The Statistical Significance Test of Regional Climate Change Caused by Land Use and Land Cover Variation in West China

The West Development Policy being implemented in China is causing significant land use and land cover （LULC） changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Database （GLCCD） that characterizes the lower boundary conditions, the regional climate model RIEMS-TEA is used to simulate possible impacts of the significant LULC variation. The model was run for five continuous three-month periods from 1 June to 1 September of 1993, 1994, 1995, 1996, and 1997, and the results of the five groups are examined by means of a student t-test to identify the statistical significance of regional climate variation. The main results are： （1） The regional climate is affected by the LULC variation because the equilibrium of water and heat transfer in the air-vegetation interface is changed. （2） The integrated impact of the LULC variation on regional climate is not only limited to West China where the LULC varies, but also to some areas in the model domain where the LULC does not vary at all. （3） The East Asian monsoon system and its vertical structure are adjusted by the large scale LULC variation in western China, where the consequences are the enhancement of the westward water vapor transfer from the east oast and the relevant increase of wet-hydrostatic energy in the middle-upper atmospheric layers. （4） The ecological engineering in West China affects significantly the regional climate in Northwest China, North China and the middle-lower reaches of the Yangtze River; there are obvious effects in South, Northeast, and Southwest China, but minor effects in Tibet.     

Evaluation of satellite derived land cover characteristics for global climate modelling

A preliminary evaluation of the suitability of a currently operational satellite data archive, namely the NOAA global vegetation index (GVI) product, as a basis for providing information on land cover characteristics for global climate modelling has been undertaken by comparing it to several existing data bases of soil and vegetation cover. It is found that temporal composites of GVI values often continue to change beyond the accepted compositing period of three or four weeks. In extreme cases the addition of another week to the compositing period changes over 90% of the pixels. Selection of GVI class boundaries is found to be rather hard and is probably a strong function of the classification technique employed. The resulting GVI classes are generally explicable by reference to other archival material although this study identifies some specific cases of locational divergence from consensus classification. In these locations monitoring with the GVI may prove useful. More importantly GVI values for very similar ecotypes vary widely from region to region thus rendering global classification very dangerous despite the graphic appeal of coloured maps. In its present form the NOAA global vegetation index is not a useful data source for climate modellers.Now at the Institute of Hydrology, Wallingford, U.K.     

Land use and land cover change in Arctic Russia: Ecological and social implications of industrial development

Sizable areas in northwestern arctic Russia have undergone fundamental change in recent decades as the exploration of vast hydrocarbon deposits has intensified. We undertook two case studies on the influence of oil and gas activities within neighbouring federal districts in the tundra zone. Employing a strongly interdisciplinary approach, we studied the ecological, spatial and social dimensions of the visible and perceived changes in land use and land cover. Our data are derived from field sampling, remote sensing and intensive participant observation with indigenous Nenets reindeer herders and non-indigenous workers. Important trends include the rapid expansion of infrastructure, a large influx of workers who compete for freshwater fish, and extensive transformation from shrub- to grass- and sedge-dominated tundra. The latter represents an alternative ecosystem state that is likely to persist indefinitely. On terrain disturbed by off-road vehicle traffic, reindeer pastures’ vegetation regenerates with fewer species among which grasses and sedges dominate, thus reducing biodiversity. To have maximum forage value such pastures must be accessible and free of trash, petro-chemicals and feral dogs. We found that a wide range of direct and indirect impacts, both ecological and social, accumulate in space and time such that the combined influence is effectively regional rather than local, depending in part on the placement of facilities. While incoming workers commonly commit poaching, they also serve as exchange partners, making barter for goods possible in remote locations. In general, the same positive and negative impacts of the presence of industry were mentioned in each study region. Even using very high-resolution remote sensing data (Quickbird-2) it is not possible to determine fully the amount of degraded territory in modern oil and gas fields. With regard to policy, both biophysical and social impacts could be substantially reduced if information flow between herders and workers were to be optimized.     

The tools of climate adaptation policy: analysing instruments and instrument selection

Governments have a key role to play in the process of climate adaptation, through the development and implementation of public policy. Governments have access to a diverse array of instruments that can be employed to adapt their operations and influence the behaviour of individuals, organizations, and other governments. However, the choice of policy instrument is political, because it affects the distribution of benefits and costs, and entrenches institutional procedures and resources that are difficult to redeploy. This article identifies four key governing resources that governments employ in the service of adaptation and analyses these resources using criteria drawn from the policy studies literature. For each category, specific policy instruments are described, and examples are provided to illustrate how they have been used in particular jurisdictions. The article also discusses instrument selection, focusing on trade-offs among the instrument attributes, processes for setting the stage for instrument choice, jurisdictional constraints on instrument selection, and ways to avoid negative vertical and horizontal policy interplay.

Policy relevance

Adaptation is a nascent field of public policy, and courses of action to reduce vulnerability and build adaptive capacity are in their infancy. This article contributes to policy development and analysis by identifying the range of policy instruments available to governments and analysing concrete ways in which they are employed to implement adaptation policy objectives. Taking stock of these adaptation tools and comparing their behavioural assumptions and attributes helps to illuminate potential policy options, and to evaluate their technical viability, political acceptability, and economic feasibility. Providing examples of how these instruments have been implemented successfully in other jurisdictions offers ideas and lessons for public officials.     

Satellite monitoring of global land cover changes and their impact on climate

Land cover is a crucial, spatially and temporally varying component of global carbon and climate systems. Therefore accurate estimation and monitoring of land cover changes is important in global change research. Although, land cover has dramatically changed over the last few centuries, until now there has been no consistent way of quantifying the changes globally.In this study we used long-term climate, soils data along with coarse resolution satellite observations to quantify the magnitude and spatial extent of global land cover changes due to anthropogenic processes. Differences between potential leaf area index, derived from climate-soil-leaf area equilibrium and actual leaf area index obtained from satellite data were used to estimate changes in land cover.Forest clearing for agriculture and irrigated farming in arid and semi-arid lands are found to be two major sources of climatically important land cover changes. Satellite derived Spectral Vegetation indices (SV I) and surface temperatures (T s) show strong impact of land cover changes on climatic processes. Irrigated agriculture in dry areas increased energy absorption and evapotranspiration (ET) compared to natural vegetation. On the other hand, forest clearing for crops decreased energy absorption andET. A land cover classification and monitoring system is proposed using satellite derivedSV I andT s that simultaneously characterize energy absorption and exchange processes. This completely remote sensing based approach is useful for monitoring land cover changes as well as their impacts on climate. Monitoring the spatio-temporal dynamics of land cover is possible with current operational satellites, and could be substantially improved with the Earth Observing System (EOS) era satellite sensors.     

Influence of modern land cover on the climate of the United States

I have used a high-resolution nested climate modeling system to test the sensitivity of regional and local climate to the modern non-urban land cover distribution of the continental United States. The dominant climate response is cooling of surface air temperatures, particularly during the warm-season. Areas of statistically significant cooling include areas of the Great Plains where crop/mixed farming has replaced short grass, areas of the Midwest and southern Texas where crop/mixed farming has replaced interrupted forest, and areas of the western United States containing irrigated crops. This statistically significant warm-season cooling is driven by changes in both surface moisture balance and surface albedo, with changes in surface moisture balance dominating in the Great Plains and western United States, changes in surface albedo dominating in the Midwest, and both effects contributing to warm-season cooling over southern Texas. The simulated changes in surface moisture and energy fluxes also influence the warm-season atmospheric dynamics, creating greater moisture availability in the lower atmosphere and enhanced uplift aloft, consistent with the enhanced warm-season precipitation seen in the simulation with modern land cover. The local and regional climate response is of a similar magnitude to that projected for future greenhouse gas concentrations, suggesting that the climatic effects of land cover change should be carefully considered when crafting policies for regulating land use and for managing anthropogenic forcing of the climate system.     

Modeling land use and cover as part of global environmental change

Land use and cover changes are important elements of the larger problem of global environmental change. Landuse patterns result in landcover changes that cumulatively affect the global biosphere and climate. We describe efforts to analyze the driving forces behind land transformations and to create land use models that can be linked to other types of global change models. Two efforts to model land use in the U.S. are reviewed. One projects aggregate agricultural, forest, and range land, and the other attempts to model forest land use change at the parcel scale in two mountain landscapes. We conclude with suggestions for new approaches that could clarify the role of land use/cover change in global change and in natural resources management.     

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     

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.     

气候变化适应行动实施框架

气候变化适应对脆弱地区和贫困群体更为重要。尽管我国急需采取适应行动,但由于缺乏可操作性的模式和评估方法,目前实际的适应行动还略显滞后。本文建立了一个适应行动实施框架,主要包含六个核心步骤,从气候风险、适应目标、适应措施、技术优化、实施示范到监测评估,基本涵盖了适应行动的关键内容。框架的构建具有一定的通用性和借鉴性,可以帮助适应实施者开发综合和战略性的适应措施。适应行动框架是一个开放和可更新的体系,可根据实践过程中新的认识,对适应行动做一定的再设计和调整,实施过程中还可提炼适应的基本信息和确定适应的优化技术。     

Legacies of 19th century land use shape contemporary forest cover

Historic land use can exert strong land-use legacies, i.e., long-lasting effects on ecosystems, but the importance of land-use legacies, alongside other factors, for subsequent forest-cover change is unclear. If past land use affects rates of forest disturbance and afforestation then this may constrain land use planning and land management options, and legacies of current land management may constrain future land use. Our goal was to assess if and how much land-use legacies affect contemporary forest disturbance, and the abundance of different forest types in the Carpathian region in Eastern Europe (265,000 km², encompassing parts of Poland, Slovakia, Ukraine, Romania, Hungary, and Czech Republic). We modeled contemporary forest disturbance (based on satellite image analysis from 1985 to 2010) as a function of historic land use (based on digitized topographic maps from 1860 and 1960). Contemporary forest disturbance was strongly related to historic land use even when controlling for environmental, accessibility and socio-political variation. Across the Carpathian region, the odds of forest disturbance were about 50% higher in areas that were not forested in 1860 (new forests) compared to areas that were forested then (old forests). The forest disturbance in new forests was particularly high in Poland (88% higher odds), Slovakia (69%) and Romania (67%) and persisted across the entire range of environmental, accessibility and socio-political variation. Reasons for the observed legacy effects may include extensive plantations outside forest ranges, predominantly spruce, poplar, and black locust, which are prone to natural disturbances. Furthermore, as plantations reach harvestable age of about 70 years for pulp and 120 year for saw-timber production, these are likely to be clear-cut, producing the observed legacy effects. Across the Carpathians, forest types shifted towards less coniferous cover in 2010 compared to the 1860s and 1960s likely due to extensive historic conifer harvest, and to recent natural disturbance events and clear-cuts of forest plantations. Our results underscore the importance of land-use legacies, and show that past land uses can greatly affect subsequent forest disturbance for centuries. Given rapid land use changes worldwide, it is important to understand how past legacies affect current management and what the impact of current land management decisions may be for future land use.     

Numerical simulation of the impact of land cover change on regional climate in China

Land use and land cover change (LUCC) can modify the physical and thermodynamic characteristics of the land surface, including surface roughness, albedo, and vegetation fraction, among others. These direct changes can result in a series of impacts on regional climate. In this paper, the simulated results over China under the scenario of LUCC using weather research and forecasting model are presented. The period for the simulation is from December 2006 to December 2011. Two experiments are initialized by the LUCC datasets derived from the MODIS data of 2001 and 2008, respectively. The results show that the LUCC in most areas of China reduces the surface albedo and increases the surface temperature. Especially in the Hetao Plain, the magnitude of increased surface temperature is above 0.5 °C in winter, and the increase in winter is more obvious than in summer. The precipitation in the Hetao Plain increases. The sensible heat in most parts of East China is reduced, while the latent heat is increased in most areas of China.     

A dampened land use change climate response towards the tropics

In climate simulations we find a pronounced meridional (equator to pole) gradient of climate response to land cover change. Climate response approaches zero in the tropics, and increases towards the poles. The meridional gradient in climate response to land cover change results from damping feedbacks in the tropics, rather than from polar amplification. The main cause for the damping in the tropics is the decrease in cloud cover after deforestation, resulting in increased incoming radiation at the surface and a lower planetary albedo, both counteracting the increase in surface albedo with deforestation. In our simulations, deforestation was also associated with a decrease in sensible heat flux but not a clear signal in evaporation. Meridional differences in climate response have implications for attribution of observed climate change, as well as for climate change mitigation strategies.     

Hard and soft paths for climate change adaptation

Amory Lovins’ distinction between ‘soft’ and ‘hard’ paths of energy technologies is applied, mutatis mutandis, to humanity's efforts to adapt to climate change. It is argued that hard adaptive measures involve capital-intensive, large, complex, inflexible technology and infrastructure, whereas soft adaptive measures prioritize natural capital, community control, simplicity and appropriateness. The prevalence of these two types of adaptation pathways is illustrated through two case studies from the Maldives: The Safer Island Development Program and the Integrating Climate Change Risks Program. Policymakers must be aware that hard and soft adaptation measures may trade off with each other, and give both paths due consideration.     

Evaluating the impacts of land use and land cover changes on surface air temperature using the WRF-mosaic approach

如何量化土地利用/覆盖变化(LUCC)对区域气候的影响,是人类活动影响气候变化研究中的一个难点。本文利用卫星遥感反映过去三十年东亚区域土地利用变化数据,基于Mosaic近似考虑土地利用及其变化次网格尺度过程,量化了LUCC对地表辐射收支及气温的影响。过去三十年土地利用/覆盖变化对东亚区域总体呈降温效应(中国东部地区增温效应),LUCC导致的地表反照率变化影响地表辐射收支,中国和东亚区域的辐射强迫分别为-0.56 W m~(-2)和-0.50 W m~(-2)。