It is through the development and maintenance of infrastructure that (most) socioeconomic societies provide critical services like sanitation, transportation, and shelter to their populations. A conversation about the carbon emissions of infrastructure is important for both developed countries, that have already established infrastructure stocks for the provision of critical services, and developed countries, that are on a development trajectory to provide critical services via the same infrastructure stocks used in developed countries. In both contexts, future infrastructure demands will be influenced by socioeconomic and demographic changes (e.g. population growth, economic growth) as well as an increasing need for infrastructure that is climate-resilient. Additionally, infrastructure has long service times, such that choice of infrastructure has long-term implications for carbon emission budgeting.
Müller et al. approach the accounting of infrastructure development of carbon emissions with a dual objective: 1) to evaluate the carbon emissions of current infrastructure stocks, and then 2) to determine the carbon emissions implications of infrastructure stock choice in developing countries. The authors use carbon replacement value (CRV) accounting to estimate the carbon emissions budget of infrastructure, using 2008 as a base year, and extrapolating total emissions from calculated steel, cement, and aluminum emissions. The material stocks for steel, cement, and aluminum were used as a proxy for infrastructure stocks as those three materials represented nearly half of total industrial emissions and 17% of total energy- and process-related emissions. The stock volumes were then multiplied against corresponding emissions coefficients. A key finding from the analysis is the current global material stock is approximately equivalent to 4 years’ worth of total CO2 emissions.
The authors were able to contextualize the findings from their analysis with the policy guardrail of limiting the average global temperature rise to 2˚C above pre-industrial levels. With this guardrail in place, the authors estimated that developing countries would consume 35-60% of the total 2012 to 2050 carbon emissions budget if infrastructure stocks were developed along the same trajectory as developed countries. The authors suggest then the importance of decoupling material use from services by reducing the emission intensity of materials and/or by reducing the material stock required per service unit. Positive examples of how this can be achieved include 1) increasing urban density as there is an inverse relationship between urban density and many infrastructural services (e.g. the carbon emission “cost” of water infrastructure can be decreased with increased urban density and a corresponding decrease in network length), 2) recycling obsolete infrastructures for materials for new mitigative infrastructure, and 3) the ever-elusive “leapfrogging” that developing countries can do to establish critical services without following the same costly development trajectory.
Müller, D. B., Liu, G., Løvik, A.N., Modaresi, R., Pauliuk, S., Steinhoff, F. S., & Brattebø, H., (2013). Carbon emissions of infrastructure development. Environmental Science & Technology, 47(20), 11739-11746.