This year, five years after the Paris Agreement, countries will come together and look ahead to reducing their carbon emissions. While the focus on curbing future emissions is essential if the world is to avoid the worse impacts of climate change, the responsibility of countries for climate damage to date is also relevant to setting their future commitments equitably, including on finance. So, how should we value those historic emissions and how does this compare to promised levels of climate finance?

This note looks at cumulative historical emissions but adds two adjustments to quantify countries’ liability for climate damage. First, we use recent thinking on carbon prices to cost emissions. Second, we allow that cost to fall for historic emissions and include a cut-off to reflect the rising certainty of climate damage.

The assumptions necessary for this are difficult and contested so, we welcome feedback on ours. Even so, in the arguably conservative estimates we present here, the total liability for historic emissions could reasonably be $26 trillion, around 31 percent of global GNI. For just the OECD countries, paying this off would cost around $150 billion per year to 2100.

Report by the Centre for Global Development