By Julia Calderone, Tech Insider from Business Insider

There’s no denying that our planet is getting warmer.
Average surface temperatures across the globe have already risen 0.8 degrees Celsius (1.4 degrees Fahrenheit) since 1880. Meanwhile, new climate models predict that, by the end of the 21st century, they could further rise by between 2 C and 6 C (between 3.6 F and 10.8 F).

This may not seem like a dramatic surge, but even small temperature fluctuations will bring potentially catastrophic consequences.

On the low end, a spike of just 2 C from today’s temperatures could melt a substantial part of Greenland’s and Antarctica’s ice sheets. That warming could also threaten coral reefs and mountain ecosystems.

On the high end of the range, a rise of 6 C would create “a scenario which is so extreme it’s almost unimaginable,” Mark Lynas, environmental writer and author of the book “Six Degrees: Our Future on a Hotter Planet,” told CNN.

To get a better perspective on what just a few degrees Celsius can do to the planet, check out the National Oceanic and Atmospheric Administration (NOAA) graphic below, which we first saw at Tim Urban’s blog, Wait But Why.

This is what the planet looked like 18,000 years ago, when the average temperature was about 5 C cooler than it is today. Those 5 degrees were “enough to put Canada, Scandinavia, and half of England and the US under a half a mile of ice,” Urban wrote.

See IMAGES

Consider, then, what just a few degrees of warming could do in modern times.

“100 million years ago, temperatures were 6 to 10 C higher than they are now — and every region of the Earth was tropical,” Urban wrote at Wait But Why. “[T]here was no permanent ice anywhere [and] ocean levels were [up to] 200 meters higher.”

We’re nowhere near this level of warming, and predicting the actual consequences of a rise in temperatures is challenging. But considering what we know about the past — and given that a 6 C increase is possible by the end of the century — scientists are speculating on the potential ramifications of a dramatic warm-up.

“Most of the planetary surface would be functionally uninhabitable,” Lynas says in the CNN article. “Agriculture would cease to exist everywhere … the oceans would become oxygen deficient, which would cause a mass extinction and a die off in the oceans, as well — which would then release gases and affect land. So it’s pretty much equivalent of a meteorite striking the planet, in terms of the overall impacts.”

IMAGES:
devastation earth Cotton Coulson/Keenpress
earth ice cover labeled 18000 anNOAA Compare this to a model of our planet today (below).
The majority of modern-day Earth’s ice lives in Antarctica and Greenland. As a whole, ice covers only about 10% of land on Earth:
earth ice cover labeled today anNOAA
The effect of a 5 C temperature increase on the planet was incredible:

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