Synopsis As Introduced Creates the Global Warming Response Act. Provides that the Illinois Environmental Protection Agency is the State agency charged with monitoring and regulating sources of emissions of greenhouse gases. Requires that on or before January 1, 2009, the State agency shall propose and the Pollution Control Board shall adopt rules to require the reporting and verification of statewide greenhouse gas emissions and to monitor and enforce compliance with the program. Requires that by July 1, 2008, the State agency shall, after one or more public workshops, determine what the statewide greenhouse gas emissions level was in 1990 and propose to the Board a statewide greenhouse gas emission limit that is equivalent to that level, to be achieved by 2020. Provides that the Board shall consider and either revise or adopt the proposed level by January 1, 2009. Requires that the State agency shall propose and the Board shall adopt rules in an open public process to achieve the maximum technologically feasible and cost-effective greenhouse gas emission reductions from sources or categories of sources. Provides for the use of market-based compliance mechanisms. Provides that the State agency shall monitor compliance with and enforce any rule, order, emission limitation, emissions reduction measure, or market-based compliance mechanism adopted by the State agency pursuant to the Act. Effective immediately.