Geology topics

Gregory D. Hayward

Publications and source records attributed to Gregory D. Hayward.

6 recordsLinked to original sources

USGS2023

So goes the snow: Alaska snowpack changes and impacts on pacific salmon in a warming climate

In Alaska’s watersheds, climate change is altering the nature and role of the snowpack, defined as snow accumulation that melts in spring. Generally, the amount of precipitation that falls as snow and the length of the snow-cover season both decrease as temperatures exceed 0°C (32°F) more frequently. The impacts of climate change on snowpack vary among watersheds. In southern, coastal parts of Alaska, large decreases in spring snowpack are expected by the mid-21st century, even with more winter precipitation because temperatures warm to above freezing, causing a shift from snow to rain or more melt during the winter. In contrast, modest early spring increases in the snowpack are expected in watersheds where temperatures remain below freezing. In these locations temperatures warm but remain cold enough for the extra winter precipitation to fall as snow, even though the snowpack will begin accumulating later in the fall and melt earlier in the spring as temperatures rise during those warmer seasons. Because potential impacts on hydrological and ecological systems will vary among watersheds, it is difficult to generalize the resulting ecological impacts at broad spatial scales. Here, we explore likely impacts on hydrology in critical anadromous fish habitat in southwest Alaska.

Alaska↗

USGS2019

Managing effects of drought and other water resource challenges in Alaska and the Pacific Northwest

This is a Cooperator Report. As such, there is no specific abstract. The physical, ecological, and social environments of Alaska and the Pacific Northwest (PNW) region of the United States are extremely diverse. Alaska ranges from the Arctic Ocean and the very cold, dry environments of the North Slope to the cool and very rainy coastal North Pacific region of Southeast Alaska. Most precipitation falls as snow at higher elevations. In Arctic Alaska, average annual temperature is 14.6 F, and average annual precipitation is 11 inches. By contrast, in Southeast Alaska, average annual temperature is 35.8 F, and annual average precipitation is 143 inches. The PNW, defined here as Idaho, Oregon, and Washington, ranges from the Pacific Coast (annual precipitation of 200 inches) to interior semi-arid regions (annual precipitation of 8 inches). Precipitation patterns in the PNW are strongly governed by orographic phenomena, with high, persistent snowpack in the higher mountains (e.g., record annual snowfall of 1,130 in at Mount Baker, Washington in 1999-2000). Ecosystems in the PNW include productive temperate coniferous forests near the Pacific coast and along the (wet) west slope of the Cascade Range, less productive mixed-conifer forest along the (dry) east slope of the Cascades and in interior mountain ranges, and sagebrush-steppe and shrublands at lower elevations in much of the interior and mountain valleys. Large rivers and thousands of smaller tributaries form an extensive network of riparian, wetland, and estuarine systems that provide both critical hydrologic function and biological diversity at broad and fine spatial scales. Although Alaska and the Pacific Northwest differ in important physical, ecological, and social features, the importance of natural resources is evident in both regions. Water is important for wildlife and people. Water provides critical habitat for salmon, which are culturally and economically valuable species. Timber production has declined in recent decades. Recreation has emerged as a major revenue source.

Alaska, Oregon, Washington↗

USGS2018

Alaska snowpack response to climate change: Statewide snowfall equivalent and snowpack water scenarios

Climatically driven changes in snow characteristics (snowfall, snowpack, and snowmelt) will affect hydrologic and ecological systems in Alaska over the coming century, yet there exist no projections of downscaled future snow pack metrics for the state of Alaska. We updated historical and projected snow day fraction (PSF, the fraction of days with precipitation falling as snow) from McAfee et al. We developed modeled snowfall equivalent (SFE) derived from the product of snow-day fraction (PSF) and existing gridded precipitation for Alaska from Scenarios Network for Alaska and Arctic Planning (SNAP). We validated the assumption that modeled SFE approximates historical decadally averaged snow water equivalent (SWE) observations from snowcourse and Snow Telemetry (SNOTEL) sites. We present analyses of future downscaled PSF and two new products, October–March SFE and ratio of snow fall equivalent to precipitation (SFE:P) based on bias-corrected statistically downscaled projections of Coupled Model Intercomparison Project 5 (CMIP5) Global Climate Model (GCM) temperature and precipitation for the state of Alaska. We analyzed mid-century (2040–2069) and late-century (2070–2099) changes in PSF, SFE, and SFE:P relative to historical (1970–1999) mean temperature and present results for Alaska climate divisions and 12-digit Hydrologic Unit Code (HUC12) watersheds. Overall, estimated historical the SFE is reasonably well related to the observed SWE, with correlations over 0.75 in all decades, and correlations exceeding 0.9 in the 1960s and 1970s. In absolute terms, SFE is generally biased low compared to the observed SWE. PSF and SFE:P decrease universally across Alaska under both Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 emissions scenarios, with the smallest changes for RCP 4.5 in 2040–2069 and the largest for RCP 8.5 in 2070–2099. The timing and magnitude of maximum decreases in PSF vary considerably with regional average temperature, with the largest changes in months at the beginning and end of the snow season. Mean SFE changes vary widely among climate divisions, ranging from decreases between −17 and −58% for late twenty-first century in southeast, southcentral, west coast and southwest Alaska to increases up to 21% on the North Slope. SFE increases most at highest elevations and latitudes and decreases most in coastal southern Alaska. SFE:P ratios indicate a broad switch from snow-dominated to transitional annual hydrology across most of southern Alaska by mid-century, and from transitional to rain-dominated watersheds in low elevation parts of southeast Alaska by the late twenty-first century.

Alaska↗

USGS2015

Icefield-to-ocean linkages across the northern Pacific coastal temperate rainforest ecosystem

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 variability and long-term trends in key physical drivers and ecological responses. To advance our knowledge of the northern PCTR, we advocate for cross-disciplinary research bridging the icefield-to-ocean ecosystem that can be paired with long-term scientific records and designed to inform decisionmakers.

Pacific coastal temperate rainforest↗

USGS2012

The Adaptation for Conservation Targets (ACT) Framework: A tool for incorporating climate change into natural resource management

As natural resource management agencies and conservation organizations seek guidance on responding to climate change, myriad potential actions and strategies have been proposed for increasing the long-term viability of some attributes of natural systems. Managers need practical tools for selecting among these actions and strategies to develop a tailored management approach for specific targets at a given location. We developed and present one such tool, the participatory Adaptation for Conservation Targets (ACT) framework, which considers the effects of climate change in the development of management actions for particular species, ecosystems and ecological functions. Our framework is based on the premise that effective adaptation of management to climate change can rely on local knowledge of an ecosystem and does not necessarily require detailed projections of climate change or its effects. We illustrate the ACT framework by applying it to an ecological function in the Greater Yellowstone Ecosystem (Montana, Wyoming, and Idaho, USA)—water flows in the upper Yellowstone River. We suggest that the ACT framework is a practical tool for initiating adaptation planning, and for generating and communicating specific management interventions given an increasingly altered, yet uncertain, climate.

Environmental Management↗

USGS2011

Land management in the Anthropocene: Is history still relevant?

Ecological restoration, conservation, and land management are often based on comparisons with reference sites or time periods, which are assumed to represent “natural” or “properly functioning” conditions. Such reference conditions can provide a vision of the conservation or management goal and a means to measure progress toward that vision. Although historical ecology has been used successfully to guide resource management in many parts of the world, the continuing relevance of history is now being questioned. Some scientists doubt that lessons from the past can inform management in what may be a dramatically different future, given profound climate change, accelerated land use, and an onslaught of plant and animal invasions.

Conference Paper↗