About 700 million years ago, a string of large volcanic eruptions raged across our planet and led to a phenomenon known as “snowball Earth.”
To shed light on the event — which ranged from present-day Alaska to Greenland — a team of researchers from Harvard University studied the connection between the icy Earth and ancient volcanic activity.
The researchers first believed that the Earth cooled as a result of interactions between basaltic rock and carbon dioxide. However, further study showed such reactions would take much too long to fit inside the time frame for the cooling process. This then caused the team to look at the aerosols ancient volcanoes spewed into the atmosphere and found that, under the right conditions, such emissions could lead to rapid cooling.
“It is not unique to have large volcanic provinces erupting,” explained Robin Wordsworth, assistant professor of Environmental Science and Engineering at the Harvard John A. Paulson School of Engineering and Applied Science, in a statement. “These types of eruptions have happened over and over again throughout geological time but they’re not always associated with cooling events. So, the question is, what made this event different?”
Researchers discovered that volcanic rocks in a region known as the Franklin large igneous province erupted through sulfur-rich sediments that would have been launched into the atmosphere as sulfur dioxide. This would have then blocked solar radiation in the upper atmosphere and caused the planet to cool.
Though such an effect usually only lasts a few days, if gases break through the tropopause — the boundary between the troposphere and the stratosphere — they can linger there for over a year. This is what happened during the snowball event, where gases mixed with airborne particles and stayed in the atmosphere.
However, this was not the only factor that led to lower temperatures.
Continental shift, which moved the Franklin large igneous province near the equator, allowed light-reflecting gas to enter Earth at just the right spot to trigger cooling. In addition, the massive stretch of volcanoes was able to erupt continuously over a long period of time and never gave the atmosphere a chance to recover. All of these elements came together to cause massive shifts around the globe, Daily Mail reports.
The research sheds light on past dramatic climate changes and could help scientists better understand future temperature shifts. It may also shed light on the mechanisms behind past extinctions, show how proposed geoengineering tactics could affect future climate change, and even reveal the way climate change occurs on other planets.
“This research shows that we need to get away from a simple paradigm of exoplanets, just thinking about stable equilibrium conditions and habitable zones,” said Wordsworth. “We know that Earth is a dynamic and active place that has had sharp transitions. There is every reason to believe that rapid climate transitions of this type are the norm on planets, rather than the exception.”
The findings were published in the journal Geophysical Research Levels.