The Experts below are selected from a list of 68307 Experts worldwide ranked by ideXlab platform
S.m. Sterling - One of the best experts on this subject based on the ideXlab platform.
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the impact of global Land Cover Change on the terrestrial water cycle
Nature Climate Change, 2013Co-Authors: S.m. Sterling, Agnès Ducharne, Jan PolcherAbstract:Human impacts on the terrestrial water cycle have the potential to influence hazards such as flooding and drought, so understanding the extent of our influence is an important research goal. A study utilizing estimates of evapotranspiration for different types of Land Cover and a database of Changes in use now shows that the extent of Land-Cover Change caused by people is already an important factor affecting the terrestrial water cycle.
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The impact of global Land-Cover Change on the terrestrial water cycle
Nature Climate Change, 2013Co-Authors: S.m. Sterling, Agnès Ducharne, Jan PolcherAbstract:Floods and droughts cause perhaps the most human suffering of all climate-related events; a major goal is to understand how humans alter the incidence and severity of these events by changing the terrestrial water cycle. Here we use over 1,500 estimates of annual evapotranspiration and a database of global Land-Cover Change to project alterations of global scale terrestrial evapotranspiration (TET) from current anthropogenic Land-Cover Change. Geographic modelling reveals that Land-Cover Change reduces annual TET by approximately 3,500 km 3 yr -1 (5%) and that the largest Changes in evapotranspiration are associated with wetLands and reservoirs. Land surface model simulations support these evapotranspiration Changes, and project increased runoff (7.6%) as a result of Land-Cover Changes. Next we create a synthesis of the major anthropogenic impacts on annual runoff and find that the net result is an increase in annual runoff, although this is uncertain. The results demonstrate that Land-Cover Change alters annual global runoff to a similar or greater extent than other major drivers, affirming the important role of Land-Cover Change in the Earth System. Last, we identify which major anthropogenic drivers to runoff Change have a mean global Change statistic that masks large regional increases and decreases: Land-Cover Change, Changes in meteorological forcing, and direct CO 2 effects on plants. © 2013 Macmillan Publishers Limited. All rights reserved.
Jan Polcher - One of the best experts on this subject based on the ideXlab platform.
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the impact of global Land Cover Change on the terrestrial water cycle
Nature Climate Change, 2013Co-Authors: S.m. Sterling, Agnès Ducharne, Jan PolcherAbstract:Human impacts on the terrestrial water cycle have the potential to influence hazards such as flooding and drought, so understanding the extent of our influence is an important research goal. A study utilizing estimates of evapotranspiration for different types of Land Cover and a database of Changes in use now shows that the extent of Land-Cover Change caused by people is already an important factor affecting the terrestrial water cycle.
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The impact of global Land-Cover Change on the terrestrial water cycle
Nature Climate Change, 2013Co-Authors: S.m. Sterling, Agnès Ducharne, Jan PolcherAbstract:Floods and droughts cause perhaps the most human suffering of all climate-related events; a major goal is to understand how humans alter the incidence and severity of these events by changing the terrestrial water cycle. Here we use over 1,500 estimates of annual evapotranspiration and a database of global Land-Cover Change to project alterations of global scale terrestrial evapotranspiration (TET) from current anthropogenic Land-Cover Change. Geographic modelling reveals that Land-Cover Change reduces annual TET by approximately 3,500 km 3 yr -1 (5%) and that the largest Changes in evapotranspiration are associated with wetLands and reservoirs. Land surface model simulations support these evapotranspiration Changes, and project increased runoff (7.6%) as a result of Land-Cover Changes. Next we create a synthesis of the major anthropogenic impacts on annual runoff and find that the net result is an increase in annual runoff, although this is uncertain. The results demonstrate that Land-Cover Change alters annual global runoff to a similar or greater extent than other major drivers, affirming the important role of Land-Cover Change in the Earth System. Last, we identify which major anthropogenic drivers to runoff Change have a mean global Change statistic that masks large regional increases and decreases: Land-Cover Change, Changes in meteorological forcing, and direct CO 2 effects on plants. © 2013 Macmillan Publishers Limited. All rights reserved.
Agnès Ducharne - One of the best experts on this subject based on the ideXlab platform.
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the impact of global Land Cover Change on the terrestrial water cycle
Nature Climate Change, 2013Co-Authors: S.m. Sterling, Agnès Ducharne, Jan PolcherAbstract:Human impacts on the terrestrial water cycle have the potential to influence hazards such as flooding and drought, so understanding the extent of our influence is an important research goal. A study utilizing estimates of evapotranspiration for different types of Land Cover and a database of Changes in use now shows that the extent of Land-Cover Change caused by people is already an important factor affecting the terrestrial water cycle.
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The impact of global Land-Cover Change on the terrestrial water cycle
Nature Climate Change, 2013Co-Authors: S.m. Sterling, Agnès Ducharne, Jan PolcherAbstract:Floods and droughts cause perhaps the most human suffering of all climate-related events; a major goal is to understand how humans alter the incidence and severity of these events by changing the terrestrial water cycle. Here we use over 1,500 estimates of annual evapotranspiration and a database of global Land-Cover Change to project alterations of global scale terrestrial evapotranspiration (TET) from current anthropogenic Land-Cover Change. Geographic modelling reveals that Land-Cover Change reduces annual TET by approximately 3,500 km 3 yr -1 (5%) and that the largest Changes in evapotranspiration are associated with wetLands and reservoirs. Land surface model simulations support these evapotranspiration Changes, and project increased runoff (7.6%) as a result of Land-Cover Changes. Next we create a synthesis of the major anthropogenic impacts on annual runoff and find that the net result is an increase in annual runoff, although this is uncertain. The results demonstrate that Land-Cover Change alters annual global runoff to a similar or greater extent than other major drivers, affirming the important role of Land-Cover Change in the Earth System. Last, we identify which major anthropogenic drivers to runoff Change have a mean global Change statistic that masks large regional increases and decreases: Land-Cover Change, Changes in meteorological forcing, and direct CO 2 effects on plants. © 2013 Macmillan Publishers Limited. All rights reserved.
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Comprehensive data set of global Land Cover Change for Land surface model applications
Global Biogeochemical Cycles, 2008Co-Authors: Shannon Sterling, Agnès DucharneAbstract:To increase our understanding of how humans have altered the Earth's surface and to facilitate Land surface modeling experiments aimed to elucidate the direct impact of Land Cover Change on the Earth system, we create and analyze a database of global Land use/Cover Change (LUCC). From a combination of sources including satellite imagery and other remote sensing, ecological modeling, and country surveys, we adapt and synthesize existing maps of potential Land Cover and layers of the major anthropogenic Land Covers, including a layer of wetLand loss, that are then tailored for Land surface modeling studies. Our map database shows that anthropogenic Land Cover totals to approximately 40% of the Earth's surface, consistent with literature estimates. Almost all (92%) of the natural grassLand on the Earth has been converted to human use, mostly grazing Land, and the natural temperate savanna with mixed C3/C4 is almost completely lost (∼90%), due mostly to conversion to cropLand. Yet the resultant Change in functioning, in terms of plant functional types, of the Earth system from Land Cover Change is dominated by a loss of tree Cover. Finally, we identify need for standardization of percent bare soil for global Land Covers and for a global map of tree plantations. Estimates of Land Cover Change are inherently uncertain, and these uncertainties propagate into modeling studies of the impact of Land Cover Change on the Earth system; to begin to address this problem, modelers need to document fully areas of Land Cover Change used in their studies.
Eric F. Lambin - One of the best experts on this subject based on the ideXlab platform.
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Land use and Land Cover Change local processes and global impacts
2010Co-Authors: Eric F. Lambin, Helmut GeistAbstract:Introduction: Local Processes with Global Impacts.- Global Land-Cover Change: Recent Progress, Remaining Challenges.- Causes and Trajectories of Land-Use/Cover Change.- Multiple Impacts of Land-Use/Cover Change.- Modeling Land-Use and Land-Cover Change.- Searching for the Future of Land: Scenarios from the Local to Global Scale.- Linking Land-Change Science and Policy: Current Lessons and Future Integration.- Conclusion.
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Impact of short-term rainfall fluctuation on interannual Land Cover Change in sub-Saharan Africa
Global Ecology and Biogeography, 2005Co-Authors: Veerle Vanacker, Marc Linderman, Frederick Lupo, Stephanne Flasse, Eric F. LambinAbstract:Aim Interannual Land Cover Change plays a significant role in food security, ecosystem processes, and regional and global climate modelling. Measuring the magnitude and location and understanding the driving factors of interannual Land Cover Change are therefore of utmost importance to improve our understanding and prediction of these impacts and to better differentiate between natural and human causes of Land Cover Change. Despite advances in quantifying the magnitude of Land Cover Change, the interpretation of the observed Land Cover Change in terms of climatic, ecological and anthropogenic processes still remains a complex issue. In this paper, we map Land Cover Change across sub-Saharan Africa and examine the influences of rainfall fluctuations on interannual Change. Location The analysis was applied to sub-Saharan Africa. Methods Ten-day rainfall estimates (RFE) obtained from National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center (CPC) were used to extract information on inter and intra-annual rainfall fluctuations. The magnitude of Land Cover Change was quantified based on the multitemporal Change vector method measuring year-to-year differences in bidirectional reflectance distribution function (BRDF) corrected 16-day enhanced vegetation index (EVI) data from the Moderate Resolution Imaging Spectro-radiometer (MODIS). Statistical models were used to estimate the relationship between short-term rainfall variability and the magnitude of Land Cover Change. The analysis was stratified first by physiognomic vegetation type and second by chorological data on species distribution to gain insights into spatial variations in response to short-term rainfall fluctuations. Results The magnitude of Land Cover Change was significantly related to rainfall variability at the 5% level. Stratification considerably strengthened the relationship between the magnitude of Change and rainfall variability. Explanatory power of the models ranged from R-2 = 0.22 for the unstratified model to 0.40-0.96 for the individual models stratified by patterns of species distribution. The total variability explained by the combined models including the influence of rainfall and differences in vegetation response ranged from 22% for the model not stratified by vegetation to 76% when stratified by chorological data. Main conclusions Using this methodology, we were able to measure the contribution of natural variation in precipitation to Land Cover Change. Several ecosystems across sub-Saharan Africa are highly sensitive to short-term rainfall variability
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The causes of Land-use and Land-Cover Change: moving beyond the myths
Global Environmental Change, 2001Co-Authors: Eric F. Lambin, Helmut Geist, Billie Turner, Samuel Babatunde Agbola, Arild Angelsen, John W. Bruce, Oliver T. Coomes, Rodolfo Dirzo, Günther Fischer, Carl FolkeAbstract:Common understanding of the causes of Land-use and Land-Cover Change is dominated by simplifications which, in turn, underlie many environment-development policies. This article tracks some of the major myths on driving forces of Land-Cover Change and proposes alternative pathways of Change that are better supported by case study evidence. Cases reviewed support the conclusion that neither population nor poverty alone constitute the sole and major underlying causes of Land-Cover Change worldwide. Rather, peoples’ responses to economic opportunities, as mediated by institutional factors, drive Land-Cover Changes. Opportunities and
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Quantifying processes of Land-Cover Change by remote sensing: Resettlement and rapid Land-Cover Changes in south-eastern Zambia
International Journal of Remote Sensing, 2001Co-Authors: Cc Petit, Thayer Scudder, Eric F. LambinAbstract:The objectives of this study are to quantify, based on remote sensing data, processes of Land-Cover Change and to test a Markov-based model to generate short-term Land-Cover Change projections in a region characterised by exceptionally high rates of Change. The region of Lusitu, in the Southern Province of Zambia, has been a Land-Cover Change 'hot spot' since the resettlement of 6000 people in the Lusitu area and the succession of several droughts, Land-Cover Changes were analysed on the basis of a temporal series of three multispectral SPOT images in three steps: (i) Land-Cover Change detection was performed by combining the postclassification and image differencing techniques; (ii) the Change detection results were examined in terms of proportion of Land-Cover classes, Change trajectories and spatio-temporal patterns of Change; (iii) the process of Land-Cover Change was modelled by a Markov chain to predict Land-Cover distributions in the near future. The remote sensing approach allowed: (i) to quantify Land-Cover Changes in terms of percentage of area affected and rates of Change; (ii) to qualify the nature of Changes in terms of impact on natural vegetation; (iii) to map the spatial pattern of Land-Cover Change. 44% of the area has been affected by at least one Change in Land Cover during the period 1986 to 1997. The average annual rate of Land-Cover Change was 4.0%. Agricultural expansion was the dominant Change process. Land-Cover Change trajectories highlighted the dynamic character of Changes. The results obtained by applying a Markov chain for projecting future evolutions showed the continuing upward trend of bare soils and cultivated Land, and the rapid downward trend of forests and other natural vegetation Covers.
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Land-Cover-Change trajectories in Southern Cameroon
Annals of the Association of American Geographers, 2000Co-Authors: B. Mertens, Eric F. LambinAbstract:The objective of this study is to better understand the complexity of deforestation processes in southern Cameroon by testing a multivariate, spatial model of Land-Cover Change trajectories as? sociated with deforestation. The spatial model integrates a spectrum of independent variables that characterize Land rent on a spatially explicit basis. The use of a time series of high-spatialresolution remote sensing images (Landsat MSS and SPOT XS), spanning two decades, allows a thorough validation of spatial projections of future deforestation. Remote sensing observations reveal a continuous trend of forest clearing and forest degradation in southern regions of Cam? eroon, but with a highly fluctuating rate. A significant proportion of the areas subject to a LandCover conversion experienced other Changes in the following years. The study also demonstrates that modeling Land-Cover Change trajectories over several observation years allows a better pro? jection of areas with a high probability of Change in Land-Cover than projecting such areas on the basis of observations from the previous time period alone. Statistical results suggest that, in our southern Cameroon study area, roads mostly increased the accessibility of the forest for migrants rather than providing incentives for a transformation of local subsistence agriculture into marketoriented farming systems. The spatial model developed in this study allows simulations of likely impacts of human actions, leading to a transformation ofthe Landscape (e.g., road projects) on key Landscape attributes (e.g., biodiversity). Currently, several road projects or major logging concessions exist in southern Cameroon.
Andrew J. Pitman - One of the best experts on this subject based on the ideXlab platform.
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The Relative Impact of Regional Scale Land Cover Change and Increasing CO2 over China
Advances in Atmospheric Sciences, 2005Co-Authors: Mei Zhao, Andrew J. PitmanAbstract:A series of 17-yr equilibrium simulations using the NCAR CCM3 (T42 resolution) were performed to investigate the regional scale impacts of Land Cover Change and increasing CO₂ over China. Simulations with natural and current Land Cover at CO₂ levels of 280, 355, 430, and 505 ppmv were conducted. Results show statistically significant Changes in major climate fields (e.g. temperature and surface wind speed) on a 15-yr average following Land Cover Change. We also found increases in the maximum temperature and in the diurnal temperature range due to Land Cover Change. Increases in CO₂ affect both the maximum and minimum temperature so that Changes in the diurnal range are small. Both Land Cover Change and CO₂ Change also impact the frequency distribution of precipitation with increasing CO₂ tending to lead to more intense precipitation and Land Cover Change leading to less intense precipitation—indeed, the impact of Land Cover Change typically had the opposite effect versus the impacts of CO₂. Our results provide support for the inclusion of future Land Cover Change scenarios in long-term transitory climate modelling experiments of the 21st Century. Our results also support the inclusion of Land surface models that can represent future Land Cover Changes resulting from an ecological response to natural climate variability or increasing CO₂. Overall, we show that Land Cover Change can have a significant impact on the regional scale climate of China, and that regionall, this impact is of a similar magnitude to increases in CO₂ of up to about 430 ppmv. This means that that the impact of Land Cover Change must be accounted for in detection and attribution studies over China.11 page(s
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Impact of Land Cover Change on the climate of southwest Western Australia
Journal of Geophysical Research, 2004Co-Authors: Andrew J. Pitman, Gemma Narisma, Roger A. Pielke, Neil J. HolbrookAbstract:[1] A sudden reduction in rainfall occurred in the southwest of Western Australia in the mid-20th century. This reduced inflows to the Perth water supply by about 120 GL (42%) and led to an acceleration of projects to develop new water sources at a cost of about $300 million. The reduction in rainfall was coincident with warmer temperatures. A major analysis of these Changes indicated that the Changes in temperature were likely caused by the enhanced greenhouse effect and that the Changes in rainfall were likely caused by a large-scale reorganization of the atmospheric circulation. We explore an alternative hypothesis that large-scale Land Cover Change explains the observed Changes in rainfall and temperature. We use three high-resolution mesoscale model configurations forced at the boundaries to simulate (for each model) five July climates for each of natural and current Land Cover. We find that Land Cover Change explains up to 50% of the observed warming. Following Land Cover Change, we also find, in every simulation, a reduction in rainfall over southwest Western Australia and an increase in rainfall inLand that matches the observations well. We show that the reduced surface roughness following Land Cover Change largely explains the simulated Changes in rainfall by increasing moisture divergence over southwest Western Australia and increasing moisture convergence inLand. Increased horizontal wind magnitudes and suppressed vertical velocities over southwest Western Australia reduce the likelihood of precipitation. InLand, moisture convergence and increased vertical velocities lead to an increase in rainfall. Our results indicate that rainfall over southwest Western Australia may be returned to the long-term average through large-scale reforestation, a policy option within the control of local government. Such a program would also provide a century-scale carbon sink to ameliorate Australia’s very high per capita greenhouse gas emissions. INDEX TERMS: 1655 Global Change: Water cycles (1836); 3322 Meteorology and Atmospheric Dynamics: Land/atmosphere interactions; 3329 Meteorology and Atmospheric Dynamics: Mesoscale meteorology; KEYWORDS: Land Cover Change, mesoscale modeling, regional climate Change
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The Effect of Including Biospheric Responses to CO2 on the Impact of Land-Cover Change over Australia
Earth Interactions, 2004Co-Authors: Gemma Narisma, Andrew J. PitmanAbstract:Abstract Increasing atmospheric carbon dioxide concentration and the resulting Change in temperature affect vegetation physiologically and structurally. These physiological and structural Changes are biospheric feedbacks that may enhance or moderate the impacts due to human-induced Land-Cover Change. It is therefore potentially important to include these biospheric feedbacks in experiments that explore the impact of Land-Cover Change on climate. In this paper, it is shown that the vegetation response to higher carbon dioxide concentrations and warmer temperatures moderates the impacts of historical human-induced Land-Cover Change in Australia. The magnitude of these biospheric feedbacks is explored, and it is shown that including them in climate simulations results in smaller Land-Cover Change impacts on latent heat flux (by about 10–20 W m−2) and temperature (by about 0.3°C), irrespective of the direction of Change caused initially by Land-Cover Change. Further, the magnitude of the feedback on temperatu...
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The regional scale impact of Land Cover Change simulated with a climate model
International Journal of Climatology, 2002Co-Authors: Mei Zhao, Andrew J. PitmanAbstract:A series of 17-year integrations using the NCAR CCM3 (at about 2.8° × 2.8° resolution) were performed to investigate the regional-scale impact of Land Cover Change. Our aim was to determine the impact of historical Land Cover Change on the regional-scale climate over the regions where most Change occurred: Europe, India and China. The Change from natural to current Land Cover was estimated using BIOME3 to predict the natural vegetation type, and then using remotely sensed data to estimate the locations where Land Cover had been Changed through human activity. Results show statistically significant Changes in the 15-year averaged 1000 hPa wind field, mean near-surface air temperature, maximum near-surface air temperature and the latent heat flux over the regions where Land Cover Change was imposed. These Changes disappeared if the Land Cover over a particular region was omitted, indicating that our results cannot be explained by model variability. An analysis of Changes on an averaged monthly time scale showed large Changes in the maximum daily temperature in (Northern Hemisphere) summer and little Change in the minimum daily temperature, resulting in Changes in the diurnal temperature range. The Change in the diurnal temperature range could be positive or negative depending on region, time of year and the precise nature of the Land Cover Changes. Our results indicate that the inclusion of Land Cover Change scenarios in simulations of the 20th century may lead to improved results. The impact of Land Cover Changes on regional climates also provides support for the inclusion of Land surface models that can represent future Land Cover Changes resulting from an ecological response to natural climate variability or increasing carbon dioxide.20 page(s
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The impact of Land Cover Change on the atmospheric circulation
Climate Dynamics, 2001Co-Authors: Mei Zhao, Andrew J. Pitman, Thomas N ChaseAbstract:The NCAR Community Climate Model (version 3), coupled to the Biosphere Atmosphere Transfer scheme and a mixed layer ocean model is used to investigate the impact on the climate of a conservative Change from natural to present Land Cover. Natural vegetation Cover was obtained from an ecophysiologically constrained biome model. The current vegetation Cover was obtained by perturbing the natural Cover from forest to grass over areas where Land Cover has been observed to Change. Simulations were performed for 17 years for each case (results from the last 15 years are presented here). We find that Land Cover Changes, largely constrained to the tropics, SE Asia, North America and Europe, cause statistically significant Changes in regional temperature and precipitation but cause no impact on the globally averaged temperature or precipitation. The perturbation in Land Cover in the tropics and SE Asia teleconnect to higher latitudes by changing the position and strength of key elements of the general circulation (the Hadley and Walker circulations). Many of the areas where statistically significant Changes occur are remote from the location of Land Cover Change. Historical Land Cover Change is not typically included in transitory climate simulations, and it may be that the simulation of the patterns of temperature Change over the twentieth century by climate models will be further improved by taking it into account.
