NW Climate Science Digest

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

River sediment: Once maligned, now much loved

Scientists are reconsidering the role that river sediments play in maintaining wetlands as sea levels continue to rise. Human activity has destroyed or badly damaged about two-thirds of the world's wetlands — but researchers have started to recognize the silt, sand and gravel carried downstream can help rebuild those ecosystems. This represents a shift in the prevalent view among wetland scientists from that sediments are harmful. Sediment restoration projects are now underway across the globe, but scientists are still looking to improve their cost-effectiveness. In Louisiana officials are trying to mimic annual flood cycles to rebuild Louisiana's coastal wetlands. Dutch engineers are using a massive, man-made peninsula of sand to encourage beaches to build up naturally along the coast. And China's Xiaolangdi Dam on the Yellow River uses specially built portals to flush sediment from behind the dam up to two weeks each year.

Arid Ecosystems

Grazing as a potential fuel management tool in shrub steppe communities

Davies Kirk W., Gearhart Amanda, Boyd Chad S., Bates Jon D. 2017. Fall and spring grazing influence fire ignitability and initial spread in shrub steppe communities. International Journal of Wildland Fire 26, 485-490. https://doi.org/10.1071/WF17065#sthash.0myeqeYl.dpuf

Authors of this paper investigated the effects of fall grazing, spring grazing and not grazing on fuel characteristics, fire ignition and initial spread during the wildfire season at five shrub steppe sites in Oregon. Both grazing treatments decreased fine fuel biomass, cover and height, and increased fuel moisture, thereby decreasing ignition and initial spread compared with the ungrazed treatment. However, effects differed between fall and spring grazing. The probability of initial spread was 6-fold greater in the fall-grazed compared with the spring-grazed treatment in August. This suggests that spring grazing may have a greater effect on fires than fall grazing, likely because fall grazing does not influence the current year’s plant growth. Grazing either the fall or spring before the wildfire season reduces the probability of fire propagation and, thus, grazing is potentially an effective fuel management tool.

Biodiversity/Species and Ecosystem Response

Bird and other animal responses to extreme climatic events: challenges and directions

Martijn van de Pol, Stéphanie Jenouvrier, Johannes H. C. Cornelissen, Marcel E. Visser. 2017. Behavioural, ecological and evolutionary responses to extreme climatic events: challenges and directions. Philosophical Transactions of the Royal Society B: Biological Sciences; 372 (1723): 20160134 DOI: 10.1098/rstb.2016.0134

Evidence suggests that the impact of extreme events on animal behavior, ecology and evolution could well be greater than that of the ‘normal’ periods in between. Climate change is expected to increase the frequency of extreme events, but predicting the consequence of this environmental change on species of plants and animals can be problematic. In a special June issue of Philosophical Transactions of the Royal Society B researchers launch a new approach to investigating the impact of extremes, outliers, cataclysms on species. One study in the issue examined the evolutionary response to climate change of oystercatchers that build their nests close to the coast despite rising sea levels. Another studied fairy-wrens — Australian passerine birds — that are increasingly exposed to heatwaves and high temperatures, with sometimes fatal consequences. Over 20 years the number of flooding events that destroy oystercatcher nests has more than doubled, yet oystercatchers do not nest on higher ground in response. Data on fairy wrens, collected over nearly 40 years, shows that two very similar species respond to increasing heat waves in completely different ways. Authors conclude with a suggested 'roadmap' for the further development of this new area of research, aimed at making it easier to compare and synthesize information across fields.

Human impacts on biodiversity and resulting loss of ecosystem services

Forest Isbell, Andrew Gonzalez, Michel Loreau, Jane Cowles, Sandra Díaz, Andy Hector, Georgina M. Mace, David A. Wardle, Mary I. O’Connor, J. Emmett Duffy, Lindsay A. Turnbull, Patrick L. Thompson, Anne Larigauderie. Linking the influence and dependence of people on biodiversity across scales. Nature, 2017; 546 (7656): 65 DOI: 10.1038/nature22899

Coauthors from eight countries on four continents provide an overview of what we know and still need to learn about the impacts of habitat destruction, overhunting, the introduction of nonnative species, and other human activities on biodiversity. In addition, they summarize previous research on how biodiversity loss affects nature and the benefits nature provides –– for example, a recent study showing that reduced diversity in tree species in forests is linked to reduced wood production. Synthesizing findings of other studies, they estimate that the value humans derive from biodiversity is 10 times what every country in the world put together spends on conservation today — suggesting that additional investments in protecting species would not only reduce biodiversity loss but provide economic benefit, too. The researchers note that all is not lost, and offer specific strategies for turning the tide on biodiversity loss before it's too late.

Coastal/Marine Ecosystems, Ocean Acidification, Sea Level Rise

Marine reserves help mitigate against climate change

Callum M. Roberts, Bethan C. O’Leary, Douglas J. McCauley, Philippe Maurice Cury, Carlos M. Duarte, Jane Lubchenco, Daniel Pauly, Andrea Sáenz-Arroyo, Ussif Rashid Sumaila, Rod W. Wilson, Boris Worm, and Juan Carlos Castilla. In press. Marine reserves can mitigate and promote adaptation to climate change. PNAS, June 2017 DOI: 10.1073/pnas.1701262114

A new review, published in the Proceedings of the National Academy of Sciences, evaluated existing peer reviewed studies on the impact of marine reserves around the world. Authors conclude that Marine Reserves and Marine Protected Areas (MPAs) protect coasts from sea-level rise, storms and other extreme weather events; help offset climate-change induced declines in ocean and fisheries productivity; provide refuges for species as they adjust their ranges to changing conditions; and can help combat acidification. Reserves also can promote uptake and long-term storage of carbon from greenhouse gas emissions, especially in coastal wetlands, which helps reduce the rate of climate change. Currently, only 3.5 per cent of the ocean has been set aside for protection with just 1.6 per cent fully protected from exploitation. International groups are working to raise the total to 10 per cent by 2020, while delegates to the International Union for the Conservation of Nature's 2016 World Conservation Congress agreed that at least 30 per cent should be protected by 2030.


New tool to estimate fire risk

The new Fire Risk Estimation or FIRE tool, automatically processes satellite and weather station data—including temperature, precipitation, relative humidity, and wind observations—into a single measurement of fire potential. The tool, developed by the NOAA National Centers for Environmental Information, NASA DEVELOP National Program, and partners, aims to give fire managers an overall view of risk in different locations, helping them quickly decide when and where to allocate their resources.


Rethinking forests and wood products in light of climate change

Data from the Pacific Institute for Climate Solutions (PICS) presented recently at Simon Fraser University’s Vancouver Campus suggests that employing multiple carbon-mitigation techniques in British Columbia’s forest industry could deliver an annual CO2 reduction of 18 million tonnes. Better forest management, more thorough extraction of wood from harvested areas and a focus on long-lasting wood products could contribute 35 per cent of British Columbia’s 2050 carbon-emissions reduction target, according to the PICS Forest Carbon Management Project. Provincial legislation dictates that B.C. reach a target of 80 per cent of 2007 carbon-emission levels by 2050, a reduction of about 52 million tonnes of carbon-dioxide equivalents annually. The measures presented by PICS to help get there include actions like harvesting two percent less wood per year, and using more of the wood left behind after to harvest to use for bioenergy or manufacturing rather than burning it in slash piles. B.C. is already taking steps to create healthier forests. The B.C. government announced earlier this year that it’ll spend $150 million to rehabilitate forests by planting tens of millions of trees. Rather than planting different kinds of trees, PICS suggests that forestry scientists can obtain seeds from species similar to the trees in the natural forest, but from locations that are hotter and drier. Subtle genetic advantages from those heat-adapted trees will help adapt the more northerly forests to Earth’s rising temperatures.

Experiment tests how much CO2 trees can absorb

British researchers are pumping carbon dioxide into sections of fenced-off woodland to learn how forests will cope with the world's rising levels of CO2. Trees absorb CO2 as a major nutrient, but it's still not clear how much more they can take or whether they can do that indefinitely, according to Michael Tausz, co-director of the University of Birmingham's Institute of Forest Research. Trees in the decade-long experiment will be exposed to 550 parts per million of CO2, an increase of 40 percent over current levels, and in line with what experts expect to become normal by 2050.

Land Use

Using cover crops to mitigate and adapt to climate change

Kaye, J.P. & M. Quemada. 2017. Using cover crops to mitigate and adapt to climate change. A review. Agron. Sustain. Dev.; 37:4 DOI 10.1007/s13593-016-0410-x

Cover crops have long been touted for their ability to reduce erosion, fix atmospheric nitrogen, reduce nitrogen leaching, and improve soil health. Now there is a resurgence in cover crop adoption that is synchronous with a heightened awareness of climate change. In this article the authors review the potential for cover crops to mitigate climate change by tallying all of the positive and negative impacts of cover crops on the net global warming potential of agricultural fields.  Two contrasting regions in Spain and Pennsylvania are used as case studies to evaluate how cover crops affect adaptive management for precipitation and temperature change. Three key outcomes from this synthesis are (1) Cover crop effects on greenhouse gas fluxes typically mitigate warming by ~100 to 150 g CO2/year, which is higher than mitigation from transitioning to no-till. (2) The surface albedo change due to cover cropping, calculated for the first time here, may mitigate 12 to 46 g CO2/year over a 100-year time horizon. And (3) Cover crop management can also enable climate change adaptation at these case study sites, especially through reduced vulnerability to erosion from extreme rain events, increased soil water management options during droughts or periods of soil saturation, and retention of nitrogen mineralized due to warming. Overall, the authors found few tradeoffs between cover cropping and climate change mitigation and adaptation, suggesting that ecosystem services that are traditionally expected from cover cropping can be promoted synergistically with services related to climate change.

Special Reports / Announcements

Climate change may take a toll on air travel

Researchers are beginning to explore how climate change affects aviation and planes’ ability to fly. A recent article in the New York Times examined the science on how increasing temperatures will decrease air density and complicate take off and landing for aircraft. Scientists predict with confidence that there will be more weight-restricted days, and larger weight restrictions in the future--a continuation of a trend seen since the 1980s. The resulting no-fly windows are likely to have ripple effects across airline operations while further squeezing airlines’ already tight profit margins. Other impacts to aviation relate to changes in the gulf stream. According to researchers, jet stream winds at high altitudes are getting more intense, making flights bumpier and affecting travel times.

Deadly heatwaves expected to continue to rise

Camilo Mora, Bénédicte Dousset, Iain R. Caldwell, Farrah E. Powell, Rollan C. Geronimo, Coral R. Bielecki, Chelsie W. W. Counsell, Bonnie S. Dietrich, Emily T. Johnston, Leo V. Louis, Matthew P. Lucas, Marie M. McKenzie, Alessandra G. Shea, Han Tseng, Thomas W. Giambelluca, Lisa R. Leon, Ed Hawkins, Clay Trauernicht. In Press. Global risk of deadly heat. Nature Climate Change; DOI: 10.1038/NCLIMATE3322

A new study published in Nature Climate Change suggests that seventy-four percent of the world's population will be exposed to deadly heatwaves by 2100 if carbon gas emissions continue to rise at current rates. Even if emissions are aggressively reduced, the percent of the world's human population affected is expected to reach 48 percent. The human body can only function within a narrow range of core body temperatures. Heatwaves pose a risk to human life because hot weather, aggravated with high humidity, can raise body temperature to lethal levels. Authors of this study conducted an extensive review of heat episodes. From over 30,000 relevant publications, the researchers identified 911 papers with data on 1,949 case studies of cities or regions, where human deaths were associated with high temperatures. By analyzing the climatic conditions of 783 lethal heat episodes in 164 cities across 36 countries, with most cases recorded in developed countries at mid-latitudes, researchers identified a threshold beyond which temperatures and humidities become deadly. The area of the planet where such a threshold is crossed for 20 or more days per year has been increasing and is projected to grow even with dramatic cuts in greenhouse gas emissions. Currently, about 30% of the world's human population is exposed to such deadly conditions each year.

Taking Action

2016 Annual Report from the Great Northern Landscape Conservation Cooperative

Recently The Great Northern Landscape Conservation Cooperative (GNLCC) released its 2016 Annual Report. The GNLCC is a network of U.S. federal, Canadian provincial and federal, Tribal Nations, state, academic, and conservation organizations working to achieve a collective landscape vision. The partnership implements a regional approach to address conservation issues across boundaries and jurisdictions by sharing data, science, and capacity. Their annual report provides highlights under four themes: A Growing Partnership; Supporting Partners for a Shared Vision; Connecting for Conservation; and Investing in Science.

Adaptation Workbook: A Climate Change Tool for Land Management and Conservation

The U.S. Forest Service’s Northern Institute of Applied Climate Science created the Adaptation Workbook to provide a structured process to help natural resource managers to consider the potential effects of climate change while designing land management and conservation actions that will help prepare society for changing environmental conditions. The Workbook is meant to be used by a diverse range of people working in forestry, natural resources, and agriculture. It includes five steps: defining goals and objectives; assessing climate impacts and vulnerabilities; evaluating objectives while considering climate impacts; identifying adaptation approaches and tactics for implementation; and monitoring the effectiveness of implemented actions.

Tribal and Indigenous Peoples Matters

Water is life for the Swinomish Indian Tribal Community

For the Swinomish people of northwestern Washington, water is life. But this symbiotic relationship between man and nature is increasingly threatened by sea-level rise and changes in Northwestern storm and rainfall patterns. The U.S. Geological Survey is working to forecast sea-level changes and coastal impacts in real time to help coastal communities prepare. The Northwest Climate Science Center provided support for the development of this work through a project focused on understanding the interactions between human health, environment, and climate in Salish Sea communities.

Columbia River sees near-record shad run; steelhead numbers are down

The Washington Department of Fish and Wildlife recently reported that 497,738 shad were counted moving over the Bonneville Dam, located on the Columbia River at the border between Oregon and Washington. This was the third-highest fish count on record since at least 1946. In contrast, steelhead numbers are at their lowest point in four decades in northwestern Oregon rivers like the Santiam and the Willamette. Poor ocean conditions and drought have significantly cut into steelhead food supply.