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1.
We estimated the impact of climatic change on wildland fire and suppression effectiveness in northern California by linking general circulation model output to local weather and fire records and projecting fire outcomes with an initial-attack suppression model. The warmer and windier conditions corresponding to a 2 × CO2 climate scenario produced fires that burned more intensely and spread faster in most locations. Despite enhancement of fire suppression efforts, the number of escaped fires (those exceeding initial containment limits) increased 51% in the south San Francisco Bay area, 125% in the Sierra Nevada, and did not change on the north coast. Changes in area burned by contained fires were 41%, 41% and –8%, respectively. When interpolated to most of northern California's wildlands, these results translate to an average annual increase of 114 escapes (a doubling of the current frequency) and an additional 5,000 hectares (a 50% increase) burned by contained fires. On average, the fire return intervals in grass and brush vegetation types were cut in half. The estimates reported represent a minimum expected change, or best-case forecast. In addition to the increased suppression costs and economic damages, changes in fire severity of this magnitude would have widespread impacts on vegetation distribution, forest condition, and carbon storage, and greatly increase the risk to property, natural resources and human life.  相似文献   

2.
Governance,complexity, and resilience   总被引:1,自引:0,他引:1  
This special issue brings together prominent scholars to explore novel multilevel governance challenges posed by the behavior of dynamic and complex social-ecological systems. Here we expand and investigate the emerging notion of “resilience” as a perspective for understanding how societies can cope with, and develop from, disturbances and change. As the contributions to the special issue illustrate, resilience thinking in its current form contains substantial normative and conceptual difficulties for the analysis of social systems. However, a resilience approach to governance issues also shows a great deal of promise as it enables a more refined understanding of the dynamics of rapid, interlinked and multiscale change. This potential should not be underestimated as institutions and decision-makers try to deal with converging trends of global interconnectedness and increasing pressure on social-ecological systems.  相似文献   

3.
The geographic distribution, vigor, virulence, and agricultural impact of weeds, insects, and plant pathogens will be affected by climatic changes accompanying the global "greenhouse effect." Weed/crop competitive interactions, particularly among species differing in photosynthetic pathway (C3 v C4), may be altered, with the C3 species favored by increasing CO2. Physiological and biochemical changes induced in host crop plants by rising CO2 may affect feeding patterns of pest insects. Compilation of climatic thresholds for phenological development of pest insects reveals the potential for shifts in pest behavior induced by global warming and other climatic change. Generation times may be reduced, enabling more rapid population increases to occur. Poleward migration may be accelerated during the crop season. The epidemiology of plant diseases also will be altered. Prediction of disease outbreaks will be more difficult in periods of rapidly changing climate and unstable weather. Environmental instability and increased incidence of extreme weather may reduce the effectiveness of pesticides on targeted pests or result in more injury to non-target organisms. Biological control may be affected either negatively or positively. Overall, the challenge to agriculture from pests probably will increase.  相似文献   

4.
This work presents evidence that ultraviolet (UV)-A solar irradiances show increasing trends at Thessaloniki, Greece, where air quality has been improving because of air pollution abatement strategies. In contrast, over Beijing, China, where air quality measures were taken later, solar brightening was delayed. It is shown that until the early 1990s, UV-A irradiances over Thessaloniki show a downward trend of –0.5% yr−1, which reverses sign and becomes positive in the last decade (+0.8% yr−1). This brightening is related to a decreasing trend in local aerosol amounts. Both the negative rate of change (dimming) and the positive rate of change (brightening) are amplified in the UV-A solar irradiances, compared with the total solar irradiance, by a factor of 2.6. Satellite derived short-wave radiation over Beijing showed negative changes of –0.4% (1984–1991) and –0.1% yr−1 during 1994–2006. The negative trend in solar radiation continued even during 2000–2006. Satellite-derived aerosol optical depth (AOD) increased by +1.0% yr−1 during 2000–2006, in agreement with in situ measurements of increasing AOD. Therefore, a statistically significant change from dimming to brightening in Beijing could not be seen in the last decade, but it is expected to occur in the near future.  相似文献   

5.
Vulnerability, adaptation and resilience are concepts that are finding increasing currency in several fields of research as well as in various policy and practitioner communities engaged in global environmental change science, climate change, sustainability science, disaster risk-reduction and famine interventions. As scientists and practitioners increasingly work together in this arena a number of questions are emerging: What is credible, salient and legitimate knowledge, how is this knowledge generated and how is it used in decision making? Drawing on important science in this field, and including a case study from southern Africa, we suggest an alternative mode of interaction to the usual one-way interaction between science and practice often used. In this alternative approach, different experts, risk-bearers, and local communities are involved and knowledge and practice is contested, co-produced and reflected upon. Despite some successes in the use and negotiation of such knowledge for ‘real’ world issues, a number of problems persist that require further investigation including the difficulties of developing consensus on the methodologies used by a range of stakeholders usually across a wide region (as the case study of southern Africa shows, particularly in determining and identifying vulnerable groups, sectors, and systems); slow delivery of products that could enhance resilience to change that reflects not only a lack of data, and need for scientific credibility, but also the time-consuming process of coming to a negotiated understanding in science–practice interactions and, finally, the need to clarify the role of ‘external’ agencies, stakeholders, and scientists at the outset of the dialogue process and subsequent interactions. Such factors, we argue, all hinder the use of vulnerability and resilience ‘knowledge’ that is being generated and will require much more detailed investigation by both producers and users of such knowledge.  相似文献   

6.
Inequalities, institutions, and forest commons   总被引:1,自引:0,他引:1  
This paper contributes to a growing literature on the commons that examines the relationship between inequality and commons outcomes. Our analysis of evidence on forest commons outcomes in 228 cases from South Asia (India and Nepal), East Africa (Kenya and Uganda) and Latin America (Mexico and Bolivia) suggests that local governance and collective action matter in shaping how socioeconomic inequalities affect forest conditions. In particular, we find that both inter-group and intra-group economic inequalities have consistently negative effects on forest outcomes, but that effectively functioning local institutions for collective action dampen the negative effect of inter-group inequality on forest outcomes.  相似文献   

7.
The present study aims at the assessment of six satellite rainfall estimates (SREs) in Pakistan. For each assessed products, both real-time (RT) and post adjusted (Adj) versions are considered to highlight their potential benefits in the rainfall estimation at annual, monthly, and daily temporal scales. Three geomorphological climatic zones, i.e., plain, mountainous, and glacial are taken under considerations for the determination of relative potentials of these SREs over Pakistan at global and regional scales. All SREs, in general, have well captured the annual north-south rainfall decreasing patterns and rainfall amounts over the typical arid regions of the country. Regarding the zonal approach, the performance of all SREs has remained good over mountainous region comparative to arid regions. This poor performance in accurate rainfall estimation of all the six SREs over arid regions has made their use questionable in these regions. Over glacier region, all SREs have highly overestimated the rainfall. One possible cause of this overestimation may be due to the low surface temperature and radiation absorption over snow and ice cover, resulting in their misidentification with rainy clouds as daily false alarm ratio has increased from mountainous to glacial regions. Among RT products, CMORPH-RT is the most biased product. The Bias was almost removed on CMORPH-Adj thanks to the gauge adjustment. On a general way, all Adj versions outperformed their respective RT versions at all considered temporal scales and have confirmed the positive effects of gauge adjustment. CMORPH-Adj and TMPA-Adj have shown the best agreement with in situ data in terms of Bias, RMSE, and CC over the entire study area.  相似文献   

8.
9.
In recent years there has been a movement by administrators and policymakers across the country to reorganize and reinvent government to improve program efficiencies, to harness resources outside government in the service of public policy goals, and to better facilitate the input of affected interests and the general public. Central to this effort are innovative, decentralized institutional arrangements which delegate significant authority either to private citizens, program managers within existing bureaucracy, or market-based mechanisms. Ecosystem- and watershed-based management, which seek to both prevent pollution and sustain development, are in the vanguard of this movement. This paper examines this trend toward decentralizing environmental policy and the use of ecosystem management from the perspective of the public. Planning and implementation of devolved environmental policy will require the support of local stakeholders and citizens. Using data from a national public opinion survey conducted during the summer of 1998, the paper examines factors associated with public acceptability of ecosystem management and the preferred level of government and citizen participation that should be involved in the implementation of such management strategies.  相似文献   

10.
《大气与海洋》2013,51(1):117-138
Abstract

Dynamics affects the distribution and abundance of stratospheric ozone directly through transport of ozone itself and indirectly through its effect on ozone chemistry via temperature and transport of other chemical species. Dynamical processes must be considered in order to understand past ozone changes, especially in the northern hemisphere where there appears to be significant low‐frequency variability which can look “trend‐like” on decadal time scales. A major challenge is to quantify the predictable, or deterministic, component of past ozone changes. Over the coming century, changes in climate will affect the expected recovery of ozone. For policy reasons it is important to be able to distinguish and separately attribute the effects of ozone‐depleting substances and greenhouse gases on both ozone and climate. While the radiative‐chemical effects can be relatively easily identified, this is not so evident for dynamics — yet dynamical changes (e.g., changes in the Brewer‐Dobson circulation) could have a first‐order effect on ozone over particular regions. Understanding the predictability and robustness of such dynamical changes represents another major challenge. Chemistry‐climate models have recently emerged as useful tools for addressing these questions, as they provide a self‐consistent representation of dynamical aspects of climate and their coupling to ozone chemistry. We can expect such models to play an increasingly central role in the study of ozone and climate in the future, analogous to the central role of global climate models in the study of tropospheric climate change.  相似文献   

11.
12.
The workshop focused on methodologies to assess the impacts of climate change on terrestrial and aquatic ecosystems and their socioeconomic consequences. It did not deal in any detail with the other components (i.e., models designed to estimate changes in atmospheric concentrations of greenhouse gases or in climatic factors) of an integrated assessment shown in Figure 2 of the introduction. This final chapter discusses some of the issues addressed during the San Diego workshop and highlights a few of the major findings of the papers. Issues discussed below include limitations of past modeling efforts and impediments to developing better models of the impacts of climate change on forest, grassland, and water resources; suggestions for future research both to develop better data and models and to employ existing data and modeling capabilities to improve the usefulness of climate impact assessments for policy purposes; and the need for developing a common assessment framework.The views expressed here are those of the authors and do not necessarily reflect those of their institutions or the other participants in the February 28 to March 3, 1993 workshop held in San Diego, California.  相似文献   

13.
Assessments of the benefits of climate change mitigation—and thus of the appropriate stringency of greenhouse gas emissions abatement—depend upon ethical, legal, and political economic considerations. Global climate change mitigation is often represented as a repeated prisoners’ dilemma in which the net benefits of sustained global cooperation exceed the net benefits of uncooperative unilateral action for any given actor. Global cooperation can be motivated either by circumspection—a decision to account for the damages one’s own actions inflict upon others—or by the expectation of reciprocity from others. If the marginal global benefits of abatement are approximately constant in total abatement, the domestically optimal price approaches the global cooperative optimum linearly with increasing circumspection and reciprocity. Approximately constant marginal benefits are expected if climate damages are quadratic in temperature and if the airborne fraction of carbon emissions is constant. If, on the other hand, damages increase with temperature faster than quadratically or carbon sinks weaken significantly with increasing CO2 concentrations, marginal benefits will decline with abatement. In this case, the approach to the global optimum is concave and less than full circumspection and/or reciprocity can lead to optimal domestic abatement close to the global optimum.  相似文献   

14.
Summary More than 70% of forest fires in the northwestern United States are caused by lightening. The Project Skyfire is an attempt to learn more about the atmospheric conditions leading to thunderstorms in this area and to investigate the possibilities of an artificial influence on their development by cloud seeding. The experiences gained with the training of amateur observers as well as the first scientific results of the project are briefly discussed. During the first year of observations, for instance, there was found to exist an intimate relationship between a certain type of fast moving thunderstorms and the intensity and position of the jet stream. Finally, the great economical value of researches in the field of applied meteorology is stressed.
Zusammenfassung Über 70% der Waldbrände im Nordwesten der Vereinigten Staaten werden durch Blitze entzündet. Das Project Skyfire hat es sich zum Ziel gesetzt, die atmosphärischen Bedingungen, welche zur Bildung von Gewittern in diesem Gebiet führen, zu untersuchen und die Möglichkeiten einer künstlichen Beeinflussung durch seeding zu erforschen. Die gesammelten Erfahrungen mit der Schulung von Amateur-Beobachtern, sowie die bisherigen wissenschaftlichen Ergebnisse werden kurz diskutiert. Schon im ersten Jahr der Beobachtungen ergaben sich interessante Zusammenhänge zwischen einer bestimmten Art von rasch ziehenden Gewittern und dem Jet-Stream. Schließlich wird auf den weitreichenden wirtschaftlichen Nutzen großzügiger Forschungen auf dem Gebiet der angewandten Meteorologie hingewiesen.

Résumé Plus de 70% des incendies de forêts dans le Nord-Ouest des Etats-Unis sont dûs à la foudre. Le «Project Skyfire» a pour but d'étudier les conditions atmosphériques conduisant dans ces régions à la formation d'orages ainsi que les possibilités d'agir sur cette formation au moyen d'inséminations artificielles. On discute brièvement les expériences faites en instruisant des observateurs amateurs ainsi que les résultats scientifiques. Dès la première année de recherches, on a constaté d'intéressantes relations entre un certain type d'orages rapides et le jet stream. Enfin on attire l'attention sur le grand intérêt économique d'études étendues dans le domaine de la métérologie appliquée.


With 7 Figures.

The Munitalp Foundation, Inc.  相似文献   

15.
The few systematic international comparisons of climate policy strength made so far have serious weaknesses, particularly those that assign arbitrary weightings to different policy instrument types in order to calculate an aggregate score for policy strength. This article avoids these problems by ranking the six biggest emitters by far – China, the US, the EU, India, Russia, and Japan – on a set of six key policy instruments that are individually potent and together representative of climate policy as a whole: carbon taxes, emissions trading, feed-in tariffs, renewable energy quotas, fossil fuel power plant bans, and vehicle emissions standards. The results cast strong doubt on any idea that there is a clear hierarchy on climate policy with Europe at the top: the EU does lead on a number of policies but so does Japan. China, the US, and India each lead on one area. Russia is inactive on all fronts. At the same time climate policy everywhere remains weak compared to what it could be.

Policy relevance

This study enables climate policy strength, defined as the extent to which the statutory provisions of climate policies are likely to restrict GHG emissions if implemented as intended, to be assessed and compared more realistically across space and time. As such its availability for the six biggest emitters, which together account for over 70% of global CO2 emissions, should facilitate international negotiations (1) by giving participants a better idea of where major emitters stand relative to each other as far as climate policy stringency is concerned, and (2) by identifying areas of weakness that need action.  相似文献   


16.
Synoptic conditions of severe squalls and two tornados in the north of Bashkortostan on June 1, 2007 and August 29, 2014 are anatyzed ustng radar and sateltite data and the forecasts of mesoscale models. The effects of geographic environment and mesoscale features are considered whose consideration enables predicting severe convective events with the lead time of 1-6 hours with the error of about 20 km.  相似文献   

17.
Climatic change is likely to affect Pacific Northwest (PNW) forests in several important ways. In this paper, we address the role of climate in four forest ecosystem processes and project the effects of future climatic change on these processes across Washington State. First, we relate Douglas-fir growth to climatic limitation and suggest that where Douglas-fir is currently water-limited, growth is likely to decline due to increased summer water deficit. Second, we use existing analyses of climatic controls on tree species biogeography to demonstrate that by the mid twenty-first century, climate will be less suitable for key species in some areas of Washington. Third, we examine the relationships between climate and the area burned by fire and project climatically driven regional and sub-regional increases in area burned. Fourth, we suggest that climatic change influences mountain pine beetle (MPB) outbreaks by increasing host-tree vulnerability and by shifting the region of climate suitability upward in elevation. The increased rates of disturbance by fire and mountain pine beetle are likely to be more significant agents of changes in forests in the twenty-first century than species turnover or declines in productivity, suggesting that understanding future disturbance regimes is critical for successful adaptation to climate change.  相似文献   

18.
This paper provides both a detailed history of environmental change in the Sierra Nevada over the past 1,800 years and evidence for climate teleconnections between the Sierra Nevada and Greenland during the late Holocene. A review of Greenland ice core data suggests that the magnitudes of abrupt changes in temperature and precipitation increased beginning c. 3,700 and 3,000 years ago, respectively. Precipitation increased abruptly 1,300 years ago. Comparing paleotemperature data from Cirque Peak, CA with paleoprecipitation data from Pyramid Lake, NV suggests that hot temperatures occurred at the beginnings of most severe droughts in the Sierra Nevada over the past 1,800 years. Severe fires and erosion also occurred at Coburn Lake, CA at the beginning of all severe droughts in the Sierra Nevada over the past 1,800 years. This suggests that abrupt climate change during the late Holocene caused vegetation and mountain slopes in some areas to be out of equilibrium with abruptly changed climates. Finally, the ending of drought conditions in Greenland coincided with the beginning of drought conditions in the Sierra Nevada over the past 1,800 years, perhaps as a result of the rapidly changed locations of the Earth??s major precipitation belts during abrupt climate change events.  相似文献   

19.
Canopy-level humidity is often less at night during fine weather in a mid-latitude city, compared to its rural surroundings. This feature has been attributed, in part, to reduced urban dew, but links are largely unproven, because urban dew data are rare. In this study, surface moisture (i.e., dew + guttation by blotting) and dewfall (by mini-lysimeter) were measured at rural and urban residential sites in Vancouver, Canada, during the summer of 1996. Air temperature and humidity were measured at both sites, and on rural-to-urban vehicle traverses. Weather and location effects were evident. Humidity data suggested the small (< 1 g m–3) urban moisture excess observed on fine nights was linked to reduced urban dew. For grass, the frequency of moisture events, and surface moisture amounts, were similar for both sites. However, on grass, rural dewfall (mean=0.10 mm per night) was more than urban dewfall (mean=0.07 mm per night). On the other hand, data for a roof lysimeter (mean dewfall=0.12 mm per night) showed that an urban roof could rival rural grass as a favoured location for dewfall in Vancouver.  相似文献   

20.
傅刚  陈莅佳  李鹏远  庞华基  张树钦 《气象》2021,47(3):261-273
温带气旋是中纬度地区每日天气舞台上最重要的“演员”.在秋冬季节的中高纬度海洋上有一类快速发展的温带气旋——“爆发性气旋”,尚未受到公众的广泛关注.文章围绕这一主题,首先回顾了温带气旋研究的历史,介绍了“爆发性气旋”这一术语产生的渊源,并对多位学者给出的爆发性气旋定义进行了系统梳理,重点介绍了一个考虑风速影响的、修正的爆...  相似文献   

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