GC31A-0100
Nature's Trust: A Paradigm for Natural Resources Stewardship
Climate change uncertainty puts a premium on all remaining natural resources. Farmland, air, water, wetlands, wildlife, soils, mineral resources and forests must be protected to ensure that Americans – present citizens and future generations - have the fundamental survival resources they need in a future that holds many unknowns. Moreover, in light of the need to manage resources given climate and particle forcing, government must mitigate dangerous carbon loading of the atmosphere. Confronting climate change and protecting natural resources requires a clear sense of government obligation that is inherent to sovereignty, not a matter of political choice. Our government representatives can and must reframe government's discretion into a trustee obligation to protect Nature and ensure natural resource stewardship. Drawing upon enduring legal principles and court decisions, government can be characterized as a trustee of the natural resources essential to human survival. A trust is a fundamental type of ownership whereby one manages property for the benefit of another. Viewed as a trust, the environment consists of a portfolio of quantified natural assets that government manages. As beneficiaries, citizens hold a common property interest in defined, bounded assets that make up Nature's Trust. Such trust principles form the bedrock of statutory law. Trustees have a fiduciary obligation to protect trust assets and may not allow destruction of property they manage. This session will provide a policy frame for current scientific efforts to address climate change and natural resources loss. Under the Nature's Trust frame, U.S. government leaders and agencies at every level inherit a strict fiduciary obligation to protect our collective natural resources, including our water and the atmosphere, as assets in the trust. Their fiduciary standard of care consists of a proportionate responsibility, which ties directly to "Nature's Mandate" as defined by current climate scientists: each jurisdiction must cap and begin reducing total GHG emissions within the decade and continue reduction until they reach 80% below 1990 levels by 2050. The trust framework positions all nations of the world in a logical relationship that can guide international diplomacy. The atmosphere, oceans and the global hydrologic cycle are commonly held assets shared as property among all nations on Earth. Thus, all Nations are sovereign co-tenant trustees, each holding the fiduciary responsibility to not degrade the common asset and to accomplish proportionate carbon reduction.
GC31A-0101
From ESM to Archeology: Bridging the Modeling Gap
Current Earth System Models (ESM) lack the inclusion of the anthroposphere, despite the widespread and deliberate anthropogenic changes in land use that occurred during the Holocene, i.e.~by the introduction of herding and subsistence-to-intensive agriculture. Prehistoric land use change should be part of paleoclimate modeling initiatives in order to quantify human impact and establish an improved baseline for evaluation of current and future impacts of changing land use. I present a generic global model and ESM submodule for simulating the fractional proportion of hunter-gatherers and agropastoralists in ancient societies, and the spread of Neolithic techniques. Using reconstructed potential vegetation and estimates of global population, the human-appropriated net primary production and land use can be calculated. At the base of the socio-technological model is an effective variable ansatz which describes the evolution of characteristic societal traits--such as the number of diverse subsistence economies---towards optimizing societal growth rate. The socio-technological model is run in the context of reconstructed or simulated Holocene paleovegetation changes. This model-based reconstruction of paleo-land use complements and extends to the distant past recent efforts in compiling data-based reconstructions of anthropogenic land use change which go back to 800~AD. The inclusion of this submodule into ESMs will allow hypothesis testing from the Earth science community and from archeology. For example, I show simulations for testing the "demic diffusion" hypothesis versus technology diffusion into Central Europe. http://www.heccan.org
GC31A-0102
Integrated assessment of socioeconomic and climate change on the Broads National Park, UK, using the ‘Regional Impact Simulator'
The Broads National Park, located in the east of England is the UK's only wetland National Park. Located in a low-lying area of intensive arable agriculture in the driest part of England, it faces many challenges. The ‘Regional Impact Simulator' is a user friendly software tool designed to allow UK stakeholders to perform regional integrated assessments of the effects of socio-economic and/or climate change on important sectors and resources. This includes assessment of agriculture, water resources, biodiversity and coastal and river flooding. The development of this regional tool arose from the need to further develop the methods applied in the first local to regional integrated assessment in the UK, which was limited by very long run times, a limited number of simulations, incomplete linkages between models and no allowance for scenario uncertainty. Using the ‘Regional Impact Simulator' for a range of socio-economic and emissions scenarios for the 2050s, The Broads in will face a diverse range of challenges related to: 1) Changes in coastal and fluvial flood risk – increased sea level and fluvial flows will increase flood risk for current flood defences; 2) Changing agricultural practices, associated with changing farmer responses to policy, will affect nutrient losses and habitats 3) Changes in water abstraction and discharge - irrigation demand will increase as water resources decrease. However future water availability is a consequence of both societal and policy priorities towards abstraction, and the changing patterns of urbanization and water usage; 4) Changes in habitats especially coastal habitats – saltmarsh will tend to be lost due to sea level rise, although managed realignment may increase stocks at the expense of coastal grazing marshes Socio-economic changes can be as (if not more) important than direct climate change-induced impacts, but the impacts of these changes depend on the choices society makes (e.g. flood defence policy; water demand, habitat recreation etc). The ‘Regional Impact Simulator' provides a tool for investigating many of these choices.
GC31A-0103
New Hampshire's Changing Wintertime Climate: Impact on Forestry Practices
Over the past four decades wintertime temperatures in New England have risen more than 2 degrees Celsius. This has had a significant impact on winter recreation in the region. Here we examine the effect of New Hampshire's warming wintertime climate on the logging industry, a vital source of revenue in New Hampshire, particularly in the northern counties such as Coos and Grafton. Recent statements from the industry have indicated that warmer wintertime temperatures have reduced the number of days for which the road is frozen and able to support the weight of the logging trucks. To assess the magnitude of change in New Hampshire, we examined the change in number of frozen road days in 15 locations for the period December through March for the years 1970 to 2007. We applied a Freeze-Thaw formula, based on daily mean temperatures, to determine when the roads were frozen or thawed. By dividing the state into three regions based on latitude and taking the mean results of the 5 towns located in each region, we find that since 1970 the northern region has lost 9 frozen road days and the central region has lost 10 frozen road days. The southern region also shows a loss in frozen days but with a much weaker trend. We also performed a sensitivity analysis by calculating trends using start years from 1965 to 1975 and found that the original results were robust. The strongest individual town trend was found in Berlin, located in Coos County, having already lost 18 days since 1970. Using estimates from a prior study suggest that the cost of a 9 day reduction in frozen road days per winter represents a loss of more than one million dollars in stumpage fees per year. The results of this study suggest that the forestry industry may need to consider alternative methods for logging in the near future.
GC31A-0104
From Large-Scale Climate Change to Socio-Economic Losses: The Case of Hurricanes in the U.S.
This paper presents a method to assess how climate change could translate into economic losses through the modelling of the different mechanisms that need to be taken into account. In this presentation, we start from a 10 percent increase in hurricane potential intensity, and we follow the causal chain from this large-scale change to total economic losses. To do so, this large-scale change is downscaled to a small spatial scale, pertinent to investigate socio-economic impacts. This downscaling is carried out using the Emanuel's hurricane model, which provides the annual probability of landfall of hurricanes from different categories of the Saffir-Simpson scale, in each region of the U.S. Atlantic and Gulf coast. As an example, the annual probability of category-5 landfall over the U.S. coastline is found to increase from 7 to 21 percent in response to the potential intensity increase. These landfall probabilities are of the foremost importance for urban planners and infrastructure designers. Other actors, however, are interested in different information. Insurers, for instance, needs these probabilities to be transformed into possible changes in the direct losses caused by hurricanes. Here, this transformation is carried out using a simple statistical analysis of past landfalls and the corresponding losses, and this analysis suggests that, if vulnerability remains unchanged, average annual losses could increase by 54 percent, from $ 8 billion to $ 12 billion a year. Of course, adaptation strategies could be undertaken to limit these losses and several strategies to do so are discussed. Finally, many economic mechanisms enter into action to reduce or amplify direct losses: propagation between economic sectors, production losses during the reconstruction period, macroeconomic feedbacks, etc. These indirect effects are investigated using a modified Input-Output model (ARIO), which provide an estimate of how the initial change in large-scale condition causes welfare losses. The model suggests that total economic losses increase like the square of direct losses, amplifying the role of the most extreme events. For instance, in Louisiana, total losses are twice as large as direct losses when the latter exceed $ 200 billion. Again, we discuss several adaptation strategies that can reduce indirect losses by improving the ability of the economy to reconstruct and deal with the disaster consequences.
GC31A-0105
Climate Variability and Ponderosa Pine Colonizations in Central Wyoming: Integrating Dendroecology and Dendroclimatology
Many tree species are predicted to expand into new territory over the coming decades in response to changing climate. By studying tree expansions over the last several centuries we can begin to understand the mechanisms underlying these changes and anticipate their consequences for forest management. Woody-plant demographics and decadal to multidecadal climate variability are often closely linked in semi-arid regions. Integrated tree-ring analysis, combining dendroecology and dendroclimatology to document, respectively, the demographic history of the population and the climatic history of the region, can reveal ecological dynamics in response to climate variability. We studied four small, disjunct populations of Pinus ponderosa in the Bighorn Basin of north-central Wyoming. These populations are located 30 to 100 kilometers from the nearest core populations of ponderosa pine in the western Bighorn Mountains. Packrat midden studies have shown that ponderosa pine colonized the western slopes of the Bighorn Range 1500 years ago, so the disjunct populations in the basin must be younger. All trees (living and dead) at each of the four disjunct populations were mapped, cored, and then aged using tree-ring based techniques. We obtained records of hydroclimatic variability from the Bighorn Basin using four tree-ring series from Pinus flexilis (3 sites) and Pseudotsuga menziesii (1 site). The four disjunct populations were all established within the past 500 years. Initially, the populations grew slowly with low recruitment rates until the early 19th century, when they experienced one or more large recruitment pulses. These pulses coincided with extended wet periods in the climate reconstruction. However, similar wet periods before the 19th Century were not accompanied by recruitment pulses, indicating that other factors (e.g., population density, genetic variability) are also important in colonization and expansion. We are currently obtaining genetic data and carrying out population modeling to differentiate the effects of population dynamics, genetic variability, and climate variability on recruitment and expansion of these populations.
GC31A-0106
Forest responses to late Holocene climate change in north-central Wisconsin: a high- resolution study from Hell's Kitchen Lake.
Forest dynamics at centennial to millennial timescales can be identified using paleoecological records with high spatial, temporal, and taxonomic resolution. These dynamics are linked to climate changes by comparing the paleoecological records with independent paleoclimate records of complementary sensitivity and temporal resolution. We analyzed plant macrofossils at contiguous 1cm intervals (representing 5 to 35 yr/cm) from late Holocene sediments of Hell's Kitchen Lake (3 ha) in north-central Wisconsin. Most of the plant macrofossils derive from trees growing on the slopes directly adjacent to the lake, and were identified to the species. We also analyzed pollen at an approximately100 year resolution to provide a regionally integrated record of forest composition. We then compared the macrofossil and pollen records with independent records of climate change in the region, particularly paleohydrological records from kettle bogs. The most notable feature of the late Holocene record occurs between 2300-2000 cal yr BP. During this period yellow birch (Betula alleghaniensis) macrofossils first appear in the record, along with a corresponding increase in pollen percentages. Hemlock (Tsuga canadensis) macrofossils and pollen also show a marked increase at this time. These changes coincide with a major transition towards wetter conditions recorded in the testate amoebae record of Hornet Bog (~200km northwest) and in a number of other kettle bog records from the region. Directly following this transition, tamarack (Larix laricina) and Sphagnum macrofossils at Hell's Kitchen Lake increase dramatically, likely representing the initiation of bog-mat growth along the southwest margin of the lake during the wet period. . We are continuing our high-resolution sampling downcore at Hell's Kitchen Lake. This will permit us to examine additional ecologic and climatic events in the early and mid-Holocene.
GC31A-0107
Changes in nitrogen cycling during the past century in a northern hardwood forest
Nitrogen availability, defined here as the supply of nitrogen to terrestrial plants and soil microorganisms relative to their demands, limits the productivity of many temperate zone forests and in part determines ecosystem carbon content. Despite multidecadal monitoring of nitrogen in streams, the long-term record of nitrogen availability in forests of the northeastern United States is largely unknown. Therefore, although these forests have been receiving anthropogenic nitrogen deposition for the past few decades, it is still uncertain whether terrestrial nitrogen availability has changed during this time and subsequently whether forest ecosystems have responded to increased nitrogen deposition. Here, we reconstructed changes in vegetation and other ecosystem characteristics using a millennial-scale lacustrine sediment record and high-intensity sampling of wood from living trees in the watershed of Mirror Lake, New Hampshire, USA. In particular, we used stable nitrogen isotopes in wood and lacustrine sediments to demonstrate that nitrogen availability in a northeastern forest has declined over the past 75 years, likely due to ecosystem recovery from EuroAmerican land use. We determined a presettlement trajectory of ecosystem change, and found the forest nitrogen availability has only recently returned to levels forecast from these trajectories, rendering the trajectory of future forest nitrogen cycling uncertain. Our results suggest that chronic disturbances caused by humans, especially logging and agriculture, are major drivers of terrestrial nitrogen cycling in forest ecosystems today, even a century after cessation.
GC31A-0108
Younger Dryas To Mid-Holocene Environmental History Of The Lowlands Of NW Transylvania, Romania
Pollen, micro-charcoal and total carbon analyses on sediments from the Turbuta profile located in the Transylvanian Basin (NW Romania) reveal information on previously unknown Younger Dryas to mid-Holocene environmental changes. The chronostratigraphy relies on AMS 14C measurements on organic matter and U/Th TIMS datings of snail shells. Results indicate the presence of Pinus and Betula open woodlands with small populations of Picea, Ulmus, Alnus and Salix before 12,000 cal yr BP, correlates well with the environmental developments expected for Younger Dryas stadial. A fairly abrupt replacement of Pinus and Betula by Ulmus dominated woodlands at ca. 11,900 cal. yr BP, likely represents competition effects of vegetation driven by climate warming at the onset of the Holocene. By 11,000 cal yr BP, the woodlands were increasingly diverse and dense with the expansion of Quercus, Fraxinus and Tilia, the establishment of Corylus, and the decline of upland herbaceous and shrubs taxa. The marked expansion of Quercus accompanied by Tilia between 10,500 and 8,000 cal yr BP could be the result of low effective moisture associated with both low elevation of the site and with regional change towards a drier climate. At 10,000 cal. yr BP Corylus spread across the region, and by 8,000 cal yr BP it replaced Quercus as a dominant forest constituent, with only little representation of Picea abies. Carpinus became established around 5,500 cal yr BP, but it was only a minor constituent in local woodlands until ca. 5,000 cal yr BP. Results from this study also indicate that the woodlands in the lowlands of Turbuta were never closed.
GC31A-0109
Paleolimnological Investigations Across a Physiographic Gradient Record Recent Aquatic Ecosystem and Watershed Scale Changes: Southwest Alaska National Parks and Preserves
Climate change effects on lake ecosystems have been shown to be pronounced at high latitudes. Oligotrophic lakes, specifically in northern areas, are very sensitive to environmental conditions and more susceptible to even small environmental changes. The changing climate sets the framework for abiotic and biotic processes within the aquatic and terrestrial systems of Lake Clark and Katmai National Parks and Preserves in Southwest Alaska, which are often regarded as some of the most pristine ecosystems remaining on Earth. Extensive paleoecological analyses have revealed rapid recent changes in lake ecology that often surpass Holocene natural variability and that are generally attributed to climate warming since the end of the Little Ice Age. However, the possibility that climate is only one dimension of these ecological shifts remains generally untested, especially given that current warming may not yet exceed maximum, naturally mediated, postglacial warmth. In this project we explored the use of carbon and nitrogen isotopes (13C and 15N), Total Phosphorus, and the presence and abundance of siliceous microfossils (biogenic silica) as proxy indicators of trophic state and aquatic productivity in Southwest Alaska lakes. Stable isotope data from a suite of 210Pb-dated sediment cores were compared stratigraphically with established proxies for historical trophic state (biogenic silica, sediment C:N ratio and total phosphorus), however, disturbances driven by climate, glacial retreat, volcanism and other natural perturbations contribute to, and perhaps at times overprint, aquatic driven processes in lake sediment cores. However, paleolimnological analyses and the suite of biogeochemical proxies (total organic matter, biogenic silica, organic N and C contents, and stable isotopic ratios) reveal a complex set of progressive changes that are expressed in the study lakes. Biogenic silica abundance began to change as early as the mid-19th century, but major inflections in the biogeochemical proxies occurred significantly later, being most pronounced after 1950. Among these changes are increases in sediment organic matter, depletions in sediment 15N, and decoupling of 13C and 15N signatures due to increasing CO2atm as reflected in 13C (e.g., Suess effect). It seems likely that climate warming, subsequently coupled to landscape change (vegetation expansion) and disturbance (deglaciation and volcanism), are synergistically driving these ecosystems towards states for which no prior natural analogs exist. However, the time lag between increases in air temperature and the response within the lake systems due to watershed changes is difficult to predict and remains unanswered. Despite direct climate influences from temperature and precipitation, the delay before terrestrial vegetation and soil cover are in balance with climate conditions could be several hundred years. The results imply that warming will have rapid effects on the productivity of high latitude oligotrophic lakes, due in part to warmer temperatures and longer ice-free periods. However, a larger although delayed stimulation of lake productivity following increased watershed production, soil maturity, and weathering in a warmer climate will potentially result in more substantial increases of essential nutrients that stimulate production of lake biota.
GC31A-0110
Effects of Holocene Climate Variability on Lago Paixban, a Perennial Wetland in Peten, Guatemala
This paper presents the results of analyses carried out on a 6-m long sediment core from Lago Paixban, a perennial wetland in northern Peten, Guatemala. Pollen, δ13Corg, magnetic susceptibility, and LOI have been used to track the vegetation and hydrology of this karstic basin from 10,000 cal yr B.P. to present. Lack of fossil preservation in the basal sediments indicates relatively dry conditions leading into the early Holocene, followed by increased humidity and the presence of a shallow marsh by ~9,000 cal yr B.P. An approximately 3-cm thick band of calcite was deposited around 8,200 cal yr B.P., representing a distinct hydrological shift likely associated with the North Atlantic 8.2 ka event. Increased humidity in the early Holocene led to the formation of an open-water lake in the basin by 7,500 cal yr B.P., which persisted for around 2,000 years. At 5,500 cal yr B.P. lake levels dropped dramatically, marked by an abrupt transition to a 1-m thick peat horizon dominated by wetland taxa. This shift from lake to marsh reflects the onset of regionally drier conditions in the latter part of the Holocene. Ecological changes during this late Holocene dry period suggest lowest recorded water levels from ~5,500-4,500 cal yr B.P., followed by increased water levels and the establishment of an extensive sawgrass marsh. Anthropogenic impacts are recorded as a dramatic increase of disturbance and agricultural taxa during the period of prehistoric Maya settlement in the late Holocene. This interval, from ~3,500-1,100 cal yr B.P., is marked by a 1-m thick horizon of calcareous clay marl, indicating a change in local hydrological conditions. It is difficult to determine whether hydrological changes during this `Maya Period` were primarily driven by climate or human activity. Shortly after the area was abandoned, a perennial wetland dominated by sawgrass ( Cladium jamaicense) developed and has persisted to the present.
GC31A-0111
Evaluating Paleoecological Patterns Using Paleoenvironmental Proxies: The Promise and the Peril