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AUGUSTIN BERNAL MOUNTAIN BIKE TRAIL PROJECT DRAFT INITIAL STUDY <br /> 12956 <br />DUDEK 56 April 2022 <br />may document the find and allow work to continue. If the discovery proves potentially <br />significant under CEQA, additional work such as preparation of a paleontological treatment <br />plan and monitoring in the area of the find may be warranted. <br />3.8 Greenhouse Gas Emissions <br /> <br />Potentially <br />Significant <br />Impact <br />Less Than <br />Significant <br />Impact With <br />Mitigation <br />Incorporated <br />Less Than <br />Significant <br />Impact No Impact <br />VIII. GREENHOUSE GAS EMISSIONS – Would the project: <br />a) Generate greenhouse gas emissions, <br />either directly or indirectly, that may <br />have a significant impact on the <br />environment? <br /> <br />b) Conflict with an applicable plan, policy or <br />regulation adopted for the purpose of <br />reducing the emissions of greenhouse <br />gases? <br /> <br />Setting <br />Climate change refers to any significant change in measures of climate, such as temperature, precipitation, <br />or wind, lasting for an extended period (decades or longer). Gases that trap heat in the atmosphere are <br />often called GHGs. The greenhouse effect traps heat in the troposphere through a threefold process: (1) <br />short-wave radiation emitted by the Sun is absorbed by the Earth; (2) the Earth emits a portion of this energy <br />in the form of long-wave radiation; and (3) GHGs in the upper atmosphere absorb this long-wave radiation <br />and emit this long-wave radiation into space and back toward the Earth. This trapping of the long-wave <br />(thermal) radiation emitted back toward the Earth is the greenhouse effect’s underlying process. <br />Principal GHGs include carbon dioxide (CO2), methane (CH4), nitrous oxide, O3, and water vapor. Some <br />GHGs, such as CO2, CH4, and nitrous oxide, occur naturally and are emitted to the atmosphere through <br />natural processes and human activities. Of these gases, CO2 and CH4 are emitted in the greatest quantities <br />from human activities. Emissions of CO2 are largely byproducts of fossil-fuel combustion, whereas CH4 <br />results mostly from off-gassing associated with agricultural practices and landfills. Manufactured GHGs, <br />which have a much greater heat-absorption potential than CO2 include fluorinated gases, such as <br />hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride, which are associated <br />with certain industrial products and processes (CAT 2006). <br />The Intergovernmental Panel on Climate Change (IPCC) developed the Global Warming Potential (GWP) <br />concept to compare the ability of each GHG to trap heat in the atmosphere relative to another gas. The <br />GWP of a GHG is defined as the ratio of the time-integrated radiative forcing from the instantaneous release <br />of 1 kilogram of a trace substance relative to that of 1 kilogram of a reference gas (IPCC 2014). The <br />reference gas used is CO2; therefore, GWP-weighted emissions are measured in metric tons of CO2 <br />equivalent (MT CO2e).