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Interactive chemistry and climate models in global change studies

Fonte: MIT Joint Program on the Science and Policy of Global Change Publicador: MIT Joint Program on the Science and Policy of Global Change
Formato: 16 p.; 170107 bytes; application/pdf
ENG
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Continually increasing atmospheric concentrations of radiatively important chemical species such as CO2, CH4, N2O, tropospheric O3, and certain halocarbons most likely will cause future climate changes, which could in turn impact chemical reaction rates and thus lifetimes of many important chemical species. Complicated interactions between climate dynamics and atmospheric chemistry strongly suggest that a fully interactive, comprehensive chemistry-climate modeling system is needed to study the issue. This article reviews recent work in the new and challenging field of interactive chemistry-climate modeling, describing major efforts in model development and summarizing in detail applications of and results from these models.; Includes bibliographical references (p. 12-16).; Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/)

Transient climate change and potential croplands of the world in the 21st century

Fonte: MIT Joint Program on the Science and Policy of Global Change Publicador: MIT Joint Program on the Science and Policy of Global Change
Formato: 25 p.; 6055829 bytes; application/pdf
ENG
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A cropland distribution model, which is based on climate, soil and topography, is applied to estimate the area and spatial distribution of global potential croplands under contemporary climate and to assess the effect of transient climate changes projected by the MIT Integrated Global System Model for assessment of climate change. The area of global potential croplands is about 32.91 x 10^6 km^2 under contemporary climate, and increases substantially over the period of 1977-2100 and differs among the three transient climate change predictions, being about +6.7% (2.20 x 10^6 km^2), +11.5% (3.78 x 10^6 km^2), and +12.5% (4.12 x 10^6 km^2) in 2100, respectively. Among twelve economic regions of the world, the Former Soviet Union and the Other OECD Countries regions have the largest increases in potential croplands, while developing countries have little increases in potential croplands. Spatial distribution of potential croplands changes considerably over time, dependent upon the transient climate change predictions.; Includes bibliographical references (p. 9-12).; Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).; Supported by the Joint Program on the Science and Policy of Global Change at the Massachusetts Institute of Technology (CE-S-462041)...

MIT Integrated Global System Model (IGSM) Version 2: Model Description and Baseline Evaluation

Sokolov, Andrei P.; Schlosser, C. Adam.; Dutkiewicz, Stephanie.; Paltsev, Sergey.; Kicklighter, David W.; Jacoby, Henry D.; Prinn, Ronald G.; Forest, Chris Eliot.; Reilly, John M.; Wang, Chien.; Felzer, Benjamin Seth.; Sarofim, Marcus C.; Scott, Jeffery.;
Fonte: MIT Joint Program on the Science and Policy of Global Change Publicador: MIT Joint Program on the Science and Policy of Global Change
Tipo: Relatório Formato: 1515580 bytes; application/pdf
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The MIT Integrated Global System Model (IGSM) is designed for analyzing the global environmental changes that may result from anthropogenic causes, quantifying the uncertainties associated with the projected changes, and assessing the costs and environmental effectiveness of proposed policies to mitigate climate risk. This report documents Version 2 of the IGSM, which like the previous version, includes an economic model for analysis of greenhouse gas and aerosol precursor emissions and mitigation proposals, a coupled atmosphere-ocean-land surface model with interactive chemistry, and models of natural ecosystems. In this global framework the outputs of the combined anthropogenic and natural emissions models provide the driving forces for the coupled atmospheric chemistry and climate models. Climate model outputs then drive a terrestrial model predicting water and energy budgets, CO2, CH4, and N2O fluxes, and soil composition, which feed back to the coupled climate/chemistry model. The first version of the integrated framework (which we will term IGSM1) is described in Prinn et al. (1999) and in publications and Joint Program Reports and Technical Notes provided on the Program’s website (http://mit.edu/globalchange/). Subsequently...

Directed Technical Change and Climate Policy

Otto, Vincent M.; Loeschel, Andreas; Reilly, John M.
Fonte: MIT Joint Program on the Science and Policy of Global Change Publicador: MIT Joint Program on the Science and Policy of Global Change
Tipo: Relatório Formato: 530774 bytes; application/pdf
EN_US
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This paper studies the cost effectiveness of climate policy if there are technology externalities. For this purpose, we develop a forward-looking CGE model that captures empirical links between CO2 emissions associated with energy use, directed technical change and the economy. We find the cost-effective climate policy to include a combination of R&D subsidies and CO2 emission constraints, although R&D subsidies raise the shadow value of the CO2 constraint (i.e. CO2 price) because of a strong rebound effect from stimulating innovation. Furthermore, we find that CO2 constraints differentiated toward CO2-intensive sectors are more cost effective than constraints that generate uniform CO2 prices among sectors. Differentiated CO2 prices, through technical change and concomitant technology externalities, encourage growth in the non-CO2 intensive sectors and discourage growth in CO2-intensive sectors. Thus, it is cost effective to let the latter bear relatively more of the abatement burden. This result is robust to whether emission constraints, R&D subsidies or combinations of both are used to reduce CO2 emissions.; Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).

Directed Technical Change and the Adoption of CO2 Abatement Technology: The Case of CO2 Capture and Storage

Otto, Vincent M.; Reilly, John M.
Fonte: MIT Joint Program on the Science and Policy of Global Change Publicador: MIT Joint Program on the Science and Policy of Global Change
Tipo: Relatório Formato: 275327 bytes; application/pdf
EN_US
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This paper studies the cost effectiveness of combining traditional environmental policy, such as CO2 trading schemes, and technology policy that has aims of reducing the cost and speeding the adoption of CO2 abatement technology. For this purpose, we develop a dynamic general equilibrium model that captures empirical links between CO2 emissions associated with energy use, directed technical change and the economy. We specify CO2 capture and storage (CCS) as a discrete CO2 abatement technology. We find that combining CO2-trading schemes with an adoption subsidy is the most effective instrument to induce adoption of the CCS technology. Such a subsidy directly improves the competitiveness of the CCS technology by compensating for its markup over the cost of conventional electricity. Yet, introducing R&D subsidies throughout the entire economy leads to faster adoption of the CCS technology as well and in addition can be cost effective in achieving the abatement target.; Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).; This study received funding from the MIT Joint Program on the Science and Policy of Global Change...

The Influence on Climate Change of Differing Scenarios for Future Development Analyzed Using the MIT Integrated Global System Model

Prinn, Ronald G.; Paltsev, Sergey; Sokolov, Andrei P.; Sarofim, Marcus C.; Reilly, John M.; Jacoby, Henry D.
Fonte: MIT Joint Program on the Science and Policy of Global Change Publicador: MIT Joint Program on the Science and Policy of Global Change
Tipo: Relatório
EN_US
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A wide variety of scenarios for future development have played significant roles in climate policy discussions. This paper presents projections of greenhouse gas (GHG) concentrations, sea level rise due to thermal expansion and glacial melt, oceanic acidity, and global mean temperature increases computed with the MIT Integrated Global Systems Model (IGSM) using scenarios for 21st century emissions developed by three different groups: intergovernmental (represented by the Intergovernmental Panel on Climate Change), government (represented by the U.S. government Climate Change Science Program) and industry (represented by Royal Dutch Shell plc). In all these scenarios the climate system undergoes substantial changes. By 2100, the CO2 concentration ranges from 470 to 1020 ppm compared to a 2000 level of 365 ppm, the CO2-equivalent concentration of all greenhouse gases ranges from 550 to 1780 ppm in comparison to a 2000 level of 415 ppm, sea level rises by 24 to 56 cm relative to 2000 due to thermal expansion and glacial melt, oceanic acidity changes from a current pH of around 8 to a range from 7.63 to 7.91. The global mean temperature increases by 1.8 to 7.0 degrees C relative to 2000.; Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).; The IGSM model used here is supported by the U.S. Department of Energy...

Unintended Environmental Consequences of a Global Biofuels Program

Melillo, Jerry M.; Gurgel, Angelo C.; Kicklighter, David W.; Reilly, John M.; Cronin, Timothy W.; Felzer, Benjamin Seth.; Paltsev, Sergey; Schlosser, C. Adam.; Sokolov, Andrei P.; Wang, Xiaodong
Fonte: MIT Joint Program on the Science and Policy of Global Change Publicador: MIT Joint Program on the Science and Policy of Global Change
EN_US
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Biofuels are being promoted as an important part of the global energy mix to meet the climate change challenge. The environmental costs of biofuels produced with current technologies at small scales have been studied, but little research has been done on the consequences of an aggressive global biofuels program with advanced technologies using cellulosic feedstocks. Here, with simulation modeling, we explore two scenarios for cellulosic biofuels production and find that both could contribute substantially to future global-scale energy needs, but with significant unintended environmental consequences. As the land supply is squeezed to make way for vast areas of biofuels crops, the global landscape is defined by either the clearing of large swathes of natural forest, or the intensification of agricultural operations worldwide. The greenhouse gas implications of land-use conversion differ substantially between the two scenarios, but in both, numerous biodiversity hotspots suffer from serious habitat loss. Cellulosic biofuels may yet serve as a crucial wedge in the solution to the climate change problem, but must be deployed with caution so as not to jeopardize biodiversity, compromise ecosystems services, or undermine climate policy.; Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).; This study received funding from the MIT Joint Program on the Science and Policy of Global Change...

15.023J / 12.848J / ESD.128J Global Climate Change: Economics, Science, and Policy, Spring 2007; Global Climate Change: Economics, Science, and Policy

Jacoby, Henry D.; Prinn, Ronald G.; Cohen, Jason Blake; Sarofim, Marcus
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
EN-US
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Introduces scientific, economic, and ecological issues underlying the threat of global climate change, and the institutions engaged in negotiating an international response. Develops an integrated approach to analysis of climate change processes, and assessment of proposed policy measures, drawing on research and model development within the MIT Joint Program on the Science and Policy of Global Change.

Global change and plant diseases.

GHINI, R.
Fonte: In: DIAS, P.L. da S.; RIBEIRO, W.C.; NEUNES, L.H. A contribution to understanding the regional impactos of global change in South America. São Paulo: Instituto de Estudos Avançados da Universidade de São Paulo, 2007. p.163-173. Publicador: In: DIAS, P.L. da S.; RIBEIRO, W.C.; NEUNES, L.H. A contribution to understanding the regional impactos of global change in South America. São Paulo: Instituto de Estudos Avançados da Universidade de São Paulo, 2007. p.163-173.
Tipo: Capítulo em livro técnico-científico (ALICE)
PT_BR
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2007; Livro disponível em: http://www.iea.usp.br/en/publications/books/a-contribution-to-understanding-the-regional-impacts-of-global-change-in-south-america/view

South Pacific security and global change: the new agenda

Fry, Greg
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Working/Technical Paper Formato: 149352 bytes; 349 bytes; application/pdf; application/octet-stream
EN_AU
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In the South Pacific, the end of the Cold War has not been the dramatic turning point in security terms assumed for other regions. It has not created new states or new conflicts or the prospect of new military threats; nor has it meant a ‘falling off the map’ in the way often assumed in conventional accounts of the post-Cold War South Pacific. The global change associated with the end of East-West rivalry has nevertheless been an important influence on the dynamics affecting societal and human security in the region, however we might define ‘security’. The end of the Cold War removed the nuclear weapons issue as a security question and it has seen the end or reduction of the diplomatic interest of Russia, the United States and Britain, thereby confirming a long term shift away from a colonial order to one in which Asian interests now play a greater part. The most important impact was on the lens through which the international community, and particularly Australia, viewed the region. The new agenda of security issues, around questions of governance, identity and development, was not created by the end of the Cold War; but these longstanding post-colonial processes could be seen for the first time in their own light rather than as part of East-West rivalry. There is now general agreement on this ‘new’ agenda providing the main dynamic that affects security in the South Pacific but there are different views about what constitutes threat and solution in relation to it...

Mediation of global change by local biotic and abiotic interactions.

Falkenberg, Laura J.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2013
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Variation in environmental conditions is a pervasive feature of natural systems that has profound consequences for the structure of ecological communities. As a result of altered local conditions produced by human urbanisation, shifts in marine habitats from kelp forests to mats of turfing algae are increasingly common. Forecasting whether such ecological change will be accelerated or reversed as a function of modified global conditions is a new form of ecological enquiry. Throughout this thesis, I assessed the conceptual model that while cross-scale abiotic stressors can combine to have interactive effects, management of local conditions can counter-balance this change. My experimental manipulations were intended to test the hypotheses that; 1) cross-scale factors (i.e. local and global) will have interactive effects that increase the probability of expansion of turfs but not kelp, and, 2) management of local conditions (e.g. presence of biota, nutrient enrichment) will dampen the effects of global change on turfs (e.g. forecasted CO₂). Change in ecological communities is anticipated where altered environmental conditions have contrasting effects on interacting taxa that determine their composition and relative abundances. Experimental enrichment of CO₂ and nutrients influenced biomass accumulation of turf and kelp differently...

Scenarios of regional development under global change (Briefing 1.1)

Onigkeit, Janina
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Sonstiges
EN
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Uncertainty is a key challenge when developing water management strategies for the long-term future. Three highly uncertain factors determining the future water situation in the Jordan River valley were identified: economic development, the potential for regional cooperation in water management and climate change. These factors shape the range of the four “GLOWA Jordan River Scenarios of Regional Development under Global Change”. The “Story and Simulation” (SAS) approach was applied to integrate qualitative information, i.e. narrative scenario storylines, and quantitative information resulting from scientific model simulations. Across several Scenario Panel meetings, experts (scientists and decision-makers) from the region gathered to design four plausible and contrasting scenarios leading up to the year 2050. The four scenarios are 1) “Poverty & Peace” Scenario (an increasingly peaceful political situation is accompanied by economic stagnation), 2) “Willingness & Ability” Scenario (the most optimistic and desirable scenario in which peace and economic prosperity reign), 3) “Modest Hopes” Scenario (assumes that no peace agreement can be reached, but that economic prosperity prevails, kindled by international donors) and 4) “Suffering of the Weak & the Environment” Scenario (worst-case scenario in which neither peace nor economic growth become reality). The focus of the scenarios is on the general socio-economic development in the Jordan River basin. They provide a wide but plausible range of different framing conditions to develop various strategies to manage water resources in order to cope with the impacts of socio-economic and climatic changes in the region.

Global change community ecology beyond species-sorting: a quantitative framework based on mediterranean-biome examples

Guerin, G.R.; Martín-Forés, I.; Biffin, E.; Baruch, Z.; Breed, M.F.; Christmas, M.J.; Cross, H.B.; Lowe, A.J.
Fonte: John Wiley Publicador: John Wiley
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
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Aim: Species-sorting predicts the influences of the environment on ecosystem composition across heterogeneous landscapes. It assumes that extinction and adaptation are negligible at ecological scales. Meanwhile, shifts associated with global change have been observed in metacommunity composition (species pools affected by extinctions and introductions) and in phenotypes. This suggests that predictions of future composition must move beyond re-sorting present-day species with fixed traits. We extend plant species-sorting concepts to consider biogeography and demography. We give an empirical context, highlighting the influences of biogeography, species-sorting and adaptation on community composition. Location: Global; case studies focus on the terrestrial mediterranean biome. Methods: We review case studies of empirical approaches that have examined community composition at various scales. We develop a mathematical model based on community mechanics that incorporates species-sorting with shifting phenotypes and species pools. Results: As illustrated by real examples, community composition is influenced by factors such as history, modern extinction risk, species-sorting, biotic interactions, adaptation and ecological drift. There is ample evidence that species pools and phenotypes are not constant at ecological scales in the context of global change. Any implicit assumption in community analysis that they are constant should therefore be revisited. Our model breaks down shifting community constraints into intraspecific components – including genotype sorting...

CTFS-ForestGEO: a worldwide network monitoring forests in an era of global change

Anderson-Teixeira, Kristin J.; Davies, Stuart J.; Bennett, Amy C.; Gonzalez-Akre, Erika B.; Muller-Landau, Helene C.; Wright, S. Joseph; Salim, Kamariah Abu; Zambrano, Angélica M. Almeyda; Alonso, Alfonso; Baltzer, Jennifer L.; Basset, Yves; Bourg, Norma
Fonte: John Wiley & Sons Ltd; West Sussex Publicador: John Wiley & Sons Ltd; West Sussex
Tipo: Artigo de Revista Científica
ENG
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Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites (CTFS-ForestGEO) useful for characterizing forest responses to global change. Within very large plots (median size 25 ha), all stems ≥1 cm diameter are identified to species, mapped, and regularly recensused according to standardized protocols. CTFS-ForestGEO spans 25°S–61°N latitude, is generally representative of the range of bioclimatic, edaphic, and topographic conditions experienced by forests worldwide, and is the only forest monitoring network that applies a standardized protocol to each of the world's major forest biomes. Supplementary standardized measurements at subsets of the sites provide additional information on plants, animals, and ecosystem and environmental variables. CTFS-ForestGEO sites are experiencing multifaceted anthropogenic global change pressures including warming (average 0.61 °C), changes in precipitation (up to ±30% change), atmospheric deposition of nitrogen and sulfur compounds (up to 3.8 g N m−2 yr−1 and 3.1 g S m−2 yr−1)...

Potassium : a neglected nutrient in global change

Sardans, Jordi; Peñuelas, Josep
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/submittedVersion
Publicado em //2015 ENG
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L'article inclou sis apèndixs; Aim: Potassium (K) is the second most abundant nutrient after nitrogen (N) in plant photosynthetic tissues. Thousands of physiological and metabolic studies in recent decades have established the fundamental role of K in plant function, especially in water use efficiency and economy, and yet macroecological studies have mostly overlooked this nutrient.- Methods: We have reviewed available studies on the contents, stoichiometries and roles of potassium in the soil-plant system and in terrestrial ecosystems. We have also reviewed the impacts of global change drivers on K contents, stoichiometries, and roles. - Conclusions: The current literature indicates that K, at a global level, is as limiting as N and phosphorus (P) for plant productivity in terrestrial ecosystems. K limitation has been seen up to some degree in 70% of all studied terrestrial ecosystems. However, atmospheric K deposition from human activities represents higher amounts than that from natural sources in some areas. We are far from understanding the K fluxes between the atmosphere and land, and the role of anthropogenic activities in these fluxes. The increasing aridity expected in wide areas of the world makes K more critical through its role in water use efficiency. N deposition exerts a strong impact on the ecosystem K-cycle...

The rural-urban socioecological transformation of Mediterranean mountain areas under global change. Local studies in Olzinelles and Matadepera (Barcelona Metropolitan Region)

Otero Armengol, Iago
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2011 ENG
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Aquesta tesi vol contribuir a comprendre millor els sistemes socioecològics i el seu canvi al llarg del temps des d'un punt de vista holístic i relacional. Pretén mostrar que les activitats productives del camp no són necessàriament incompatibles amb la conservació de la biodiversitat, i que algunes d'aquestes activitats, fins i tot en situacions d'integració en economies de mercat, són indispensables per conservar els paisatges culturals que les societats urbanes modernes volen protegir. La tesi es pregunta si la recuperació i l'expansió de la superfície forestal poden tenir un efecte negatiu en l'escolament de les conques i el cabal dels cursos d'aigua, així com en la biodiversitat pròpia d'hàbitats oberts a escala local. També explora la transformació del camp durant el procés d'industrialització i urbanització per recolzar la noció d'una interrelació i hibridació històriques entre el rural i l'urbà, i mostra que l'expansió urbana és el resultat d'intenses lluites polítiques entre diferents grups socials amb una distribució desigual dels costos i els beneficis del canvi socioecològic. La Mediterrània és una regió especialment idònia per als objectius d'aquesta recerca, ja que es considera un ‘hotspot' de biodiversitat mundial el qual és resultat de la integració entre processos naturals i humans. A més...

Reassessing global change research priorities in mediterranean terrestrial ecosystems : how far have we come and where do we go from here?

Doblas Miranda, Enrique; Martínez Vilalta, Jordi,; Lloret Maya, Francisco; Álvarez Nebot, Albert; Àvila i Castells, Anna; Bonet, F. J.; Brotons Alabau, Lluís; Castro, J.; Curiel Yuste, Jorge; Díaz, M.; Ferrandiz, P.; García-Hurtado, E.; Iriondo, J.
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/acceptedVersion
Publicado em //2015 ENG
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Aim: Mediterranean terrestrial ecosystems serve as reference laboratories for the investigation of global change because of their transitional climate, the high spatiotemporal variability of their environmental conditions, a rich and unique biodiversity and a wide range of socio-economic conditions. As scientific development and environmental pressures increase, it is increasingly necessary to evaluate recent progress and to challenge research priorities in the face of global change. - Location: Mediterranean terrestrial ecosystems. - Methods: This article revisits the research priorities proposed in a 1998 assessment. - Results: A new set of research priorities is proposed: (1) to establish the role of the landscape mosaic on fire-spread; (2) to further research the combined effect of different drivers on pest expansion; (3) to address the interaction between drivers of global change and recent forest management practices; (4) to obtain more realistic information on the impacts of global change and ecosystem services; (5) to assess forest mortality events associated with climatic extremes; (6) to focus global change research on identifying and managing vulnerable areas; (7) to use the functional traits concept to study resilience after disturbance; (8) to study the relationship between genotypic and phenotypic diversity as a source of forest resilience; (9) to understand the balance between C storage and water resources; (10) to analyse the interplay between landscape-scale processes and biodiversity conservation; (11) to refine models by including interactions between drivers and socio-economic contexts; (12) to understand forest–atmosphere feedbacks; (13) to represent key mechanisms linking plant hydraulics with landscape hydrology. - Main conclusions:(1) The interactive nature of different global change drivers remains poorly understood. (2) There is a critical need for the rapid development of regional- and global-scale models that are more tightly connected with large-scale experiments...

Applying correlative ecological niche models to global change studies the usefulness of climate - species distribution approaches /

Serra Díaz, Josep M.
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis Formato: application/pdf
Publicado em //2012 ENG; ENG
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56.05%
La distribució de les espècies ha estat objecte d'estudi per part de diverses disciplines donada la seva naturalesa multifactorial. Així, entendre veritablement la distribució de les espècies implica necessàriament un millor coneixement del funcionament de la biosfera. D'altra banda, el canvi global que està patint el nostre planeta previsiblement afectarà en gran mesura moltes espècies, variant així la distribució i composició dels ecosistemes tal i com els coneixem avui dia i implícitament dels serveis que proporcionen. La modelització ha permès augmentar el nostre grau de comprensió sobre el sistema Terra així com de les potencials conseqüències que els canvis antropogènics poden provocar (canvi climàtic, alteració de cicles biogeoquímics, destrucció d'hàbitats, etc.). En el camp de la distribució d'espècies, els models de nínxol ecològic han estat àmpliament utilitzats per estudiar i preveure canvis en la distribució dels organismes. Aquests models es basen en la determinació de les condicions ambientals òptimes on una determinada espècie pot viure i reproduir-se (nínxol). Tanmateix, aquests models fan ús d'aproximacions correlatives entre presències i variables ambientals actuals, fet que presenta diverses desavantatges que posen de manifest una gran incertesa en les prediccions i fins i tot...

How valid are the biological and ecological principles underpinning Global Change science?

Makarieva, Anastassia; Gorshkov, Victor G; Mackey, Brendan; Gorshkov, Vadim V
Fonte: MultiScience Publishing Co. Publicador: MultiScience Publishing Co.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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The prevailing scientific approach to investigating and understanding the environmental consequences of human-induced global change is underpinned by two basic biological principles. First, the principle that species genetically adapt to changing environment conditions. Second, the principle that nutrients present in the environment in the smallest relative concentrations limit biological productivity. We contend that both principles have been formulated based on the results of investigations into either artificially selected organisms, or anthropogenically perturbed landscapes. In both these cases, organisms are studied outside their natural ecological niche. We argue that natural ecosystems do not conform to the above two principles. Non-perturbed biota of natural ecological communities form and maintain optimal environment conditions by buffering the flux of primary environmental resources that would otherwise randomly fluctuate as the result of purely physical processes. In such a biotically-mediated environment the availability of nutrients does not limit biological productivity. Critically, the capacity of the biota to regulate local environment conditions obviates the need for species to continually adapt to random environmental fluctuations. We illustrate how the failure to distinguish between the functioning of perturbed and unperturbed biota prevents the development of policies and strategies that will lead to the long term resolution of the global ecological crisis.

Econometric analysis of global climate change

Stern, David; Kaufmann, R K
Fonte: Pergamon-Elsevier Ltd Publicador: Pergamon-Elsevier Ltd
Tipo: Artigo de Revista Científica
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This paper reports on research that applies econometric time series methods to the analysis of global climate change. The aim of this research was to test hypotheses concerning the causes of the historically observed rise in global temperatures. Longer term applications include quantification of the contribution of different forcing variables to historic warming and use of the model as a module in integrated assessment. Research to date has comprised three stages. In the first stage we used the concept of Granger causality and differences between the temperature record in the northern and southern hemispheres to investigate the causes of temperature increase. In the second stage we tested various global change time series for the presence of stochastic trends. We found that most series contain a stochastic trend with the greenhouse gas series containing I(2) stochastic trends. In the third stage we developed a structural time series to investigate some of the hypotheses suggested by the earlier stages and further tested for the presence of an I(2) trend in hemispheric temperature series. We found that the two temperature series share a common I(2) stochastic trend that may have its source in radiative forcing due to greenhouse gases. There is a second non-stationary component that appears only in the northern hemisphere and appears to be related to radiative forcing due to anthropogenic sulphur emissions.