Article 2 of the UNFCCC: Historical Origins,Recent Interpretations   总被引：4，自引：2，他引：2  

Michael?OppenheimerEmail author  Annie?Petsonk 《Climatic change》2005,73(3):195-226

Article 2 of the UN Framework Convention on Climate Change (UNFCCC), which states the treaty's long-term objective, is the subject of a growing literature that examines means to interpret and implement this provision. Here we provide context for these studies by exploring the intertwined scientific, legal, economic, and political history of Article 2. We review proposed definitions for “dangerous anthropogenic interference” and frameworks that have been proposed for implementing these definitions. Specific examples of dangerous climate changes suggest limits on global warming ranging from 1 to 4 ^∘C and on concentrations ranging from 450 to 700 ppm CO₂ equivalents. The implications of Article 2 for near term restrictions on greenhouse-gas emissions, e.g., the Kyoto Protocol, are also discussed.  相似文献   

Assessing the Consequences of Climate Change for Food and forest Resources: A View from the IPCC   总被引：1，自引：0，他引：1  

William Easterling  Michael Apps 《Climatic change》2005,70(1-2):165-189

Important findings on the consequences of climate change for agriculture and forestry from the recently completed Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC) are reviewed, with emphasis on new knowledge that emerged since the Second Assessment Report (SAR). The State-Pressure-Response-Adaptation model is used to organize the review. The major findings are:

• Constant or declining food prices are expected for at least the next 25 yr, although food security problems will persist in many developing countries as those countries deal with population increases, political crisis, poor resource endowments, and steady environmental degradation. Most economic model projections suggest that low relative food prices will extend beyond the next 25 yr, although our confidence in these projections erodes farther out into the 21st century.
• Although deforestation rates may have decreased since the early 1990s, degradation with a loss of forest productivity and biomass has occurred at large spatial scales as a result of fragmentation, non-sustainable practices and infrastructure development.
• According to United Nations estimates, approximately 23% of all forest and agricultural lands were classified as degraded over the period since World War II.
• At a worldwide scale, global change pressures (climate change, land-use practices and changes in atmospheric chemistry) are increasingly affecting the supply of goods and services from forests.
• The most realistic experiments to date – free air experiments in an irrigated environment – indicate that C₃ agricultural crops in particular respond favorably to gradually increasing atmospheric CO₂ concentrations (e.g., wheat yield increases by an average of 28%), although extrapolation of experimental results to real world production where several factors (e.g., nutrients, temperature, precipitation, and others) are likely to be limiting at one time or another remains problematic. Moreover, little is known of crop response to elevated CO₂ in the tropics, as most of the research has been conducted in the mid-latitudes.
• Research suggests that for some crops, for example rice, CO₂ benefits may decline quickly as temperatures warm beyond optimum photosynthetic levels. However, crop plant growth may benefit relatively more from CO₂ enrichment in drought conditions than in wet conditions.
• The unambiguous separation of the relative influences of elevated ambient CO₂ levels, climate change responses, and direct human influences (such as present and historical land-use change) on trees at the global and regional scales is still problematic. In some regions such as the temperate and boreal forests, climate change impacts, direct human interventions (including nitrogen-bearing pollution), and the legacy of past human activities (land-use change) appear to be more significant than CO₂ fertilization effects. This subject is, however an area of continuing scientific debate, although there does appear to be consensus that any CO₂ fertilization effect will saturate (disappear) in the coming century.
• Modeling studies suggest that any warming above current temperatures will diminish crop yields in the tropics while up to 2–3 ^°C of warming in the mid-latitudes may be tolerated by crops, especially if accompanied by increasing precipitation. The preponderance of developing countries lies in or near the tropics; this finding does not bode well for food production in those countries.
• Where direct human pressures do not mask them, there is increasing evidence of the impacts of climate change on forests associated with changes in natural disturbance regimes, growing season length, and local climatic extremes.
• Recent advances in modeling of vegetation response suggest that transient effects associated with dynamically responding ecosystems to climate change will increasingly dominate over the next century and that during these changes the global forest resource is likely to be adversely affected.
• The ability of livestock producers to adapt their herds to the physiological stress of climate change appears encouraging due to a variety of techniques for dealing with climate stress, but this issue is not well constrained, in part because of the general lack of experimentation and simulations of livestock adaptation to climate change.
• Crop and livestock farmers who have sufficient access to capital and technologies should be able to adapt their farming systems to climate change. Substantial changes in their mix of crops and livestock production may be necessary, however, as considerable costs could be involved in this process because investments in learning and gaining experience with different crops or irrigation.
• Impacts of climate change on agriculture after adaptation are estimated to result in small percentage changes in overall global income. Nations with large resource endowments (i.e., developed countries) will fare better in adapting to climate change than those with poor resource endowments (i.e., developing countries and countries in transition, especially in the tropics and subtropics) which will fare worse. This, in turn, could worsen income disparities between developed and developing countries.
• Although local forest ecosystems will be highly affected, with potentially significant local economic impacts, it is believed that, at regional and global scales, the global supply of timber and non-wood goods and services will adapt through changes in the global market place. However, there will be regional shifts in market share associated with changes in forest productivity with climate change: in contrast to the findings of the SAR, recent studies suggest that the changes will favor producers in developing countries, possibly at the expense of temperate and boreal suppliers.
• Global agricultural vulnerability is assessed by the anticipated effects of climate change on food prices. Based on the accumulated evidence of modeling studies, a global temperature rise of greater than 2.5 ^°C is likely to reverse the trend of falling real food prices. This would greatly stress food security in many developing countries.

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Sediment quality survey of the Choctawhatchee Bay system in the Florida panhandle     

Hemming JM  Brown JM  Brim M  Jarvis R 《Marine pollution bulletin》2005,50(8):889-898

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Simulation of gaseous diffusion in partially saturated porous media under variable gravity with lattice Boltzmann methods     

Chau JF  Or D  Sukop MC 《Water resources research》2005,41(8):W08410

Liquid distributions in unsaturated porous media under different gravitational accelerations and corresponding macroscopic gaseous diffusion coefficients were investigated to enhance understanding of plant growth conditions in microgravity. We used a single-component, multiphase lattice Boltzmann code to simulate liquid configurations in two-dimensional porous media at varying water contents for different gravity conditions and measured gas diffusion through the media using a multicomponent lattice Boltzmann code. The relative diffusion coefficients (D rel) for simulations with and without gravity as functions of air-filled porosity were in good agreement with measured data and established models. We found significant differences in liquid configuration in porous media, leading to reductions in D rel of up to 25% under zero gravity. The study highlights potential applications of the lattice Boltzmann method for rapid and cost-effective evaluation of alternative plant growth media designs under variable gravity.  相似文献   

Resolving mechanisms of toxicity while pursuing ecotoxicological relevance?     

Hinton DE  Kullman SW  Hardman RC  Volz DC  Chen PJ  Carney M  Bencic DC 《Marine pollution bulletin》2005,51(8-12):635-648

In this age of modern biology, aquatic toxicological research has pursued mechanisms of action of toxicants. This has provided potential tools for ecotoxicologic investigations. However, problems of biocomplexity and issues at higher levels of biological organization remain a challenge. In the 1980s and 1990s and continuing to a lesser extent today, organisms residing in highly contaminated field sites or exposed in the laboratory to calibrated concentrations of individual compounds were carefully analyzed for their responses to priority pollutants. Correlation of biochemical and structural analyses in cultured cells and tissues, as well as the in vivo exposures led to the production and application of biomarkers of exposure and effect and to our awareness of genotoxicity and its chronic manifestations, such as neoplasms, in wild fishes. To gain acceptance of these findings in the greater environmental toxicology community, “validation of the model” versus other, better-established often rodent models, was necessary and became a major focus. Resultant biomarkers were applied to heavily contaminated and reference field sites as part of effects assessment and with investigations following large-scale disasters such as oil spills or industrial accidents.

Over the past 15 years, in the laboratory, small aquarium fish models such as medaka (Oryzias latipes), zebrafish (Danio rerio), platyfish (Xiphophorus species), fathead minnow (Pimephales promelas), and sheepshead minnow (Cyprinodon variegatus) were increasingly used establishing mechanisms of toxicants. Today, the same organisms provide reliable information at higher levels of biological organization relevant to ecotoxicology. We review studies resolving mechanisms of toxicity and discuss ways to address biocomplexity, mixtures of contaminants, and the need to relate individual level responses to populations and communities.  相似文献   

Models of bed formation     

Michael F. Dacey 《Mathematical Geology》1979,11(6):655-668

The model for bed formation by Kolmogorov consists of an unending sequence of alternating periods of deposition and erosion of sediments, with the amounts of deposition and erosion being independent random variables. This paper examines this model in relation to recent mathematical studies that are relevant to, and simplify, the analysis of the thickness of the bed that remains after the sequence is operated for a long time. This thickness obeys the exponential probability law when the amounts of deposition and erosion also obey the exponential law distributed. For the discrete version formulated by Schwarzacher, the thickness obeys the geometric probability law when the amounts of deposition and erosion obey the geometric law.  相似文献   

A new approach to the estimation of analytical precision     

Michael Thompson  Richard J. Howarth 《Journal of Geochemical Exploration》1978,9(1):23-30

Methods used for the estimation of analytical precision commonly suffer from two deficiencies which give rise to misleading results. These are: (1) the methods take no account of changes in absolute or relative error over the concentration range, and (2) they tend for other reasons to produce optimistically-biassed results. The difficulties can be avoided by the correct use of duplicate determinations. One method presented allows precision parameters to be estimated. The other gives rise to a simple control chart for use in geochemical analysis.  相似文献   

Spectrophotometry (0.3 to 1.1µ) of visited and proposed apollo lunar landing sites     

Thomas B. McCord  Michael P. Charette  Torrence V. Johnson  Larry A. Lebofsky  Carle Pieters 《Earth, Moon, and Planets》1972,5(1-2):52-89

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Magnetic remanence acquisition in Finnish lake sediments   总被引：2，自引：0，他引：2  

Julie C. Stober  Roy Thompson 《Geophysical Journal International》1979,57(3):727-739

Summary. Magnetic studies have been carried out on organic sediments from five Finnish lakes to determine the carrier(s) of the stable NRM and to find how the remanence is acquired. Single or pseudo-single domain 'magnetite' is thought to carry the NRM. It was found that drying and cooling sediment samples resulted in a loss of NRM which was attributed to the misalignment of small magnetic particles. Low-field experiments were carried out on sediment samples in different physical states and from the results of these investigations it was concluded that post-depositional processes are important in the acquisition of an NRM. Stabilization of magnetic grains is thought to be due to the growth of gels in the organic sediment rather than to dewatering.  相似文献   

Improvement of photomultiplier performance in astronomical applications     

Michael Andrew Dopita 《Astrophysics and Space Science》1972,18(2):350-362

The physics of an EMI 9558 Å photomultiplier has been investigated in some detail, and this study has led to a gain of more than thirty times in the signal-to-noise obtainable in a given observation time when used in receiver noise limited conditions. The importance of giant pulses in limiting performance is demonstrated.  相似文献