Volcano eruptions have quite a few positive impacts on Earth and one such positive is the cooling effect that these eruptions have on Earth. However, climate change may be impeding with this ability of volcanoes, a new study by Canadian scientists has shown.
University of British Columbia researchers have published a study in Journal of Geophysical Research: Atmosphere wherein they have shown that climate change is causing the lower layers of the atmosphere to expand thereby hindering the ability of aerosol making sulfur from rising to the stratosphere – the layer where the aerosol reflects sunlight and heat and keeps Earth cool.
According to the researchers volcano eruptions contain sulfur among other gases and this sulfur rises through the atmosphere until it reaches the stratosphere. Once there, the surfur particles form aerosol and stay there for a couple of years. During these years, it actively reflects the heat and sunlight from the Sun and helps our planet cool down. On average, there are anywhere from three to five eruptions that reach the stratosphere every year.
Previous studies have established that climate change is responsible for expansion of lower layers of atmosphere and this expansion makes it harder for gasses including sulfur to reach higher layers of the atmosphere. Because they can’t reach the stratosphere, they remain at the troposphere where after turning into aerosols and clouds and precipitate back down to earth as rain or snow.
This means that because there is not enough sunlight-reflecting aerosol in the stratosphere, more heat and sunlight reaches the lower layers of the atmosphere thereby warming up the atmosphere and the Earth as a whole.
With our Earth warming at a rapid pace, researchers at the university point out that fewer eruptions will be able to reflect the sun’s radiation and hence the volcanic gases won’t be able to cool the planet. While there have been reports that there has been cooling of our planet in the last 10 to 15 years, it is because there have been many large volcanic eruptions over the last decade that have sent sulfur gasses high up into the stratosphere.
For the study researchers used models of volcanic eruptions and global climate to calculate the impact on gasses released from volcanic eruptions. According to climate model projections and global warming the team found the amount of volcanic sulfur gasses in the stratosphere will decrease anywhere from two to twelve per cent in the next 100 years. Longer term, they predict anywhere from 12 to 25 per cent less sulfur gas in the stratosphere by the 22nd and 23rd centuries. They say the range is large because it is difficult to predict future eruptions and future greenhouse gas emissions.
To determine the precise impact on the Earth’s surface temperature in the future will require further study. It also raises interesting questions about Earth’s history. The study is published in Journal of Geophysical Research: Atmosphere.