Twelve months at 1.5 °C signals earlier than expected breach of Paris Agreement threshold

June 2024 was the twelfth month in a row with global mean surface temperatures at least 1.5 °C above pre-industrial conditions, but it is not clear if this implies a failure to meet the Paris Agreement goal of limiting long-term warming below this threshold. Here we show that in climate model simulations, the long-term Paris Agreement target is usually crossed well before such a string of unusually warm temperatures occurs. The 12 months before July 2024 were more than 1.5 °C warmer than the pre-industrial baseline. Using climate models, the author shows that the first year that exceeds 1.5 °C of warming most probably also occurs within the first 20-year period with an average temperature that exceeds temperature targets.