Global forest fires emitted 33.9 billion tons of carbon dioxide (CO2) between 2001 and 2022, according to a report by the Chinese Academy of Sciences (CAS). This makes the CO2 emissions generated by forest fires each year higher than those from burning fossil fuels in Japan — the world’s sixth-largest CO2 emitter. Driving the emissions spike was the growing frequency of “extreme forest-fire events”. Yuhang Wang, professor in the School of Earth and Atmospheric Sciences, tells Nature the report complements his work, which “indicates a roughly 20 percent rise in global burnt area by the 2050s compared to the 2000s”.