Greenhouse Emission Scenarios Research Articles

A century-long tendency of change in surface air temperature on the territory of Ukraine

A century-long tendency of change in surface air temperature on the territory of Ukraine

Season-specific impacts of climate change on canopy-forming seaweed communities.

Understory assemblages associated with canopy-forming species such as trees, kelps, and rockweeds should respond strongly to climate stressors due to strong canopy-understory interactions. Climate change can directly and indirectly modify these assemblages, particularly during more stressful seasons and climate scenarios. However, fully understanding the seasonal impacts of different climate conditions on canopy-reliant assemblages is difficult due to a continued emphasis on studying single-species responses to a single future climate scenario during a single season. To examine these emergent effects, we used mesocosm experiments to expose seaweed assemblages associated with the canopy-forming golden rockweed, Silvetia compressa, to elevated temperature and pCO2 conditions reflecting two projected greenhouse emission scenarios (RCP 2.6 [low] & RCP 4.5 [moderate]). Assemblages were grown in the presence and absence of Silvetia, and in two seasons. Relative to ambient conditions, predicted climate scenarios generally suppressed Silvetia biomass and photosynthetic efficiency. However, these effects varied seasonally-both future scenarios reduced Silvetia biomass in summer, but only the moderate scenario did so in winter. These reductions shifted the assemblage, with more extreme shifts occurring in summer. Contrarily, future scenarios did not shift assemblages within Silvetia Absent treatments, suggesting that climate primarily affected assemblages indirectly through changes in Silvetia. Mesocosm experiments were coupled with a field Silvetia removal experiment to simulate the effects of climate-mediated Silvetia loss on natural assemblages. Consistent with the mesocosm experiment, Silvetia loss resulted in season-specific assemblage shifts, with weaker effects observed in winter. Together, our study supports the hypotheses that climate-mediated changes to canopy-forming species can indirectly affect the associated assemblage, and that these effects vary seasonally. Such seasonality is important to consider as it may provide periods of recovery when conditions are less stressful, especially if we can reduce the severity of future climate scenarios.

Projected distribution of the westernmost subpopulation of Assamese macaques (Macaca assamensis pelops) under climate change: conservation implications of a threatened population

Anthropogenic climate change can have a negative impact on the distribution of habitat specialist species with narrow distributional ranges. Among the many areas around the world affected by climate change, the Himalayan region in particular is experiencing marked effects of global warming on its climatic patterns and life forms. This study assessed the current distribution of Assamese macaques (Macaca assamensis) in western Nepal, and projected their likely distribution (via habitat suitability modeling) for the years 2050 and 2070 under the two most plausible greenhouse gas emission scenarios (RCP4.5 and RCP6.0). We recorded a total of 159 Assamese macaques belonging to 10 groups (nine of them residing outside of protected area networks) between 684m and 2550m asl in western Nepal. Climatic niche modeling predicted that 37.03% (25,114 km2) of the total area of western Nepal (67,813 km2) represented suitable habitat of the species, the majority of which ranged between 1000 m and 2000 m asl. Future projections of the current climatic niche of the Assamese macaques revealed a consistent decrease in the suitable habitat for 2050 and 2070 in both of the greenhouse emission scenarios tested. With the RCP6.0 scenario, almost 57% of the current highly suitable habitat would be lost by 2070 with remaining suitable habitat shifted towards higher elevations. The loss of habitat directly affects the species survival and the range shift towards higher elevation exposes them to new areas for conflict with humans. Therefore, the Assamese macaque population in western Nepal requires a high conservation priority with the establishment of new protected areas.

Current distribution of two species of Chinese macaques (Macaca arctoides and Macaca thibetana) and the possible influence of climate change on future distribution

Predicting the spatial distribution of species and suitable areas under global climate change could provide a reference for species conservation and long-term management strategies. Macaca thibetana and Macaca arctoides are two endangered species of Chinese macaques. However, limited information is available on their distribution, and their habitat needs lack proper assessment due to complicated taxonomy and less research attention. In recent years, scholars widely used the maximum entropy (MaxEnt) model to predict the impact of global climate and certain environmental factors on species distribution. Therefore, we used the MaxEnt model to predict the spatiotemporal distribution of both macaque species under six climate change scenarios using occurrence and high-resolution ecological data. We identified climatic factors, elevation, and land cover that shape their distribution range and determined shifts in their habitat range. The results demonstrated that temperature range, annual precipitation, forest land cover, and temperature seasonality, including the precipitation of the driest month are the main factors affecting their distribution. Currently, M. thibetana is mainly concentrated in central, eastern, southern, and southwestern China, and M. arctoides is mainly concentrated in three provinces (Yunnan, Guangxi, and Guangdong) in southern China. The MaxEnt model predicted that the suitable habitat for both species will increase with increased greenhouse emission scenarios. We also found that with the further increase in greenhouse emissions M. thibetana is expected to migrate to western China, and M. arctoides is expected to migrate to western or eastern China. This reinterpretation of the distribution of M. thibetana and M. arctoides in China, and predicted potential suitable habitat and possible migration direction, may provide new insights into the future conservation and management of these two species.

Projections of wildfire risk and activities under 1.5 °C and 2.0 °C global warming scenarios

Wildfires are important ecosystem processes that have a significant impact on terrestrial vegetation, environment, and climate. This study investigates how future wildfire risk and activities could change under 1.5 °C and 2.0 °C warming scenarios relative to pre-industrial levels using a modified McArthur Forest Fire Danger Index (FFDIn) and the CLM4.5-BGC land surface model. Sixteen Earth System Models (ESMs) from CMIP5 and CMIP6 were employed to supply the variables of climate change under low, middle, and high greenhouse emission scenarios in the 1.5 °C and 2.0 °C scenarios. The ensemble means from the FFDIn and results from the CLM4.5-BGC with multiple forcings show that the dry areas in the southwestern US, Brazilian Highlands, and Arabian islands are projected to face higher wildfire risk with larger burned areas and more carbon emissions under a warmer climate. The Congo Basin and part of the Amazon could have a lower wildfire risk with smaller burned areas and less carbon emissions. The absolute changes in the projected FFDIn are small, although large increases are observed in boreal areas, particularly in the winter and spring. Burned area and carbon emissions are projected to increase in general in the boreal area but decrease in northeastern Asia. Compared to the 1.5 °C scenario, the wildfire risk and burned area levels are projected to increase under the 2.0 °C scenario except in the western Amazon. However, fire carbon emissions are projected to decrease more in tropical areas under the 2.0 °C scenario. The different change directions in eastern North America and eastern China produced by the FFDIn and CLM4.5-BGC suggest the potential effect of non-meteorological elements on fire activities.

Assessing future climate trends and their impact on different fractured rock aquifers in Northern Togo

Abstract Water resources in the West African Sudan Savannah are concentrated in fractured crystalline and sedimentary rock aquifers. Due to their low storage, these aquifers are vulnerable to changes in climate. This study assesses future temperature and precipitation trends in the Koumfab watershed of northern Togo. The impact of these future climate trends on surface water and the two types of fractured rock aquifers is also investigated. A fully integrated hydrologic model of the Koumfab watershed in Northern Togo is used to study the impact of climate change on water resources. Bias-corrected temperature and precipitation from four regional climate models (RCMs) and two greenhouse emissions scenarios are used as climate forcings for the integrated model. Climate projections from the four RCMs indicate a rise (1.4 −5.5 °C) in average temperature, from the control (1971–2000) to the future period (2031–2060). Projected precipitation follows two contrasting trends with some RCMs predicting an increase (by up to 14%) in mean annual precipitation, while others predict a decline (by up to −14%). These changes in precipitation and temperature will have a noticeable effect on groundwater levels and stream flow. The hydrologic model indicates a decline in groundwater levels for all future climate projections by 1.4−5.7 m. The decline in groundwater levels is not uniformly distributed in the two types of aquifers. The decline in the fractured sandstone aquifer will be four times greater than that of the fractured granodiorite/migmatite aquifer. Projected stream flow at the watershed outlet shows increasing (59 -332%) and decreasing trends (−39 −100%).

Predicting habitat suitability of Caiman yacare and assessing the role of protected areas under current and future climate and deforestation models

Climate change and habitat degradation are recognized as serious threats for wildlife and an important aspects to be considered in conservation biology. However, little is known about how such environmental changes might impact crocodylians inhabiting the Neotropics and the effectiveness of Protected Areas (PAs) for long-term species conservation. To fill this gap, we used the Yacare Caiman (Caiman yacare) as a model to explore how climate change and habitat degradation might affect its distribution by 2050 and the effectiveness of current PAs for species conservation in response to future environmental changes. To this end, we estimated C. yacare suitable habitat using an ensemble modeling and consensus approach and assessed the species distribution variation inside and outside PAs as a consequence of two greenhouse emission scenarios (Representative Concentration Pathways [RCPs] 4.5 and 8.5), and three General Circulation Models (GCMs; ACCESS1-0, CANESM2, and MRI-CGCM3) for 2050. We estimated the current suitable habitat for C. yacare to be 854,494 km2 divided across five countries: Brazil (396,476 km2), Bolivia (377,853 km2), Paraguay (38,288 km2), Argentina (35,423 km2), and Peru (6,451 km2). Of these countries, Peru is the only one that can be considered “potential” because the species has not been registered there yet. We found that currently only 26.8% (228,835 km2) of C. yacare suitable habitat is under any type of protection of the IUCN Protected Area Categories System, which is currently well preserved from habitat degradation with only 1.9% reduced due to deforestation. We predicted that on average 56.2% of the current species range might be lost because of climate change and habitat degradation and only 14.7% of its suitable range could be preserved based on the current PAs system. Based on our assessment, we showed that future climate change scenarios and habitat degradation processes will require the establishment of additional PAs as well as the implementation of sustainable management strategies emphasizing corridors and suitable habitat linkages. These integrative approaches can be implemented in several ecoregions including the Pantanal flooded savannas, Cerrado woodlands and savannas, Beni savanna, Chiquitano dry forests, and Amazon moist forests, which we predict will be relatively well-preserved under most of the future climate change scenarios and constituting as priority regions for the long-term conservation of the species and tropical biodiversity.

Projected Changes in Terrestrial Vegetation and Carbon Fluxes under 1.5 °C and 2.0 °C Global Warming

The terrestrial ecosystem plays a vital role in regulating the exchange of carbon between land and atmosphere. This study investigates how terrestrial vegetation coverage and carbon fluxes change in a world stabilizing at 1.5 °C and 2 °C warmer than pre-industrial level. Model results derived from 20 Earth System Models (ESMs) under low, middle, and high greenhouse emission scenarios from CMIP5 and CMIP6 are employed to supply the projected results. Although the ESMs show a large spread of uncertainties, the ensemble means of global LAI are projected to increase by 0.04 ± 0.02 and 0.08 ± 0.04 in the 1.5 and 2.0 °C warming worlds, respectively. Vegetation density is projected to decrease only in the Brazilian Highlands due to the decrease of precipitation there. The high latitudes in Eurasia are projected to have stronger increase of LAI in the 2.0 °C warming world compared to that in 1.5 °C warming level caused by the increase of tree coverage. The largest zonal LAI is projected around 70° N while the largest zonal NPP is projected around 60° N and equator. The zonally inhomogeneous increase of vegetation density and productivity relates to the zonally inhomogeneous increase of temperature, which in turn could amplify the latitudinal gradient of temperature with additional warming. Most of the ESMs show uniform increases of global averaged NPP by 10.68 ± 8.60 and 15.42 ± 10.90 PgC year−1 under 1.5 °C and 2.0 °C warming levels, respectively, except in some sparse vegetation areas. The ensemble averaged NEE is projected to increase by 3.80 ± 7.72 and 4.83 ± 10.13 PgC year−1 in the two warming worlds. The terrestrial ecosystem over most of the world could be a stronger carbon sink than at present. However, some dry areas in Amazon and Central Africa may convert to carbon sources in a world with additional 0.5 °C warming. The start of the growing season in the northern high latitudes is projected to advance by less than one month earlier. Five out of 10 CMIP6 ESMs, which use the Land Use Harmonization Project (LUH2) dataset or a prescribed potential vegetation distribution to constrain the future change of vegetation types, do not reduce the model uncertainties in projected LAI and terrestrial carbon fluxes. This may suggest the challenge in optimizing the carbon fluxes modeling in the future.

Far future climate (2060–2100) of the northern Adriatic air–sea heat transfers associated with extreme bora events

The northernmost part of the Mediterranean Sea, the northern Adriatic shelf, is a complex area where the intensity of dense water formation and the consequent Adriatic-Ionian thermohaline circulation are shaped by a combination of extreme wintertime bora winds and substantial freshwater loads. To better understand the impact of global warming on extreme bora dynamics and the associated sea surface cooling, this study applies the Adriatic Sea and Coast (AdriSC) kilometer-scale modelling suite to the far future climate (2060–2100) period. Under both Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 greenhouse emission scenarios, the AdriSC simulations are carried out via the combination of a statistical approach—consisting of an ensemble of 3-day simulations for 22 extreme bora events, and a pseudo-global warning (PGW) methodology—imposing a climatological change to the forcing used to produce the evaluation (present climate) runs. Despite a noteworthy decrease in intensity of the bora winds (by up to 3 m/s), the latent heat losses are simulated to increase (by up to 150 W/m2) due to the reduction in relative humidity in the northern Adriatic (by up to 3%). Consequently, the sea surface cooling associated with severe bora events and preconditioning the dense shelf water formation in the northern Adriatic is projected to not significantly change compared to present climate. Although these results need to be further confirmed, this study thus provides a new view on the future of processes driven by sea surface cooling, such as the dense shelf water formation or the Adriatic-Ionian thermohaline circulation, that were projected to decrease in the future climate by regional climate models an order of magnitude coarser than the AdriSC simulations.

Hydro- and Morphodynamic Impacts of Sea Level Rise: The Minho Estuary Case Study

The understanding and anticipating of climate change impacts is one of the greatest challenges for humanity. It is already known that, until the end of the 21st century, the mean sea level (MSL) will rise at a global scale, but its effects at the local scale need to be further analyzed. In this context, a numerical modelling tool and a methodological approach for the river Minho estuary (NW of the Iberian Peninsula) are presented, to predict possible consequences of local MSL rise, considering the greenhouse emission scenarios RCP 4.5 and RCP 8.5. Hydrodynamic and morphodynamic impacts were analyzed considering several driving factors, such as tides, sea level rise, storm surge, wave set-up, and different river flood peak discharges, taking into account their probabilities of occurrence. The model was calibrated using in-situ data and a data assimilation tool, the OpenDA, which automates this process, allowing to reach reliable results in a considerably short time when compared with traditional techniques. The results forecast that the predicted MSL rise will reduce the flow velocity magnitude and the sediment transport into the coastal platform but will aggravate the inundation risks along the estuarine banks. In the worst scenario (RCP 8.5) the water level near the river mouth of the estuary is expected to rise 0.20 m for 50 years return period ocean water rising, and 0.60 m for 100 years return period. It was also possible to identify that floods are the most important driver for the sediment transport along the estuary, while the tide effect in the morphodynamics is restricted to the downstream estuarine region. This work demonstrated the importance of the numerical modelling tools to better understand the effects of climate change at local scales through the representation of the estuarine hydrodynamic pattern evolution for future climate scenarios.

Trends in airborne pollen and pollen-season-related features of anemophilous species in Jaen (south Spain): A 23-year perspective

Over the last few decades, global warming is prompting phenological changes in numerous plant species across Europe, and a trend towards rising airborne pollen concentrations has been detected. This study, focused on the most frequent pollen types from arboreal and herbaceous species in the airborne spectrum of Jaen (southern Spain), revealed significant changes in airborne pollen intensity and duration of the pollen season over the 23-year study period. Here Cupressaceae, Olea, Pinus, Platanus, Quercus as arboreal taxa and Plantago as herbaceous taxa were the most important with notable changes of at least three pollen season characteristics. Airborne pollen trends from arboreal taxa with high to very high allergenic potential are rising in line with the local temperature increasing trend, and their pollen seasons tend to end later and last longer. However, both the pollen concentrations and the duration of the pollen season of some herbaceous taxa are declining. The climate conditions projected for south Europe under different greenhouse emissions scenarios could continue to prompt greater pollen release and longer pollen season in tree species, especially those that flowering in winter and early spring, but these warming trends might be adverse for the local development of some herbaceous species and favorable for others sharing the same ecological niche. If similar warming trends accompany long-term climate change, greater exposure times to seasonal allergens may occur with subsequent effects on health.

Genes Left Behind: Climate Change Threatens Cryptic Genetic Diversity in the Canopy-Forming Seaweed Bifurcaria bifurcata.

The global redistribution of biodiversity will intensify in the coming decades of climate change, making projections of species range shifts and of associated genetic losses important components of conservation planning. Highly-structured marine species, notably brown seaweeds, often harbor unique genetic variation at warmer low-latitude rear edges and thus are of particular concern. Here, a combination of Ecological Niche Models (ENMs) and molecular data is used to forecast the potential near-future impacts of climate change for a warm-temperate, canopy forming seaweed, Bifurcaria bifurcata. ENMs for B. bifurcata were developed using marine and terrestrial climatic variables, and its range projected for 2040-50 and 2090-2100 under two greenhouse emission scenarios. Geographical patterns of genetic diversity were assessed by screening 18 populations spawning the entire distribution for two organelle genes and 6 microsatellite markers. The southern limit of B. bifurcata was predicted to shift northwards to central Morocco by the mid-century. By 2090-2100, depending on the emission scenario, it could either retreat further north to western Iberia or be relocated back to Western Sahara. At the opposing margin, B. bifurcata was predicted to expand its range to Scotland or even Norway. Microsatellite diversity and endemism were highest in Morocco, where a unique and very restricted lineage was also identified. Our results imply that B. bifurcata will maintain a relatively broad latitudinal distribution. Although its persistence is not threatened, the predicted extirpation of a unique southern lineage or even the entire Moroccan diversity hotspot will erase a rich evolutionary legacy and shrink global diversity to current (low) European levels. NW Africa and similarly understudied southern regions should receive added attention if expected range changes and diversity loss of warm-temperate species is not to occur unnoticed.

Monitoring the future behaviour of urban drainage system under climate change: a case study from north-western England

Abstract Catchments hydrological conditions and responses are anticipated to be affected by the changes in weather patterns, increasing in climate variability and extreme rainfall. Thus, engineers have no choice but to consider climate change in their practices in order to adapt and serve the public interests. This paper is an exploration of the impacts of climate change on the hydrology that underlies the hydraulic design of urban drainage system. Future rainfall has been downscaled from the Global Climate Model (GCM) employing a hybrid Generalised Linear Model (GLM) and Artificial Neural Network (ANN) downscaling techniques under different greenhouse emission scenarios. The output from this model is applied to a combined sewer system of an urban drainage catchment in the Northwest of England during the 21st Century to monitor its future behaviour in winter and summer seasons. Potential future changes in rainfall intensity are expected to alter the level of service of the system, causing more challenges in terms of surface flooding and increase in surcharge level in sewers. The results obtained demonstrate that there is a real chance for these effects to take place and therefore would require more attention from designers and catchment managers.

A New Method to Determine the Upper Boundary Condition for a Permafrost Thermal Model: An Example from the Qinghai‐Tibet Plateau

ABSTRACTAssessing possible permafrost degradation related to engineering projects, climate change and land use change is of critical importance for protecting the environment and in developing sustainable designs for vital infrastructure in cold regions. A major challenge in modelling the future degradation of permafrost is finding ways to constrain changes in the upper thermal boundary condition over time and space at appropriate scales. Here, we report on an approach designed to predict time series of air, ground surface and shallow ground temperatures at a spatial scale on the order of 102 m2 for engineering design of a railway or highway project. The approach uses a regional‐scale atmospheric model to downscale global climate model output, and then stepwise multiple regression to develop an equation that provides a best‐fit prediction of site‐specific observational data using bilinearly interpolated output from the atmospheric model. This approach bridges the scale difference between atmospheric climate models and permafrost thermal models, and allows for a wider range of factors to be used in predicting the thermal boundary condition. For a research site located in Beiluhe, China, close to the Qinghai‐Tibet Railway, a comparison of model predictions with observational data not used in the construction of the model shows that this method can be used with a high degree of accuracy to determine the upper boundary condition for a permafrost thermal model. Once a model is constructed, it can be used to predict future changes in boundary condition parameters under different greenhouse emission scenarios for climate change. Copyright © 2012 John Wiley & Sons, Ltd.

Potential Impacts of Climate Change on Ecosystem Services in Europe: The Case of Pest Control by Vertebrates

Global environmental changes threaten ecosystems and cause significant alterations to the supply of ecosystem services that are vital for human well-being. We provide an assessment of the potential impacts of climate change on the European diversity of vertebrates and their associated pest-control services. We modeled the distributions of the species that provide these services using forecasts from bioclimatic envelope models and then used the results to generate maps of potential species richness among vertebrate providers of pest-control services. We assessed how the potential richness of pest-control providers would change according to different climate and greenhouse emissions scenarios. We found that the potential richness of pest-control providers was likely to face substantial reductions, especially in southern European countries whose economies were highly dependent on agricultural yields. In much of central and northern Europe, where countries’ economies were less dependent on agriculture, climate change was likely to benefit pest-control providers.

Environmental Implications of global climate change in Hong Kong

There is growing concern that human activities are increasing the atmospheric concentrations of greenhouse gases, mainly carbon dioxide, methane, nitrous oxide and chlorofluorocarbons. This increase in greenhouse gases concentrations will intensify the greenhouse effect, leading to changes in regional and global climate. Comprehensive assessments of the climate change issue have been carried out by the Intergovernmental Panel on Climate Change (IPCC). The IPCC has developed a range of future greenhouse emissions scenarios. IS92af, based on assumptions concerning population and economic growth, landuse, technological changes, energy availability and emission control policies during the period 1990 to 2100. Through understanding of the global carbon cycle and of atmospheric chemistry, these scenarios can be used to project future atmospheric concentrations of greenhouse gases. Climate models can then be used to develop projections of future climate change. In Hong Kong, however, little literature exists in addressing the climate change issue and its impacts. The major objectives of this study are, therefore, to assess the potential impacts of climate change in Hong Kong and to suggest possible responses to climate change.

Bayesian estimation of local signal and noise in multimodel simulations of climate change

In this study, a Bayesian maximum‐likelihood method is used to estimate local probability distributions of projected climate changes in continental temperature T and precipitation P under greenhouse emission scenarios of two different severity levels. These estimates are derived from multimodel climate simulations of the 20th and 21st centuries. Bayesian‐weighted multimodel consensus estimates of the local climate‐change signal and noise are determined from the statistical agreement of each model's simulation of historical climate with observations and of its 21st‐century climate projection with suitably chosen target data. The consensus estimates of climatic changes in T are found to be universally positive and statistically significant under either future emissions scenario. In contrast, changes in P vary locally in sign, and they are statistically significant only in limited regions under the more severe scenario. The impacts of jointly considering more than one variable or statistical parameter on the Bayesian estimation of 21st‐century climate change also are explored. The multivariate approach allows estimation of a probability distribution of the joint projected climate change in T and P, while inclusion of both first‐ and second‐moment statistics of either variable results in a greater differentiation of the Bayesian weights and a general enhancement of the local signal‐noise ratio.

Effects of climate change on the intensity and frequency of heavy snowfall events in the Pyrenees

The intensity and frequency of heavy snowfall events in the Pyrenees were simulated using data from the HIRHAM regional climate model for a control period (1960–1990) and two greenhouse emission scenarios (SRES B2 and A2) for the end of the twenty-first century (2070–2100). Comparisons between future and control simulations enabled a quantification of the expected change in the intensity and frequency of these events at elevations of 1,000, 1,500, 2,000 and 2,500 m a.s.l. The projected changes in heavy snowfall depended largely on the elevation and the greenhouse gas emission scenario considered. At 1,000 m a.s.l., a marked decrease in the frequency and intensity of heavy snowfall events was projected with the B2 and A2 scenarios. At 1,500 m a.s.l., a decrease in the frequency and intensity is only expected under the higher greenhouse gas emission scenario (A2). Above 2,000 m a.s.l., no change or heavier snowfalls are expected under both emission scenarios. Large spatial variability in the impacts of climate change on heavy snowfall events was found across the study area.

Uncertainties in the response of a forest landscape to global climatic change

AbstractMany studies have been conducted to quantify the possible ecosystem/landscape response to the anticipated global warming. However, there is a large amount of uncertainty in the future climate predictions used for these studies. Specifically, the climate predictions can be very different based on a variety of global climate models and alternative greenhouse emission scenarios. In this study, we coupled a forest landscape model, LANDIS‐II, and a forest process model, PnET‐II, to examine the uncertainty (that results from the uncertainty in the future climate predictions) in the forest‐type composition prediction for a transitional forest landscape [the Boundary Water Canoe Area]. Using an improved global‐sensitivity analysis technique [Fourier amplitude sensitivity test], we also quantified the amount of uncertainty in the forest‐type composition prediction contributed by different climate variables including temperature, CO2, precipitation and photosynthetic active radiation (PAR). The forest landscape response was simulated for the period 2000–2400 ad based on the differential responses of 13 tree species under an ensemble of 27 possible climate prediction profiles (monthly time series of climate variables). Our simulations indicate that the uncertainty in the forest‐type composition becomes very high after 2200 ad, which is close to the time when the current forests are largely removed by windthrow disturbances and natural mortality. The most important source of uncertainty in the forest‐type composition prediction is from the uncertainty in temperature predictions. The second most important source is PAR, the third is CO2 and the least important is precipitation. Our results also show that if the optimum photosynthetic temperature rises due to CO2 enrichment, the forest landscape response to climatic change measured by forest‐type composition may be substantially reduced.

Modeling GCM and scenario uncertainty using a possibilistic approach: Application to the Mahanadi River, India

Climate change impact assessment on water resources with downscaled General Circulation Model (GCM) simulation output is characterized by uncertainty due to incomplete knowledge about the underlying geophysical processes of global change (GCM uncertainties) and due to uncertain future scenarios (scenario uncertainties). Disagreement between different GCMs and scenarios in regional climate change impact studies indicates that overreliance on a single GCM with a scenario could lead to inappropriate planning and adaptation responses. This paper focuses on modeling GCM and scenario uncertainty using possibility theory in projecting streamflow of Mahanadi river, at Hirakud, India. A downscaling method based on fuzzy clustering and Relevance Vector Machine (RVM) is applied to project monsoon streamflow from three GCMs with two green house emission scenarios. Possibilities are assigned to all the GCMs with scenarios based on their performance in modeling the streamflow of the recent past (1991–2005), when there are signals of climate forcing. The possibilities associated with different GCMs and scenarios are used as weights in computing the possibilistic mean of the CDFs projected for three standard time slices 2020s, 2050s, and 2080s. The result shows that the value of streamflow at which the CDF reaches 1 reduces with time, which shows the reduction in probability of occurrence of extreme high flow events in future. Historic record of monsoon streamflow of Mahanadi river also shows similar decreasing trend, which may be due to the effect of high surface warming. Reduction in Mahandai streamflow is likely to pose a major challenge for water resources engineers in meeting water demands in future.