Worldwide inventory reveals the frequency and variability of pyrocumulonimbus and stratospheric smoke plumes during 2013–2023

Abstract An inventory of 761 confirmed pyrocumulonimbus (pyroCb) events observed worldwide during 2013-2023 answers many open questions on the inter-annual, seasonal, sub-daily, and regional variability of this hazardous fire weather phenomenon, along with potential controlling factors. It reveals that the 2023 fire season set new records for total pyroCb activity regionally (142 events in Canada alone) and worldwide (169 events). Smoke injection altitudes range from the mid-troposphere to the lower stratosphere (8–18 km), with 414 pyroCb events (55%) linked to smoke injection within 1 km of the tropopause or higher. Estimated aerosol mass in these plumes spans four orders of magnitude, which has significant implications for climate-scale radiative effects and ozone chemistry. The cumulative aerosol particle mass injected near the tropopause over an active fire season can rival that of recent extreme pyroCb events and significant volcanic eruptions. This pyroCb inventory is critical for advancing fire weather prediction capabilities to aid firefighting efforts and improving smoke transport forecasts. It sets a foundation for an Earth System Data Record that can be used to identify longer-term trends in pyroCb activity and consequent impacts.