Article 14 of the Paris Agreement stated that the "global stocktake", assessing progress towards the long-term goals of the Paris Agreement, should be informed "by the best available science". As part of this effort, Richard Millar, Fellow on the Oxford Martin Net Zero Carbon Investment Initiative, and Honorary Research Associate at the Environmental Change Institute, was invited to present to the United Nations' Subsidiary Body for Scientific and Technological Advice (SBSTA) at the Bonn Climate Change Conference this month.

"Talking directly to delegates participating in the UNFCCC process offers a fantastic opportunity to take up-to-date scientific work to the coal-face of the climate change policy process," Millar explains.

In his presentation he gave an up-to-date report on human-induced global warming to date - which is currently at about 1°C above the 1861-1880 reference period - using data from the Global Warming Index (GWI). The GWI project, led by Professor Myles Allen - also of ECI and the Oxford Martin Net Zero Carbon Investment Initiative - and developed by ECI climate scientists including Millar, launched its website in 2016 and shows an up-to-the-second index of human-induced warming relative to the mid-19th century, based on the standard "detection and attribution" approach introduced by Hasselmann (1997). This estimates contributions to observed climate change, removing the impact of natural year-to-year fluctuations.

The team behind the GWI believe that such an index could help inform carbon emission targets, which will be vital to avoiding global temperatures of 1.5° and above, as per the Paris Agreement's long-term goals.

Using the index Millar can work out that, if we are to reach net zero warming by the time human-induced climate change reaches 2°C above pre-industrial levels (if global warming was to slow to a halt at 2°c), emissions must fall by, on average, 10% of their current rate for every additional 0.1°C increase in human-induced warming. Likewise, he says, for a 1.5°C goal, emissions must fall by, on average, 20% per additional 0.1°C of human-induced warming to reach net zero in time.

Richard Millar said "Ensuring that delegates are aware of the utility of the latest policy-relevant climate research is essential to ensure that the next steps in the international climate policy process are compatible with our scientific understanding of the climate system."