Landscape Partnership Resources Library
Modeling sediment accumulation in North American playa wetlands in response to climate change, 1940–2100
Playa wetlands on the west-central Great Plains of North America are vulnerable to sediment infilling from upland agriculture, putting at risk several important ecosystem services as well as essential habitats and food resources of diverse wetland-dependent biota. Climate predictions for this semi-arid area indicate reduced precipitation which may alter rates of erosion, runoff, and sedimentation of playas. We forecasted erosion rates, sediment depths, and resultant playa wetland depths across the west-central Great Plains and exam- ined the relative roles of land use context and projected changes in precipitation in the sedimentation process. We estimated erosion with the Revised Universal Soil Loss Equation (RUSLE) using historic values and downscaled precipitation predictions from three general circulation models and three emissions scenarios. We calibrated RUSLE results using field sediment measurements. RUSLE is appealing for regional scale modeling because it uses climate forecasts with monthly resolution and other widely available values including soil texture, slope and land use. Sediment accumulation rates will continue near historic levels through 2070 and will be sufficient to cause most playas (if not already filled) to fill with sediment within the next 100 years in the absence of mitigation. Land use surrounding the playa, whether grassland or tilled cropland, is more influential in sediment accumulation than climate-driven precipitation change.
Model Projections of an Imminent Transition to a More Arid Climate in Southwestern North America
How anthropogenic climate change will impact hydroclimate in the arid regions of Southwestern North America has implications for the allocation of water resources and the course of regional development. Here we show that there is a broad consensus amongst climate models that this region will dry significantly in the 21st century and that the transition to a more arid climate should already be underway. If these models are correct, the levels of aridity of the recent multiyear drought, or the Dust Bowl and 1950s droughts, will, within the coming years to decades, become the new climatology of the American Southwest.
Late Pleistocene California droughts during deglaciation and Arctic warming
Recent studies document the synchronous nature of shifts in North Atlantic regional climate, the intensity of the East Asian monsoon, and productivity and precipitation in the Cariaco Basin during the last glacial and deglacial period. Yet questions remain as to what climate mechanisms influenced continental regions far removed from the North Atlantic and beyond the direct influence of the inter-tropical convergence zone. Here, we present U-series calibrated stable isotopic and trace element time series for a speleothem from Moaning Cave on the western slope of the central Sierra Nevada, California that documents changes in precipitation that are approximately coeval with Greenland temperature changes for the period 16.5 to 8.8 ka. From 16.5 to 10.6 ka, the Moaning Cave stalagmite proxies record drier and possibly warmer conditions, signified by elevated à18O, à13C, [Mg], [Sr], and [Ba] and more radiogenic 87Sr/86Sr, during Northern Hemisphere warm periods (Bølling, early and late Allerød) and wetter and possibly colder conditions during Northern Hemisphere cool periods (Older Dryas, Inter-Allerød Cold Period, and Younger Dryas). Moaning Cave stable isotope records indicate that wet conditions persisted in this area well beyond 11.5 ka, suggesting the effects of the Younger Dryas event may have been longer lived in the western Sierra Nevada than in Greenland. However, a shifting drip center and corresponding change in seepage water routing may have influenced the trace element records between 10.6 and 9.6 ka. Linkages between northern high-latitude climate and precipitation in the Sierra Nevada suggested here could indicate that, under conditions of continued global warming, this drought-prone region may experience a reduction in Pacific-sourced moisture.
TUNDRA’S BURNING
More than 20,000 lightning strikes were recorded on the North Slope of Alaska in 2007. Some struck the vast stretches of lakes; some hit the treeless tundra. And one of them torched into life the largest and longest-lasting tundra fire recorded in the state’s history. The blaze, which started near the Anaktuvuk River on 16 July, burned 7,000 hectares a day at its peak, and eventually consumed 100,000 hectares, an area larger than that of New York City. It finally stopped burning in early October, smothered by thick snow. Arctic lightning fire
The millennial atmospheric lifetime of anthropogenic CO2
The notion is pervasive in the climate science community and in the public at large that the climate impacts of fossil fuel CO2 release will only persist for a few centuries. This conclusion has no basis in theory or models of the atmosphere/ocean carbon cycle, which we review here. The largest fraction of the CO2 recovery will take place on time scales of centuries, as CO2 invades the ocean, but a significant fraction of the fossil fuel CO2, ranging in published models in the literature from 20–60%, remains airborne for a thousand years or longer. Ultimate recovery takes place on time scales of hundreds of thousands of years, a geologic longevity typically associated in public perceptions with nuclear waste. The glacial/interglacial climate cycles demonstrate that ice sheets and sea level respond dramatically to millennial-timescale changes in climate forcing. There are also potential positive feedbacks in the carbon cycle, including methane hydrates in the ocean, and peat frozen in permafrost, that are most sensitive to the long tail of the fossil fuel CO2 in the atmosphere.
Turning back from the brink: Detecting an impending regime shift in time to avert it
Ecological regime shifts are large, abrupt, long-lasting changes in ecosystems that often have considerable impacts on human econ- omies and societies. Avoiding unintentional regime shifts is widely regarded as desirable, but prediction of ecological regime shifts is notoriously difficult. Recent research indicates that changes in ecological time series (e.g., increased variability and autocorrela- tion) could potentially serve as early warning indicators of im- pending shifts. A critical question, however, is whether such indicators provide sufficient warning to adapt management to avert regime shifts. We examine this question using a fisheries model, with regime shifts driven by angling (amenable to rapid reduction) or shoreline development (only gradual restoration is possible). The model represents key features of a broad class of ecological regime shifts. We find that if drivers can only be manipulated gradually management action is needed substantially before a regime shift to avert it; if drivers can be rapidly altered aversive action may be delayed until a shift is underway. Large increases in the indicators only occur once a regime shift is initiated, often too late for management to avert a shift. To improve usefulness in averting regime shifts, we suggest that research focus on defining critical indicator levels rather than detecting change in the indicators. Ideally, critical indicator levels should be related to switches in ecosystem attractors; we present a new spectral density ratio indicator to this end. Averting ecological regime shifts is also dependent on developing policy pro- cesses that enable society to respond more rapidly to information about impending regime shifts. early warning indicator ecological threshold spectral density ratio
HOW LONG HAVE WE BEEN IN THE ANTHROPOCENE ERA?
Editorial- 1st paragraph: With great interest we have read Ruddiman’s intriguing article which is in favor of placing the start of the Anthropocene at 5–8 millennia BP instead of the late quarter of the 18th century. He shows how land exploitation for agriculture and animal husbandry may have led to enhanced emissions of CO2 and CH4 to the atmosphere, thereby modifying the expected changes in the concentrations of these gases beyond those expected from variations in the Milankovich orbital parameters. Much of his argument depends on the correctness of their projected CH4 concen- tration curve from 7,000 years BP to pre-industrial times showing a decline to about 425 ppb, according to Milankovich, instead of the measured 700 ppb. It appears, however, strange that in Ruddiman’s analysis the proposed increase of CH4 due to anthropogenic activities stopped at about 1000 years BP, because ice core data showed almost constant mixing ratios of CH4 between 1000 years BP and about 200 years ago before the rapid rise of CH4 in the industrial period (IPCC, 2001). A major feature of Ruddiman’s argument is that natural atmospheric CH4 concentrations depend strongly on geological varying summer time insolations in the tropical northern hemisphere, controlling tropical wetlands and methane release from decaying organic matter under anaerobic conditions.
The Rescaling of Global Environmental Politics
Key Words governance, international, linked issues, networks, scale Abstract In the past half-century, the practice and study of global environmental politics and governance have been dramatically rescaled. They have be- come increasingly complex and interconnected with respect to the level (between local and global) at which they take place, the range of actors engaged in them, and the linkages between them and nominally nonen- vironmental issues. Global environmental politics and governance have been rescaled vertically down toward provincial and municipal gov- ernments and up toward supranational regimes. They have also been rescaled horizontally across regional and sectoral organizations and net- works and across new issues, such as development, security, and trade among others. This rescaling reflects shifts in the magnitude, complexity, and interconnectedness of the global environmental problems humans face as well as epistemological shifts in how humans understand and respond to these problems, and rescaling has implications for both the practice and study of global environmental politics.
Insect Responses to Major Landscape-Level Disturbance
Keywords tolerance, dispersal, succession, local extinction, outbreak, population dynamics Abstract Disturbances are abrupt events that dramatically alter habitat conditions and resource distribution for populations and communities. Terrestrial land- scapes are subject to various disturbance events that create a matrix of patches with different histories of disturbance and recovery. Species tolerances to ex- treme conditions during disturbance or to altered habitat or resource condi- tions following disturbances determine responses to disturbance. Intolerant populations may become locally extinct, whereas other species respond posi- tively to the creation of new habitat or resource conditions. Local extinction represents a challenge for conservation biologists. On the other hand, out- breaks of herbivorous species often are triggered by abundant or stressed hosts and relaxation of predation following disturbances. These insect re- sponses can cause further changes in ecosystem conditions and predispose communities to future disturbances. Improved understanding of insect re- sponses to disturbance will improve prediction of population and community dynamics, as well as ecosystem and global changes.
Global Cooling by Grassland Soils of the Geological Past and Near Future
Keywords grass, mammal, coevolution, paleosol, paleoclimate, carbon sequestration, albedo Abstract Major innovations in the evolution of vegetation such as the Devonian ori- gin of forests created new weathering regimes and soils (Alfisols, Histosols) that increased carbon consumption and sequestration and ushered in the Permian-Carboniferous Ice Age. Similarly, global expansion of grasslands and their newly evolved, carbon-rich soils (Mollisols) over the past 40 mil- lion years may have induced global cooling and ushered in Pleistocene glacia- tion. Grassland evolution has been considered a consequence of mountain uplift and tectonic reorganization of ocean currents, but it can also be viewed as a biological force for global change through coevolution of grasses and grazers. Organisms in such coevolutionary trajectories adapt to each other rather than to their environment, and so can be forces for global change. Some past farming practices have aided greenhouse gas release. However, modern grassland agroecosystems are a potential carbon sink already under intensive human management, and carbon farming techniques may be useful in curbing anthropogenic global warming.
Toward an Era of Restoration in Ecology: Successes, Failures, and Opportunities Ahead
Keywords resilience, ecosystem restoration, restoration ecology, recovery, degradation, ecosystem services, environmental change, novel ecosystems Abstract As an inevitable consequence of increased environmental degradation and anticipated future environmental change, societal demand for ecosystem restoration is rapidly increasing. Here, I evaluate successes and failures in restoration, how science is informing these efforts, and ways to better ad- dress decision-making and policy needs. Despite the multitude of restora- tion projects and wide agreement that evaluation is a key to future progress, comprehensive evaluations are rare. Based on the limited available infor- mation, restoration outcomes vary widely. Cases of complete recovery are frequently characterized by the persistence of species and abiotic processes that permit natural regeneration. Incomplete recovery is often attributed to a mixture of local and landscape constraints, including shifts in species distributions and legacies of past land use. Lastly, strong species feedbacks and regional shifts in species pools and climate can result in little to no recovery. More forward-looking paradigms, such as enhancing ecosystem services and increasing resilience to future change, are exciting new direc- tions that need more assessment. Increased evidence-based evaluation and cross-disciplinary knowledge transfer will better inform a wide range of critical restoration issues such as how to prioritize sites and interventions, include uncertainty in decision making, incorporate temporal and spatial dependen- cies, and standardize outcome assessments. As environmental policy increasingly embraces restoration, the opportunities have never been greater.
Slow Recovery from Perturbations as a Generic Indicator of a Nearby Catastrophic Shift
The size of the basin of attraction in ecosystems with alternative stable states is often referred to as “ecological resilience.” Ecosystems with a low ecological resilience may easily be tipped into an alternative basin of attraction by a stochastic event. Unfortunately, it is very difficult to measure ecological resilience in practice. Here we show that the rate of recovery from small perturbations (some- times called “engineering resilience”) is a remarkably good indicator of ecological resilience. Such recovery rates decrease as a catastrophic regime shift is approached, a phenomenon known in physics as “crit- ical slowing down.” We demonstrate the robust occurrence of critical slowing down in six ecological models and outline a possible ex- perimental approach to quantify differences in recovery rates. In all the models we analyzed, critical slowing down becomes apparent quite far from a threshold point, suggesting that it may indeed be of practical use as an early warning signal. Despite the fact that critical slowing down could also indicate other critical transitions, such as a stable system becoming oscillatory, the robustness of the phenom- enon makes it a promising indicator of loss of resilience and the risk of upcoming regime shifts in a system. Keywords: alternative stable states, catastrophic bifurcations, critical slowing down, early warning signals, resilience, return time.
AGU: Human-induced climate change requires urgent action.
1st paragraph: concentrations of carbon dioxide and other heat-trapping greenhouse gases have increased sharply since the Industrial Revolution. Fossil fuel burning dominates this increase. Human-caused increases in greenhouse gases are responsible for most of the observed global average surface warming of roughly 0.8°C (1.5°F) over the past 140 years.
Trees on farms: Tackling the triple challenge of 07 mitigation, adaptation and food security
Policy recommendations ␣␣Increased adoption of agroforestry should be supported through finance for agricultural development and adaptation as well as mitigation. ␣␣Payments for environmental services – including carbon finance – should be geared towards increasing the extent of trees on farms ␣ More support is needed to increase the contribution of tree-based crops to smallholder incomes, thus diversifying income sources and increasing food security in the face of climate change.
TOO EARLY TO TELL, OR TOO LATE TO RESCUE? ADAPTIVE MANAGEMENT UNDER SCRUTINY
“The Forest Service’s definition of adaptive management does not emphasize experimentation but rather rational planning coupled with trial and error learning. Here ‘adaptive’ management has become a buzzword, a fash- ionable label that means less than it seems to promise.” Kai Lee, 1999 KEY FINDINGS • A new approach to the research-management relations is required.The natural tension between the two arenas can produce strengthened relations and improved learning, particularly with focussed input from lead scientists and AMA coordinators. • The AMA research effort is an important complement to PNW Research Station direction and priorities.The AMAs represent an additional research setting, one that offers important opportunities to test, validate, and possibly revise standards and guides contained within the NWFP. • The AMA research must be grounded in a local sense of priority and need, established by strong links between management and research.At the same time, designing research to maximize its applicability across the whole AMA system is also productive.
Integrated assessment of global water scarcity over the 21st century under multiple climate change mitigation policies
Water scarcity conditions over the 21st century both globally and regionally are assessed in the context of climate change and climate mitigation policies, by estimating both water availability and water demand within the Global Change Assessment Model (GCAM), a leading community- integrated assessment model of energy, agriculture, climate, and water. To quantify changes in future water availabil- ity, a new gridded water-balance global hydrologic model – namely, the Global Water Availability Model (GWAM) – is developed and evaluated. Global water demands for six ma- jor demand sectors (irrigation, livestock, domestic, electricity generation, primary energy production, and manufacturing) are modeled in GCAM at the regional scale (14 geopolitical regions, 151 sub-regions) and then spatially downscaled to 0.5◦ × 0.5◦ resolution to match the scale of GWAM. Using a baseline scenario (i.e., no climate change mitigation pol- icy) with radiative forcing reaching 8.8 W m−2 (equivalent to the SRES A1Fi emission scenario) and three climate pol- icy scenarios with increasing mitigation stringency of 7.7, 5.5, and 4.2 W m−2 (equivalent to the SRES A2, B2, and B1 emission scenarios, respectively), we investigate the ef- fects of emission mitigation policies on water scarcity. Two carbon tax regimes (a universal carbon tax (UCT) which in- cludes land use change emissions, and a fossil fuel and in- dustrial emissions carbon tax (FFICT) which excludes land use change emissions) are analyzed. The baseline scenario results in more than half of the world population living un- der extreme water scarcity by the end of the 21st century. Additionally, in years 2050 and 2095, 36 % (28 %) and 44 % (39 %) of the global population, respectively, is projected to live in grid cells (in basins) that will experience greater water demands than the amount of available water in a year (i.e., the water scarcity index (WSI) > 1.0). When comparing the climate policy scenarios to the baseline scenario while main- taining the same baseline socioeconomic assumptions, water scarcity declines under a UCT mitigation policy but increases with a FFICT mitigation scenario by the year 2095, particu- larly with more stringent climate mitigation targets. Under the FFICT scenario, water scarcity is projected to increase, driven by higher water demands for bio-energy crops. water: supply; demand; tax; scarcity
The timing of climate change
An innovative assessment of climate change calculates the year in which ongoing warming will surpass the limits of historical climate variability. Three experts explain this calculation’s significance compared with conventional approaches, and its relevance to Earth’s biodiversity.
The rebound effect is overplayed
Increasing energy efficiency brings emissions savings. Claims that it backfires are a distraction, say Kenneth Gillingham and colleagues.
Social Science at the Wildland-Urban Interface: a Compendium of Research Results to Create Fire-Adapted Communities
Over the past decade, a growing body of research has been conducted on the human dimensions of wildland fire. Building on a relatively small number of foundational studies, this research now addresses a wide range of topics including mitigation activities on private lands, fuels reduction treatments on public land, community impacts and resident behaviors during fire, acceptance of approaches to postfire restoration and recovery, and fire management policy and decisionmaking. As this research has matured, there has been a recognition of the need to examine the full body of resulting literature to synthesize disparate findings and identify lessons learned across studies. These lessons can then be applied to fostering fire-adapted communities—those communities that understand their risk and have taken action to mitigate their vulnerability and increase resilience. This compendium of social science research findings related to fire-adapted communities has resulted from a project funded by the Joint Fire Science Program (JFSP). As part of these efforts, the research team reviewed more than 200 publications of research results. Then the team convened a workshop with 16 scientists with extensive experience in the human dimensions of fire management issues. Workshop participants evaluated collective findings and discussed their application to support fire management activities. In addition to this compendium, project outputs were: 1) a synthesis of published literature specific to eight management questions identified by the JFSP, 2) a list of future research needs, 3) a bibliography, including abstracts, with accompanying subject area guide, and 4) a video featuring the experiences of agency personnel and community leaders in successful collaborative fire planning settings. This video is accompanied by a field guide for use by agency managers to more effectively participate in building fire-safe communities. In the sections that follow, we describe our approach to completing this review and present key findings from the literature. Our discussion is organized around five major topical areas: 1) homeowner/community mitigation, 2) public acceptance of fuels treatments on public lands, 3) homeowner actions during a fire, 4) postfire response and recovery, and 5) wildland fire policy and planning. The compendium concludes with a presentation of management implications and a bibliography of all material in this review.
NWF:A Letter from Scientists to the United States Congress Urging Action to Address the Threats of Global Warming to Wildlife and Ecosystems
“We write to you to convey our sense of urgency. Global warming is already causing serious damage and disruptions to wildlife and ecosystems, and reliable projections call for significant additional damage and disruptions. To fulfill the nation’s longstanding commitment to conserving abundant wildlife and healthy ecosystems for future generations, Congress must craft legislation that greatly reduces greenhouse gas pollution and generates substantial dedicated funding to protect and restore wildlife and ecosystems harmed by global warming.” – 612 Scientific Experts Concerned About Global Warming and Its Effect on Wildlife and Natural Resources
