Global extreme heat season expands by 39 days over four decades

A study published in Nature Climate Change by researchers including the Chinese Academy of Sciences reveals that the extreme heat season is expanding globally. Between 1979 and 2023, the first heat wave of the year arrived approximately 15 days earlier, while the last heat wave of the year occurred about 24 days later. This shift has extended the potential annual period for extreme heat by roughly 39 days over the 45-year period.

The trend is nearly universal, with 72% of landmasses seeing earlier heat waves and nearly 80% seeing later conclusions. Most significantly, 92.1% of land areas have experienced an increase in the duration of the season susceptible to heat waves.

In urban environments like Mexico City, these rising temperatures are exacerbated by urban heat islands. Experts note that the combination of global warming and urban materials like concrete and asphalt intensifies evaporation and water stress. Addressing these issues requires a shift toward sustainable construction, bioclimatic design, and green infrastructure to mitigate the impact of increasing temperature frequencies.