The geographical distribution of fossil fuels unused when limiting global warming to 2°C

This article explores the implications of a 2°C warming limit for fossil fuel production in different regions. The article provides estimates of unburnable reserves and resources using TIAM-UCL, a bottom-up, whole-system model that assesses all primary energy sources from production to conversion to end use. Note that the climate target used is based on having at least a 50 per cent chance of keeping warming below 2°C.  

The study’s findings are expressed in terms the implications for ‘resources’ (“quantity of oil, gas or coal remaining that is recoverable over all time with both current and future technology, irrespective of current economic conditions”) and ‘reserves’ (“subset of resources defined to be recoverable under current economic conditions and have a specific probability of being produced”). 

A large share of current gas, oil and coal reserves should remain unused until 2050 to meet the 2°C target. Results with respect to reserves: 82% of coal, 49% of gas and 33% of oil remains unburned before 2050. For coal, the United States and Former Soviet Union countries use less than 10% of current coal reserves, leaving over 200 Gt reserves unburned. China and India use 34% of reserves but leave unburned nearly 200 Gt of current coal reserves. The Middle East carries over half of the unburnable oil in the world, and leaves 38% of its reserves (260 billion barrels) in the ground. The Middle East also holds half of the world’s unburnable gas reserves (leaving 61% unburned) and the Former Soviet countries hold one third (leaving 50% unburned). 

The results with respect to resources include: the vast majority of resources of coal and unconventional oil remain unburned. Over 80% of unconventional gas resources are unburnable before 2050 while the Middle East holds the largest share of unburnable resources of conventional oil. 99% of Canada and Venezuela’s extra-heavy oil resources are unburnable, and all Arctic resources are unburnable. 

Notably, the use of carbon capture storage is estimated to have relatively modest effects on the overall fossil fuels that can be produced before 2050 in a 2°C scenario.  

The article concludes that stark transformation is needed in our understanding of fossil fuel availability as large proportions of the reserve base and a greater proportion of the resource base would not be produced under a 2°C scenario. 

The article highlights that there is a global emissions budget that requires a large proportion of fossil fuels to remain unextracted. In some countries, the proportion of fossil fuels that must not be extracted is incredibly high, making it difficult to justify extraction under a 2°C scenario. The article challenges arguments that individual country producers can continue producing and still be Paris-aligned. 

Note the article updates McGlade & Ekins (2014) and that a more recent paper that draws on the same model considers the distribution of unused fossil fuels under a 1.5C scenario (see Welsby et al (2021)).