Earth’s Orbit Blamed for Ancient Hot Spells
About 55 million years ago, an intense heat wave hit the planet. Earth’s surface temperature surged by 9 degrees Fahrenheit (5 degrees Celsius). Then, after a relatively short time, the heat subsided, only to be followed by at least two similar, but smaller heat waves.
ANALYSIS: Climate Change Loads Disaster Dice
Based on chemical clues preserved in rocks, scientists believe a surge of carbon dioxide warmed the planet. But where did all of this greenhouse gas come from?
A team of scientists is proposing that it came from the melting of permafrost, frozen soil packed with organic matter, after cycles in the Earth’s orbit warmed up the areas near the poles. The melting released a massive amount of carbon into the atmosphere, keeping reflected sunlight from escaping and causing the heat wave.
Previously, other scientists have theorized that the release of the carbon compound methane trapped in marine sediments — in a form known as methane hydrates — changed the atmosphere. But the study published in the April 5 issue of the journal Nature argues that not enough methane would have been released to account for the magnitude of the warming.
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