Climate change is already altering the planet, but the warmth we’re headed for may be greater than anything Earth has experienced in around half a billion years. Three scientists collaborated on a study and penned an article for The Conversation, in which they find Earth could see carbon dioxide (CO2) values not seen since the Eocene Epoch. Carbon concentrations today that match previous high CO2 periods could lead to worse warming.

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Today’s CO2 concentrations may lead to more warming because the sun has also been getting stronger, according to the University of Southampton’s Gavin Foster, Wesleyan University’s Dana Royer, and the University of Bristol’s Dan Lunt. They explain Earth’s temperature isn’t simply a result of greenhouses gases in the atmosphere; the sun plays a role as well. They write, “…due to the way the sun generates energy through nuclear fusion of hydrogen into helium, its brightness has increased over time. Four and half billion years ago when the Earth was young the sun was around 30 percent less bright.”

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The scientists point out 1 degree Celsius warming hasn’t been too unusual in terms of geological time. They said the planet has been warmer than it is today for much of Earth’s past. During the last greenhouse state in the Eocene, temperatures on Earth were 10 to 15 degrees Celsius hotter than today. There was no ice in the polar regions and palm trees thrived on Antarctica’s coast then, according to the scientists. But Earth today is technically in an icehouse state – or a time when both poles have ice – even though warming is happening.

In the past when the sun got stronger, atmospheric CO2 decreased, in contrast to today, according to the scientists. They wrote, “We found no past time period when the drivers of climate, or climate forcing, was as high as it will be in the future if we burn all the readily available fossil fuel. Nothing like it has been recorded in the rock record for at least 420 million years.”

The journal Nature Communications published the three scientists’ research online yesterday.

Via The Conversation

Images via Wikimedia Commons (1,2)