Moderate volcanic eruptions and extreme wildfires are humidifying the stratosphere, according to a study published in Nature News. The findings suggest that these events, often considered primarily for their cooling or polluting effects, are also major sources of stratospheric water vapor. This moisture can linger for years, influencing atmospheric chemistry and radiative balance.
Researchers analyzed satellite data from recent moderate eruptions and intense wildfire seasons, discovering that both phenomena bypass the usual barriers to stratospheric moisture injection. Unlike massive volcanic blasts that cool the planet with sulfur aerosols, these smaller eruptions and fires contribute water vapor that can warm the stratosphere. This shifts the understanding of how non-standard events shape the upper atmosphere.
The study quantifies the water vapor added by these events, though specific figures were not provided in the available source. The authors emphasize that the cumulative effect of multiple moderate events may rival that of a single large eruption. This finding underscores the need to monitor these frequent, yet previously overlooked, contributors to stratospheric composition.
Ongoing climate change is expected to increase the frequency and intensity of wildfires, potentially amplifying this humidification effect. Changes in stratospheric water vapor can impact ozone chemistry and global weather patterns, including monsoon systems. The research highlights a feedback loop where warming fuels fires that then further alter the atmosphere.
The findings challenge models that treat stratospheric moisture as solely controlled by volcanic super-eruptions. As wildfire seasons lengthen, this newly recognized mechanism may become a more dominant factor in climate projections.