A year above 1.5°C signals the onset of a 20-year period exceeding the Paris Agreement limit

Abstract A single year exceeding a global mean temperature of 1.5 °C above pre-industrial levels might be imminent. This raises questions about the implications for the Paris Agreement temperature goal. We show that, while the first year above 1.5 °C does not imply that the long-term warming level is reached, it is highly probable that it signals the onset of a 20-year period with an average warming of 1.5 °C.