Pyrocumulonimbus and its Role in the Climate System: What is known and unknown? (Invited Presentation)

Pyrocumulonimbus (pyroCb) are fire-induced and smoke-infused thunderstorms that serve as the primary pathway for smoke to reach the upper troposphere and lower stratosphere (UTLS). Recent pyroCb events have injected volcanic-scale smoke plumes into the stratosphere that encircled the globe, resided for more than a year, altered stratospheric circulations, and extended the lifetime and size of the Antarctic ozone hole. We summarize what the community has learned from these events and identify science questions that remain unanswered. An inventory of 761 confirmed pyroCb events observed worldwide during 2013-2023 answers many open questions on inter-annual, seasonal, sub-daily, and regional variability, along with potential controlling factors. At least 55% (414) of the inventoried pyroCb events are linked to smoke injection within one kilometer of the tropopause or higher. Given the ongoing and projected increases in fire activity and severity linked to a warming climate, there is an urgent need to better understand and predict climate-scale impacts from pyroCb activity. Field experiments are required to identify which fires will produce pyroCbs, how much smoke a given pyroCb will inject in the UTLS, and how this smoke alters the Earth’s radiative balance. The upcoming INjected Smoke and PYRocumulonimbus Experiment (INSPYRE) will test the hypothesis that: Increasing wildfire size and intensity in a warming climate will amplify pyroCb-driven smoke injection into the stratosphere resulting in measurable changes in Earth’s radiative balance.