How Our the Changes in Our Climate Today Are Different Than Climate Changes of the Past

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If global warming is man-made, what would the climate be like if not for it? Would it not change at all? originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better understand the world.

Answer by Michael Barnard, Low-carbon Innovation Strategist, on Quora:

The climate is changing all the time, but very, very slowly.

The most recent abrupt shift in the climate took about 5,000 years and happened almost 20,000 years ago. The Earth’s atmosphere warmed about five degrees Celsius or 10 degrees Fahrenheit over those 5,000 years.

Almost all of the glaciers on every continent except Antarctica melted.

Humans went from freezing bands of relatively hairless apes to the dominant species on the planet in a few thousand years because of that change in climate.

In about 50,000 years, barring humans being really stupid or really smart, the glaciers are expected to return. So major changes in climate, if humans aren’t messing with it, take several thousand years and happen every 50,000 to 100,000 years.

But in the past 200 years we’ve already managed to achieve 20% of the warming that took 5,000 years. And in the next 100 years we’re likely to achieve 60 percent of the warming that took 5,000 years.

A massive and radical and abrupt change in the climate 20,000 years ago that took 5,000 years is being experienced in a tenth or less of that time.

Climate change ‘skeptics’ like to say that 1 or 2 degrees Celsius isn’t a big deal. But when it’s 40% of what melted the glaciers and happening 10 or 20 times as fast, well, you can do the math.

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