Modelling global biogeochemical cycles; an integrated assessment approach
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Series / Report no.
Open Access
Type
Report
Language
en
Date
1995-08-31
Research Projects
Organizational Units
Journal Issue
Title
Modelling global biogeochemical cycles; an
integrated assessment approach
Translated Title
Modellering van mondiale biogeocemische
kringlopen; een geintegreerde benadering
Published in
Abstract
Mondiale kringlopen beschrijven het transport van
chemische verbindingen op aarde. Verstoringen in deze kringlopen, met name
die van de elementen koolstof (C), stikstof (N), fosfor (P) en zwavel (S),
veroorzaakt door menselijke activiteiten, leiden tot lokale, regionale en
mondiale milieuproblemen. Door de belangstelling, zowel wetenschappelijk
als beleidsmatig, naar dit complexe verschijnsel mondiale
milieuveranderingen, groeit ook de behoefte naar een geintegreerd
beleidswetenschappelijk simulatiemodel. Dit model dient rekening te houden
met het feit dat: (i) vele mondiale milieuproblemen gezamenlijke oorzaken,
mechanismen en effecten hebben, (ii) er vele interacties en
terugkoppelingsmechanismen bestaan tussen de diverse kringlopen. In dit
rapport wordt een dergelijk model beschreven, namelijk het CYCLES model, als
onderdeel van het gehele computersimulatiemodel TARGETS. Dit CYCLES model
beschrijft op een overzichtelijke wijze de complexe dynamiek van de mondiale
kringlopen van de elementen C, N, P en S, en de onderlinge interacties,
alswel de effecten van verstoringen van deze kringlopen op het mondiale
milieu. Naast de chemische verbindingen van de basiselementen C, N, P en S
bevat het model ook andere chemische verbindingen: CFK's, tropospferisch
ozon, en enige representatieve toxische chemicalien, zoals: lood, fatalaten,
PCBs en DDT. Andere karakteristieken van dit model: (i) de opzet is
generiek, en daarbij toepasbaar op ieder schaalniveau, (ii) de terrestrische
biosfeer is opgedeeld in diverse klimaat-,bodem- en landgebruiksklassen, en
(iii) het model is gekoppeld aan een raamwerk van indices en indicatoren.
De voornaamste doelstellingen van dit model zijn: (i) een zo volledig
mogelijk overzicht te geven van de mondiale kringlopen, (ii) de
synergetische effecten van de interacties tussen de kringlopen te
identificeren en te analyseren, (iii) diverse lange-termijn
milieubeleidsstrategieen te evalueren in termen van risico's op het milieu,
alsmede het analyseren van de 'trade-offs' tussen de oorzaken van de diverse
milieuproblemen. Op deze manier kan het model worden gebruikt voor het
analyseren van de mate waarin de kringlopen zijn verstoord, en de mogelijke
effecten hiervan op het milieu. Dit wordt onder andere gedemonstreerd in
een serie van modelexperimenten met het CYCLES model, welke zich speciaal
concentreren op de interacties tussen de kringlopen.
Global biogeochemical cycles describe the transformation and movement of chemical substances in the global environment. Disturbances in these global biogeochemical cycles, in particular the cycles of carbon (C), nitrogen (N) phosphorus (P), and sulphur (S), initiated by a variety of human activities, lead to global environmental change. For a comprehensive analysis of the phenomenon of global environmental change one needs an integrated approach that considers the facts that: (i) many global environmental issues have common causes, state dynamics of the global biogeochemical cycles and common impacts (global environmental change) ; (ii) many interactions and feedback mechanisms exist between the biogeochemical cycles. Here we describe an integrated modelling framework, the CYCLES model, as an integral modular part of the overall framework TARGETS: a Tool to Assess Regional and Global Environmental and health Targets for Sustainability. The CYCLES model captures, in a simple but comprehensive way, the complex, long-term dynamics of the global cycles of C, N, P and S, and their interactions, as well as their impact on global environmental change. More specifically, the model considers the relationships between the causes (human disturbances of the cycles), the mechanisms (changes in state of global biogeochemical cycles), and the impacts (global environmental change). In addition to the basic elements, the model comprises several chemical compounds, such as halocarbons, tropospheric ozone and its precursors, and some representative toxic pollutants: lead, phthalates, PCBs and DDT. Other characteristics of the model are: first, its design is generic, and it could in principle therefore also be applied on the regional scale using regional mass budgets. Second, although the model acts on a global scale, spatial heterogeneities are introduced for the terrestrial biosphere, subdivided into highly aggregated climate, soil and land use classes. Third, the model is linked to a framework of indices, which can be used to yield insight into the complex dynamics under consideration. We realize that the modelling approach we have adopted is too simple, and that there are much more advanced models available for the individual global cycles. However, the complexity of the CYCLES model arises from the linkage of simple, highly aggregated subsystems, as a result of which the model as a whole may show strongly nonlinear and complex behaviour. This means that incremental changes in one of the subsystems may result in considerable changes in the overall system. The primary objectives of the CYCLES model are: (i) to sketch a biogeochemical cycles ; (ii) to study and analyze the synergetic effects of the interactions between the global cycles ; (iii) to evaluate different environmental policies with respect to their overall impacts on the global environment, and thereby to analyze the trade-offs between the causes of the different environmental issues (some strategies directed at a single issue can have reverse effects on the global environment). In this way, the CYCLES model can be used to assess the extent to which the global biogeochemical cycles are being disturbed by human activities, and what the possible future implications might be for the global environment. This is demonstrated by a series of preliminary model experiments with the CYCLES model which focus on the interactions between the various cycles and the synergetic effects.
Global biogeochemical cycles describe the transformation and movement of chemical substances in the global environment. Disturbances in these global biogeochemical cycles, in particular the cycles of carbon (C), nitrogen (N) phosphorus (P), and sulphur (S), initiated by a variety of human activities, lead to global environmental change. For a comprehensive analysis of the phenomenon of global environmental change one needs an integrated approach that considers the facts that: (i) many global environmental issues have common causes, state dynamics of the global biogeochemical cycles and common impacts (global environmental change) ; (ii) many interactions and feedback mechanisms exist between the biogeochemical cycles. Here we describe an integrated modelling framework, the CYCLES model, as an integral modular part of the overall framework TARGETS: a Tool to Assess Regional and Global Environmental and health Targets for Sustainability. The CYCLES model captures, in a simple but comprehensive way, the complex, long-term dynamics of the global cycles of C, N, P and S, and their interactions, as well as their impact on global environmental change. More specifically, the model considers the relationships between the causes (human disturbances of the cycles), the mechanisms (changes in state of global biogeochemical cycles), and the impacts (global environmental change). In addition to the basic elements, the model comprises several chemical compounds, such as halocarbons, tropospheric ozone and its precursors, and some representative toxic pollutants: lead, phthalates, PCBs and DDT. Other characteristics of the model are: first, its design is generic, and it could in principle therefore also be applied on the regional scale using regional mass budgets. Second, although the model acts on a global scale, spatial heterogeneities are introduced for the terrestrial biosphere, subdivided into highly aggregated climate, soil and land use classes. Third, the model is linked to a framework of indices, which can be used to yield insight into the complex dynamics under consideration. We realize that the modelling approach we have adopted is too simple, and that there are much more advanced models available for the individual global cycles. However, the complexity of the CYCLES model arises from the linkage of simple, highly aggregated subsystems, as a result of which the model as a whole may show strongly nonlinear and complex behaviour. This means that incremental changes in one of the subsystems may result in considerable changes in the overall system. The primary objectives of the CYCLES model are: (i) to sketch a biogeochemical cycles ; (ii) to study and analyze the synergetic effects of the interactions between the global cycles ; (iii) to evaluate different environmental policies with respect to their overall impacts on the global environment, and thereby to analyze the trade-offs between the causes of the different environmental issues (some strategies directed at a single issue can have reverse effects on the global environment). In this way, the CYCLES model can be used to assess the extent to which the global biogeochemical cycles are being disturbed by human activities, and what the possible future implications might be for the global environment. This is demonstrated by a series of preliminary model experiments with the CYCLES model which focus on the interactions between the various cycles and the synergetic effects.
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