LONDON — Sunday, July 21 was the hottest day ever recorded globally, according to preliminary data from the European Union’s Copernicus Climate Change Service. The global average surface air temperature on Sunday reached 17.09 degrees Celsius (62.76 F) — slightly higher than the previous record set last July of 17.08 C (62.74 F). Heatwaves have scorched large swathes of the United States, Europe and Russia over the past week. Last year saw four days in a row break the record, from July 3 through July 6, as climate change, driven by the burning of fossil fuels, drove extreme heat across the Northern Hemisphere. Every month since June 2023 – 13 months in a row – has now ranked as the planet’s hottest since records began, compared with the corresponding month in previous years, Copernicus said.