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Climate Extremes (climate + extreme)
Selected AbstractsClimate extremes: progress and future directionsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2009Lisa V. Alexander No abstract is available for this article. [source] Impact of summer warming on the thermal characteristics of a polymictic lake and consequences for oxygen, nutrients and phytoplanktonFRESHWATER BIOLOGY, Issue 2 2008SUSANN WILHELM Summary 1. The impact of long thermal stratification events on some key properties in a polymictic lake was studied by determining the mixing regime of Müggelsee, Germany, using water temperature profiles taken hourly over 4 years. The period included two exceptional summer heatwaves. 2. Long thermal stratification events lasted from about 1 week to 2 months, and exhibited a high variability in thermocline depth and stratification intensity within and between events. 3. During stratification events, hypolimnetic oxygen concentrations strongly decreased while hypolimnetic SRP accumulation increased, depending on the duration and intensity of stratification and on hypolimnetic water temperature. 4. The impact of stratification on the functional phytoplankton composition increased with increasing stratification duration, but was rather different for the heatwaves. 5. Stratification events were followed by strong nutrient pulses into the euphotic zone and intense phytoplankton growth, particularly after the heatwaves. Hence, the influence of the climate extremes counteracted effects of reduced external nutrient loading. [source] A review of climate risk information for adaptation and development planningINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2009R. L. Wilby Abstract Although the use of climate scenarios for impact assessment has grown steadily since the 1990s, uptake of such information for adaptation is lagging by nearly a decade in terms of scientific output. Nonetheless, integration of climate risk information in development planning is now a priority for donor agencies because of the need to prepare for climate change impacts across different sectors and countries. This urgency stems from concerns that progress made against Millennium Development Goals (MDGs) could be threatened by anthropogenic climate change beyond 2015. Up to this time the human signal, though detectable and growing, will be a relatively small component of climate variability and change. This implies the need for a twin-track approach: on the one hand, vulnerability assessments of social and economic strategies for coping with present climate extremes and variability, and, on the other hand, development of climate forecast tools and scenarios to evaluate sector-specific, incremental changes in risk over the next few decades. This review starts by describing the climate outlook for the next couple of decades and the implications for adaptation assessments. We then review ways in which climate risk information is already being used in adaptation assessments and evaluate the strengths and weaknesses of three groups of techniques. Next we identify knowledge gaps and opportunities for improving the production and uptake of climate risk information for the 2020s. We assert that climate change scenarios can meet some, but not all, of the needs of adaptation planning. Even then, the choice of scenario technique must be matched to the intended application, taking into account local constraints of time, resources, human capacity and supporting infrastructure. We also show that much greater attention should be given to improving and critiquing models used for climate impact assessment, as standard practice. Finally, we highlight the over-arching need for the scientific community to provide more information and guidance on adapting to the risks of climate variability and change over nearer time horizons (i.e. the 2020s). Although the focus of the review is on information provision and uptake in developing regions, it is clear that many developed countries are facing the same challenges. Copyright © 2009 Royal Meteorological Society [source] Trends in indices for extremes in daily temperature and precipitation in central and western Europe, 1901,99INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2005Anders Moberg Abstract We analyse 20th century trends in six indices for precipitation extremes and four indices for temperature extremes, calculated from daily observational data for European stations. The indices chosen reflect rather moderate extremes. Most of the ,80 stations used are situated in central and western Europe; therefore, results mainly refer to this region. Trends are calculated over 1901,99, 1921,99, 1901,50 and 1946,99. Two different trend estimators are used, and significance is assessed with a bootstrap technique. We find that: Significant increasing precipitation trends over the 20th century dominate in winter for both average precipitation intensity and moderately strong events. Simultaneously, the length of dry spells generally increased insignificantly. There are few significant trends of any sign for precipitation indices in summer, but there are insignificant drying trends over Scandinavia and wetting trends over central and western Europe for 1921,99. The length of dry spells in summer generally increased insignificantly. Both the warm and cold tails of the temperature distribution in winter warmed over the entire 20th century. Notably low values in the cold tail for daily Tmax and Tmin occurred in the early 1940s, leading to strong but insignificant negative trends for 1901,50, whereas little change occurred before 1940. Warming of winters during 1946,99 occurred in both the warm and cold tails for both Tmax and Tmin, with the largest warming in the cold tail for Tmin. The warm tail of daily Tmin (and to a smaller extent Tmax) in summer warmed significantly during the past century. There is more evidence for summer warming in the first half of the century compared with the second half. During 1946,99, the warm tail of daily Tmax in summer was generally warming while the cold tail was cooling (both insignificantly). More digitized daily observational data from various European sub-regions are needed to permit a spatially more extensive analysis of changes in climate extremes over the last century. Copyright © 2005 Royal Meteorological Society [source] The Quaternary of the British Isles: factors forcing environmental change,JOURNAL OF QUATERNARY SCIENCE, Issue 4 2010James Rose Abstract This paper considers the processes that have controlled cool temperate latitude terrestrial environments over the last ca 3,Ma, with particular reference to the British Isles. A scheme is proposed that is based on the processes that act on the land over any given period of time and are the product of climate modulated by rock type (the resisting agent) and relief (determined by tectonics and antecedent relief-forming factors). Climate is generalised in terms of the range and rates of climate change determined by orbital forcing. During precession cycles climate change was small and insolation levels were forced by chemically and biologically driven processes. The period of obliquity cycles is characterised by patterns of climate change in which physical processes became effective and high-magnitude fluvial and slope processes were reinforced by periglaciation and glaciation in susceptible regions. Eccentricity cycles include climate extremes of longer duration, and glaciation and periglaciation were the major contributors to landscape change, sediment transfer and sediment mixing. These climate-forced processes produce distinctive landform, sediment and soil assemblages characteristic of particular episodes of Quaternary time. The lags between the successive systems are identified. Copyright © 2010 John Wiley & Sons, Ltd. [source] Characteristics of Australia's rangelands and key design issues for monitoring biodiversityAUSTRAL ECOLOGY, Issue 1 2004ANITA K. SMYTH Abstract We explored the key issues that are most likely to influence any set of guiding principles for developing biodiversity monitoring programmes in Australia's rangelands. We defined the Australian rangelands and came up with an overview of their climate extremes, land-use pressures and biodiversity loss, and then focussed on issues underpinning the design phase of any monitoring programme. Using Noss's 1990 framework of compositional, structural and functional attributes of biodiversity and its new revisions by others, we showed how the elusive, abstract concept of biodiversity can be used to identify many measurable attributes that can form a minimum and necessary set of indicators for any biodiversity monitoring task. We then described the steps in the monitoring process, with a particular focus on the reasons for monitoring biodiversity as they strongly influence the selection of indicators. We concluded by compiling a table of key issues as background information for developing guiding principles (Table 4). The list is by no means an exhaustive list for the design phase but it does indicate that considerable attention needs to be given to this phase when developing monitoring programmes. We have intentionally not addressed the equally important issues associated with the planning and delivery phases of developing a monitoring programme, as Wallace et al. and Watson and Novelly cover these in their papers in the present issue of Austral Ecology. [source] | ||||||||||