December 2, 2019，The 25th Convention on the Framework of the United Nations Climate Change Framework Convention opened in Madrid, the capital of Spain，Because there are differences on key issues，The meeting was postponed two days closing，All parties failed to reach a consensus on core issues。As the global warming situation is becoming increasingly severe，Climate change issues are increasingly attracting the attention of academic circles，On the one hand, it reflects the urgency and importance of this problem，On the other hand, it reflects the country、Government、Enterprise and other departments on the growing needs of scientific judgment and decision -making basis for climate influence。Because slowing and adaptation is the main response measure of global climate change，Academic research around these two aspects is also the most concentrated。For the former，Analysis of emission reduction paths、Evaluation cost evaluation、emission reduction policy design、Selection of emission reduction technology, etc.; The latter includes adapting cost analysis、Adaptation effect evaluation、Adaptation measures，and an analysis of interactive impact of adaptation and emission reduction。

It is worth mentioning is，Most climate economic research and policy comprehensive evaluation work is based on comprehensive evaluation，IA) Model。This model is describing the economy、Complex dynamic interaction relationships between energy and climate systems have unique advantages，And these relationships often play a decisive role in future climate change and effective climate policy choices。Comprehensive evaluation model was first born in the 1970s，The dynamic integrated climate economy model (DICE) developed bet365 Play online games by Professor William Nordhaus of Yale University (DICE) is the most outstanding representative。Early IA models despite the interaction between economic and climate，But only choose carbon dioxide (CO2) concentration and average temperature change as an environment variable，and only considers carbon emissions related to artificial activities，Subsequent models gradually expanded to containing the Earth carbon cycle、Land use carbon emissions、Multi -dimensional environmental variables such as non -carbon emissions and local air pollutants emissions and greenhouse gas (GHGS) emissions，At the same time, the impact mechanism of the feedback of climate change on the economic system was fully considered。Looking at the development of the IA model，It can be said that it is derived from economics，Experience Earth、Integration and development of climate and environmental system，Finally returned to economic problems research。

Different IA models are divided in the area、Start Year Selection、Simulation time span, there are large differences。For example，DICE and E3METL and other models are typical global single -regional single department models，and RICE and WITCH, etc., have expanded to multiple regional standards。other，Even if you look at the global single department model，Each IA model is expected to grow economic growth in the future、Population growth、Energy Technology Progress、Technical investment portfolio、Slowing or adapting to policy selection and many aspects of assumptions are not consistent。Taking economic growth expectations as an example，DICE model is the most optimistic for future economic growth expectations，Followed by Rice and E3METL models，and the WITCH model is relatively pessimistic about the global future economic situation。This also explains to a large extent why the research results of different models on the same policy issue will be significantly bet365 live casino games different。The optimal carbon tax path (or social carbon cost SCC) problem that has attracted much attention，At 2 ° C temperature control target，GCAM model、The simulation results of DICE model and WITCH model indicate that the end carbon tax path is monotonous，and the best carbon tax level at the end of the 22nd century in the GCAM model is about $ 310/ton carbon，This result is closer to the WITCH model，But only 1/3 of the corresponding DICE model results。

So，How to ensure the stability of the results of different IA models，Especially the conclusion that summarizes less differences or relatively consistently summarizes from it，It is particularly important to support decision -making more scientific and reliable，This actually brings challenges to the current climate economic modeling theory。In this background，Model comparative methods based on different IA frameworks came into being。Especially in the past 5 years，Model comparative research has gradually become a new trend in climate policy research。Although European and American countries were established in 1979, "AC model differences，The official forum of improving government decision -making " -Energy Modeling Forum (EMF)，But until Around 2010，Related research based on model comparative methods has gradually appeared and became a hot spot for solving the stability of policy research。Subsequent，Many projects and related conclusions based on model -based comparison are included in the IPCC's fifth comprehensive evaluation report and 1.5 ℃ special report。Driven by policy stability Decision needs，In recent years，Multi -model comparative analysis method has gradually become the risk of climate change in academia to evaluate global and regional climate change、Hot methods for climate -related issues such as emission reduction and adaptation mechanism design。

Current，The theoretical development and empirical research of multi -model Bet365 app download comparison global levels have achieved a series of innovative results，and got a lot of unanimous discovery。First，Requirement of 2 ° C temperature control target requires comprehensive participation in countries around the world and perform effective emission reduction，Compared with some participation situations，The cost of reaching the set goal is greatly reduced。Next，If you do not consider the current feasibility and not optimistic direct air carbon removal (CDR)、Negative emission technology such as biomass carbon capture and sealing (beccs)，Effective emission reduction since the beginning of the moment is the most secure choice to achieve this goal。Last，Wind energy、Solar energy and other key renewable energy technology，and the vigorous development of CCS technology will be a technical guarantee for the feasibility of 2 ° C temperature control target。Last，The intensity of the independent contribution target (NDC) promised in the Paris Agreement (NDC) in the Paris Agreement is far less powerful to support the achievement of the 2 ° C temperature control target，Therefore，The policy cost of achieving NDC targets is far lower than that of temperature control threshold targets。

Dested，Multi -model comparative analysis methods The significance of the development method is far from being limited to policy design，It is of great significance to comprehensively evaluate the modeling method and the improvement of the entire climate economic theory。Through model comparison and analysis，Source that helps us find the result of uncertainty，To modify the model to better make policy simulation。Generally speaking，Model structure (from top to bottom or bottom)，Valuation of key parameters (production factor input elasticity、Technical substitution elasticity, etc.)，For future economic growth、Population growth、Expectation of energy demand, etc.Bet365 lotto review ，Technical selection and feasibility settings，Choice of time preference rate and discount rate，The main source of the currently caused the IA model policy simulation and assessment result uncertainty。

Since 2010，The emphasis on the multi -model comparative analysis method of the academic world has obviously improved，But the number of related research is still less，Obviously not match the research needs of climate change issues。One aspect，Current research concentrated on the analysis of emission reduction paths under the established climate target、Policy cost assessment、Development of Energy Technology、The relationship between climate policy and energy security has limited aspects，and the carbon market、Energy Tax、Renewable Energy Subsidies (FIT) and other representative climate policies for emissions、The impact of technical replacement evolution，Economy during the achievement of climate goals、Technology、Multiple uncertainty played by climate sensitivity，Climate adaptation to the reduction effect of climate loss risk，4006_4037。On the other hand，The current multi -model comparative studies are concentrated in the global scope，But in fact，The regional characteristics of climate change issues are also very significant。This is not only reflected in the regional differences of GHGS emissions and climate change，More importantly，Global greenhouse gas emission reduction tasks need to be implemented to specific countries or regions。Therefore，From the regional level，Especially for China、United States、Climate policy issues in India and other economies are significant for multi -model comparative research。

Statistical results of multi -model comparative research show，The current IA model research is mainly led by Europe and the United States，These models have the top -down economic -oriented model，There are also bottom -up technology -driven models，But the Bet365 lotto review common features are all in consideration of GHGS emission control policies and energy technology replacement policies.。From the geographical distribution of the model，The most widely used model is mostly distributed in Europe and the United States，Europe is dominated by the Netherlands and Germany。This is because the two countries have a famous climate change research institution，、Dutch Energy Research Center (ECN) and Dutch Environment Evaluation Department (PBL)。and other countries or regions except Japan，A model research forces in China and India, which are mainly discharged, are weak。

It can be expected，Model comparative research methods will play more important roles in future climate change research。According to IPCC's sixth comprehensive evaluation report，Analysis of emission paths at the national level budget、Stable emission reduction policy design, etc., all have greater requirements for the comparative study of the model。Of course，Further strengthening the cross -model climate economic research requires focusing on some key issues。One，Vigorously develop a model for the specific national conditions in various countries，Especially developing countries such as China and India，It is the most important prerequisite for these countries to carry out multi -model comparative research work，It is also a key link to improve regional climate economic theory。Although the current multi -regional models developed by Europe and the United States are often listed separately，But modeling foundation (data and parameter valuation reliability，For the economy、Prediction of energy consumption trends, etc.) Faculture is not as good as the model facing the country。Its two，Establish an effective cross -country/area、Research and cooperative relationship between cross -team，This is the basis for building a multi -model comparative research framework。On the one hand, need specific bet365 live casino games research problems，Especially the importance of the problem achieves multi -party consensus，On the other hand, you also need to design some good incentive mechanisms to improve the enthusiasm of multiple parties。Its three，Reasonable selection of qualified models，Study on a better support for reality。In fact，In addition to the will of the model team，The model of the model itself is suitable for specific problems is also very critical。For example，Model structure Question、Micro -level data can get sexual problems、Solve feasibility issues, etc.，All important considerations for model selection。

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