NW Climate Science Digest

Aquatic Resources, Stream Flow, Hydrology in the Western U.S.

Seasonal snowpack characteristics influence soil temperature and water content at multiple scales in interior western U.S. mountain ecosystems

Maurer, G. E., and D. R. Bowling (2014), Seasonal snowpack characteristics influence soil temperature and water content at multiple scales in interior western U.S. mountain ecosystems, Water Resour. Res., 50, doi:10.1002/2013WR014452

Predicting Climate Change Impacts on Aquatic Ecosystems across the Pacific Northwest

In case you missed it last December, USGS ecologist, Clint Muhlfeld’s, webinar about climate impacts to NW trout and salmon is now available online.

Stream Temperature Patterns over 35 Years in a Managed Forest of Western Washington:

Reiter & colleagues. 2015. Stream temperature patterns over 35 years in a managed forest of western Washington. Journal of the American Water Resources Association DOI:10.1111/1752-1688.12324

Water temperature in the upper Deschutes River watershed, Washington has been monitored since 1975 and represents one of the longest studies of water quality on managed forests in the Pacific Northwest. The authors used this data to examine the combined effects of hydro-climatic patterns and forest management on stream temperature. They found that the effects of harvest conducted prior to buffer regulations were obvious and most pronounced on smaller streams. They did not detect any response on larger channels to more recent timber harvest where riparian buffers were required.  In many cases the temperature improvements associated with more stringent buffer requirements implemented over the last 35 years in the Deschutes watershed have been offset by warming climatic conditions. This emphasizes that it is critical to account for changing climate when examining long-term temperature patterns.

Incorporating climate change projections into riparian restoration planning and design

Perry, L.G., Reynolds, L.V., Beechie, T.J., Collins, M.J. and Shafroth, P.B.  2015.  Incorporating climate change projections into riparian restoration planning and design. Ecohydrology DOI: 10.1002/eco.1645

Riparian restoration may help shade and cool streams to mitigate the impacts of climate change and other human disturbances. However, climate change may alter which restoration methods are most effective and which restoration goals can be achieved. In this review the authors discuss and provide examples of how climate change might be incorporated into restoration planning at the key stages of assessing the project context, establishing restoration goals and design criteria, evaluating design alternatives and monitoring restoration outcomes. Given high uncertainty in future conditions, planners will need to consider multiple potential future scenarios, implement a variety of restoration methods, design projects with flexibility and plan to respond adaptively to climate change.

The Beaver Restoration Guidebook- Working with Beaver to Restore Streams, Wetlands, and Floodplains:

The North Pacific Landscape Conservation Cooperative partnered with U.S. Fish & Wildlife, NOAA, Portland State University, and the U.S. Forest Service to develop a comprehensive guide on using beaver for stream restoration. The goal of this guidebook, which was just released, is to provide an accessible, useful resource for anyone involved in using beaver to restore streams, floodplains, wetlands, and riparian areas. It provides a practical synthesis of the best available science, an overview of management techniques, and case studies from throughout the western US. Target audiences are landowners, biologists, engineers, scientists, foresters, farmers, ranchers, the regulatory and funding communities, and others interested in how beaver activity can be effectively used to restore riparian habitat and improve water quality. The information contained in the guide is meant to inform decisions on fish and wildlife habitat restoration and management, range land improvement, wetland management, mitigation, transportation system planning and maintenance, and water management.

Seeing the landscape for the trees: Metrics to guide riparian shade management in river catchments

Johnson & Wilby. 2015. Seeing the landscape for the trees: Metrics to guide riparian shade management in river catchments. Water Resources Research DOI 10.1002/2014WR016802

The warming effect of solar radiation on rivers varies across space and time. Thus the benefits of shading through riparian restoration will also vary from site to site.  These authors used a network of high-resolution temperature measurements from two upland rivers in the UK along with topographic shade modeling to assess how shade affects water temperature. Conditions under which shade is most effective at reducing water temperature and amount of shade needed to offset warming of 1 degree Celsius are discussed.   

Biodiversity/Species and Ecosystem Response

Feds release plan for recovering Northwest fish species

Federal authorities have released their final recovery plan for a fish species that teetered on the brink of extinction in the early 1990s in one of the Pacific Northwest’s major rivers.  The National Oceanic and Atmospheric Administration released the plan on June 8th with the goal of creating a self-sustaining population of Snake River sockeye salmon over the next 50 to 100 years.

Knowledge co-production and boundary work to promote implementation of conservation plans

This paper shows how working with stakeholders from diverse knowledge systems and creating shared knowledge boundaries to satisfy these different groups can help bridge the gap between conservation planning and implementation, and promote cross-sectorial cooperation. In this case knowledge co-production occurred in stakeholder workshops held over the course of four years.  These iterative workshops included co-development of goals, dialogue and negotiation, and capacity building for multi-scale implementation. The resulting maps and information integrated diverse knowledge types of over 450 stakeholders and provide a consistent national information source that has been applied in 25 of the 37 use contexts since launching 3.5 years ago. This work provides practical guidance for conservation planners interested in promoting uptake of their science, and contributes to an evidence base for reflection on how conservation efforts can be improved.

Conserving Biodiversity: Practical Guidance about Climate Change Adaptation Approaches in Support of Land-use Planning

Lawler, J.J., Beier, P., Groves, G., Knight, G., Boyce Jr, D.A., Bulluck, J., Johnston, K.M., Klein, M.L., Muller, K., Pierce, D.J., Singleton, W.R., Strittholt, J.R., Theobald, D.M., Tombulak, S.C., and Trainor, A. (2015) Conserving Biodiversity: Practical Guidance about Climate Change Adaptation Approaches in Support of Land-use Planning. Natural Areas Journal 35(1)

This paper presents a framework that synthesizes six promising adaptation approaches for conserving biodiversity. The authors provide guidance on implementing these adaptation approaches and include case studies that highlight how biodiversity conservation can be used in planning. It concludes with general guidance on choosing appropriate climate adaptation approaches to amend for conservation planning.

Meager snows spell trouble ahead for salmon

Warm winter temperatures in the mountains of the western United States this past winter sharply reduced the region's snowpack, which normally reaches its high point at this time each year. That snow typically serves as a vital water storage reservoir that is slowly released as the snow melts over the dry summer months. Without this snowmelt, stream flows are expected to drop sharply this summer, which in turn is expected to cause water temperatures to rise to a level unhealthy for migrating salmon. As a result, fisheries biologists expect a looming calamity for endangered salmon stocks this year.

Wildlife density data better predicts conservation success

A recent study published in the journal Conservation Biology makes a case for using more robust data sets in order to better protect birds, plants, and animals. The concept is fairly simple, but relies on scientists sharing data across studies. Presence/ absence data is now the type of data most commonly used in conservation planning, but including data on species richness could improve the ability of scientists and managers to prioritize efforts. The authors of this study encouraged partners to make their bird observation data accessible through the Avian Knowledge Network leading to the addition of over 900,000 new bird observations from 23 different studies. They then combined the information with bird data in the California Avian Data Center and developed species distribution and density models covering coastal Northern California, Oregon and Washington for 26 species of land birds representing four different habitat types. They used both the presence/absence and density models to map conservation priorities and compared the estimated population size of each species protected using both approaches. The prioritizations based on count data protected more individuals of each species than the prioritizations based on presence/absence data in the areas of highest conservation priority.

Climate and Weather Reports and Services

NOAA says ‘hiatus’ disappears once data corrected

The ongoing conversation as to why the planet had apparently experienced what has been termed a ‘hiatus’ or pause in global warming since just before the turn of the millennium, has received another contribution, this time with US National Oceanographic and Atmospheric Administration (NOAA) suggesting that there actually was no hiatus. Researchers with NOAA say in a new paper out this week in the journal Science that once adjustments to data are made correcting for errors, the slowdown disappears. That is, the hiatus is in fact nothing more than an artifact of inaccurate data. Instead, the research suggests that global warming may now be accelerating.

Elevation-dependent warming in mountain regions of the world

Mountain Research Initiative EDW Working Group.  2015.  Elevation-dependent warming in mountain regions of the world.  Nature Climate Change 5, 424–430. doi:10.1038/nclimate2563

The authors review important mechanisms that contribute to amplified warming at high elevations: snow albedo and surface-based feedbacks; water vapor changes and latent heat release; surface water vapor and radiative flux changes; surface heat loss and temperature change; and aerosols. All lead to enhanced warming with elevation, and it is believed that combinations of these mechanisms may account for contrasting regional patterns of elevation-dependent warming. The authors also discuss future needs to increase knowledge of mountain temperature trends and their controlling mechanisms through improved observations, satellite-based remote sensing and model simulations.

Attribution of climate extreme events

Trenberth, K.E., Fasullo, J.T., Shepard, T.G.  2015.  Attribution of climate extreme events.  Nature Climate Change. doi:10.1038/nclimate2657

Authors of a new paper published in Nature Climate Change suggest a different framing for the attribution of extreme weather events- one which asks why such extremes unfold the way they do. Specifically, they suggest that it is more useful to regard extreme weather events as being largely unaffected by climate change, and to question whether known changes in the climate system's thermodynamic state affected the impact of the particular event. Some examples briefly illustrated include 'snowmaggedon' in February 2010, superstorm Sandy in October 2012 and supertyphoon Haiyan in November 2013, and, in more detail, the Boulder floods of September 2013, all of which were influenced by high sea surface temperatures that had a discernible human component.

NASA Releases Detailed Global Climate Change Projections

On June 9th NASA released data showing how temperature and rainfall patterns worldwide may change through the year 2100 because of growing concentrations of greenhouse gases in Earth’s atmosphere. The new dataset shows projected changes worldwide on a regional level in response to different scenarios of increasing carbon dioxide. The high-resolution data, which can be viewed on a daily timescale at the scale of individual cities and towns, will help scientists and planners conduct climate risk assessments to better understand local and global effects of hazards, such as severe drought, floods, heat waves and losses in agriculture productivity. The new dataset is the latest product from the NASA Earth Exchange (NEX), a big-data research platform within the NASA Advanced Supercomputing Center at the agency's Ames Research Center in Moffett Field, California. In 2013, NEX released similar climate projection data for the continental United States that is currently being used to quantify climate risks to the nation’s agriculture, forests, rivers and cities.

Despite Drought in California and the Northwest, May 2015 was the Wettest Month Ever for the Lower 48 States

According to a report just released by the National Centers for Environmental Information (formerly the National Climatic Data Center), May of 2015 was it the wettest May on record for the contiguous 48 states.  It was also the wettest month ever in 121-years of record-keeping.

Coastal/Marine Ecosystems, Ocean Acidification, Sea Level Rise

Analysis of Otoliths Suggest that Growth Slows With Sea Level Rise for a Deepwater Predatory Fish

Otoliths are little structures that most fish have in their skulls. Because layers of mineral are added to otoliths throughout a fish’s life, they can act as a reliable record of growth patterns — periods of feast and famine — just like tree rings. Now, scientists are using these structures to show how fish size may decrease as a result of a changing ocean.

Largest Ever Toxic Algae Bloom Contaminate Coasts from California to Alaska

Scientists are investigating what could be the largest toxic algae bloom ever recorded off the West Coast. The effects stretch from Central California to British Columbia, and possibly as far north as Alaska. Dangerous levels of the natural toxin domoic acid have shut down recreational and commercial shellfish harvests in Washington, Oregon and California. At the same time, two other types of toxins rarely seen in combination are turning up in shellfish in Puget Sound and along the Washington coast.  Scientists suspect this year’s unseasonably high temperatures are playing a role, along with “ the blob” — a vast pool of unusually warm water that blossomed in the northeastern Pacific late last year. The blob has morphed since then, but offshore waters are still about two degrees warmer than normal. Domoic-acid outbreaks aren’t unusual in the fall, but the toxin has never hit so hard in the spring, or required such widespread closures for crabs.

Climate mediates hypoxic stress on fish diversity and nursery function at the land–sea interface

Hughes, B.B.; Levey, M.D.; Fountain, M.C.; Carlisle, A.B.; Chavez, F.P. and Gleason, M.G.  2015.  Climate mediates hypoxic stress on fish diversity and nursery function at the land-sea interface.  PNAS 112(26) 8025-8030.

Researchers have found that climate can be a powerful moderator of coastal hypoxia, but the effects of climate change are hard to predict. In the future water will be warmer, and warm water holds less oxygen than cold water. Climate change is also likely to influence the frequency and intensity of El Niño events, but exactly how is still unclear. Reducing the stress caused by nutrient enrichment and hypoxia will improve the resilience of the ecosystems and help buffer the effects of climate change. Opportunities for improving coastal land management practices are numerous and varied. Conservation groups and land managers can partner with farmers and fishers to manage nutrient applications, restore or rebuild wetlands that will reduce nutrient levels in agricultural discharge water.

Climate-linked Mechanisms Drive Spatial and Temporal Variation in Eelgrass Growth and Assemblage Structure in the Pacific Northwest

Thom, R., Southard, S. and Bourde, A. 2014. Climate-linked Mechanisms Driving Spatial and Temporal Variation in Eelgrass (Zostera marina L.) Growth and Assemblage Structure in the Pacific Northwest Estuaries, USA. Journal of Coastal Research. 68:1-11. DOI: 10.2112/SI68-001.1

Using a combination of field data and laboratory experiments, the authors have shown that variations in water temperature, mean sea level, and stress from drying appear to drive spatial and temporal patterns in eelgrass. Complicated interactions among these variables make it difficult to predict the effects of climate change on this important resource. However many characteristics of eelgrass make it a suitable indicator of the effects of climate variation on marine and estuarine ecosystems.  

Ocean 'blob' of warm water bringing poor food for B.C. wild salmon

A University of Victoria oceanographer studying the so-called "warm blob" of water off the B.C. coast has observed unusual, "squishy" visitors from the south — and that could be bad news for young salmon. John Dower, who just returned from a research cruise north of Vancouver Island, said he saw remarkably high amounts of tiny animals called zooplankton in the "blob," a huge mass of ocean water about 2 degrees warmer than normal. And the varieties he saw are normally found off northern California — not Canada.

Fire

Climate and Fires Tightly Linked Over the Past Century in the Northern Rocky Mountains

Higuera, P.E., Abatzoglou, J.T., Littell, J.S. and Morgan, P.  2015.  The changing strength and nature of fire-climate relationships in the northern Rocky Mountains, U.S.A., 1902-2008.  PLoS ONE 10(6): e0127563. doi:10.1371/journal.pone.0127563

A new paper by a team of University of Idaho and U.S. Geological Survey scientists suggests that climate strongly influences wildfire activity in the northern Rocky Mountains, despite large changes in forest management and fire suppression.

Increases in wildfires over the past 30 years coincide with an increase in warm, dry summer conditions, according to the study. The same is true for a period in the early 20th century, including the dramatic fires of 1910. During a cooler, wetter period in the mid-20th century, fire activity decreased. The team compared fire patterns found in previously published records of burned areas in Idaho and western Montana with seasonal climate records to reveal the flammability of forest vegetation.

Forests

Changing climate prompts boreal forest shift

Glenn P. Juday, Claire Alix, Thomas A. Grant. Spatial coherence and change of opposite white spruce temperature sensitivities on floodplains in Alaska confirms early-stage boreal biome shift. Forest Ecology and Management, 2015; 350: 46 DOI: 10.1016/j.foreco.2015.04.016

A study by researchers at the University of Alaska Fairbanks has demonstrated that a biome shift is already underway in Alaska. The boreal forest in Interior Alaska is suffering from unsuitably warm temperatures while the forest in Western Alaska near the tundra has increased in productivity. The authors spent ten years gathering white spruce tree cores and disks from 540 trees in 36 stands, sampling from easternmost Alaska downriver to the western edge of the boreal forest near the Bering Sea. Two measurements were taken to determine how much the trees grew each year. Ten growth data was compared to temperature data from historical records and weather stations. They found that in Interior Alaska, as summer temperatures rose, the growth of the trees slowed. Meanwhile, in Western Alaska, which is also warming, the trees are growing more rapidly. In other words the boreal forest is already shifting away from lowlands in Interior Alaska to higher elevations and the western part of the state.

Mismanaged Forests are a Source of Nitrogen Pollution

Masaaki Chiwa, Takami Saito, Hirokazu Haga, Hiroaki Kato, Kyoichi Otsuki, Yuichi Onda. A Nitrogen-Saturated Plantation of and in Japan Is a Large Nonpoint Nitrogen Source. Journal of Environment Quality, 2015; 0 (0): 0 DOI: 10.2134/jeq2014.09.0401

Older, overcrowded cypress and cedar plantations in Japan with little to no undergrowth have become a source of non-point nitrogen pollution according to a new study.  Trees in these older plantations grow slowly and use fewer soil nutrients like nitrogen, than younger trees. The crowding and lack of understory prevents nutrients in fallen needles from being reabsorbed.  Instead it forms runoff during rainfall and snowmelt- heading to nearby streams where it contributes to algal blooms. The authors recommend thinning and returning the forest to a more natural forest state to reduce this unexpected source of pollution.

Land Use

Can Better Grazing Help Dairy Farmers Cope With Drought and Climate Change?

Dairy farmers in Oregon have found that rotating their 200 cows between fields, and keeping them there for a day at a time produces healthier, more robust cows and pasture than letting the herd graze at random. Rotation also helps the grass retain water, resulting in a savings of a month to a month-and-a-half of irrigation water a year.

Special Reports / Announcements

Press Statement on Climate Change Adaptation and Resilience by John Kerry Secretary of State Washington, DC June 9, 2015

Last month Secretary Kerry announced the launch of the Climate Services for Resilient Development partnership, along with the government of the United Kingdom and partners at the American Red Cross, the Asian Development Bank, Esri, Google, the Inter-American Development and the Skoll Global Threats Fund. The private-public partnership was created as part of President Obama’s Climate Action Plan, unveiled last fall. The effort is aimed at helping other countries- particularly those that are poorest and most vulnerable- adapt to a changing climate. The U.S. and its partners are putting $34 million toward the effort. As part of the program the partners will create a volunteer “climate resilience corps” that the Peace Corps and AmeriCorps will be launching in developing countries, and NASA will release the first-ever climate modeling system that breaks data down to the country level, which will enable countries to better target their individual adaptation planning efforts.

Federal Advisory Committee Issues Recommendations for Addressing Climate Change to NCCWSC & CSCs

The report from the Advisory Committee on Climate Change and Natural Resource Science recognizes the U.S. Geological Survey and the Department of the Interior for achieving significant accomplishments since the establishment of the NCCWSC and CSCs and provides several key recommendations to clarify, focus, and enhance the program's efforts. The committee also recommends that the NCCWSC/CSC program should expand its capacity to work closely with partners, including states, tribes and other indigenous groups, and environmental organizations, both within DOI and with other federal agencies. A “how-to guide” for “actionable science” is included as an appendix to the Committee’s report. The report also includes two other documents to which committee members contributed: one is a summary of a primer on climate change and indigenous peoples and the other provides guidelines for considering traditional knowledge in climate change initiatives.

Pope Francis Calls for Climate Action

On June 18th Pope Francis issued an unprecedented encyclical on the subject of the environment, arguing that humanity’s exploitation of the planet’s resources has crossed the Earth’s natural boundaries, and that the world faces ruin without a revolution in hearts and minds.  In it he called for an ethical and economic revolution to prevent catastrophic climate change and growing inequality. The message was sent to the world’s 5,000 Catholic bishops and published online in five languages. It has already inspired demonstrations, lobbying and activism among the world’s 1.2 billion Catholics.

Taking Action

2016-17 Puget Sound Action Agenda Strategy Work Available for Public Comment Through July 10

The Puget Sound Partnership will soon be updating the Puget Sound Action Agenda, a plan that describes priorities to help recover Puget Sound.  The strategy includes three initiatives- protecting and restoring habitat, preventing pollution from stormwater and recovering shellfish beds. Puget Sound Partnership is currently asking for input from the public on recommendations resulting from a series of meetings and discussions about the update. Online public comments will be accepted through July 10, 2015.

Climate Change Adaptation in United States Federal Natural Resource Science and Management Agencies

A Synthesis: Federal agencies with responsibility for natural resource management are mandated to consider climate change in planning and projects, and to begin preparing for the effects of climate change. Federal agencies are making significant progress in climate change adaptation, although lack of financial resources has slowed implementation of climate-focused activities. This report reviews adaptation activities in several federal agencies.

Inaction on climate change would cost billions, major EPA study finds

On June 20th the White House released a report examining the likely effects of a global agreement to curb greenhouse gases. The report, titled “Climate Change in the United States: Benefits of Global Action,” seeks to measure the potential gains for Americans under an international accord to keeps global temperatures from rising by more than 2 degrees Celsius over historical averages. Researchers compared what would likely happen in a business-as-usual world, in which carbon-dioxide levels in the atmosphere exceed 800 parts per million by the year 2100, compared to levels of about 462 parts per million expected if aggressive action is taken over the coming decades to limit greenhouse-gas pollution. The five-year study was led by the Environmental Protection Agency and incorporated research from peer-reviewed studies and modeling by scientists from the Energy Department’s Laboratory complex and the Massachusetts Institute of Technology. Researchers found that a global agreement to curb greenhouse gas emissions would likely prevent nearly 70,000 premature American deaths annually by the end of the century while sparing the country hundreds of billions of dollars’ worth of economic losses. Slowing the carbon build-up in the atmosphere would also prevent severe damage to a wide range of critical ecosystems, from Hawaiian coral reefs that support tourism to shellfish beds off the East Coast. The report concludes that every region of the country could be spared the severe economic disruptions that would result if greenhouse gas concentrations continue to soar.

Oregon’s House Bill 3470, the Climate Stability and Justice Act

Oregon’s HB 3470 is a Greenhouse Gas Cap and Trade bill that is modeled off of California's AB 32 legislation that caps and then incrementally ratchets down greenhouse gas emissions.  There are many organizations around the state that are now coordinating efforts to try and help clue legislators in to the extreme urgency of needing to pass this bill this legislative session. 

Washington State Board Aims to Remove Stream Barriers for Fish

In Washington the Fish Passage Barrier Removal Board is starting to develop a strategy for removing the many barriers that block fish access to streams across the state. The board cites about 14,000 known impediments in Washington and estimates that the total number is closer to 35,000 or 40,000. The barrier removal board was created by the Washington Legislature last year and now operates under the Washington State Department of Fish and Wildlife. It came with no funding, but officials are now working with local entities to identify priority areas for barrier removal.

Shopping for Water: How the market can mitigate water shortages in the West

A report by The Hamilton Project at the Brookings Institution proposes to give farmers the ability to lease or sell water that they have conserved by reducing their consumption.  The authors argue that reducing agricultural water consumption by just 4% would increase the water available for residential, commercial and industrial uses by roughly 50%, according to their analysis of U.S. Geological Survey data. They consider current laws to be outdated and wasteful and traditional practices to deal with shortages like diverting more water from rivers, building new reservoirs and drilling additional groundwater wells to be unsustainable. Using market tools to promote water trading, they argue, is one way to ensure that we can continue to meet growing water needs in the West.

Tribal and Indigenous Peoples Matters

Squaxin Tribe setting summer streamflow targets in the Deschutes River

In order to establish how much water salmon need to survive during the summer months, the Squaxin Island Tribe is examining streamflow in the Deschutes River. The end result of the tribe’s research will be a set of minimum flow targets or standards for the watershed between April and December. A state-adopted standard would mean that if flows drop beneath the minimum, the state would take corrective action to bring flows back up. The current standard was set by the state over 30 years ago for winter months, but didn’t address summer flows. Historical analysis by the tribe shows that summer flows have gotten lower and winter and spring floods more frequent and larger in recent decades. The analysis points to an increase in impervious surfaces and a loss of forest cover as prime causes of the change in hydrology. Those changes have decreased flow during the summer months by at least 20 percent.

What Tribal Hatcheries Are Doing to Save Salmon from the Drought

Record low streamflows and higher water temperatures are a potentially deadly combination for local salmon. Temperatures higher than 60 degrees cause pathogens such as Ichthyophthirius multifiliis (ich) and columnaris (gill rot) thrive in warm water, and diseases spread more quickly when the rivers are crowded by low flows. Tribes are taking action to protect salmon from these threats by changing the timing of when they let salmon in and out of their hatcheries. On the Olympic Peninsula, the Makah Tribe’s Hoko Hatchery released Chinook three weeks early and sockeye a month early. In some instances, hatchery managers may also bring adult spawners into their facilities early because conditions will be better in a controlled environment. Changes are contingent upon the approval of the National Oceanic and Atmospheric Administration.

Indigenous knowledge can be key to fighting climate change

While indigenous communities have developed knowledge over centuries to manage their lands and adapt to challenges such as rising sea levels or wildfires, they are still deeply affected by climate change. Two University of Kansas professors have authored research exploring cases of indigenous communities that have had success in applying traditional knowledge to fighting climate change and how American and international law falls short in preventing exploitation of those tribes and methods.