Bringing albedo to the GHG market

A global warming potential of albedo (GWPA) is proposed, that represents the carbon dioxide emissions equivalent to a 0.01 increase in albedo over 1 m2 of horizontal surface. A survey of prior literature suggests GWPA ≈ −4.2 kgCO2/m2. Taking Los Angeles, CA as a test site for urban global warming mitigation actions, a residential “cool roof” project offers approximately seven times as much radiative forcing benefit from albedo change as from GHG reduction of energy efficiency; and a citywide increase to commercial building roof albedo offers radiative forcing benefit equivalent to the first 6½ years of all commercial sector GHG emission reductions proposed in the City of Los Angeles climate action plan. Discussion explores pathways and challenges to making albedo increases fungible with GHG reductions in GHG markets.

本研究提出反照率全球变暖潜势（GWPA），其定义为1平方米水平地表上，反照率（albedo）每提升0.01所对应的等效二氧化碳排放量。对既往学术文献的调研显示，GWPA约为-4.2千克二氧化碳当量/平方米。以加利福尼亚州洛杉矶市作为城市全球变暖减缓行动的试点区域，某住宅“冷屋顶”项目通过反照率改变获得的辐射强迫（radiative forcing）收益，约为通过能源效率提升实现温室气体（Greenhouse Gas, GHG）减排所获收益的7倍；而全市范围内提升商业建筑屋顶反照率所带来的辐射强迫收益，等效于洛杉矶市气候行动计划中拟定的全部商业部门温室气体减排举措在头6.5年内的减排总量。本研究还探讨了在温室气体交易市场中，使反照率提升与温室气体减排实现等效互换的可行路径与现实挑战。