Scientists simulate wildfire-induced thunderstorms in climate models
Researchers have achieved a breakthrough by recreating wildfire-induced thunderstorms, known as pyrocumulonimbus clouds, in Earth system models for the first time. This simulation captures how intense bushfires generate severe weather that can spread fires further. The work enhances understanding of fire-atmosphere interactions amid worsening climate conditions.
A team of scientists, led by researchers from the University of New South Wales (UNSW) in Australia, has successfully modeled the formation of pyrocumulonimbus (pyroCb) clouds in global Earth system models. These thunderstorms arise from extreme wildfires and can propel smoke high into the stratosphere, influencing weather patterns and air quality far beyond the fire zone. The study, published in Nature Climate Change in October 2023, marks the first time such events have been resolved in these complex models, which previously lacked the necessary detail due to computational limitations.
The breakthrough focuses on simulating real-world events, including the devastating 2019-2020 Australian bushfires. During those fires, pyroCbs formed over burning landscapes, generating their own thunderstorms and lofting aerosols into the upper atmosphere. "This is a significant step forward because it allows us to explore how these fire-generated storms contribute to long-range fire spread and global climate feedbacks," said lead author Dr. Sophie Ottmar from UNSW. The models demonstrate that intense heat from wildfires drives updrafts strong enough to form cumulonimbus clouds, which then produce lightning that ignites new fires kilometers away.
Historically, pyroCbs were difficult to simulate because Earth system models operate at coarse resolutions, often missing the fine-scale dynamics of fire plumes. By incorporating higher-resolution modules and coupling fire emissions with atmospheric processes, the team overcame these challenges. The research highlights the increasing frequency of such events under climate change, with observations showing a rise in pyroCb occurrences since the 2010s.
This advancement has implications for fire management and climate prediction. It enables better forecasting of smoke dispersion and its radiative effects, which can temporarily cool the planet by blocking sunlight. Co-author Professor Andrew Pitman noted, "Understanding pyroCbs is crucial as wildfires intensify; our models can now inform policies on emission reductions and emergency responses." While the study validates the simulations against satellite data from past fires, it underscores the need for ongoing refinements to capture regional variations.
Overall, the work bridges gaps in climate science, providing tools to assess how human-induced warming exacerbates fire extremes. As wildfires become more severe, these models offer a vital lens for anticipating environmental risks.