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The East Asian Monsoon (EAM) is a regional factor affecting the East Asian climate and the oceanographic processes of the marginal seas along the Western Pacific. Finding proxies for the EAM intensity and reconstructing the interannual and interdecadal variations of the EAM using high-resolution records are necessary to improve our understanding of the EAM's role in the global climate system and for predicting climate change. In this paper, high-resolution sedimentary records of sedimentary core C0702 obtained from the inner continental shelf of the East China Sea were comprehensively analyzed using a laser particle size analyzer, an ItraxTM core scanner, and a 210Pb and 137Cs radionuclide analyzer to explore potential proxies for the East Asian Winter Monsoon (EAWM). By combining the obtained results with instrumental observations of the EAM, we established a quantitative formula for the EAWM, which enables to reconstruct the evolution trend of the EAWM during the past 130 years. The sensitive grain-size component F2, with a grain-size range of 14.35–230 µm, and principal component PC1 of the sedimentary deposits of the East China Sea inner shelf can be used as EAWM proxies. The evolution of EAWM in 1880–1950 could be roughly divided into two stages: a weak EAWM period from 1882 to 1900 and a strong EAWM period from 1900 to 1945. This study improves our understanding of the variations in the EAWM on interannual and interdecadal temporal scales. [ABSTRACT FROM AUTHOR]

The assessment of the potential impact of climate change on transport is an area of research very much in its infancy, and one that requires input from a multitude of disciplines including geography, engineering and technology, meteorology, climatology and futures studies. This paper investigates the current state of the art for assessments on urban surface transport, where rising populations and increasing dependence on efficient and reliable mobility have increased the importance placed on resilience to weather. The standard structure of climate change impact assessment (CIA) requires understanding in three important areas: how weather currently affects infrastructure and operations; how climate change may alter the frequency and magnitude of these impacts; and how concurrent technological and socio-economic development may shape the transport network of the future, either ameliorating or exacerbating the effects of climate change. The extent to which the requisite knowledge exists for a successful CIA is observed to decrease from the former to the latter. This paper traces a number of developments in the extrapolation of physical and behavioural relationships on to future climates, including a broad move away from previous deterministic methods and towards probabilistic projections which make use of a much broader range of climate change model output, giving a better representation of the uncertainty involved. Studies increasingly demand spatially and temporally downscaled climate projections that can represent realistic sub-daily fluctuations in weather that transport systems are sensitive to. It is recommended that future climate change impact assessments should focus on several key areas, including better representation of sub-daily extremes in climate tools, and recreation of realistic spatially coherent weather. Greater use of the increasing amounts of data created and captured by ‘intelligent infrastructure’ and ‘smart cities’ is also needed to develop behavioural and physical models of the response of transport to weather and to develop a better understanding of how stakeholders respond to probabilistic climate change impact projections. [ABSTRACT FROM AUTHOR]

James C. Knox’s 1977 paper “Human Impacts on Wisconsin Stream Channels,” published in the Annals of the Association of American Geographers, was a key component of a suite of three papers by him defining the response of rivers to the introduction and management of agriculture and to climate change. In this paper he used the Driftless Area of southwest Wisconsin as a laboratory where he could define fluvial responses by their sedimentary signatures in floodplain deposits. Land-use records dating back to the early 19th century along with shorter climate records provided his understanding of the drivers of change. He found that floods increased as an outcome of land-cover change. Upstream tributaries became wider and shallower as coarse deposits limited their adjustments, while main stem channels became narrower and deeper. His paper reflected the influence of his graduate advisor and especially of prominent faculty colleagues at the University of Wisconsin from fields ranging from soils and climatology to geomorphology and history. The paper was the subject of considerable debate in the professional community, but it remains a much-cited example of Knox’s work in unraveling the Quaternary and Holocene history of rivers of the Driftless Area and by extension the upper Mississippi River system. [ABSTRACT FROM PUBLISHER]

This paper provides a review of research and techniques that focus on the seasonally thawed portion of the Earth above permafrost terrain known as the active layer. The paper examines various different conceptual active layer systems, identifying five active layer types: bedrock (Type I), rock glacier or debris covered (Type II), mineral soil (Type III), organic mat or soil (Type IV) and submerged (Type V) active layer systems. These systems can be independent or mixed (frequently) in a permafrost environment, but all respond differently to climatic change or disturbance based on the thermal properties of the material and ice/water content. The review also highlights various active layer monitoring techniques including: probing, the Circumpolar Active Layer Monitoring Program (CALM) and frost tubes. Active layer modelling techniques are also reviewed, including the Stefan and the Kudryavtsev equations. In addition, the study highlights the active layer in a changing climate, examining the sensitivities of this layer to changes in temperature, precipitation and surface changes. Although the active layer has been well studied, knowledge gaps still exist including conflicting definitions between the thermal definition (0°C) and the physical definition (frozen water), which can become significant in areas with pore water that contains high levels of dissolved solids. [ABSTRACT FROM PUBLISHER]

Use of multi-model ensembles from global climate models to simulate the current and future climate change has flourished as a research topic during recent decades. This paper assesses the performance of multi-model ensembles in simulating global land temperature from 1960 to 1999, using Nash-Sutcliffe model efficiency and Taylor diagrams. The future trends of temperature for different scales and emission scenarios are projected based on the posterior model probabilities estimated by Bayesian methods. The results show that ensemble prediction can improve the accuracy of simulations of the spatiotemporal distribution of global temperature. The performance of Bayesian model averaging (BMA) at simulating the annual temperature dynamic is significantly better than single climate models and their simple model averaging (SMA). However, BMA simulation can demonstrate the temperature trend on the decadal scale, but its annual assessment of accuracy is relatively weak. The ensemble prediction presents dissimilarly accurate descriptions in different regions, and the best performance appears in Australia. The results also indicate that future temperatures in northern Asia rise with the greatest speed in some scenarios, and Australia is the most sensitive region for the effects of greenhouse gas emissions. In addition to the uncertainty of ensemble prediction, the impacts of climate change on agriculture production and water resources are discussed as an extension of this research. [ABSTRACT FROM PUBLISHER]

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]

Over recent decades, analyses of the structure and impact of atmospheric teleconnections have substantially increased our understanding of the climate system and the role of climate variability. Moving beyond simple correlations between teleconnection indices and temperature and precipitation anomalies, synoptic climatology has been able to provide insight on the spatiotemporal manifestation of teleconnection anomalies, as well as further understanding in terms of teleconnection-related anomalies in circulation pattern frequencies that can lead to extreme events over individual areas. In this progress report, we focus on a number of recent papers that, broadly defined, assess two realms of teleconnections: the North Atlantic circulation, largely focusing on the North Atlantic Oscillation; and the north and tropical Pacific circulation, as manifest in El Niño–Southern Oscillation, the Pacific North American pattern, and the Pacific Decadal Oscillation. In each of these two regions, we highlight the major goals and results of recent synoptic research. [ABSTRACT FROM PUBLISHER]

The semi-arid US Intermountain West is characterized by complex hydroclimatic variability, influenced both by topography and by atmosphere and ocean processes operating over a large range of time and space scales. Understanding climate–hydrology interactions has become increasingly important as demands on water resources grow from both within and beyond the region, particularly in light of projected climate changes. This paper reviews key atmospheric and oceanic controls that impact the Intermountain West’s water supply, how those controls vary over multiple timescales, the tree-ring record of hydroclimatic variability in the region, projected climate change impacts, and research needs for the future. Water availability in the Intermountain West is largely influenced by interrelated atmospheric features that include the strength and position of the Pacific subtropical high, the intensity and geographic location of the Aleutian low, the latitude of the westerly storm track, and teleconnections such as the Pacific North American pattern and the El Niño−Southern Oscillation system. The tree-ring record of pre-instrumental conditions in the Intermountain West indicates that there have been droughts in the past that were more severe than those experienced in the historical record. Climate model projections of future moisture-related changes, including decreased snowpack and changing seasonality of precipitation, may exacerbate strain on the region’s water supply. Advances in climate modeling and in our understanding of climate variability over multiple time and space scales would improve capacity for water resource management in the Intermountain West. [ABSTRACT FROM PUBLISHER]

In the coastal lowlands of Mozambique, an expansion of savannas at the cost of forests has been attributed to anthropogenic influence. There are few investigations that have studied vegetation dynamics over the long term. Pollen analysis from two sedimentary cores in the Chibuene area, 7 km south of Vilanculos presented in this paper show that the coastal area 1600 years ago consisted of a mosaic of forests, Miombo woodlands and grasslands. The data also show that the area supported extensive forests in the past until AD 1400-1600 when the forests declined dramatically. Changing settlement patterns, as suggested from archaeological excavations, cannot be correlated with the forest decline and the charcoal abundance, in the sedimentary cores does not suggest an intensification of farming. Instead the decline of forests appears to be temporally correlated with a prolonged period of repeated dry spells associated with the 'Little Ice Age', which caused a shift in vegetation whereby typical forest species as Trema, Celtis and Moraceae were outcompeted on account of the droughts. This study challenges rooted assumptions about the cause of decline of forests in the coastal region. It also suggests that the forest fragments present on the Mozambique coast today are naturally subject to threat from climatic stress and as such are highly sensitive areas to future climate change. [ABSTRACT FROM AUTHOR]

On the basis of sediment and pollen analyses of a radiocarbon-dated sediment sequence from Lake Joux in the Swiss Jura Mountains (west-central Europe), this paper presents a high-resolution record of lake-level and vegetation changes for the last millennium. The lake-level record makes it possible to determine that lowstands of the water-table dominated at c. AD 1200-1400, and from 1720 onward, with interruptions by short-lived rise events at c. AD 1340 and 1840. Highstands prevailed at c. AD 1100, and around AD 1450, 1550 and 1700. The comparison of the Joux lake-level record with a solar irradiance record based on cosmogenic nucleides supports the hypothesis of a major solar forcing of climate variations in west-central Europe over the last millennium. In agreement with other palaeohydrological records established in Western Europe and in the central North Atlantic Ocean, the Joux lake-level record suggests that, on a multicentennial scale, the period of the 'Little Ice Age' coincided in the European mid-latitudes with wetter climatic conditions, and probably with an increase in summer precipitation. Variations in the hydrological cycle appear to have been associated with changes in the general atmospheric circulation pattern, probably coupled with variations in oceanic circulation and solar activity. The Joux record also points to changes in water resources expected to result from ongoing global warming. Finally, despite the severe climatic conditions which prevail in the Joux Valley, the human impact history at Lake Joux over the last millennium seems to reflect political choices and economic context more than climatic changes. [ABSTRACT FROM AUTHOR]

Interpretation of proxy-climate records depends on a thorough understanding of the proxy—climate relationship. Peatland surface wetness records have been interpreted as reflecting changes between cool and/or wet conditions and warm and/or dry conditions. This paper analyses a high-resolution record of reconstructed water-table changes based on testate amoebae analysis in relation to instrumental weather records since AD 1775. Replicate peat records are reconciled by multiple chronological techniques and tuning, and demonstrate that the reconstructions preserve many replicable high-frequency changes. Watertable variability is highly correlated with the total seasonal moisture deficit (precipitation — evapotranspiration, P-E) expressed as the sum of all months with negative P-E. The reconstructed water-table record reflects antecedent periods of 5 or 10 years (maximum r² = 52.4%) and proxy bog surface wetness records can therefore be interpreted as reflecting the length and intensity of the summer water deficit period. Response surfaces of the summer deficit in relation to temperature and precipitation variability support the hypothesis that the summer deficit is determined by summer precipitation in mid-latitude oceanic peatlands and that summer temperature plays a greater but still subsidiary role in higher latitude, continental settings. These relationships apply for all plausible past Holocene climate changes and future twenty-first century climate scenarios. Non-linear responses to longer-term climate states prevent the direct application of a calibration of the reconstructed water-table records to infer quantitative estimates of climate variables. Models that combine peat accumulation, mire growth and hydrological processes are required to undertake this task. [ABSTRACT FROM AUTHOR]

This paper describes an approach that gives an estimate of the reconstructive skill of a proxy-based palaeoclimatological reconstruction. Uncertainties in proxy data are likely to be reflected in variations in reconstructive skill of the proxy-based climatic reconstructions. The method is based on making an ensemble of reconstructions, providing a probability distribution of each reconstruction estimate. The relative breadth of the distribution for a particular reconstructed value should give an indication of the reconstructive skill. The ensemble reconstruction approach draws on the ensemble prediction system as used for operational weather forecasting. The ensemble reconstruction approach is tested using a recent multiproxy reconstruction of the winter North Atlantic Oscillation (NAO) index. It is shown that the ensemble approach provides a representation of the degree of certainty associated with the reconstructed NAO-index values. [ABSTRACT FROM AUTHOR]

This paper reviews recently published literature, most of which was published in Chinese, and searches for regional patterns of Holocene changes useful in depicting global patterns. The Holocene in the Xinjiang region can be divided into three stages: a warming and dry early stage (from 11 ∼ 10 to 8 ∼ 7 ka BP), a warm and wet middle stage (from 8 ∼ 7 to 4.5 ∼ 3 ka BP) and a fluctuating cool and dry late stage (since 4.5 ∼ 3 ka BP). The Holocene in the northern Tibetan Plateau can also be divided into three stages: a warming and wet stage (from 10.5 ∼ 10 to 5 ∼ 4 ka BP), followed by a variable drying and probably warm stage (5 ∼ 4 to 3 ka BP) and ending with a cool and dry stage (since 3 ka BP). In the Inner Mongolian Plateau, the early Holocene (from 10.5 ∼ 9.5 to 8 ∼ 7.5 ka BP) was warming and dry, and a warm and wet climate occurred from 7.5 to 3.5, during which the best time was 6.3–3.8 ka BP; the climate has been variably drying and probably cooling since 3.5 ka BP. In the northwestern part of the Loess Plateau, several Holocene palaeosols have been identified (10–9, 7.5–5, 4–3 and 2.7–2 ka BP) with the 7.5–5 ka BP palaeosol being most strongly expressed. The best-developed palaeosol-equivalent in major valleys is a swamp-wetland facies deposited between 8885 and 3805 14C yr BP under an extremely wet regime. The climate has fluctuated significantly at least three times around a dry and probably cool regime after the swamp-wetland facies-depositional period. Our summary shows that the Holocene Climatic Optimum occurred nearly contemporaneously (8–5 ka BP) at all sites in the Xinjiang region, in the Inner Mongolian Plateau and in the northwestern part of the Loess Plateau. A warming and wet early Holocene (10–8 ka BP) in the northern Tibetan Plateau is most likely related to high effective soil moisture resulting from snow and ice melting. We propose here that the middle Holocene Climatic Optimum (8–5 ka BP) in arid to semi-arid China was primarily a delayed response of the low latitude oceans to high latitude peak insolation (9–8 ka BP). [ABSTRACT FROM AUTHOR]