Sensitivity of carbon cycling in the European Alps to changes of climate and land cover

Assessments of the impacts of global change on carbon stocks in mountain regions have received little attention to date, in spite of the considerable role of these areas for the global carbon cycle. We used the regional hydro-ecological simulation system RHESSys in five case study catchments from different climatic zones in the European Alps to investigate the behavior of the carbon cycle under changing climatic and land cover conditions derived from the SRES scenarios of the IPCC. The focus of this study was on analyzing the differences in carbon cycling across various climatic zones of the Alps, and to explore the differences between the impacts of various SRES scenarios (A1FI, A2, B1, B2), and between several global circulation models (GCMs, i.e., HadCM3, CGCM2, CSIRO2, PCM). The simulation results indicate that the warming trend generally enhances carbon sequestration in these catchments over the first half of the twenty-first century, particularly in forests just below treeline. Thereafter, forests at low elevations increasingly release carbon as a consequence of the changed balance between growth and respiration processes, resulting in a net carbon source at the catchment scale. Land cover changes have a strong modifying effect on these climate-induced patterns. While the simulated temporal pattern of carbon cycling is qualitatively similar across the five catchments, quantitative differences exist due to the regional differences of the climate and land cover scenarios, with land cover exerting a stronger influence. The differences in the simulations with scenarios derived from several GCMs under one SRES scenario are of the same magnitude as the differences between various SRES scenarios derived from one single GCM, suggesting that the uncertainty in climate model projections needs to be narrowed before accurate impact assessments under the various SRES scenarios can be made at the local to regional scale. We conclude that the carbon balance of the European Alps is likely to shift strongly in the future, driven mainly by land cover changes, but also by changes of the climate. We recommend that assessments of carbon cycling at regional to continental scales should make sure to adequately include sub-regional differences of changes in climate and land cover, particularly in areas with a complex topography.     

Scenarios of land use and land cover change in the conterminous United States: Utilizing the special report on emission scenarios at ecoregional scales

Global environmental change scenarios have typically provided projections of land use and land cover for a relatively small number of regions or using a relatively coarse resolution spatial grid, and for only a few major sectors. The coarseness of global projections, in both spatial and thematic dimensions, often limits their direct utility at scales useful for environmental management. This paper describes methods to downscale projections of land-use and land-cover change from the Intergovernmental Panel on Climate Change's Special Report on Emission Scenarios to ecological regions of the conterminous United States, using an integrated assessment model, land-use histories, and expert knowledge. Downscaled projections span a wide range of future potential conditions across sixteen land use/land cover sectors and 84 ecological regions, and are logically consistent with both historical measurements and SRES characteristics. Results appear to provide a credible solution for connecting regionalized projections of land use and land cover with existing downscaled climate scenarios, under a common set of scenario-based socioeconomic assumptions.     

A comparison of a GCM response to historical anthropogenic land cover change and model sensitivity to uncertainty in present-day land cover representations

This study assesses the sensitivity of the fully coupled NCAR-DOE PCM to three different representations of present-day land cover, based on IPCC SRES land cover information. We conclude that there is significant model sensitivity to current land cover characterization, with an observed average global temperature range of 0.21 K between the simulations. Much larger contrasts (up to 5 K) are found on the regional scale; however, these changes are largely offsetting on the global scale. These results show that significant biases can be introduced when outside data sources are used to conduct anthropogenic land cover change experiments in GCMs that have been calibrated to their own representation of present-day land cover. We conclude that hybrid systems that combine the natural vegetation from the native GCM datasets combined with human land cover information from other sources are best for simulating such impacts. We also performed a prehuman simulation, which had a 0.39 K ~higher average global temperature and, perhaps of greater importance, temperature changes regionally of about 2 K. In this study, the larger regional changes coincide with large-scale agricultural areas. The initial cooling from energy balance changes appear to create feedbacks that intensify mid-latitude circulation features and weaken the summer monsoon circulation over Asia, leading to further cooling. From these results, we conclude that land cover change plays a significant role in anthropogenically forced climate change. Because these changes coincide with regions of the highest human population this climate impact could have a disproportionate impact on human systems. Therefore, it is important that land cover change be included in past and future climate change simulations.     

21世纪增暖情景下西北太平洋热带气旋频数的预估

利用IPCC发布的5个全球气候模式在高（SRES A2）、低（SRES B1）两种不同排放情景下的预报集成结果,对21世纪大尺度环境进行分析,进而对西北太平洋夏季热带气旋（TC）的频数进行预估。结果表明：两种情景下热带西北太平洋均呈现500 hPa位势高度偏高、太平洋东部海表温度偏高、低层菲律宾以东为异常反气旋性环流控制的特征。这种大尺度环境不利于TC生成,在高排放情景下或21世纪中叶后该环境特征更显著。未来TC频数总体呈减少的趋势,低排放情景下的TC频数变化趋势比高排放情境下平缓,TC频数存在年代际和年际变化。     

中国西部积雪的2—3周振荡及其对大气环流异常的影响

本文能过对美国宇航局Ｎｉｍｂｕｓ－７卫星观测的１９７９－１９８６年中国西部积雪资料的分析发现，２－３周的低频振荡现象普遍存在并与大气环流异常密切相关；大气环流对半年积雪２－３周的低频振荡有着明显的线性响应；冬半年积雪的这种低频振荡能激发出北半球５００ｈＰａ高度场准定常Ｒｏｓｓｂｙ波，并通过二维的Ｒｏｓｓｂｙ波能量频散而影响到北美。     

Daily relative humidity projections in an Indian river basin for IPCC SRES scenarios

A two-stage methodology is developed to obtain future projections of daily relative humidity in a river basin for climate change scenarios. In the first stage, Support Vector Machine (SVM) models are developed to downscale nine sets of predictor variables (large-scale atmospheric variables) for Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (SRES) (A1B, A2, B1, and COMMIT) to R _H in a river basin at monthly scale. Uncertainty in the future projections of R _H is studied for combinations of SRES scenarios, and predictors selected. Subsequently, in the second stage, the monthly sequences of R _H are disaggregated to daily scale using k-nearest neighbor method. The effectiveness of the developed methodology is demonstrated through application to the catchment of Malaprabha reservoir in India. For downscaling, the probable predictor variables are extracted from the (1) National Centers for Environmental Prediction reanalysis data set for the period 1978–2000 and (2) simulations of the third-generation Canadian Coupled Global Climate Model for the period 1978–2100. The performance of the downscaling and disaggregation models is evaluated by split sample validation. Results show that among the SVM models, the model developed using predictors pertaining to only land location performed better. The R _H is projected to increase in the future for A1B and A2 scenarios, while no trend is discerned for B1 and COMMIT.     

Rossby wave propagation into the tropics in two GFDL general circulation models

During the northern winter the eastern Pacific is characterized by upper level westerly flow extending from the equator into the midlatitudes of both hemispheres. Theoretical and simple modeling studies suggest that such a region should favor the penetration of Rossby waves into the tropics from higher latitudes. Observational results by Kiladis and Weickmann using 200 mb data indicate that Rossby waves do indeed propagate freely into the tropical eastern Pacific during the northern winter from the Asian jet exit region. They also confirmed that cross-equatorial dispersion of energy from the Northern into the Southern Hemisphere occurs frequently. The present study examines these interactions in climatological runs of two GFDL GCMs. The northern wintertime mean states of these models are characterized by a rather realistically simulated upper level westerly regime in the tropical Pacific. Despite the relative weakness of the Asian jet and wave activity with respect to observations, propagation of Rossby waves into the tropics is present in both models, and these waves are strongly positively tilted as seen in the observations. A momentum budget of the zonal wind and E vector diagnostics over the tropical Pacific indicate that these transients are an important component of the momentum balance of the equatorial westerlies in both the observations and in the models.This paper was presented at the Second International Conference on Modelling of Global Climate Variability, held in Hamburg 7–11 September 1992 under the auspices of the Max Planck Institute for Meteorology. Guest Editor for these papers is L. Dümenil     

夏季东亚高空副热带西风急流季节内异常的环流特征及前兆信号

位于东亚中纬度上空的东亚高空副热带西风急流是东亚季风环流系统中的重要成员,我国夏季降水雨带的季节内变化受东亚高空副热带西风急流位置季节内异常变化影响。根据1979~2008年中国降水资料、NCEP/NCAR再分析资料以及NOAA ERSST V3月平均海表温度资料,利用统计分析和物理量诊断方法对夏季东亚高空副热带西风急流位置季节内异常的东亚大气环流特征及外强迫信号的物理过程进行了探讨。研究指出:6月东亚高空副热带西风急流位置异常主要受欧亚大陆中高纬东传的Rossby波列位相变化影响,春季北大西洋海温异常是欧亚大陆中高纬度Rossby波列位相变化的最显著的外强迫信号;7月东亚高空副热带西风急流位置异常主要受西太平洋热带向副热带传播的Rossby波列位相变化影响,春季西太平洋热带海温异常是西太平洋热带向副热带传播的Rossby波列位相变化的最显著的外强迫信号;8月东亚高空副热带西风急流位置异常主要受南亚大陆向东亚大陆热带、副热带传播的Rossby波列位相变化影响,春季印度洋海温异常是南亚大陆向东亚大陆热带、副热带传播的Rossby波列位相变化的最显著的外强迫信号。     

Simulated impacts of historical land cover changes on global climate in northern winter

This ten-year general circulation model experiment compared a simulation where land surface boundary conditions were represented by observed, present day land cover to a simulation where the surface was represented by natural, potential land cover conditions. As a result of these estimated changes in historical land cover, significant temperature and hydrology changes affected tropical land surfaces, where some of the largest historical disruptions in total vegetation biomass have occurred. Also of considerable interest because of their broad scope and magnitude were changes in high-latitude Northern Hemisphere winter climate which resulted from changes in tropical convection, upper-level tropical outflow, and the generation of low-frequency tropical waves which propagated to the extratropics. These effects combined to move the Northern Hemisphere zonally averaged westerly jet to higher latitudes, broaden it, and reduce its maximum intensity. Low-level easterlies were also reduced over much of the tropical Pacific basin while positive anomalies in convective precipitation occurred in the central Pacific. Globally averaged changes were small. Comparisons of recent, observed trends in tropical and Northern Hemisphere, mid-latitude climate with these simulations suggests an interaction between the climatic effects of historical land cover changes and other modes of climate variability. Received: 8 September 1998 / Accepted: 31 July 1999     

Improvements in a half degree atmosphere/land version of the CCSM

A decadal climate projection between 1980 and 2030 using a nominal 0.5° resolution in the atmosphere and land components has been performed using the Community Climate System Model, version 3.5. The mean climate is compared to a companion simulation using a nominal 2° resolution in the atmosphere and land components. The increased atmosphere resolution has several benefits, and produces a significantly better mean climate. The maximum sea surface temperature biases in the major upwelling regions, including the West Coast of the USA, are reduced by more than 60%. Precipitation patterns are improved in the summer Asian monsoon, mostly due to the better resolved orography, and in the eastern tropical Pacific Ocean south of the equator. The improved precipitation patterns lead to better river flows in many rivers worldwide. The atmospheric circulation in the Arctic also improves, which leads to a better regional sea ice thickness distribution in the Arctic Ocean.     

ENSO teleconnections in projections of future climate in ECHAM5/MPI-OM

The teleconnections of the El Niño/Southern Oscillation (ENSO) in future climate projections are investigated using results of the coupled climate model ECHAM5/MPI-OM. For this, the IPCC SRES scenario A1B and a quadrupled CO₂ simulation are considered. It is found that changes of the mean state in the tropical Pacific are likely to condition ENSO teleconnections in the Pacific North America (PNA) region and in the North Atlantic European (NAE) region. With increasing greenhouse gas emissions the changes of the mean states in the tropical and sub-tropical Pacific are El Niño-like in this particular model. Sea surface temperatures in the tropical Pacific are increased predominantly in its eastern part and redistribute the precipitation further eastward. The dynamical response of the atmosphere is such that the equatorial east–west (Walker) circulation and the eastern Pacific inverse Hadley circulation are decreased. Over the subtropical East Pacific and North Atlantic the 200 hPa westerly wind is substantially increased. Composite maps of different climate parameters for positive and negative ENSO events are used to reveal changes of the ENSO teleconnections. Mean sea level pressure and upper tropospheric zonal winds indicate an eastward shift of the well-known teleconnection patterns in the PNA region and an increasing North Atlantic oscillation (NAO) like response over the NAE region. Surface temperature and precipitation underline this effect, particularly over the North Pacific and the central North Atlantic. Moreover, in the NAE region the 200 hPa westerly wind is increasingly related to the stationary wave activity. Here the stationary waves appear NAO-like.     

Probabilistic evaluation of climate change impacts on paddy rice productivity in Japan

Projecting the impacts of climate change includes various uncertainties from physical, biophysical, and socioeconomic processes. Providing a more comprehensive impact projection that better represents the uncertainties is a priority research issue. We used an ensemble-based projection approach that accounts for the uncertainties in climate projections associated with general circulation models (GCMs) and biophysical and empirical parameter values in a crop model. We applied the approach to address the paddy rice yield change in Japan in the 2050s (2046–2065) and 2090s (2081–2100) relative to the 1990s (1981–2000). Seventeen climate projections, nine (eight) climate projections performed by seven (six) GCMs conditional on the Special Report on Emission Scenarios (SRES) A1B (A2), were included in this projection. In addition, 50 sets of biophysical and empirical parameter values of a large-scale process-based crop model for irrigated paddy rice were included to represent the uncertainties of crop parameter values. The planting windows, cultivation practices, and crop cultivars in the future were assumed to be the same as the level in the baseline period (1990s). The resulting probability density functions conditioned on SRES A1B and A2 indicate projected median yield changes of +?17.2% and +?26.9% in Hokkaido, the northern part of Japan, in the 2050s and 2090s with 90% probability intervals of (??5.2%, +?40.3%) and (+?6.3%, +?51.2%), relative to the 1990s mean yield, respectively. The corresponding values in Aichi, on the Pacific side of Western Japan, are 2.2% and ??0.8%, with 90% probability intervals of (??15.0%, +?14.9%) and (??33.4%, +?17.9%), respectively. We also provided geographical maps of the probability that the future 20-year mean yield will decrease and that the future standard deviation of yield for 20 years will increase. Finally, we investigated the relative contributions of the climate projection and crop parameter values to the uncertainty in projecting yield change in the 2090s. The choice of GCM yielded a relatively larger spread of projected yield changes than that of the other factors. The choice of crop parameter values could be more important than that of GCM in a specific prefecture.     

The activity of convectively coupled equatorial waves in CMIP3 global climate models

This study evaluates the convectively coupled equatorial waves in ten coupled general circulation models (GCMs) in the twentieth century experiment from the Coupled Model Intercomparison Project phase 3 of the World Climate Research Programme. The antisymmetric bands in all GCMs are weaker than in observations, and the mixed Rossby-gravity (MRG) wave seems to be a mixture of the equatorial Rossby (ER) and tropical depression-type (TD-type) waves rather than a mixture of the ER and inertiogravity waves found in observations. The simulated TD-type wave is more organized than in observations with a quasilinear wavenumber–frequency relationship. In most GCMs, the two observed activity centers of the MRG and TD-type waves over the southern Indian Ocean and the southwestern Pacific cannot be separated; only one wave activity center is found over the Maritime Continent. The observed northwestward propagation of the TD-type wave over the western North Pacific is also not well simulated in the GCMs. The simulated active season of the MRG and TD-type waves over the northern hemisphere during the boreal summer and fall is much shorter than in observations. The models from CCSR utilizing the Pan and Randall scheme with the convection suppression simulate the realistic Kelvin wave activity with the maximum activity near the equator, while the wave activities filtered for the Kelvin wave in the other GCMs are similar to the extratropical Rossby wave with the maximum activity at higher latitudes. Likewise, only these two models produce a realistic seasonal cycle of the Kelvin wave activity.     

El Niño事件发生对南北半球大气环流异常的对称及非对称性影响及其机理分析

利用合成分析方法, 分析了1971～2003年间7个El Niño事件发生时南、北半球大气环流异常的对称与反对称特性。分析结果表明, El Niño事件发生期间, 在热带地区15°S～15°N大气环流异常以对称性为主, 但也有一定的反对称分量: 高度场异常和纬向风异常的对称性较强, 而经向风异常的反对称较强; 同时在El Niño事件演变的各阶段, 高度场异常和纬向风异常的变化较明显, 而经向风的变化较小, 高度场和风场异常在低层 (700 hPa) 和高层 (200 hPa) 呈明显的反位相分布。并且, 为探讨El Niño事件对南、北半球大气环流异常的非对称性影响的机理, 本研究进一步利用ERA－40逐日资料, 应用Hough函数分析了El Niño事件发生期间这些赤道波动的演变特征。结果表明, El Niño事件发生期间, 热带地区大气环流异常对称性较强的主要原因是对称性Rossby波异常较强, 而Rossby重力混合波异常对经向风场的反对称分量有重要作用; 并且, 研究结果还表明, 在El Niño事件发生期间, 热带东太平洋的海温正异常能够激发由对称性Rossby波和Kelvin波组成的Gill型环流异常。此外, 分析表明Hough函数在分析热带大气波动的对称性及反对称性上具有明显的优越性。     

热带积云对流加热在全球大气遥响应中的重要作用──数值试验结果

利用ＩＡＰ两层大气环流模式模拟研究了热带地区积云对流加热在大气对赤道东太平洋海温正异常响应中的作用。通过对积分结果进行分析发现：热带地区积云对流在大气对赤道东太平洋海温正异常的响应过程中起着非常重要的作用。若热带地区的积云对流加热减弱则大气中的遥响应（相关）型也减弱。同时我们还发现，热带地区的积云对流加热加强则响应场的３０—６０ｄ低频振荡也得到加强。     

Temperature Extremes from Canadian Regional Climate Model (CRCM) Climate Change Projections

Future climate projections of extreme events can help forewarn society of high-impact events and allow the development of better adaptation strategies. In this study a non-stationary model for Generalized Extreme Value (GEV) distributions is used to analyze the trend in extreme temperatures in the context of a changing climate and compare it with the trend in average temperatures.

The analysis is performed using the climate projections of the Canadian Regional Climate Model (CRCM), under an IPCC SRES A2 greenhouse gas emissions scenario, over North America. Annual extremes in daily minimum and maximum temperatures are analyzed. Significant positive trends for the location parameter of the GEV distribution are found, indicating an expected increase in extreme temperature values. The scale parameter of the GEV distribution, on the other hand, reveals a decrease in the variability of temperature extremes in some continental regions. Trends in the annual minimum and maximum temperatures are compared with trends in average winter and summer temperatures, respectively. In some regions, extreme temperatures exhibit a significantly larger increase than the seasonal average temperatures.

The CRCM projections are compared with those of its driving model and framed in the context of the Coupled Model Intercomparison Project, phase 3 (CMIP3) Global Climate Model projections. This enables us to establish the CRCM position within the CMIP3 climate projection uncertainty range. The CRCM is validated against the HadEX2 dataset in order to assess the CRCM representation of temperature extremes in the present climate. The validation is also framed in the context of CMIP3 validation results. The CRCM cold extremes validate better and are closer to the driving model and CMIP3 projections than the hot extremes.     

Projection of future climate change conditions using IPCC simulations, neural networks and Bayesian statistics. Part 2: Precipitation mean state and seasonal cycle in South America

Evaluating the response of climate to greenhouse gas forcing is a major objective of the climate community, and the use of large ensemble of simulations is considered as a significant step toward that goal. The present paper thus discusses a new methodology based on neural network to mix ensemble of climate model simulations. Our analysis consists of one simulation of seven Atmosphere–Ocean Global Climate Models, which participated in the IPCC Project and provided at least one simulation for the twentieth century (20c3m) and one simulation for each of three SRES scenarios: A2, A1B and B1. Our statistical method based on neural networks and Bayesian statistics computes a transfer function between models and observations. Such a transfer function was then used to project future conditions and to derive what we would call the optimal ensemble combination for twenty-first century climate change projections. Our approach is therefore based on one statement and one hypothesis. The statement is that an optimal ensemble projection should be built by giving larger weights to models, which have more skill in representing present climate conditions. The hypothesis is that our method based on neural network is actually weighting the models that way. While the statement is actually an open question, which answer may vary according to the region or climate signal under study, our results demonstrate that the neural network approach indeed allows to weighting models according to their skills. As such, our method is an improvement of existing Bayesian methods developed to mix ensembles of simulations. However, the general low skill of climate models in simulating precipitation mean climatology implies that the final projection maps (whatever the method used to compute them) may significantly change in the future as models improve. Therefore, the projection results for late twenty-first century conditions are presented as possible projections based on the “state-of-the-art” of present climate modeling. First, various criteria were computed making it possible to evaluate the models’ skills in simulating late twentieth century precipitation over continental areas as well as their divergence in projecting climate change conditions. Despite the relatively poor skill of most of the climate models in simulating present-day large scale precipitation patterns, we identified two types of models: the climate models with moderate-to-normal (i.e., close to observations) precipitation amplitudes over the Amazonian basin; and the climate models with a low precipitation in that region and too high a precipitation on the equatorial Pacific coast. Under SRES A2 greenhouse gas forcing, the neural network simulates an increase in precipitation over the La Plata basin coherent with the mean model ensemble projection. Over the Amazonian basin, a decrease in precipitation is projected. However, the models strongly diverge, and the neural network was found to give more weight to models, which better simulate present-day climate conditions. In the southern tip of the continent, the models poorly simulate present-day climate. However, they display a fairly good convergence when simulating climate change response with a weak increase south of 45°S and a decrease in Chile between 30 and 45°S. Other scenarios (A1B and B1) strongly resemble the SRES A2 trends but with weaker amplitudes.     

Parallel climate model (PCM) control and transient simulations

The Department of Energy (DOE) supported Parallel Climate Model (PCM) makes use of the NCAR Community Climate Model (CCM3) and Land Surface Model (LSM) for the atmospheric and land surface components, respectively, the DOE Los Alamos National Laboratory Parallel Ocean Program (POP) for the ocean component, and the Naval Postgraduate School sea-ice model. The PCM executes on several distributed and shared memory computer systems. The coupling method is similar to that used in the NCAR Climate System Model (CSM) in that a flux coupler ties the components together, with interpolations between the different grids of the component models. Flux adjustments are not used in the PCM. The ocean component has 2/3° average horizontal grid spacing with 32 vertical levels and a free surface that allows calculation of sea level changes. Near the equator, the grid spacing is approximately 1/2° in latitude to better capture the ocean equatorial dynamics. The North Pole is rotated over northern North America thus producing resolution smaller than 2/3° in the North Atlantic where the sinking part of the world conveyor circulation largely takes place. Because this ocean model component does not have a computational point at the North Pole, the Arctic Ocean circulation systems are more realistic and similar to the observed. The elastic viscous plastic sea ice model has a grid spacing of 27?km to represent small-scale features such as ice transport through the Canadian Archipelago and the East Greenland current region. Results from a 300?year present-day coupled climate control simulation are presented, as well as for a transient 1% per year compound CO₂ increase experiment which shows a global warming of 1.27?°C for a 10?year average at the doubling point of CO₂ and 2.89?°C at the quadrupling point. There is a gradual warming beyond the doubling and quadrupling points with CO₂ held constant. Globally averaged sea level rise at the time of CO₂ doubling is approximately 7?cm and at the time of quadrupling it is 23?cm. Some of the regional sea level changes are larger and reflect the adjustments in the temperature, salinity, internal ocean dynamics, surface heat flux, and wind stress on the ocean. A 0.5% per year CO₂ increase experiment also was performed showing a global warming of 1.5?°C around the time of CO₂ doubling and a similar warming pattern to the 1% CO₂ per year increase experiment. El Niño and La Niña events in the tropical Pacific show approximately the observed frequency distribution and amplitude, which leads to near observed levels of variability on interannual time scales.     

Atmospheric circulation anomalies due to 115 kyr BP climate forcing dominated by changes in the North Pacific Ocean

Climate at the time of inception of the Laurentide Ice Sheet (LIS) at ~115 kyr BP is simulated with the fully coupled NCAR Community Climate System Model (CCSM3) and compared to a simulated preindustrial climate (circa 1870) in order to better understand land surface and atmospheric responses to orbital and greenhouse cooling at inception. The interaction between obliquity and eccentricity produces maximum decrease in TOA insolation in JJA over the Arctic but increases occur over the tropics in DJF. The land surface response is dominated by widespread summer cooling in the Northern Hemisphere (NH), increases in snowfall, and decreases in melt rates and total precipitation. CCSM3 responds to the climate forcing at 115 kyr BP by producing incipient glaciation in the areas of LIS nucleation. We find that the inception of the LIS could have occurred with atmospheric circulation patterns that differ little from the present. The location of the troughs/ridges, mean flow over the Canadian Arctic and dominant modes of the atmospheric circulation are all very similar to the present. Larger changes in mean sea level pressure occur upstream of the inception region in the North Pacific Ocean and downstream in Western Europe. In the North Pacific region, the 115 kyr BP anomalies weaken both the Pacific high and Aleutian low making NH summers look more like the PREIND winters and vice versa. The occurrence of cold JJA anomalies at 115 kyr BP favors outbreaks of cold air not in the winter as in contemporary climates but during the summer instead and reinforces the cooling from orbital and GHG reductions. Increased poleward eddy transport of heat and moisture characterizes the atmospheric response in addition to reduced total cloud cover in the Arctic.     

Evaluation of hydrological effect of stakeholder prioritized climate change adaptation options based on multi-model regional climate projections

An integrated process involving participatory and modelling approaches for prioritizing and evaluating climate change adaptation options for the Kangsabati reservoir catchment is presented here. We assess the potential effects of climate change on water resources and evaluate the ability of stakeholder prioritized adaptation options to address adaptation requirements using the Water Evaluation And Planning (WEAP) model. Two adaptation options, check dams and increasing forest cover, are prioritized using pair-wise comparison and scenario analysis. Future streamflow projections are generated for the mid-21^st century period (2021–2050) using four high resolution (~25 km) Regional Climate Models and their ensemble mean for SRES A1B scenario. WEAP simulations indicate that, compared to a base scenario without adaptation, both adaptation options reduce streamflow. In comparison to check dams, increasing forest cover shows greater ability to address adaptation requirements as demonstrated by the temporal pattern and magnitude of streamflow reduction. Additionally, over the 30 year period, effectiveness of check dams in reducing streamflow decreases by up to 40 %, while that of forest cover increases by up to 47 %. Our study highlights the merits of a comparative assessment of adaptation options and we conclude that a combined approach involving stakeholders, scenario analysis, modelling techniques and multi-model projections may support climate change adaptation decision-making in the face of uncertainty.