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Water shortage has plagued the social development and human well-being of global closed basins. However, the hydroclimate research on different time scales in these regions remains inadequate at a global scale. In this paper, the hydrological responses from global closed basins to millennial-scale and centennial-scale cold/warm events since the Last Glacial Maximum were explored. Closed-basin lake records indicate that the westerlies-dominated closed basins are generally wetter during cold events than the corresponding warm ones on the millennial and centennial scales. In contrast, the monsoon-influenced closed basins prevail wetter climates during warm events. According to the hydroclimate simulations, precipitation seasonality plays a significant role in causing above spatial–temporal patterns. There is more winter rainfall in westerlies-dominated closed basins during cold events in the Last Glacial Maximum and Little Ice Age and more summer rainfall in monsoon-influenced closed basins during warm events in the mid-Holocene and Medieval Climate Anomaly. Under modern and future global warming, the hydroclimate changes in global closed basins show more regional differentiation, resulting in wetter mid-latitude Asian and low-latitude African closed basins but drier southwest North American and Australian closed basins. [ABSTRACT FROM AUTHOR]

This paper adopts a technique common in the dynamical climate modelling literature, that of pattern scaling, and applies it to previously available statistically downscaled station level data for Ireland for two climatically relevant variables, that of temperature and precipitation. This technique allows for the rapid development of climate scenarios for additional emissions scenarios not previously available from the GCM modelling centres. Having derived the end of century (2080s) change in both these variables for four marker emissions scenarios (A1FI, A2, B2, B1), regional response rates, or the regional rate of warming per °C global warming at each station, were calculated. The estimated ranges in regional responses at each station were then compared to regional response rates for the Irish ‘grid box’ derived from a larger sample of 14 GCMs, in order to determine if the calculated response rates were illustrative of a wider suite of GCMs. A Monte Carlo (MC) resampling approach was then employed to sample regional response rates for selected stations and for different estimates of future warming. On the basis of the MC approach, probability distribution functions (pdfs) of simulated changes in temperature and precipitation were constructed and compared to the original statistically downscaled data. The methodology and results presented represent a significant contribution to the traditional approach of statistical downscaling through the development of associated likelihoods, rather than just a change in the mean value. While the methodology presented should enable the rapid development of probabilistic based climate projections, based on a limited availability of downscaled climate scenarios, caution needs to be exercised in the interpretation of the results. While they provide a basis for risk or policy assessment, estimates of the level of risk are not independent of the method employed. [ABSTRACT FROM AUTHOR]

The recent rapid mass loss of mountain glaciers in response to climate warming has been reported for high and low latitudes all over the Earth. The paper analyses and discusses the recent evolution of a representative glacierized group within the Italian Alps, the Piazzi—Dosdè, where small glaciers are experiencing considerable retreat and shrinking. We analysed aerial photos to calculate area and geometry changes in the time window 1954—2003, and glaciological and geomorphological surveys were also performed. The estimated area change during 1954—2003 was —3.97 km2 (—51% of the area coverage in 1954). Area reduction increased more recently: area change during 1991—2003 (12 years) was —1.74 km2, against —0.67 km2 during 1981—1991 (10 years), and —1.57 km 2 during 1954—1981 (27 years). Moreover, analysis of the most recent orthophotos acquired during the summer of 2003 under exceptional conditions (i.e. total absence of snow cover) allowed observation and mapping of changes affecting glacier shape and morphology, including growing rock outcrops, tongue separations, formation of proglacial lakes, increasing supraglacial debris and collapse structures. Such processes cause positive feedbacks that accelerate further glacier disintegration once they appear. From a geodynamical perspective, the Dosdè Piazzi is now experiencing transition from a glacial system to a paraglacial one; areas where in the past the shaping and driving factors were glaciers are now subject to the action of melting water, slope evolution and periglacial processes. [ABSTRACT FROM PUBLISHER]

Mediterranean ecosystems contain some of the highest levels of plant diversity of any region on Earth and are amongst those believed to be most at risk from the consequences of global warming. Yet such ecosystems are not static and have responded to environmental changes at a variety of scales and from a variety of causes, particularly climatic and anthropogenic. The purpose of this paper is to review recent research on environmental change and ecosystem response. Long-term records are available to analyse changes over glacial-interglacial cycles, while high resolution records show the sensitivity and coupling of Mediterranean, North Atlantic and Greenland records. For the Holocene, there is continued debate about the relative impact of anthropogenic activity, but there is also increasing recognition that mediterraneantype ecosystems should not be regarded as fragile, degraded landscapes, but are disturbanceadapted. Nevertheless, conservation measures face increasing challenges from contemporary climate change and human pressures. Some insights into the identification of refugial areas, either in glacial times or for present-day conservation purposes, come from molecular biogeographical studies of past faunal and floral distribution. [ABSTRACT FROM AUTHOR]

The article examines the consideration of an ecosystem's benefit to humans, known as ecosystem services, within the scope of scientific studies of degraded peatlands and peatland restoration. One example of such a benefit is indicated as the balance of greenhouse gases and their role in global climate regulation. The author indicates that the subject was not commonly addressed in the literature examined.

The main objective of this research was to study the streamflow evolution of a representative sample of the Spanish near-natural-regime fluvial system over the last four decades of the 20th century. The focus of this study was on those headwater river basins that, not having been subject to substantial human alteration directly via the flow regime, might still have been affected by changes in land management. A representative sample of 74 rivers was selected and a statistical analysis was performed to detect seasonal and annual trends, and the magnitude of streamflow change. Almost all of the rivers studied experienced reductions in streamflow, and three quarters of them had negative and significant (p<0.05) trends in streamflow change. It was impossible to detect any spatial pattern in terms of the type or trend magnitude. The main decreases in the discharge of these near-natural rivers in Spain was observed in the spring and summer, when 81% and 70% of the rivers, respectively, exhibited significant negative trends. The magnitudes of the changes are also remarkable. The average annual percentage change in streamflow magnitude of the 74 basins was –1.45% per year, which corresponds to an average streamflow reduction equivalent to 153 hm3 every year. The results of this study are relevant in view of future climatic scenarios and the evolution of land management in rural and mountain areas, as has already been observed in many parts of the Mediterranean and other regions. Global warming, resulting in continuous temperature increases and therefore evapotranspiration increases, is clearly one factor potentially affecting streamflow, together with land abandonment and subsequent continuous forest expansion. These results obtained in Spain could be extrapolated to other areas in the Mediterranean and beyond and should be taken into account in any water policy and water management in the near future. [ABSTRACT FROM AUTHOR]

Climate sensitivity is defined as the change in global mean equilibrium temperature after a doubling of atmospheric CO2 concentration and provides a simple measure of global warming. An early estimate of climate sensitivity, 1.5-4.5°C, has changed little subsequently, including the latest assessment by the Intergovernmental Panel on Climate Change. The persistence of such large uncertainties in this simple measure casts doubt on our understanding of the mechanisms of climate change and our ability to predict the response of the climate system to future perturbations. This has motivated continued attempts to constrain the range with climate data, alone or in conjunction with models. The majority of studies use data from the instrumental period (post-1850), but recent work has made use of information about the large climate changes experienced in the geological past. In this review, we first outline approaches that estimate climate sensitivity using instrumental climate observations and then summarize attempts to use the record of climate change on geological timescales. We examine the limitations of these studies and suggest ways in which the power of the palaeoclimate record could be better used to reduce uncertainties in our predictions of climate sensitivity. [ABSTRACT FROM AUTHOR]

On examining the scientific literature of recent years, one notices an increase in the number of studies of global warming and its impact on the Earth's various environments. Research has been undertaken in various fields such as geomorphology, hydrology and many others. In the context of climatic change, there is growing interest in the study of past floods, or palaeofloods. Researchers are attempting to reconstitute the chronology of past floods, especially with respect to past or subrecent climatic changes. The work involves using different methodological approaches borrowed from various disciplines including geology, geomorphology and ecology. The reconstruction of ancient hydrological events such as palaeofloods in fact requires that different methods and techniques be combined in order to trace the chronology of events as precisely as possible using different biophysical parameters. A wide variety of indicators are used in the chronological reconstruction of ancient fluvial environments, whether in humid, subhumid or desert regions. These indicators involve analysing stratigraphic sequences and sedimentary deposits, organic matter and macrorest deposits, as well as using radiocarbon dating (14C), thermoluminescence (TL), and dendrochronology and lichenometry. In fact, most work on the reconstitution of the frequency and magnitude of ancient floods uses several methods and techniques to obtain the long-term chronology of flood events in relation to the specific conditions (e. g., climate, geomorphology) of a region or study area. With the publication of several studies in palaeohydrology, it was interesting to examine, through a literature review, the various approaches used in the study of palaeofloods. This kind of study has seen major advances, which can be explained partly by the interest generated by global climate change and its effect on river-system dynamics. [ABSTRACT FROM AUTHOR]

Focuses on the outcome of the 1997 Kyoto Climate Treaty and the significance of the conference to the global climate change. Need to reduce net equivalent carbon dioxide emissions from Annex I countries; Asymmetry of warming in the hemisphere; Human adaptation to climate change.

The extent, and variability of seasonal snow cover are important parameters in the climate system. Changes in snow cover may provide an indicator of global climatic trends and are of considerable practical significance. The question of the most suitable indices of changes in snow cover conditions, in terms of their use for change detection and for monitoring applications, is discussed. The use of passive microwave-derived estimates of snow cover extent and water equivalent for continental and regional-scale mapping is illustrated. Problems in interpreting the microwave signatures, as well as difficulties in comparing such data to ground observations, are also noted.Up to now analyses have focused primarily on trends in Northern Hemisphere snow extent based on monthly averages using the NOAA weekly snow charts 1972-present, or on station data spanning 50-100 years. However, the latter are generally less readily available, or accessible. An overview is provided of current information on recent hemispheric trends and, for the former USSR, the relationship of changes in snow depth, to variations in temperature and precipitation since the late nineteenth century are described, based on newly available station records. Interpretation of these changes and comparisons with other records are presented.Model projections of changes in snow cover conditions and associated snowmelt runoff that may occur as a result of greenhouse gas-induced warming are discussed for several mountain regions. Long-term station records of snow depth variability provided a valuable context within which such modeling results can be examined. [ABSTRACT FROM PUBLISHER]