Big eruptions and wildfires can launch vast amounts of particles and gases into the atmosphere, sometimes affecting temperatures worldwide. Recent research has found a method to distinguish the specific impacts of these events from the overall climate noise.
The study looked at three significant events: the 1991 Mount Pinatubo eruption, the Australian wildfires of 2019–2020, and the underwater Hunga Tonga eruption in 2022. Each event impacted global temperatures in unique ways.
Researchers discovered that all three caused notable changes in the stratosphere, the atmospheric layer above where we live. However, their effects on surface temperatures were less clear. For instance, the Pinatubo eruption led to a short-term cooling effect due to the sulfate aerosols it released. In contrast, the Australian wildfires caused warming high in the atmosphere, while Hunga Tonga introduced massive amounts of water vapor, resulting in cooling.
Study lead author Yaowei Li from MIT noted, “These events inject different materials at different altitudes, affecting climate in unique ways.” Their findings point to significant warming in the stratosphere but suggest that these events aren’t responsible for the rise in temperatures we’re experiencing at ground level.
To achieve these insights, the researchers processed satellite data beginning from 1979 and adjusted for long-term trends and natural climate variability, such as El Niño and La Niña cycles. This method allowed them to isolate the climatic effects of these individual disasters.
With the data in hand, Pinatubo’s effects were as expected, cooling lower atmospheric temperatures by about 1.3°F (0.7°C) for over two years. For the wildfires, strong heating of about 1.4°F (0.77°C) in the stratosphere was observed but didn’t translate to the lower atmosphere.
Interestingly, the Hunga Tonga eruption’s water vapor led to a cooling effect, which is unusual since water vapor generally contributes to warming. This finding highlights the complexity of atmospheric reactions.
The researchers concluded that while these events can significantly impact the stratosphere, they don’t explain the consistent warming observed at Earth’s surface. This emphasizes the need to consider human contributions to climate change, as atmospheric changes alone can’t account for the persistent warming we are witnessing today.
For more detailed insights, you can refer to the study published in the Proceedings of the National Academy of Sciences here.
