MIT Study Traces Climate Impact of Fires, Eruptions

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MIT scientists have developed a way to identify the specific impact of wildfires and volcanic eruptions on global atmospheric temperatures. The study found that the 1991 eruption of Mount Pinatubo, the 2019-2020 Australian wildfires, and the 2022 eruption of the Hunga Tonga volcano all significantly affected temperatures in the stratosphere, the layer of the atmosphere above the troposphere where global warming has accelerated. While the events differed in their effects, the researchers were able to isolate the temperature signals from these natural forcings against a background of other factors influencing global temperatures.

Why it matters

Understanding the climate responses to natural forcings like volcanoes and wildfires is essential for interpreting the effects of human-caused climate change. This new approach allows scientists to better separate the impacts of natural events from the acceleration of global surface warming in recent years, which is mainly driven by human activities that have emitted large amounts of greenhouse gases.

The details

The researchers looked at satellite measurements of global temperatures at different atmospheric layers from 1986 to the present. They subtracted out the long-term trends associated with greenhouse gas emissions as well as the effects of natural variability like El Niño and the 11-year solar cycle. This allowed them to isolate the temperature signals from the three major natural events: the Pinatubo eruption injected 20 million tons of aerosols into the stratosphere, the Australian wildfires put 1 million tons of smoke particles into the upper troposphere and stratosphere, and the Hunga Tonga eruption launched 150 million tons of water vapor into the stratosphere.

• The Pinatubo eruption occurred in 1991.
• The Australian wildfires took place in 2019-2020.
• The Hunga Tonga eruption happened in 2022.

What they’re saying