The declining performance of the oil sector: Implications for global climate change mitigation.

• The declining performance of the oil sector is studied with relational analysis. • Aging fields and unconventional sources may hinder climate change mitigation. • Emissions per barrel are expected to increase by 6–26% in 40 years. • The emission overhead is comparable to emissions of entire EU economic sectors. • The option space of potential changes is explored by running "what if" simulations. This article presents a relational analysis of the performance of the petroleum sector in the context of climate change mitigation. The oil sector is described as a complex network of transformations carried out by structural and functional elements, exploiting different types of crude oils. Energy carrier requirements and emissions of viable sequential pathways of extraction and refining are assessed and scaled across different levels of organization, using the concept of metabolic processor. Based on the analysis of seventy-one oil fields around the world - about 25% of global production - we provide a diagnostic analysis of the current state and explore possible scenarios simulating the progressive aging of conventional oil sources and an increasing exploitation of unconventional crudes. Results show how future oil exploitation will be more energy intensive, entailing an increase of emissions per barrel in the range of 6–26% over the baseline, depending on the simulation. Under the existing policy frameworks and international pledges, this increase will translate into an amount of extra CO 2 comparable to entire European economic sectors. Implications of our findings for future energy policies are discussed and the need to complement Integrated Assessment Models (IAMs) with more robust methodologies is emphasized. It is concluded that the declining performance of the oil sector could potentially undermine the plausibility of global low-carbon aspirations. [ABSTRACT FROM AUTHOR]