A method for quantifying the upfront carbon footprint of urban densification in Texas through 2050

Urbanization is a major contributor to greenhouse gas emissions, and the Intergovernmental Panel on Climate Change projects that urban areas may grow by up to 211% globally by 2050. Embodied emissions make up a considerable portion of the total carbon footprint of urban areas. This study explores the relationship between urban densification and its upfront carbon footprint in Texas through 2050, using a novel method that combines land cover change projections, building stock analysis, and carbon sequestration quantification. Three densification trajectories–Sprawl, Business as Usual, and Built-Up–were used to demonstrate the method's ability to quantify upfront carbon footprint for a range of plausible urbanization outcomes. The analysis found that embodied emissions from building materials made up 71% of the upfront carbon footprint in Built-Up scenarios but only 40% in Sprawl scenarios, where lost carbon sequestration from the conversion of fields and forests to buildings and roads was the most significant factor. The central finding of this study is that high levels of urban densification lead to a larger upfront carbon footprint. Dense urban cores reduce natural land conversion but at the expense of increased emissions from the construction materials required for vertical development. Therefore, urban densification comes with a tradeoff between land-carbon effects and embodied emissions from buildings that should be taken into account in development of urbanization policy. Importantly, that same densification might lead to substantial avoided carbon emissions from more efficient operation and reduced transportation distances, but operational analysis was beyond the scope of this study.