and managers into the foreseeable future.

Scientific Investigations Report↗
USGS2007

Invasive species management and research using GIS

Geographical Information Systems (GIS) are powerful tools in the field of invasive species management. GIS can be used to create potential distribution maps for all manner of taxa, including plants, animals, and diseases. GIS also performs well in the early detection and rapid assessment of invasive species. Here, we used GIS applications to investigate species richness and invasion patterns in fish in the United States (US) at the 6-digit Hydrologic Unit Code (HUC) level. We also created maps of potential spread of the cane toad (Bufo marinus) in the southeastern US at the 8-digit HUC level using regression and environmental envelope techniques. Equipped with this potential map, resource managers can target their field surveys to areas most vulnerable to invasion. Advances in GIS technology, maps, data, and many of these techniques can be found on websites such as the National Institute of Invasive Species Science (www.NIISS.org). Such websites provide a forum for data sharing and analysis that is an invaluable service to the invasive species community.

Conference Paper↗
USGS2019

Cloud cover and delayed herbivory relative to timing of spring onset interact to dampen climate change impacts on net ecosystem exchange in a coastal Alaskan wetland

Rapid warming in northern ecosystems over the past four decades has resulted in earlier spring, increased precipitation, and altered timing of plant–animal interactions, such as herbivory. Advanced spring phenology can lead to longer growing seasons and increased carbon (C) uptake. Greater precipitation coincides with greater cloud cover possibly suppressing photosynthesis. Timing of herbivory relative to spring phenology influences plant biomass. None of these changes are mutually exclusive and their interactions could lead to unexpected consequences for Arctic ecosystem function. We examined the influence of advanced spring phenology, cloud cover, and timing of grazing on C exchange in the Yukon–Kuskokwim Delta of western Alaska for three years. We combined advancement of the growing season using passive-warming open-top chambers (OTC) with controlled timing of goose grazing (early, typical, and late season) and removal of grazing. We also monitored natural variation in incident sunlight to examine the C exchange consequences of these interacting forcings. We monitored net ecosystem exchange of C (NEE) hourly using an autochamber system. Data were used to construct daily light curves for each experimental plot and sunlight data coupled with a clear-sky model was used to quantify daily and seasonal NEE over a range of incident sunlight conditions. Cloudy days resulted in the largest suppression of NEE, reducing C uptake by approximately 2 g C m −2 d −1 regardless of the timing of the season or timing of grazing. Delaying grazing enhanced C uptake by approximately 3 g C m −2 d −1 . Advancing spring phenology reduced C uptake by approximately 1.5 g C m −2 d −1 , but only when plots were directly warmed by the OTCs; spring advancement did not have a long-term influence on NEE. Consequently, the two strongest drivers of NEE, cloud cover and grazing, can have opposing effects and thus future growing season NEE will depend on the magnitude of change in timing of grazing and incident sunlight.

Alaska↗
USGS2017

Multinomial N-mixture models improve the applicability of electrofishing for developing population estimates of stream-dwelling Smallmouth Bass

Failure to account for variable detection across survey conditions constrains progressive stream ecology and can lead to erroneous stream fish management and conservation decisions. In addition to variable detection’s confounding long-term stream fish population trends, reliable abundance estimates across a wide range of survey conditions are fundamental to establishing species–environment relationships. Despite major advancements in accounting for variable detection when surveying animal populations, these approaches remain largely ignored by stream fish scientists, and CPUE remains the most common metric used by researchers and managers. One notable advancement for addressing the challenges of variable detection is the multinomial N -mixture model. Multinomial N -mixture models use a flexible hierarchical framework to model the detection process across sites as a function of covariates; they also accommodate common fisheries survey methods, such as removal and capture–recapture. Effective monitoring of stream-dwelling Smallmouth Bass Micropterus dolomieu populations has long been challenging; therefore, our objective was to examine the use of multinomial N -mixture models to improve the applicability of electrofishing for estimating absolute abundance. We sampled Smallmouth Bass populations by using tow-barge electrofishing across a range of environmental conditions in streams of the Ozark Highlands ecoregion. Using an information-theoretic approach, we identified effort, water clarity, wetted channel width, and water depth as covariates that were related to variable Smallmouth Bass electrofishing detection. Smallmouth Bass abundance estimates derived from our top model consistently agreed with baseline estimates obtained via snorkel surveys. Additionally, confidence intervals from the multinomial N -mixture models were consistently more precise than those of unbiased Petersen capture–recapture estimates due to the dependency among data sets in the hierarchical framework. We demonstrate the application of this contemporary population estimation method to address a longstanding stream fish management issue. We also detail the advantages and trade-offs of hierarchical population estimation methods relative to CPUE and estimation methods that model each site separately.

Missouri, Oklahoma↗
USGS2011

Moderate-resolution sea surface temperature data for the nearshore North Pacific

Coastal sea surface temperature (SST) is an important environmental characteristic in determining the suitability of habitat for nearshore marine and estuarine organisms. This publication describes and provides access to an easy-to-use coastal SST dataset for ecologists, biogeographers, oceanographers, and other scientists conducting research on nearshore marine habitats or processes. The data cover the Temperate Northern Pacific Ocean as defined by the 'Marine Ecosystems of the World' (MEOW) biogeographic schema developed by The Nature Conservancy. The spatial resolution of the SST data is 4-km grid cells within 20 km of the shore. The data span a 29-year period - from September 1981 to December 2009. These SST data were derived from Advanced Very High Resolution Radiometer (AVHRR) instrument measurements compiled into monthly means as part of the Pathfinder versions 5.0 and 5.1 (PFSST V50 and V51) Project. The processing methods used to transform the data from their native Hierarchical Data Format Scientific Data Set (HDF SDS) to georeferenced, spatial datasets capable of being read into geographic information systems (GIS) software are explained. In addition, links are provided to examples of scripts involved in the data processing steps. The scripts were written in the Python programming language, which is supported by ESRI's ArcGIS version 9 or later. The processed data files are also provided in text (.csv) and Access 2003 Database (.mdb) formats. All data except the raster files include attributes identifying realm, province, and ecoregion as defined by the MEOW classification schema.

Open-File Report↗
USGS2012

Recent advances in statistical methods for the estimation of sediment and nutrient transport in rivers

This paper reviews advances in methods for estimating fluvial transport of suspended sediment and nutrients. Research from the past four years, mostly dealing with estimating monthly and annual loads, is emphasized. However, because this topic has not appeared in previous IUGG reports, some research prior to 1990 is included. The motivation for studying sediment transport has shifted during the past few decades. In addition to its role in filling reservoirs and channels, sediment is increasingly recognized as an important part of fluvial ecosystems and estuarine wetlands. Many groups want information about sediment transport [ Bollman , 1992]: Scientists trying to understand benthic biology and catchment hydrology; citizens and policy-makers concerned about environmental impacts (e.g. impacts of logging [ Beschta , 1978] or snow-fences [ Sturges , 1992]); government regulators considering the effectiveness of programs to protect in-stream habitat and downstream waterbodies; and resource managers seeking to restore wetlands.

Reviews of Geophysics↗
USGS2025

Using imaging spectroscopy and elevation in machine learning to estimate soil salinity in intermittently tidal wetlands

Coastal soil salinization patterns are changing due to drought, sea level rise (SLR), and changing freshwater inflow. These changes are expected to impact coastal wetland plant health and ecosystem function, such as changes to biomass and productivity. These impacts have led to greater interest in how we monitor soil salinization across spatial and temporal scales. Remote sensing is a promising tool for estimating soil salinity at the spatial scales required for decision making by land managers. However, the development of a remote sensing estimation approach for wetland soil salinity must account for two factors: (1) the high spatial and temporal heterogeneity of coastal wetlands and (2) the fact that soil salinity is the result of multiple historical land use, hydrological, and geomorphic processes. In spring 2022, a combined airborne-field campaign, known as SHIFT, collected a weekly time series of airborne visible to shortwave infrared (VSWIR) image spectroscopy data. This dataset provides a unique opportunity to assess the application of fine spatial (5 m) and temporal (weekly) resolution VSWIR data to estimate root zone soil salinity; when combined with environmental variables such as elevation, these data can account for some of these factors. In this study, we utilized VSWIR and elevation datasets in a random forest regression to predict and map soil salinity in an intermittently tidal estuary, Devereux Slough, located in Santa Barbara County, California. The final model combined spectral indices with elevation to better capture soil salinity dynamics despite lower correlation ( r = 0.85) than solely using elevation ( r = 0.92). This research demonstrates the utility of remote sensing datasets, namely, elevation and the modified Anthocyanin Reflectance Index (mARI), for predicting root zone soil salinity in intermittently tidal coastal wetlands. These findings are an important step in advancing coastal remote sensing by creating a gridded salinity dataset that can be used for salinity monitoring and other coastal applications, such as modeling change in vegetation communities or ecosystems facing the impacts of climatic variability and change.

California↗
USGS2025

Factors structuring macrofaunal communities of hydrocarbon seeps along the Cascadia margin

Cold seeps, fueled by hydrocarbon-based chemosynthesis, support unique benthic communities that can vary across small spatial scales influenced by local geochemistry. We examined the community structure and function of macrofauna in cold seeps along the Cascadia margin on the edge of gas hydrate stability—a dynamic environment that may fluctuate as seafloor temperatures change. These communities were assessed in relation to their sediment environment to provide baseline data for these previously uninvestigated seeps and decipher the most significant variables structuring them. Specific environmental drivers investigated include sediment organic carbon, total nitrogen, C:N ratios, stable isotopes (δ 13 C and δ 15 N), redox potential, grain size, and porefluid chemistry. Macrofaunal community composition varied across locations separating into twelve distinct clusters. Several co-located cores clustered separately, indicating high heterogeneity in these communities at small spatial scales. Significant drivers of macrofauna communities included clay and sand content, C:N, δ 15 N values, organic carbon content, and depth. Functional trait composition was influenced by similar drivers, including depth, δ 15 N values, C:N, and sand content. Our results indicate similar environmental variables structure macrofaunal community composition and function across small- and large-scale gradients, contributing to our understanding of heterogeneity in local and regional factors that shape seep macrofaunal communities. This is the first investigation of macrofauna at these recently discovered seeps and provides baseline data on the hydrate stability zone for future comparisons, advancing our knowledge of broad-scale trends in seep macrofauna ecology.

California, Oregon, Washington↗
USGS2005

A method for the use of landscape metrics in freshwater research and management

Freshwater research and management efforts could be greatly enhanced by a better understanding of the relationship between landscape-scale factors and water quality indicators. This is particularly true in urban areas, where land transformation impacts stream systems at a variety of scales. Despite advances in landscape quantification methods, several studies attempting to elucidate the relationship between land use/land cover (LULC) and water quality have resulted in mixed conclusions. However, these studies have largely relied on compositional landscape metrics. For urban and urbanizing watersheds in particular, the use of metrics that capture spatial pattern may further aid in distinguishing the effects of various urban growth patterns, as well as exploring the interplay between environmental and socioeconomic variables. However, to be truly useful for freshwater applications, pattern metrics must be optimized based on characteristic watershed properties and common water quality point sampling methods. Using a freely available LULC data set for the Santa Clara Basin, California, USA, we quantified landscape composition and configuration for subwatershed areas upstream of individual sampling sites, reducing the number of metrics based on: (1) sensitivity to changes in extent and (2) redundancy, as determined by a multivariate factor analysis. The first two factors, interpreted as (1) patch density and distribution and (2) patch shape and landscape subdivision, explained approximately 85% of the variation in the data set, and are highly reflective of the heterogeneous urban development pattern found in the study area. Although offering slightly less explanatory power, compositional metrics can provide important contextual information.

Landscape Ecology↗
USGS2012

Wildlife contact analysis: Emerging methods, questions, and challenges

Recent technological advances, such as proximity loggers, allow researchers to collect complete interaction histories, day and night, among sampled individuals over several months to years. Social network analyses are an obvious approach to analyzing interaction data because of their flexibility for fitting many different social structures as well as the ability to assess both direct contacts and indirect associations via intermediaries. For many network properties, however, it is not clear whether estimates based upon a sample of the network are reflective of the entire network. In wildlife applications, networks may be poorly sampled and boundary effects will be common. We present an alternative approach that utilizes a hierarchical modeling framework to assess the individual, dyadic, and environmental factors contributing to variation in the interaction rates and allows us to estimate the underlying process variation in each. In a disease control context, this approach will allow managers to focus efforts on those types of individuals and environments that contribute the most toward super-spreading events. We account for the sampling distribution of proximity loggers and the non-independence of contacts among groups by only using contact data within a group during days when the group membership of proximity loggers was known. This allows us to separate the two mechanisms responsible for a pair not contacting one another: they were not in the same group or they were in the same group but did not come within the specified contact distance. We illustrate our approach with an example dataset of female elk from northwestern Wyoming and conclude with a number of important future research directions.

Behavioral Ecology and Sociobiology↗
USGS2019

Speaking the same language: Can the Sustainable Development Goals translate the needs of inland fisheries into irrigation decisions?

Irrigated agriculture and inland fisheries both make important contributions to food security, nutrition, livelihoods, and well-being. Typically, in modern irrigation systems, these components operate independently. Some practices, commonly associated with water use and intensification of crop production, can be in direct conflict with and have adverse impacts on fisheries. Food security objectives may be compromised if fish are not considered in the design phases of irrigation systems. The 2030 Agenda for Sustainable Development provides a framework that can serve as a backdrop to help integrate both sectors in policy discussions and optimize their contributions to achieving the Sustainable Development Goals (SDGs). Inland fisheries systems do play an important role in supporting many SDG objectives, but these contributions can sometimes be at odds with irrigated agriculture. Using case studies of two globally important river catchments, the Lower Mekong and Murray-Darling Basins, we highlight the conflicts and opportunities for improved outcomes between irrigated agriculture and inland fisheries. We explore SDG 2 (Zero Hunger) as a path to advance our irrigation systems as a means to benefit both agriculture and inland fisheries, preserving biodiversity and enhancing the economic, environmental, and social benefits they both provide to people.

Marine and Freshwater Research↗
USGS2018

USA National Phenology Network observational data documentation

The goals of the USA National Phenology Network (USA-NPN, www.usanpn.org ) are to advance science, inform decisions, and communicate and connect with the public regarding phenology and species’ responses to environmental variation and climate change. The USA-NPN seeks to advance the science of phenology and facilitate ecosystem stewardship by providing phenological information freely and openly. To accomplish these goals, the USA-NPN National Coordinating Office (NCO) delivers observational data on plant and animal phenology in several formats, including minimally processed status and intensity datasets and derived phenometrics for individual plants, sites, and regions. This document describes the suite of observational data products delivered by the USA National Phenology Network, covering the period 2009–present for the United States and accessible via the Phenology Observation Portal ( http://dx.doi.org/10.5066/F78S4N1V ) and via an Application Programming Interface. The data described here have been used in diverse research and management applications, including over 30 publications in fields such as remote sensing, plant evolution, and resource management.

Open-File Report↗
USGS2024

Methods of analysis—Determination of pesticides in filtered water and suspended sediment using liquid chromatography- and gas chromatography-tandem mass spectrometry

The widespread application of pesticides in agricultural and urban areas leads to their presence in surface waters. Presence of these biologically active chemicals in environmental waters potentially has adverse effects on nontarget organisms. To better understand the environmental fate of these contaminants, a robust method to capture chemicals with wide-ranging physicochemical properties has been developed. The method was developed by the U.S. Geological Survey’s Organic Chemistry Research Laboratory to monitor pesticides, pesticide degradates, and other agrochemicals in environmental surface waters throughout the country. The analysis involves a multiresidue method to determine 183 pesticides and pesticide degradates in filtered water samples and 178 pesticides and pesticide degradates in paired suspended sediment samples. After the filtration of whole water, contaminants are individually measured in the filtered water and the collected suspended sediment. Filtered water is extracted via solid-phase extraction, whereas suspended sediment is extracted using an ultrasonication, solid-liquid extraction. Samples are analyzed by liquid chromatography-tandem mass spectrometry using an electrospray ionization source in positive and negative modes and analyzed by gas chromatography-tandem mass spectrometry using an advanced electron ionization source in positive mode. Instrument parameters were optimized for the highest sensitivity, and at least two transitions (quantifier and qualifier) were monitored for each analyte. Recoveries in test filtered water ( n =9; 183 analytes) from the American River, California, and suspended sediment ( n =9; 178 analytes) samples fortified at 15 nanograms per liter (ng/L) ranged from 70.1 to 121.0 and 71.1 to 117.0 percent in water and suspended sediment filter samples, respectively. Method detection limits of pesticides and pesticide degradates ranged from 0.5 to 10.6 ng/L in water and 0.7 to 11.8 ng/L in suspended sediment filters. Reporting limits were 1.1–21.1 ng/L and 1.5–23.7 ng/L in water and filter samples, respectively. The developed method is applied to surface-water samples for the analysis of pesticides, pesticide degradates, and other agrochemicals.

Techniques and Methods↗
USGS2018

Toward a resilience-based conservation strategy for wetlands in Puerto Rico: Meeting challenges posed by environmental change

Designing conservation strategies in human-dominated landscapes is challenging, owing to complex human-natural systems and evolving societal values. To meet this challenge, a robust, adaptive strategy should have a process for flexible implementation of incremental actions. We describe a hypothetical example for the Rio Grande de Arecibo watershed and coastal wetlands in Puerto Rico to address the first component. The process begins by identifying shared stakeholder objectives. This process benefits from a review of foundational research and knowledge base that includes global forcings and vulnerability of resources of interest. Forcings include climate change and pervasive urban sprawl. We focus on two taxonomic groups with differing life histories but strong dependence on water resource dynamics, another resource valued by humans. We stipulate objectives and multiple actions, but focus on those pertaining to hydro-management as the common thread in our example. We advanced two decision contexts of contrasting complexity, illustrated links between objectives and actions, and highlighted trade-offs triggered by varying resource valuation. Our focus was to highlight various components necessary to frame a resilience-based strategy, but we cannot overemphasize the importance of accommodating institutional and stakeholder changing priorities and values to ensure its successful implementation.

Puerto Rico↗
USGS2024

Current advances in coastal wetland elevation dynamics: Introduction to the special issue

The thematic issue entitled, “Current Advances in Coastal Wetland Elevation Dynamics,” draws on topics from two special sessions at the CERF 2021 conference plus additional recent research describing scientific insights gained from the Surface Elevation Table–Marker Horizon (SET–MH) method and its application across the globe to quantify and understand subsurface process influences on wetland elevation change and wetland responses to sea-level rise. The findings group articles within each of five thematic topics. (1) A 30-year retrospective on the scientific insights gained on surface and shallow subsurface process dynamics. (2) Investigations of the subsurface soil process influences on wetland elevation. (3) How the scientific community applies the SET–MH method to quantify and understand wetland responses to RSLR and other environmental drivers such as altered hydrology and sediment supply. (4) How SET–MH data are used in long-term monitoring networks at different geographic scales. (5) Pairing the SET-MH method with (a) survey techniques to increase lateral coverage of wetland elevation trends and (b) geodetic measurements to increase vertical coverage of vertical land motion.

Estuaries and Coasts↗
USGS2015

Glaciological and marine geological controls on terminus dynamics of Hubbard Glacier, southeast Alaska

Hubbard Glacier, located in southeast Alaska, is the world's largest non-polar tidewater glacier. It has been steadily advancing since it was first mapped in 1895; occasionally, the advance creates an ice or sediment dam that blocks a tributary fjord (Russell Fiord). The sustained advance raises the probability of long-term closure in the near-future, which will strongly impact the ecosystem of Russell Fiord and the nearby community of Yakutat. Here, we examine a 43-year record of flow speeds and terminus position to understand the large-scale dynamics of Hubbard Glacier. Our long-term record shows that the rate of terminus advance has increased slightly since 1895, with the exception of a slowed advance between approximately 1972 and 1984. The short-lived closure events in 1986 and 2002 were not initiated by perturbations in ice velocity or environmental forcings, but were likely due to fluctuations in sedimentation patterns at the terminus. This study points to the significance of a coupled system where short-term velocity fluctuations and morainal shoal development control tidewater glacier terminus position.

Alaska↗