Comparing Long-Term and Short-Term Emission Impacts from Infrastructure Using a Simple Model

Abstract:

Existing infrastructure such as building shells or roads have long lifetimes, and thus the emissions they cause can persist well into the future. Although present-day emissions from these sources are quantified, long-lived infrastructure can also lock in future development and transportation choices and shape emission trajectories and climate as a result. To understand the impacts of infrastructure choice on the expected Earth system response, it is important to quantify the carbon commitment or lock-in resulting from the infrastructure’s long lifetime. Impacts from infrastructure can be evaluated by estimating the following components: (1) how emissions of short-lived and long-lived climate pollutants are affected by long-lived infrastructure; (2) how atmospheric concentration and radiative forcing are driven by these emissions, and (3) the resulting response of Earth’s temperature. In this study a simple model was used to estimate the emissions, radiative forcing, and temperature response to a time-dependent function characterizing the lifetime of the infrastructure. Outputs from this model are used to compare the short-term and long-term climate forcing resulting from infrastructure alternatives. The MAGICC climate model was used to validate the forcing and temperature outputs of the simple model.