This study investigates the expanding spatial extent of heatwaves in the terrestrial Arctic using atmospheric reanalysis and global climate models. The findings reveal a substantial increase in the area affected by heatwaves of varying severity since the mid-20th century, with severe heatwaves doubling, extreme heatwaves tripling, and very extreme heatwaves quadrupling in affected area. Climate model projections suggest this trend will continue throughout the 21st century, although regional differences in heatwave magnitudes are anticipated due to summer intraseasonal temperature variability. The increased spatial extent of heatwaves highlights the growing vulnerability of the Arctic to extreme heat, with potential severe impacts on ecosystems and societies.

Mika Rantanen, Matti Kämäräinen, Miska Luoto, Juha Aalto