.. _scenario_type:

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Commonly used scenarios
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In the GAINS model, different scenarios are used to explore and analyze various potential futures based on different assumptions and policy measures. Here are some commonly used scenarios:

Current Legislation (CLE) Scenario
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The CLE scenario is the GAINS representation of the existing air pollution control legislation in a given region. It assumes the continued enforcement of those regulations and does not consider any additional policies beyond the current legal requirements. The implementation of the latter results in baseline emission levels reflecting the environmental performance if current policies remain unchanged over the simulation period.

.. Cost Optimal Baseline (COB) Scenario
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.. The COB scenario is directly derived from the CLE scenario and represents the most cost-effective way to reach the baseline emission levels for each activity-sector combination. The COB scenario is the starting point/baseline for other optimizations with non-trivial environmental targets, such as the following Custom Policy or MTFR scenarios.

Custom Policy Scenario
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Custom policy scenarios allow users to design and implement their own policy assumptions, targets, and implementation timelines to explore the potential impacts of customized emission control strategies within the GAINS framework.


Maximum Technically Feasible Reductions (MTFR)
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The MTFR scenario in the GAINS model focuses on achieving the maximum feasible emission reductions based on existing and potential technological advancements. Assuming the widespread implementation of current technical capabilities to their limits, it represents a hypothetical ambitious pathway providing valuable insights into the upper bounds of emission reductions that could be achieved solely through technological improvements without considering cost constraints or policy implementation.