New research reveals the cooling effect of volcanic eruptions may be impeded by climate change.
If an eruption is forceful enough, volcanoes spew sulfur gases about 10 to 15 kilometres above the Earth’s atmosphere, reaching a layer called the Stratosphere.
The gases then react with water to form aerosol particles which stick around for one or two years. These particles reflect sunlight and heat from the sun and as a result cool the planet.
On average there are three to five eruptions that make their way to the stratosphere every year.
Previous research has shown that the warming of the planet causes the atmosphere to expand, making it more difficult for the gases to reach the stratosphere.
At lower altitudes, in the troposphere, the gases change into aerosols and clouds and come back to earth as rain or snow.
“Volcanic eruptions tend to counteract global warming but as the planet heats up and our atmosphere changes, we’ve found that fewer eruptions will be able to reflect the sun’s radiation,” said Thomas Aubry, a PhD student studying climate and volcanoes. “It will be harder for the volcanic gasses to reach high enough into atmosphere to help cool the planet.”
Aubry said scientists have noticed a slight drop in the rate of global warming in the last 10 to 15 years while the planet continues to warm. Scientist believe this decline is due to the number of large eruptions over the last decade that have sent sulfur gases high up into the stratosphere.
Aubry and his co-authors found that according to climate model projections and global warming, the amount of volcanic sulfur gases in the stratosphere will decline in the next century some where between two to 12 percent. This could result in reduction of sulfur gas in the atmosphere between 12-25 percent by the 22nd and 23rd centuries
Nonetheless, further studies are needed in order to determine the precise impact on temperature change on the Earth.
To determine the precise impact on the Earth’s surface temperature in the future, further studies are required. It also raises interesting questions about Earth’s history.
“Understanding this positive feedback loop has provocative implications for understanding climate variability in Earth’s past,” said Professor Mark Jellinek, whose lab Aubry works in at the department of earth, ocean and atmospheric sciences. “In particular, this mechanism may have contributed to Earth’s entry into a long period of global glaciation around 700 million years ago, a theory known as the Snowball Earth hypothesis.”