Immediately starting to phase out fossil fuel infrastructure as it reaches the end of its expected lifetime may result in a 64% chance that global mean temperature rise will remain below 1.5°C relative to pre-industrial levels. The research suggests that delaying mitigation until 2030 reduces the likelihood that 1.5°C would be attainable, even if the rate of retirement was accelerated. The modelling study is published in Nature Communications.
Christopher Smith and colleagues used a climate model under different scenarios to determine what would happen to global temperature rise if CO2 emissions were phased out from the end of 2018 at a close to linear rate, becoming near-zero after 40 years. In these scenarios, fossil fuel power plants, cars, aircraft, ships, and industrial infrastructure would be replaced with zero-carbon alternatives at the end of their life.
Based on their results, the authors suggest that starting to phase out existing CO2-emitting infrastructure immediately means there is a 64% probability warming could be kept below 1.5°C, whereas delaying action until 2030 reduces this probability to below 50%. However, their results rely on no large-scale climate tipping points being breached in the coming decades, for example from extensive melting of permafrost.