Scientific American, 8 December 2025

2025 Likely to Tie for Second-Hottest Year on Record

This year may be the second-hottest year on record, likely tying for silver with 2023. Europe’s climate agency on Monday reported that 2025 is slightly less scorching than 2024—which was the first year to exceed 1.5 degrees Celsius above preindustrial levels.

The European Union’s Copernicus Climate Change Service (C3S) reported data up to November 2025 that show this year has been 1.48 degrees C above the average from 1850 to 1900. That’s right around the target set by the 2015 Paris climate agreement, under which countries pledged to limit warming to below 1.5 degrees C and “well below” 2 degrees C. Despite 2024’s record-setting temperatures and 2025’s proximity to the 1.5-degrees-C threshold, scientists must take into account many years of data before they can say with certainty that the Paris Agreement’s target has been breached.