The Earth underwent a complete makeover after the last Ice Age, turning from a frozen wasteland to a slushy planet surrounded by oceans. In a new study, researchers looked at how it was possible for the once snowball Earth to rapidly melt and enter its “plumeworld ocean” era.
The surface ocean remained deeply frozen for several million years during the Ice Ages, which occurred about 635 to 650 million years ago. Scientists believe global temperatures dropped, causing the polar ice caps to spread around the hemispheres. More ice meant more sunlight reflected away from the Earth, contributing further to the frigid temperatures.
In a new study published in the Proceedings of the National Academy of Sciences journal, researchers show the first geochemical evidence of Earth setting conditions for the climate to change, with carbon dioxide from the sky eventually thawing out the ice.
“Our results have important implications for understanding how Earth’s climate and ocean chemistry changed after the extreme conditions of the last global ice age,” says Tian Gan, a former Virginia Tech postdoctoral researcher and lead author of the study, in a press release.
Along with sunlight reflected off the polar ice caps, a quarter of the ocean stayed deeply frozen because of low carbon dioxide levels. The frozen ocean stopped several chain reactions. The water cycle locked up, preventing evaporation, rain, and snow. With no water available, chemical weathering declined. This carbon dioxide-consuming process involves rocks breaking down because they interact with environmental chemicals. A lack of weathering and erosion causes carbon dioxide to build up in the atmosphere, trapping heat.
“It was just a matter of time until the carbon dioxide levels were high enough to break the pattern of ice,” says Shuhai Xiao, a geologist at Virginia Tech and study coauthor. “When it ended, it probably ended catastrophically.”
Over time, the accumulation of carbon dioxide trapping sunlight caused more heat to pile in the atmosphere. This caused ice caps to melt, and Earth’s climate turned frozen to slushy. Over 10 million years, the average global temperatures moved from -50 to 120 degrees Fahrenheit.
In the current study, researchers analyzed lithium isotopes from carbonate rocks formed after the Ice Age ended. The rocks’ geochemical signatures would give researchers a better idea of what the climate was like after the Ice Age.
Source:https://studyfinds.org/climate-change-after-ice-age-slushy-earth/