Integrated Assessment

1. determine sectoral regional climate impacts in physical terms
2. translate in monetary value using monetizing methods
3. aggregate sectoral and regional results 

result: curve of aggregated global economic damage in $ as a function of t° increase 

• fix objective andapply it to determine backwards the activities necessary to achieve the goal
  • determine damage cost curve
  • determine mitigation cost curve
  • = total cost of climate change
  • derive globally optimal climate protection strategy that minimizes total cost or maximizes total welfare 

considers dynamic relationships in cause effect chain (feedbacks) 

dynamic integrated model of climate and the economy, Nordhaus 1989 

• conceptual, global, intemporal model
• reference case: optimal growth development path neglecting climate problem 
• global output = capital stock x labor force 

1. mu(t): how large emission reduction should be as function of time (% of deviation of reference path) 
2. c(t): the share of global output devoted to consumption (vs investment) 
   1. investment can be used to increase capital stock 

• determine optimal emission path maximizing present value of global welfare 

rate to express future value into present value 

discounted future damage costs < mitigation costs -> future damage costs have no worth today 

• individual level: value loss of life
• intra-generational level: money is worth more in poor regions, would maximize welfare without compensating damages
• inter-generational level: damages for future generations 
• social welfare: ≠ derived from rational individual preferences 
• utility theory: based on subjective probabilities 

• lack of individual decision maker
• utility problems 
• incomplete information 
• -> cannot serve for international decision making
  • need to identify long term objective and define steps to achieve it
  • negotiation process 

• economic growth
• technology
• population
• governance 

• ghg
• aerosols 

• air and sea t°
• precipitation
• snow and ice cover 

• land use
• food and water systems
• ecosytsems and biodiversity
• animal and plant health

society adapts to environmental impacts, autonomous of government driven 

reduces environmental impacts 

is even lower in combination w mitigation 

reduce enhanced ghg, reducing their effect on climate system and natural system 

overall impacts of climate change are reduced, reducing need to adapt

mitigation reduces emissions at start of cycle and throughout the cycle -> reduces risk more than adaptiation 

mitigation = global problem requiring global action, ≠ adaptation which is local 

•  
  • demography
  • technical progress
• economy model
• energy system model and agriculture model
• atmospheric chemistry
• climate model
• Goal 
  • climate impact model 1
  • climate impact model 2 
  • climate impact model 3 
• endogenous socio-economic evaluation 

fixing the maximum amount of tolerable climate damage and find the least costly approach to stay under that limit 

minimize climate change until a certain mitigation burden 

room btw intolerable climate damage and intolerable mitigation cost 

• policies to unlock cost effective energy efficiency potential
• carbon price to mediate action economy wide 
• technology support policies to reduce costs for long-term decarbonisation 

ghg concentration as input, t° change as output 

questions: impacts of t° chage? control ghg concentrations?

results of each scientific field used as input for next one 

problem: uncoordinated assumptions 

group of scientists work together and exchange knowledge

pro: common assumptions 

con: no feedbacks considered 

information flow based on annual schedule 

pro: considers feedbacks

con: not invertible 

one common equation for all submodel. timeline 10-100y

• coherent framework considering feedbacks
• identifies knowledge gaps 
• consistent modeling of interaction btw systems
• enforces collaboration and ongoing research 

• provide dataset 
• establish benchmark 

• alternative images of how future might unfold 
• result of complex interactions in socio-ecc system
• diff scenarios are conceivable and equally sound 

intergovernmental panel on climate change