Climatic change impacts on the ecohydrology of Mediterranean watersheds

Impact of climate change on ecohydrologic processes of Mediterranean watersheds are significant and require quick action toward improving adaptation and management of fragile system. Increase in water shortages and land use can alter the water balance and ecological health of the watershed systems. Intensification of land use, increase in water abstraction, and decline in water quality can be enhanced by changes in temperature and precipitation regimes. Ecohydrologic changes from climatic impacts alter runoff, evapotranspiration, surface storage, and soil moisture that directly affect biota and habitat of the region. This paper reviews expected impacts of climatic change on the ecohydrology of watershed systems of the Mediterranean and identifies adaptation strategies to increase the resilience of the systems. A spatial assessment of changes in temperature and precipitation estimates from a multimodel ensemble is used to identify potential climatic impacts on watershed systems. This is augmented with literature on ecohydrologic impacts in watershed systems of the region. Hydrologic implications are discussed through the lens of geographic distribution and upstream-downstream dynamics in watershed systems. Specific implications of climatic change studied are on runoff, evapotranspiration, soil moisture, lake levels, water quality, habitat, species distribution, biodiversity, and economic status of countries. It is observed that climatic change can have significant impacts on the ecohydrologic processes in the Mediterranean watersheds. Vulnerability varied depending on the geography, landscape characteristics, and human activities in a watershed. Increasing the resilience of watershed systems can be an effective strategy to adapt to climatic impacts. Several strategies are identified that can increase the resilience of the watersheds to climatic and land use change stress. Understanding the ecohydrologic processes is vital to development of effective long-term strategies to improve the resilience of watersheds. There is need for further research into ecohydrologic dynamics at multiple scales, improved resolution of climatic predictions to local scales, and implications of disruptions on regional economies.     

Assessment of Climate Change Impacts on the Economic Development of the Russian Arctic in the 21st Century

The problem of increasing the informativeness of climate projections in the Russian Arctic in order to meet the current economy needs is considered. The detailed estimates are presented of changes for the most important specialized indicators of the thermal and moisture regimes which characterize climatic impacts on the economic development of the Russian Arctic in the 21st century. The calculations are based on the data of numerical experiments with the regional climate model which were conducted for the Arctic region in the framework of the international CORDEX project. The high resolution of the model (50 km) and the consideration of mesoscale factors helped to detect significant spatial differences in the estimates of changes in the analyzed parameters which should be taken into account when adapting to climate change at the regional level.     

Adapting dryland agriculture to climate change: Farming implications and research and development needs in Western Australia

The Western Australian wheat-belt has experienced more rainfall decline than any other wheat-cropping region in Australia. Future climate change scenarios suggest that the Western Australian wheat-belt is likely to see greater future reductions in rainfall than other regions, together with a further increase in temperatures. While these changes appear adverse for water-limited rain-fed agriculture, a close analysis of the changes and their impacts reveals a more complex story. Twentieth century changes in rainfall, temperature and atmospheric CO₂ concentration have had little or no overall impact on wheat yields. Changes in agricultural technology and farming systems have had much larger impacts. Contrary to some claims, there is no scientific or economic justification for any immediate actions by farmers to adapt to long-term climate change in the Western Australian wheat-belt, beyond normal responses to short-term variations in weather. Rather than promoting current change, the most important policy response is research and development to enable farmers to facilitate future adaptation to climate change. Research priorities are proposed.     

Regional hydrologic consequences of increases in atmospheric CO2 and other trace gases

Concern over changes in global climate caused by growing atmospheric concentrations of carbon dioxide and other trace gases has increased in recent years as our understanding of atmospheric dynamics and global climate systems has improved. Yet despite a growing understanding of climatic processes, many of the effects of human-induced climatic changes are still poorly understood. Major alterations in regional hydrologic cycles and subsequent changes in regional water availability may be the most important effects of such climatic changes. Unfortunately, these are among the least well-understood impact. Water-balance modeling techniques - modified for assessing climatic impacts - were developed and tested for a major watershed in northern California using climate-change scenarios from both state-of-the-art general circulation models and from a series of hypothetical scenarios. Results of this research suggest strongly that plausible changes in temperature and precipitation caused by increases in atmospheric trace-gas concentrations could have major impacts on both the timing and magnitude of runoff and soil moisture in important agricultural areas. Of particular importance are predicted patterns of summer soil-moisture drying that are consistent across the entire range of tested scenarios. The decreases in summer soil moisture range from 8 to 44%. In addition, consistent changes were observed in the timing of runoff-specifically dramatic increases in winter runoff and decreases in summer runoff. These hydrologic results raise the possibility of major environmental and socioeconomic difficulties and they will have significant implications for future water-resource planning and management.     

Do Regional Disparities in Research on Climate and Water Influence Adaptive Capacity?

As part of a long-term effort to both improve access to information on climate change and freshwater resources, and to understand the state of the science, we compiled an electronic bibliography of scientific literature in that area. We analyzed the distribution of information on climatic impacts on freshwater resources, with an emphasis on differences between developed and developing regions as well as differences in the types and focus of research carried out among regions. There has been more research overall in developed countries than in the developing world. Proportionally more of the available research on natural and human systems pertains to developed regions, while most of the analysis done in developing countries is limited to higher-level climatology and hydrology. We argue that scientific information and understanding are important elements of the ability to adapt to potential climatic changes. The distribution of the scientific literature in our database suggests that the types of science most directly relevant to adaptive capacity are skewed towards developed countries, which may exacerbate existing disparities in adaptive capacity, and ultimately worsen the consequences of climatic impacts in developing countries.     

Unusual Climate in Northwest Europe During the Period 1730 to 1745 Based on Instrumental and Documentary Data

This study focuses on one of the most interesting times of the early instrumental period in northwest Europe (from 1730–1745) attempting to place the extremely cold year of 1740 and the unusual warmth of the 1730s decade in a longer context. The similarity of the features in the few long (and independent) instrumental records together with extensive documentary evidence clearly indicates that remarkable climatic changes occurred rapidly in this period. We use unpublished subjective circulation charts developed by the late Hubert Lamb, to assist in understanding the course of events, particularly during the extreme year of 1740 and the four subsequent years. We also compare these subjective charts with others recently developed using more objective modern reconstruction techniques. Apart from evidence of a reduction in the number of explosive volcanic eruptions following the 1690s, it is difficult to explain the changes in terms of our knowledge of the possible factors that have influenced this region during the 19th and 20th centuries. The study, therefore, highlights how estimates of natural climatic variability in this region based on more recent data may not fully encompass the possible known range.     

Focusing on the real environmental culprits — urban areas UNU's City Inspirations Initiative

UNU Monitor is a quarterly review of the United Nations University's (UNU) current research activities, publications and forthcoming projects in the area of environment and sustainable development. This issue features an article by Dr. Hari Srinivas of the UNU. It describes the criticality of urban areas and its impacts on the global environment, and introduces the newly launched ‘City Inspirations Initiative’. Further information on the Initiative can be obtained from Dr. Srinivas, UNU Environment and Sustainable Development Programme     

在气候影响研究中引入随机天气发生器的方法和不确定性

通过采用不同的随机天气发生器生成一定气候背景下各种气候变率情景，许多学者在最近的研究中已经认识到气候变率对农作物生长发育影响的重要性。传统的气候影响评估方法直接以大气环流模式的模拟试验结果作为未来气候情景，这样不可能理解如上的重要性。本文着重评述将随机天气发生器应用于气候变化影响研究的一般方法框架，以及作者的具体个例研究方法。文中最后分析了目前该领域研究中还存在的一些不确定性。 在当前的气候变化影响研究中，有不同的方法用来研制一种称为WGEN的典型随机天气发生器的参数化方案及其随机试验方法。不同的研究者也有不同的参数调控方法。通常的思路是通过气候控制试验和2×CO2试验之间的气候变量平均值和方差的变化来扰动随机天气发生器的参数，以生成未来逐日气候变化情景。本文作者根据短期气候预测模式的输出产品建立了一套WGEN的参数化方案及其随机试验方法，并且在时间和空间两个尺度上检验和评估了此参数化方案下WGEN的模拟能力。另外，作者由未来降水的变化，调试随机天气发生器参数，生成了气候变率变化情景。这些参数调节可以产生各种不同类型和定性大小的气候变率变化，用于气候影响评估的敏感性分析。通过如上方法，作为一个个例，文中评估了未来气候变率变化     

A necessary voice: Climate change and lived experiences of youth in Rigolet,Nunatsiavut, Canada

Globally, youth voices and their experiences, observations, and perceptions about climatic and environmental change and variability are relatively absent in the published literature to date. To address this gap, the goal of this research was to explore the observations and perceptions of climate change held by youth (12–25 years old) in the Inuit community of Rigolet, Nunatsiavut, Canada. Twenty in-depth interviews were conducted with youth in Rigolet to gather data about climatic and environmental changes young people have observed, and the subsequent impacts of these changes on their lives, culture, and community. Youth reported observing and experiencing climatic and environmental changes throughout their lives, with reported impacts falling within five main themes: changing travel conditions and access to hunting; challenges to Inuit culture; a concern for Elder and senior well-being; strong climate-related emotional responses; and youth-identified potential adaptation strategies. More broadly, this research demonstrated that young people have valuable knowledge and perspectives to offer. In particular, researchers, community leaders, and policy makers are encouraged to meaningfully engage youth as crucial stakeholders in future climate change work, research, dialogue, and policy.     

Temporal and Spatial Variations in the Climate Controls of Vegetation Dynamics on the Tibetan Plateau during 1982–2011

The ecosystem of the Tibetan Plateau is highly susceptible to climate change. Currently, there is little discussion on the temporal changes in the link between climatic factors and vegetation dynamics in this region under the changing climate.By employing Normalized Difference Vegetation Index data, the Climatic Research Unit temperature and precipitation data,and the in-situ meteorological observations, we report the temporal and spatial variations in the relationships between the vegetation dynamics and climatic factors on the Plateau over the past three decades. The results show that from the early 1980s to the mid-1990s, vegetation dynamics in the central and southeastern part of the Plateau appears to show a closer relationship with precipitation prior to the growing season than that of temperature. From the mid-1990s, the temperature rise seems to be the key climatic factor correlating vegetation growth in this region. The effects of increasing temperature on vegetation are spatially variable across the Plateau: it has negative impacts on vegetation activity in the southwestern and northeastern part of the Plateau, and positive impacts in the central and southeastern Plateau. In the context of global warming, the changing climate condition(increasing precipitation and significant rising temperature) might be the potential contributor to the shift in the climatic controls on vegetation dynamics in the central and southeastern Plateau.     

重庆岩溶地区气候变化对植被的影响

岩溶生态系统是一种脆弱的生态系统,植被类型与盖度成为岩溶环境中最重要、最敏感的自然要素。介绍了以重庆岩溶地区为对象,利用气象和NDVI数据,采用相关分析等方法探讨了植被对气候变化的响应。结果表明:(1)在多年平均水平上,气候对重庆岩溶植被生态系统起着比降水大的作用;在植被生长的年际变化方面,气温和降水对植被生长起着大致相反的趋势。(2)年际变化方面,气温和降水对植被生态系统的生长起着大致相反的作用。一般来说,气温与NDVI之间的关系为正相关。(3)植被指数的动态变化受气候波动的影响较大,近20 a来,总体呈增加的趋势。可为岩溶生态系统恢复和重建提供科学依据。     

Impacts of recent climate change on wheat production systems in Western Australia

The wheatbelt of Western Australia shows a distinct Mediterranean climate with most of the rainfall occurring in the winter months. The main factor limiting plant production in this region is rainfall. Due to clearing of native vegetation, dryland salinity is a major problem in south-west Australia. Since the mid 1970s the region has experienced a significant decrease in winter rainfall. Across nine sites, growing season rainfall (May to October) decreased by an average of 11% and the sum of rainfall in June and July (June + July) decreased by 20%. We used the ASPIM-Nwheat model in combination with historic climate data to study the impact of recent climate change on the hydrology and production of wheat based farming systems by comparing results for before and after 1975. Despite the large decline in rainfall, simulated yields based on the actual weather data did not fall. At the same time, simulated drainage decreased by up to 95% which will significantly reduce the spread of dryland salinity. These results were due to the rainfall changes mainly occurring in June and July, a period when rainfall often exceeds crop demand and large amounts of water are usually lost by deep drainage. The findings will have significant implications for estimates of future climate change impacts in this region with changes in rainfall causing non-proportional impacts on production and hydrological aspects, such as deep drainage and waterlogging, where proportionality is often presumed.     

Climate and cultural history in the Americas: An overview

There is abundant historical evidence that climatic extremes in the past have led to significant and sometimes severe societal impacts. The severity of these impacts depends on the intensity and duration of the climatic event, social organization, and the prevailing socioeconomic conditions at the time of the climatic extreme. In this issue of Climatic Change we present the results from 12 studies, which document climatic extremes on different time scales and provide interesting evidence for direct and indirect social impacts of climatic changes in the Americas during the pre-Hispanic, colonial, and modern eras.     

An assessment of climate change impacts and adaptation for the Torres Strait Islands, Australia

Adaptive practices are taking place in a range of sectors and regions in Australia in response to existing climate impacts, and in anticipation of future unavoidable impacts. For a rich economy such as Australia’s, the majority of human systems have considerable adaptive capacity. However, the impacts on human systems at the intra-nation level are not homogenous due to their differing levels of exposure, sensitivity and capacity to adapt to climate change. Despite past resilience to changing climates, many Indigenous communities located in remote areas are currently identified as highly vulnerable to climate impacts due to their high level of exposure and sensitivity, but low capacity to adapt. In particular, communities located on low-lying islands have particular vulnerability to sea level rise and increasingly intense storm surges caused by more extreme weather. Several Torres Strait Island community leaders have been increasingly concerned about these issues, and the ongoing risks to these communities’ health and well-being posed by direct and indirect climate impacts. A government agency is beginning to develop short-term and long-term adaptation plans for the region. This work, however, is being developed without adequate scientific assessment of likely ‘climate changed futures.’ This is because the role that anthropogenic climate change has played, or will play, on extreme weather events for this region is not currently clear. This paper draws together regional climate data to enable a more accurate assessment of the islands’ exposure to climate impacts. Understanding the level of exposure and uncertainty around specific impacts is vital to gauge the nature of these islands’ vulnerability, in so doing, to inform decisions about how best to develop anticipatory adaptation strategies over various time horizons, and to address islanders’ concerns about the likely resilience and viability of their communities in the longer term.     

自然气候变异与人为气候变化对径流影响研究进展

 在回顾IPCC于1990-2007年4次关于气候变化对径流影响的评估报告进展的基础上,将第一次与第二次评估报告归纳为第一代--以气候均值变化对径流影响及其适应为主要特征;第三次与第四次评估报告为第二代--突出人为气候变化与自然气候变异对径流影响及其适应问题,分析了常规的气候变化对水文水资源影响评估方法的发展过程及存在的问题。研究结果反映了年代际时间尺度的自然气候变异的影响,而未能考虑与极端事件发生频次和强度变化密切相联的日、季和年际尺度的气候变异的影响,从而低估了气候变暖对洪水、干旱以及农业灌溉需水的负面作用。在介绍国内外研究的基础上,为第五次IPCC评估报告提出了加强交叉学科综合研究的建议。     

The effect of changing climate on Australian biomass production — a preliminary study

Increasing concentrations of carbon dioxide and other infrared absorbing gases are widely proposed as a mechanism for a global surface warming over the next several decades. Various methods have been used to anticipate the regional climatic changes which might result. In earlier papers Pittock has concluded that for Australia an increase in the extent of the summer rainfall regime is likely, with a decrease in winter rainfall. This is similar to a change which took place over much of Australia in the 1940's.In this paper a climate scenario, roughly corresponding to the climate which might be expected to occur by about the middle of the twenty-first century, has been used as the input into the Miami Model of net primary productivity due to Lieth. Results show that about half of Australia might experience productivity increases in excess of 20%. A small area in the extreme south-west of Australia shows a small decrease in productivity.The direct response of plants to higher ambient carbon dioxide concentrations, and many other possible effects such as changes in the incidence of plant diseases, pests, and soil erosion have not been assessed.Whether or not increasing carbon dioxide will lead to further climatic change in the next few decades, the results show that Australian primary productivity is quite sensitive to climatic variations within the range found in the historical records.     

自然气候变异与人为气候变化对径流影响研究进展

在回顾IPCC于1990-2007年4次关于气候变化对径流影响的评估报告进展的基础上,将第一次与第二次评估报告归纳为第一代--以气候均值变化对径流影响及其适应为主要特征;第三次与第四次评估报告为第二代--突出人为气候变化与自然气候变异对径流影响及其适应问题,分析了常规的气候变化对水文水资源影响评估方法的发展过程及存在的问题。研究结果反映了年代际时间尺度的自然气候变异的影响,而未能考虑与极端事件发生频次和强度变化密切相联的日、季和年际尺度的气候变异的影响,从而低估了气候变暖对洪水、干旱以及农业灌溉需水的负面作用。在介绍国内外研究的基础上,为第五次IPCC评估报告提出了加强交叉学科综合研究的建议。     

Quantification of the influence of snow course measurement date on climatic trends

The Natural Resources Conservation Service measures high elevation snowpack manually at snow courses across the western US. In addition to supporting the production of seasonal snowmelt-driven streamflow forecasts, this long-term dataset is widely used throughout the research community to study historical climatic change impacts. Therefore it is critical to understand what factors may affect the quality of the measurements, especially if those non-climatic factors possess long-term trends. For example, the snowpack measurement dates are nominally the first and fifteenth of the month although they actually average approximately 2?days earlier. This study found that the variability of measurement dates are determined by, 1) the epoch of the measurement, 2) the day of the week of the nominal measurement date, 3) the presence or absence of snow at the site and 4) if the measurement is for the first or the fifteenth of the month. The measurement date is less variable if snow is absent from the site. Mid-month data are collected closer to the nominal measurement date, and first of month data have a greater early bias. Since 1957, there has been a stronger aversion to collecting data on Fridays and weekends. Measurements are taken today on average 1.35?days earlier than they were before 1957. The effect on measurement bias depended on the time of year and was generally less than 5?% of the measurement. Therefore, changes in measurement date only slightly mask one’s ability to accurately detect long-term climatic trends.     

A FARMer's View of the Ricardian Approach to Measuring Agricultural Effects of Climatic Change

During the past few years two new methods, each based on the analogous region concept, have been developed to account for farmer adaptation in response to global climatic change. The first, called 'Ricardian' by Mendelsohn, Nordhaus, and Shaw (1994), econometrically estimates the impact of climatic and other variables on the value of farm real estate. Under some conditions, estimates of climate-induced changes in farm real estate capture first-round adaptations by farmers and represent the economic value of climatic change on agriculture. The second method, promulgated by Darwin et al. (1994) in the Future Agricultural Resources Model (FARM), uses a geographic information system to empirically link climatically derived land classes with other inputs and agricultural outputs in an economic model of the world. FARM provides estimates of economic impacts that fully account for all responses by economic agents under global climate change as well as estimates of Ricardian rents. The primary objective of this analysis is to evaluate how well changes in Ricardian rents measure agricultural or other effects of climatic change after all economic agents around the world have responded. Results indicate that changes in Ricardian rents on agricultural land are poor quantitative, but good qualitative, measures of how global climatic change is likely to affect the welfare of agricultural landowners, if one recognizes that increases in Ricardian rents actually indicate losses in landowner welfare and vice versa. Results also indicate that regional changes in Ricardian rents on all land are good qualitative measures of changes in regional welfare. They are poor quantitative welfare measures because they systematically overestimate both benefits and losses and are on average upwardly biased because inflated benefits are larger than exaggerated losses. Results also indicate that, when based on existing land-use patterns, changes in Ricardian rents on all the world's land are poor quantitative and qualitative measures of changes in world welfare. Despite these shortcomings, changes in Ricardian rents can provide useful information when other measures are not available. In this analysis, for example, estimated changes in Ricardian rents on all land indicate that climatic change would likely have detrimental effects in Latin America and Africa, beneficial effects in the former Soviet Union, and either detrimental or beneficial impacts in eastern and northern Europe and western and southern Asia. This is consistent with previous studies showing that climatic change would likely have detrimental, beneficial, and mixed effects on economic welfare in, respectively, equatorial, high latitude, and temperate areas. Estimated changes in Ricardian rents also indicate that aggregating Africa, Latin America, the former Soviet Union, eastern and northern Europe, and western and southern Asia into one region causes FARM's economic model to generate upwardly biased changes in world welfare. Modified results from scenarios with moderately flexible land-use change and which account for current land-use patterns indicate that world welfare may increase if the average surface land temperature does not increase by more than 1.0 or 2.0°C. If the average surface land temperature increases by 3.0°C or more, however, then world welfare may decline.     

The question of climatic stability in America before 1900

Belief that regional climates had significantly changed in historic times, possibly as a result of human activities, is firmly established in the Western tradition. Europe itself was believed to have undergone such changes, especially a warming trend, since ancient times. It was also widely believed that the European colonization of North America would duplicate many of the changes that had occurred in Europe, including the climatic changes that were supposed to have taken place. In the New World, it was at first believed that climatic change was occurring, as a result of human settlement and land use changes, but these views gave way to the idea of climatic stability. The first extensive compilations of reliable North American precipitation and temperature data in the latter part of the nineteenth century seemed to support the notion of stable climates. Ideas relating to macroclimatic change and stability that were entertained in America before 1900, mainly between 1770 and 1870, are examined.