Climate Science PDFs
Climate Science PDFs Collection
- 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.
- The Role of Local Governance and Institutions in Livelihoods Adaptation to Climate Change
- The most important implications of climate change from the perspective of the World Bank concern its potentially disastrous impacts on the prospects for development, especially for poorer populations in the global South. Earlier writings on climate change had tended to focus more on its links with biodiversity loss, spread of pathogens and diseases, land use planning, ecosystem change, and insurance markets, rather than its connections with development (Easterling and Apps 2005, Harvell et al. 2002, Tompkins and Adger 2004). But as the Social Development Department of the World Bank recently noted, “Climate change is the defining development challenge of our generation” (SDV, 2007: 2). These words echo the World Bank President Robert Zoellick’s statement at the United Nations Climate Change Conference in 2007 in Bali where he called climate change a “development, economic, and investment challenge.” Indeed, understanding the relationship between climate change, the human responses it necessitates, and how institutions shape such responses is an increasingly urgent need. This report directs attention towards a subset of such relationships, focusing on rural institutions and poor populations in the context of climate variability and change-induced adaptations.
- Temperature control of larval dispersal and the implications for marine ecology, evolution, and conservation
- Temperature controls the rate of fundamental biochemical processes and thereby regulates organismal attributes including development rate and survival. The increase in metabolic rate with temperature explains substantial among-species variation in lifehistory traits, population dynamics, and ecosystem processes. Temperature can also cause variability in metabolic rate within species. Here, we compare the effect of temperature on a key component of marine life cycles among a geographically and taxonomically diverse group of marine fish and invertebrates. Although innumerable lab studies document the negative effect of temperature on larval development time, little is known about the generality versus taxon-dependence of this relationship. We present a unified, parameterized model for the temperature dependence of larval development in marine animals. Because the duration of the larval period is known to influence larval dispersal distance and survival, changes in ocean temperature could have a direct and predictable influence on population connectivity, community structure, and regional-to-global scale patterns of biodiversity.
- Politics for the day after tomorrow: The logic of apocalypse in global climate politics
- The recent global climate change discourse is a prominent example of a securitization of environmental issues. While the problem is often framed in the language of existentialism, crisis or even apocalypse, climate discourses rarely result in exceptional or extraordinary measures, but rather put forth a governmental scheme of piecemeal and technocratic solutions often associated with risk management. This article argues that this seeming paradox is no accident but follows from a politics of apocalypse that combines two logics – those of security and risk – which in critical security studies are often treated as two different animals. Drawing on the hegemony theory of Ernesto Laclau and Chantal Mouffe, however, this article shows that the two are inherently connected. In the same way as the Christian pastorate could not do without apocalyptic imageries, today’s micro-politics of risk depends on a series of macro-securitizations that enable and legitimize the governmental machinery. This claim is backed up by an inquiry into current global discourses of global climate change regarding mitigation, adaptation and security implications. Although these discourses are often framed through the use of apocalyptic images, they rarely result in exceptional or extraordinary measures, but rather advance a governmental scheme of risk management. Tracing the relationship between security and risk in these discourses, we use the case of climate change to highlight the relevance of our theoretical argument.
- Prolonged suppression of ecosystem carbon dioxide uptake after an anomalously warm year
- Terrestrial ecosystems control carbon dioxide fluxes to and from the atmosphere1,2 through photosynthesis and respiration, a balance between net primary productivity and heterotrophic respiration, that determines whether an ecosystem issequestering carbon or releasing it to the atmosphere. Global1,3–5 and site-specific6 data sets have demonstrated that climate and climate variability influence biogeochemical processes that determine net ecosystem carbon dioxide exchange (NEE) at multiple timescales. Experimental data necessary to quantify impacts of a single climate variable, such as temperature anomalies, on NEE and carbon sequestration of ecosystems at interannual timescales have been lacking. This derives from an inability of field studies to avoid the confounding effects of natural intra-annual and interannual variability in temperature and precipitation. Here we present results from a fouryear study using replicate 12,000-kg intact tallgrass prairie monoliths located in four 184-m3 enclosed lysimeters7 . We exposed 6 of 12 monoliths to an anomalously warm year in the second year of the study8 and continuously quantified rates of ecosystem processes, including NEE. We find that warming decreases NEE in both the extreme year and the following year by inducing drought that suppresses net primary productivity in the extreme year and by stimulating heterotrophic respiration of soil biota in the subsequent year. Our data indicate thattwo years are required for NEE in the previously warmed experimental ecosystems to recover to levels measured in the control ecosystems. Thistime lag caused net ecosystem carbon sequestration in previously warmed ecosystems to be decreased threefold over the study period, compared with control ecosystems. Our findings suggest that more frequent anomalously warm years9 , a possible consequence of increasing anthropogenic carbon dioxide levels10, may lead to a sustained decrease in carbon dioxide uptake by terrestrial ecosystems. Vol 455| 18 September 2008
- Aeolian process effects on vegetation communities in an arid grassland ecosystem
- Many arid grassland communities are changing from grass dominance to shrub dominance, but the mechanisms involved in this conversion process are not completely understood. Aeolian processes likely contribute to this conversion from grassland to shrubland. The purpose of this research is to provide information regarding how vegetation changes occur in an arid grassland as a result of aeolian sediment transport. The experimental design included three treatment blocks, each with a 25 × 50 m area where all grasses, semi-shrubs, and perennial forbs were hand removed, a 25 × 50 m control area with no manipulation of vegetation cover, and two 10 × 25 m plots immediately downwind of the grass-removal and control areas in the prevailing wind direction, 19◦ north of east, for measuring vegetation cover. Aeolian sediment flux, soil nutrients, and soil seed bank were monitored on each treatment area and downwind plot. Grass and shrub cover were measured on each grass-removal, control, and downwind plot along continuous line transects as well as on 5 × 10 m subplots within each downwind area over four years following grass removal. On grass-removal areas, sediment flux increased significantly, soil nutrients and seed bank were depleted, and Prosopis glandulosa shrub cover increased compared to controls. Additionally, differential changes for grass and shrub cover were observed for plots downwind of vegetation-removal and control areas. Grass cover on plots downwind of vegetation-removal areas decreased over time (2004–2007) despite above average rainfall throughout the period of observation, while grass cover increased downwind of control areas; P. glandulosa cover increased on plots downwind of vegetation-removal areas, while decreasing on plots downwind of control areas. The relationships between vegetation changes and aeolian sediment flux were significant and were best described by a logarithmic function, with decreases in grass cover and increases in shrub cover occurring with small increases in aeolian sediment flux
- Coupling of Vegetation Growing Season Anomalies and Fire Activity with Hemispheric and Regional-Scale Climate Patterns in Central and East Siberia
- An 18-yr time series of the fraction of absorbed photosynthetically active radiation (fAPAR) taken in by the green parts of vegetation data from the NOAA Advanced Very High Resolution Radiometer (AVHRR) instrument series was analyzed for interannual variations in the start, peak, end, and length of the season of vegetation photosynthetic activity in central and east Siberia. Variations in these indicators of seasonality can give important information on interactions between the biosphere and atmosphere. A second-order local moving window regression model called the “camelback method” was developed to determine the dates of phenological events at subcontinental scale. The algorithm was validated by comparing the estimated dates to phenological field observations. Using spatial correlations with temperature and precipitation data and climatic oscillation indices, two geographically distinct mechanisms in the system of climatic controls of the biosphere in Siberia are postulated: central Siberia is controlled by an “Arctic Oscillation–temperature mechanism,” while east Siberia is controlled by an “El Niño–precipitation mechanism.” While the analysis of data from 1982 to 1991 indicates a slight increase in the length of the growing season for some land-cover types due to an earlier beginning of the growing season, the overall trend from 1982 to 1999 is toward a slightly shorter season for some land-cover types caused by an earlier end of season. The Arctic Oscillation tended toward a more positive phase in the 1980s leading to enhanced high pressure system prevalence but toward a less positive phase in the 1990s. The results suggest that the two mechanisms also control the fire regimes in central and east Siberia. Several extreme fire years in central Siberia were associated with a highly positive Arctic Oscillation phase, while several years with high fire damage in east Siberia occurred in El Niño years. An analysis of remote sensing data of forest fire partially supports this hypothesis VOLUME 20
- Illuminating the Modern Dance of Climate and CO2
- Records of Earth’s past climate imply higher atmospheric carbon dioxide concentrations in the future 19 SEPTEMBER 2008 VOL 321 SCIENCE
- Soil Temperature following Logging-Debris Manipulation and Aspen Regrowth in Minnesota: Implications for Sampling Depth and Alteration of Soil Processes
- Soil temperature is a fundamental controller of processes influencing the transformation and flux of soil C and nutrients following forest harvest. Soil temperature response to harvesting is influenced by the amount of logging debris (biomass) removal that occurs, but the duration, magnitude, and depth of influence is unclear. Logging debris manipulations (none, moderate, and heavy amounts) were applied following clearcut harvesting at four aspendominated (Populus tremuloides Michx.) sites in northeastern Minnesota, and temperature was measured at 10-, 30-, and 50-cm depths for two growing seasons. Across sites, soil temperature was significantly greater at all sample depths relative to uncut forest in some periods of each year, but the increase was reduced with increasing logging-debris retention. When logging debris was removed compared to when it was retained in the first growing season, mean growing season soil temperatures were 0.9, 1.0, and 0.8°C greater at 10-, 30-, and 50-cm depths, respectively. These patterns were also observed early in the second growing season, but there was no discernible difference among treatments later in the growing season due to the modifying effect of rapid aspen regrowth. Where vegetation establishment and growth occurs quickly, effects of logging debris removal on soil temperature and the processes influenced by it will likely be short-lived. The significant increase in soil temperature that occurred in deep soil for at least 2 yr after harvest supports an argument for deeper soil sampling than commonly occurs in experimental studies.
- Climate-induced changes in the small mammal communities of the Northern Great Lakes Region
- We use museum and other collection records to document large and extraordinarily rapid changes in the ranges and relative abundance of nine species of mammals in the northern Great Lakes region (white-footed mice, woodland deer mice, southern red-backed voles, woodland jumping mice, eastern chipmunks, least chipmunks, southern flying squirrels, northern flying squirrels, common opossums). These species reach either the southern or the northern limit of their distributions in this region. Changes consistently reflect increases in species of primarily southern distribution (white-footed mice, eastern chipmunks, southern flying squirrels, common opossums) and declines by northern species (woodland deer mice, southern red-backed voles, woodland jumping mice, least chipmunks, northern flying squirrels). White-footed mice and southern flying squirrels have extended their ranges over 225 km since 1980, and at particularly well-studied sites in Michigan’s Upper Peninsula, small mammal assemblages have shifted from numerical domination by northern species to domination by southern species. Repeated resampling at some sites suggests that southern species are replacing northern ones rather than simply being added to the fauna. Observed changes are consistent with predictions from climatic warming but not with predictions based on recovery from logging or changes in human populations. Because of the abundance of these focal species (the eight rodent species make up 96.5% of capture records of all forest-dwelling rodents in the region and 70% of capture records of all forest-dwelling small mammals) and the dominating ecological roles they play, these changes substantially affect the composition and structure of forest communities. They also provide an unusually clear example of change that is likely to be the result of climatic warming in communities that are experienced by large numbers of people.
- Linking climate change to lemming cycles
- The population cycles of rodents at northern latitudes have puzzled people for centuries1,2 , and their impact is manifest throughout the alpine ecosystem2,3 . Climate change is known to be able to drive animal population dynamics between stable and cyclic phases 4,5 , and has been suggested to cause the recent changesin cyclic dynamics of rodents and their predators 3,6–9 . But although predator–rodent interactions are commonly argued to be the cause of the Fennoscandian rodent cycles 1,10–13 , the role of the environment in the modulation of such dynamics is often poorly understood in natural systems 8,9,14 . Hence, quantitative links between climatedriven processes and rodent dynamics have so far been lacking. Here we show that winter weather and snow conditions, together with density dependence in the net population growth rate, account for the observed population dynamics of the rodent community dominated by lemmings (Lemmus lemmus) in an alpine Norwegian core habitat between 1970 and 1997, and predictthe observed absence of rodent peak years after 1994. These local rodent dynamics are coherentwith alpine bird dynamics both locally and over all ofsouthern Norway, consistent with the influence of large-scale fluctuations in winter conditions. The relationship between commonly available meteorological data and snow conditions indicates that changes in temperature and humidity, and thus conditions in the subnivean space, seem to markedly affect the dynamics of alpine rodents and their linked groups. The pattern of less regular rodent peaks, and corresponding changes in the overall dynamics of the alpine ecosystem, thusseemslikely to prevail over a growing area under projected climate change.
- Impact of disturbed desert soils on duration of mountain snow cover
- Snow cover duration in a seasonally snow covered mountain range (San Juan Mountains, USA) was found to be shortened by 18 to 35 days during ablation through surface shortwave radiative forcing by deposition of disturbed desert dust. Frequency of dust deposition and radiative forcing doubled when the Colorado Plateau, the dust source region, experienced intense drought (8 events and 39–59 Watts per square meter in 2006) versus a year with near normal precipitation (4 events and 17–34 Watts per square meter in 2005). It is likely that the current duration of snow cover and surface radiation budget represent a dramatic change from those before the widespread soil disturbance of the western US in the late 1800s that resulted in enhanced dust emission. Moreover, the projected increases in drought intensity and frequency and associated increases in dust emission from the desert southwest US may further reduce snow cover duration
- The Historical Dynamics of Socio-ecological Traps
- Environmental degradation is a typical unintended outcome of collective human behavior. Hardin’s metaphor of the ‘‘tragedy of the commons’’ has become a conceived wisdom that captures the social dynamics leading to environmental degradation. Recently, ‘‘traps’’ has gained currency as an alternative concept to explain the rigidity of social and ecological processes that produce environmental degradation and livelihood impoverishment. The trap metaphor is, however, a great deal more complex compared to Hardin’s insight. This paper takes stock of studies using the trap metaphor. It argues that the concept includes time and history in the analysis, but only as background conditions and not as a factor of causality. From a historical–sociological perspective this is remarkable since social–ecological traps are clearly path-dependent processes, which are causally produced through a conjunction of events. To prove this point the paper conceptualizes social–ecological traps as a process instead of a condition, and systematically compares history and timing in one classic and three recent studies of social– ecological traps. Based on this comparison it concludes that conjunction of social and environmental events contributes profoundly to the production of trap processes. The paper further discusses the implications of this conclusion for policy intervention and outlines how future research might generalize insights from historical–sociological studies of traps.
- The influence of conversion of forest types on carbon sequestration and other ecosystem services in the South Central United States
- This paper develops a forestland management model for the three states in the South Central United States (Arkansas, Louisiana, and Mississippi). Forest type and land-use shares are estimated to be a function of economic and physical variables. The results suggest that while historically pine plantations in this region have been established largely on old agricultural land, in the future pine plantations are likely to occur on converted hardwood-forest lands. This shift in the supply of land for plantations could have large effects on above-ground carbon storage and other ecosystem services. Subsidies of approximately $12–27 per ha per year would maintain the area of hardwood forests and reduce carbon emissions from the above-ground and product pool carbon stocks over the next 30 years. Across the several scenarios considered, results suggest that maintaining hardwoods could be an efficient carbon sequestration alternative.
- Understanding Soil Time
- Efforts to maintain soils in a sustainable manner are complicated by interactions among soil components that respond to perturbation at vastly different rates. VOL 321 SCIENCE
- An Uncertain Future for Soil Carbon
- Predictions of how rapidly the large amounts of carbon stored as soil organic matter will respond to warming are highly uncertain (1). Organic matter plays a key role in determining the physical and chemical properties of soils and is a major reservoir for plant nutrients. Understanding how fast organic matter in soils can be built up and lost is thus critical not just for its net effect on the atmospheric CO2 concentration but for sustaining other soil functions, such as soil fertility, on which societies and ecosystems rely. Recent analytic advances are rapidly improving our understanding of the complex and interacting factors that control the age and form of organic matter in soils, but the processes that destabilize organic matter in response to disturbances (such as warming or land use change) are poorly understood
- Impact of terrestrial biosphere carbon exchanges on the anomalous CO2 increase in 2002–2003
- Understanding the carbon dynamics of the terrestrial biosphere during climate fluctuations is a prerequisite for any reliable modeling of the climate-carbon cycle feedback. We drive a terrestrial vegetation model with observed climate data to show that most of the fluctuations in atmospheric CO2 are consistent with the modeled shift in the balance between carbon uptake by terrestrial plants and carbon loss through soil and plant respiration. Simulated anomalies of the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) during the last two El Nin˜o events also agree well with satellite observations. Our model results suggest that changes in net primary productivity (NPP) are mainly responsible for the observed anomalies in the atmospheric CO2 growth rate. Changes in heterotrophic respiration (Rh) mostly happen in the same direction, but with smaller amplitude. We attribute the unusual acceleration of the atmospheric CO2 growth rate during 2002–2003 to a coincidence of moderate El Nin˜o conditions in the tropics with a strong NPP decrease at northern mid latitudes, only partially compensated by decreased
- Emerging Techniques for Soil Carbon measurements
- Soil carbon sequestration is one approach to mitigate greenhouse gases. However, to reliably assess the quantities sequestered as well as the chemical structure of the soil carbon, new methods and equipment are needed. These methods and equipment must allow large scale measurements and the construction of dynamic maps. This paper presents results from some emerging techniques to measure carbon quantity and stability. Each methodology has specific capabilities and their combined use along with other analytical tools will improve soil organic matter research. New opportunities arise with the development and application of portable equipment, based on spectroscopic methods, as laser-induced fluorescence, laser-induced breakdown spectroscopy and near infrared, for in situ carbon measurements in different ecosystems. These apparatus could provide faster and lower cost field analyses thus improving soil carbon contents and quality databases. Improved databases are essential to model carbon balance, thus reducing the uncertainties generated through the extrapolation of limited data.
- Protected Areas as Frontiers for Human Migration
- Causes of human population growth near protected areas have been much debated. We conducted 821 interviews in 16 villages around Budongo Forest Reserve, Masindi district, Uganda, to explore the causes of human migration to protected areas and to identify differences in forest use between migrant and nonmigrant communities. We asked subjects for information about birthplace, migration, household assets, household activities, and forest use. Interview subjects were categorized as nonmigrants (born in one of the interview villages), socioeconomic migrants (chose to emigrate for economic or social reasons) from within Masindi district (i.e., local migrants) and from outside the Masindi district (i.e., regional migrants), or forced migrants (i.e., refugees or internally displaced individuals who emigrated as a result of conflict, human rights abuses, or natural disaster). Only 198 respondents were born in interview villages, indicating high rates of migration between 1998 and 2008. Migrants were drawn to Budongo Forest because they thought land was available (268 individuals) or had family in the area (161 individuals). A greater number of regional migrants settled in villages near Lake Albert than did forced and local migrants. Migration category was also associated with differences in sources of livelihood. Of forced migrants 40.5% earned wages through labor, whereas 25.5% of local and 14.5% of regional migrants engaged in wage labor. Migrant groups appeared to have different effects on the environment. Of respondents that hunted, 72.7% were regional migrants. Principal component analyses indicated households of regional migrants were more likely to be associated with deforestation. Our results revealed gaps in current models of human population growth around protected areas. By highlighting the importance of social networks and livelihood choices, our results contribute to a more nuanced understanding of causes of migration and of the environmental effects of different migrant groups. Conservation Biology, Volume 26, No. 3, 547–556
- Barking up the Wrong Tree? Forest Sustainability in the wake of Emerging Bioenergy Policies
- The spotted owl controversy revealed that federal forest management policies alone could not guarantee functioning forest ecosystems. At the same time as the owl’s listing, agreements made at the 1992 Rio Earth Summit highlighted the mounting pressures on natural systems, thus unofficially marking the advent of sustainable forestry management (SFM).2 While threats to forest ecosystems from traditional logging practices certainly remain,3 developed and developing countries have shifted generally toward more sustainable forest management, at least on paper, including codifying various sustainability indicators in public laws.4 Nevertheless, dark policy clouds are gathering on the forest management horizon. Scientific consensus has grown in recent years around a new and arguably more onerous threat to all of the world’s ecosystems—climate change. Governments’ responses have focused on bioenergy policies aimed at curtailing anthropogenic greenhouse gas (GHG) emissions, and mandatesfor renewables in energy supplies now abound worldwide. [Vol. 37:000
