Environmental Impact Report, etc.) and has discretion to adopt significance criteria more conservative than those required by CEQA. §15064.4 provides a lead agency discretion to determine which type of analysis approach to utilize for a given project level GHG analysis: “(1) Use a model or methodology to quantify greenhouse gas emissions resulting from a project, and which model or methodology to use. The lead agency has discretion to select the model or methodology it considers most appropriate provided it supports its decision with substantial evidence. The lead agency should explain the limitations of the particular model or methodology selected for use; and/or (2) Rely on a qualitative analysis or performance based standards.” The lead agency is charged with making a good-faith effort to “describe, calculate, or estimate the amount of greenhouse gas emissions resulting from a project.” Lifecycle analysis of GHG includes the full aggregate quantity of GHG generated from the extraction, production, distribution and use of energy or fuel. If a lead agency had to complete a GHG lifecycle analysis under CEQA, they would have to quantify GHGs produced not only within the spatial boundary of the project site, but GHGs generated from transportation of products to the site and product supply chain production emissions. Several of these energy emissions could be produced overseas leading to difficulty by the lead agency in verification and enforcement of emission thresholds. CEQA guidance currently does not require lifecycle analysis of GHG emissions since the term is not well defined and too speculative, and the Office of Planning and Research (OPR) removed the term “Life Cycle” from CEQA guidelines in 2010. If any portion of the analysis is considered speculative by the lead agency and not supported by defensible and quantifiable scientific evidence, the impact must be eliminated pursuant to CEQA Guidelines 15145. Thresholds of significance can be determined by reference of air quality management district CEQA guidelines, although the ultimate discretion for thresholds remains with the lead agency. The Bay Area Air Quality Management District, South Coast Air Quality Management District, and San Joaquin Valley Air Pollution Control District are the only districts to date that have adopted CEQA guidelines. Below are highlights from the BAAQMD and SCAQMD: Bay Area Air Quality Management District The Bay Area Air Quality Management District (BAAQMD) typically acts as the responsible agency for setting CEQA air emission thresholds within the San Francisco Bay Area Air Basin.