Climate Science PDFs
Climate Science PDFs Collection
- Changes in Climatic Water Balance Drive Downhill Shifts in Plant Species’ Optimum Elevations
- Uphill shifts of species’ distributions in response to historical warming are well documented, which leads to widespread expectations of continued uphill shifts under future warming. Conversely, downhill shifts are often considered anomalous and unrelated to climate change. By comparing the altitudinal distributions of 64 plant species between the 1930s and the present day within California, we show that climate changes have resulted in a significant downward shift in species’ optimum elevations. This downhill shift is counter to what would be expected given 20th-century warming but is readily explained by species’ niche tracking of regional changes in climatic water balance rather than temperature. Similar downhill shifts can be expected to occur where future climate change scenarios project increases in water availability that outpace evaporative demand.
- The Greening of Synfuels
- An old, dirty technology to make transportation fuels from coal could fight global warming, say proponents. The trick is using more biomass and burying the carbon dioxide that’s generated 18 APRIL 2008 VOL 320 SCIENCE
- All Downhill From Here?
- Biologists say climate change may already be affecting high-mountain ecosystems around the world, where plants and animals adapted to cold, barren conditions now face higher temperatures and a surge of predators and competitors
- Human Evolution Out of Africa: The Role of Refugia and Climate Change
- Although an African origin of the modern human species is generally accepted, the evolutionary processes involved in the speciation, geographical spread, and eventual extinction of archaic humans outside of Africa are much debated. An additional complexity has been the recent evidence of limited interbreeding between modern humans and the Neandertals and Denisovans. Modern human migrations and interactions began during the buildup to the Last Glacial Maximum, starting about 100,000 years ago. By examining the history of other organisms through glacial cycles, valuable models for evolutionary biogeography can be formulated. According to one such model, the adoption of a new refugium by a subgroup of a species may lead to important evolutionary changes.
- Rescuing Wolves from Politics: Wildlife as a Public Trust Resource
- Long-term conservation of gray wolves is possible if states recognize a legal obligation to conserve species as a public trust resource
- Rapid Range Shifts of Species Associated with High Levels of Climate Warming
- The distributions of many terrestrial organisms are currently shifting in latitude or elevation in responseto changing climate. Using a meta-analysis, we estimated that the distributions of species haverecently shifted to higher elevations at a median rate of 11.0 meters per decade, and to higher latitudes at a median rate of 16.9 kilometers per decade. These rates are approximately two and three times faster than previously reported. The distances moved by species are greatest in studies showing thehighest levels of warming, with average latitudinal shifts being generally sufficient to track temperature changes. However, individual species vary greatly in their rates of change, suggesting that the range shift of each species depends on multiple internal species traits and external drivers of change. Rapid average shifts derive from a wide diversity of responses by individual species.
- Seeds of Change for Restoration Ecology
- FORESTS PROVIDE A WIDE VARIETY OF ECOSYSTEM SERVICES, INCLUDING PROVISIONS SUCH AS food and fuel and services that affect climate and water quality (1). In light of the increasing global population pressure, we must not only conserve, but also restore forests to meet the increasing demands for ecosystem services and goods that they provide (2). Ecological restoration has recently adopted insights from the biodiversity-ecosystem function (BEF) perspective (3). This emphasis on functional rather than taxonomic diversity (3, 4), combined with increasing acceptance of perennial, global-scale effects on the environment (5, 6) and the associated species gains and losses (“Terrestrial ecosystem responses to species gains and losses,” D. A. Wardle et al., Review, 10 June, p. 1273), may be the beginning of a paradigm shift in forest conservation and restoration ecology. As a result, we may see increased tolerance toward and the use of nonnative tree species in forests worldwide 8 JULY 2011 VOL 333 SCIENCE
- From Ocean to Stratosphere
- Rising tropical sea surface temperatures alter atmospheric dynamics at heights of 16 kilometers or more. SCIENCE VOL 322 3 OCTOBER 2008
- Linked in: Connectiong Riparian areas to support Forest Biodiversity
- Many forest-dwelling species rely on both terrestrial and aquatic habitat for their survival. These species, including rare and little-understood amphibians and arthropods, live in and around headwater streams and disperse overland to neighboring headwater streams. Forest management policies that rely on riparian buffer strips and structurebased management—practices meant to preserve habitat—address only some of these habitat needs. They generally do not consider the overland connectivity necessary for these species to successfully move across a landscape to maintain genetically diverse populations. Management in headwater areas also can affect downstream salmon habitat. Landslides and debris flows initiated in these areas can severely degrade habitat by dumping too much sediment and not enough large wood into the stream. Carefully managing sensitive headwater areas can aid not only amphibians and arthropods, but also threatened salmon populations and other forest organisms. Pacific Northwest Research Station scientists are exploring scenarios for protecting headwaters by extending riparian buffers and connecting them over ridgelines to neighboring drainages. A range of management practices designed to achieve multiple objectives may be appropriate in these protected areas to facilitate cost-effective, ecologically integrated management plans. Headwater links could piggyback on lands that are already protected and could consider such factors as sensitivity to debris flows and landslides, land ownerships and objectives, and climate change.
- Mount St. Helens: Still Erupting Lessons 31 Years Later
- The massive volcanic eruption of Mount St. Helens 31 years ago provided the perfect backdrop for studying the earliest stages of forest development. Immediately after the eruption, some areas of the blast area were devoid of life. On other parts of the volcanic landscape, many species survived, although their numbers were greatly reduced. Reassembly began at many different starting points along the spectrum of disturbance. Within the national volcanic monument, natural regeneration generally has been allowed to proceed at its own pace. Charlie Crisafulli and Fred Swanson, scientists with the Pacific Northwest Research Station, along with numerous collaborators, have found that the sunlit environment, dominated by shrubs, herbs, and grasses that characterize early-seral ecosystems, supports complex food webs involving numerous herbivores. These biologically rich areas provide habitat for plant and animal species that are either found only in these early-seral ecosystems or reach their highest densities there. Although much of the focus of forest ecosystem management over the past 20 years in the Pacific Northwest has been on protecting old forests and hastening development of conditions associated with older forests, the research on Mount St. Helens points to the ecological value of allowing a portion of a managed landscape to develop characteristics of a complex early-seral ecosystem
- Thinking Big: Linking Rivers to Landscapes
- Exploring relationships between landscape characteristics and rivers is an emerging field of study, bolstered by the proliferation of satellite data, advances in statistical analysis, and increased emphasis on largescale monitoring. Climate patterns and landscape features such as road networks, underlying geology, and human developments determine the characteristics of the rivers flowing through them. A multiagency team of scientists developed novel modeling methods to link these landscape features to instream habitat and to abundance of coho salmon in Oregon coastal streams. This is the first comprehensive analysis of landscape-scale data collected as part of the state’s Oregon Plan for Salmon and Watersheds. The research team found that watershed characteristics and human activities far from the river’s edge influence the distribution and habitats of coho salmon. Although large-scale landscape characteristics can predict stream reaches that might support greater numbers of coho salmon, smaller scale features and random chance also play a role in whether coho spawn in a particular stream and in a particular year. The team developed new models that successfully predicted the distribution of instream habitat features. Volume of instream wood and pool frequency were the features most influenced by human activities. Studying these relationships can help guide large-scale monitoring and management of aquatic resources.
- Seasonal Neighbors: Residential Development Encroaches on Mule Deer Winter Range in Central Oregon
- Mule deer populations in central Oregon are in decline, largely because of habitat loss. Several factors are likely contributors. Encroaching juniper and invasive cheatgrass are replacing deer forage with high nutritional value, such as bitterbrush and sagebrush. Fire suppression and reduced timber harvests mean fewer acres of early successional forest, which also offer forage opportunities. Human development, including homes and roads, is another factor. It is this one that scientists with the Pacific Northwest Research Station and their collaborators investigated in a recent study. As part of an interagency assessment of the ecological effects of resort development near Bend, Oregon, researchers examined recent and potential development rates and patterns and evaluated their impact on mule deer winter range. They found that residential development in central Oregon is upsetting traditional migratory patterns, reducing available habitat, and possibly increasing stress for mule deer. Many herds of mule deer spend the summer in the Cascade Range and move to lower elevations during the winter. An increasing number of buildings, vehicle traffic, fencing, and other obstacles that accompany human land use are making it difficult for mule deer to access and use their winter habitat. The study provides valuable information for civic leaders, land use planners, and land managers to use in weighing the ecological impact of various land use decisions in central Oregon.
- Ecosystem Service Markets 101: Supply and Demand for Nature
- Establishing markets for ecosystem services—the benefits that nature provides, such as clean air, water, and wildlife habitat—has gained traction in some circles as a way to finance the conservation of these public goods. Market influences on supply and demand work in tandem to encourageecosystem protection. Jeff Kline and Trista Patterson, scientists with the Pacific Northwest (PNW) Research Station, have identified several criteria needed for ecosystem service markets to achieve their potential. These include regulatory limits on environmental damage, ecosystem services that are amenable to trading, and manageable transaction costs related to administering market programs and the necessary measuring and monitoring of marketed resources. If these criteria are not met, other conservation methods such as conservation easements, landowner incentive programs for environmental enhancement or protection, or taxes on environmental damage may be more effective. Discussions about ecosystem services often focus on increasing supply— storing more carbon or delivering more water, for example. However, net pressures on ecosystems can also be reduced by addressing consumption. Many energy efficiencies can be achieved by promoting awareness, informed choices, and behavior change. The PNW Research Station is examining both supply and demand approaches to ecosystem protection by encouraging the development of ecosystem services markets and identifying ways to reduce its own environmental footprint.
- Logging Debris Matters: Better Soil, Fewer Invasive Plants
- The logging debris that remains after timber harvest traditionally has been seen as a nuisance. It can make subsequent tree planting more difficult and become fuel for wildfire. It is commonly piled, burned, or taken off site. Logging debris, however, contains significant amounts of carbon and nitrogen—elements critical to soil productivity. Its physical presence in the regenerating forest creates microclimates that influence a broad range of soil and plant processes. Researchers Tim Harrington of the Pacific Northwest Research Station; Robert Slesak, a soil scientist with the Minnesota Forest Resources Council; and Stephen Schoenholtz, a professor of forest hydrology and soils at Virginia Tech, conducted a five-year study at two sites in Washington and Oregon to see how retaining logging debris affected the soil and other growing conditions at each locale. They found that keeping logging debris in place improved soil fertility, especially in areas with coarse-textured, nutrient-poor soils. Soil nitrogen and other nutrients important to tree growth increased, and soil water availability increased due to the debris’ mulching effect. The debris cooled the soil, which slowed the breakdown and release of soil carbon into the atmosphere. It also helped prevent invasive species such as Scotch broom and trailing blackberry from dominating the sites. Forest managers are using this information to help maximize the land’s productivity while reducing their costs associated with debris disposal.
- Adaptation: Planning for Climate Change and Its Effects on Federal Lands
- National forest managers are charged with tackling the effects of climate change on the natural resources under their care. The Forest Service National Roadmap for Responding to Climate Change and the Climate Change Performance Scorecard require managers to make significant progress in addressing climate change by 2015. To help land managers meet this challenge, Forest Service scientists conducted three case studies on national forests and adjacent national parks and documented a wide range of scientific issues and solutions. They summarized the scientific foundation for climate change adaptation and made the information accessible to land managers by creating a climate change adaptation guidebookand web portal. Case study teams discovered that collaboration among scientists and land managers is crucial to adaptation planning, as are management plans targeted to the particular ecosystem conditions and management priorities of each region. Many current management practices are consistent with climate change adaptation goals. Because timely implementation is critical, strategies are in development at the national level to speed the implementation of science-based climate change adaptation processes in national forests throughout the country.
- Tangled Trends for Temperate Rain Forests as Temperatures Tick Up
- Climate change is altering growing conditions in the temperate rain forest region that extends from northern California to the Gulf of Alaska. Longer, warmer growing seasons are generally increasing the overall potential for forest growth in the region. However, species differ in their ability to adapt to changing conditions. For example, researchers with Pacific Northwest Research Station examined forest trends for southeastern and southcentral Alaska and found that, in 13 years, western redcedar showed a 4.2-percent increase in live-tree biomass, while shore pine showed a 4.6-percent decrease. In general, the researchers found that the amount of live-tree biomass in extensive areas of unmanaged, higher elevation forest in southern Alaska increased by as much as 8 percent over the 13-year period, contributing to significant carbon storage. Hemlock dwarf mistletoe is another species expected to fare well under warmer conditions in Alaska. Model projections indicate that habitat for this parasitic species could increase 374 to 757 percent over the next 100 years. This could temper the prospects for western hemlock—a tree species otherwise expected to do well under future climate conditions projected for southern Alaska. In coastal forests of Washington and Oregon, water availability may be a limiting factor in future productivity, with gains at higher elevations but declines at lower elevations
- Forests in Decline: Yellow-Cedar Research Yields Prototype for Climate Change Adaptation Planning
- Yellow-cedar has been dying across 600 miles of North Pacific coastal rain forest—from Alaska to British Columbia—since about 1880. Thirty years ago, a small group of pathologists began investigating possible biotic causes of the decline. When no biotic cause could be found, the scope broadened into a research program that eventually encompassed the fields of ecology, soils, hydrology, ecophysiology, dendrochronology, climatology, and landscape analysis. Combined studies ultimately revealed that the loss of this culturally, economically, and ecologically valuable tree is caused by a warming climate, reduced snowpack, poor soil drainage, and the species’ shallow roots. These factors lead to fine-root freezing, which eventually kills the trees. The considerable knowledge gained while researchers sought the cause of widespread yellow-cedar mortality forms the basis for a conservation and adaptive management strategy. A new approach to mapping that overlays topography, cedar populations, soil drainage, and snow enables land managers to pinpoint locations where yellowcedar habitat is expected to be suitable or threatened in the future, thereby bringing climate change predictions into management scenarios. The research program serves as a prototype for evaluating the effects of climate change in other landscapes. It shows the value of long-term, multidisciplinary research that encourages scientists and land managers to work together toward developing adaptive management strategies
- Managing Wildfire Risk in Fire-Prone Landscapes: How Are Private Landowners Contributing?
- The fire-prone landscapes of the West include both public and private lands. Wildfire burns indiscriminately across property boundaries, which means that the way potential fuels are managed on one piece of property can affect wildfire risk on neighboring lands. Paige Fischer and Susan Charnley, social scientists with the Pacific Northwest Research Station, surveyed private landowners in eastern Oregon to learn how they perceive fire risk on their land and what they do, if anything, to reduce that risk. The scientists found that owners who live on a forested parcel are much more likely to reduce fuels than are those who live elsewhere. Private forest owners are aware of fire risk and knowledgeable about methods for reducing fuels, but are constrained by the costs and technical challenges of protecting large acreages of forested land. Despite the collective benefits of working cooperatively, most of these owners reduce hazardous fuels on their land independently, primarily because of their distrust about working with others, and because of social norms associated with private property ownership. These results provide guidance for developing more effective fuel reduction programs that accommodate the needs and preferences of private forest landowners. The findings also indicate the potential benefits of bringing landowners into collective units to work cooperatively, raising awareness about landscape-scale fire risk, and promoting strategies for an “alllands” approach to reducing wildfire risk
- DO CARBON OFFSETS WORK? THE ROLE OF FOREST MANAGEMENT IN GREENHOUSE GAS MITIGATION
- As forest carbon offset projects become more popular, professional foresters are providing their expertise to support them. But when several members of the Society of American Foresters questioned the science and assumptions used to design the projects, the organization decided to convene a task force to examine whether these projects can provide the intended climate benefits.The authors emphasize the carbon-storage benefits of using wood products in place of nonrenewable, energy-intensive materials and using woodbased energy instead of fossil fuels.
- Looking at the Big Picture: The Importance of Landbase Interactions Among Forests, Agriculture, and Climate Mitigation Policies
- Land use change is a key part of global change. Deforestation, urban sprawl, agriculture, and other human influences have substantially altered natural ecosystems and fragmented the global landscape. Slowing down deforestation and afforesting environmentally sensitive agricultural land are important steps for mitigating climate change. Because no policy operates in a vacuum, however, it’s important to consider how separate climate mitigation policies might interact with each other. Ralph Alig, a scientist with the Pacific Northwest Research Station, and his colleagues evaluated the potential impacts of policy instruments available for climate change mitigation. By using the Forest and Agriculture Sector Optimization Greenhouse Gases model, the researchers analyzed how land might shift between forestry and agriculture and to more developed uses depending on different land use policies and several carbon pricing scenarios. They also examined the likely effects on timber, crop prices, and bioenergy production if landowners were paid to sequester carbon on their land. The researchers found that projected competition for raw materials is greatest in the short term, over the first 25 years of the 50-year projections. Climate change is occurring within a matrix of other changes. By 2050, an additional 3 billion people are expected to be living on Earth, needing food, clean water, and places to live. Incentives for landowners to maintain undeveloped land will be vital to sequestering carbon and providing other services of intact ecosystems
