Stone Cold: Just How Chilly was the Ice Age?

If you ever want to feel warmer during the midst of winter, consider this – at least we’re not in the middle of an ice age. Concluding about 11,700 years ago, the last ice age caused much of the planet to be literally covered in sheets of ice. Thanks to researchers from the University of Arizona, climate scientists now have a better idea as to how cold the last ice age actually was.

Checking the Thermometer

Published in the journal Nature, this study was actually able to put a number on the average global temperature – and that number was 46 degrees Fahrenheit. But wait, you might say, – that doesn’t seem that cold at all. In fact, that figure is only 11 degrees Fahrenheit lower than the 57 degree global average of the twentieth century.

But as lead researcher Jessica Tierney notes, even a relatively small temperature gap can have huge weather-related ramifications. “In your own personal experience that might not sound like a big difference, but, in fact, it’s a huge change,” stated Tierney in a University of Arizona press release. “In North America and Europe, the most northern parts were covered in ice and were extremely cold. Even here in Arizona, there was big cooling.” As you might expect, this global freeze also extended to the arctic, which was a whopping 25 degrees colder than modern temperatures.

Using the Past to Chart the Future

Believe it or not, documenting temperature shifts from the past can help meteorologists better understand current weather patterns. Specifically, the authors found that carbon levels in the earth’s atmosphere had a major impact on the planet’s climate. With the aid of climate models, the study authors noted that worldwide temperatures rose over 6 degrees Fahrenheit each time atmospheric carbon levels doubled.

So how did these models document temperatures from centuries ago? The answer is relatively straightforward; the authors collected data from fossilized ocean plankton, and used a common weather forecasting technique called data assimilation to convert this information into ice age temperature estimates.

Having tackled the chilliest era in history, the researcher’s next plan to use the same modeling technology to analyze warmer periods. “If we can reconstruct past warm climates,” Tierney opined, “then we can start to answer important questions about how the Earth reacts to really high carbon dioxide levels, and improve our understanding of what future climate change might hold.”

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