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Temperature Cycles
Jun. 2nd, 2006 02:13 pmBeen doing some research, which is always a dangerous thing. I knew Europe used to be warmer than it is now, but was surprised at how much warmer and when. During the Medieval Warm Period Greenland was actually green! (Of course, within a few centuries the Little Ice Age had set in and anyone who didn't leave starved...)
The Roman Warm Period was another time when Europe - and the entire world - was much warmer than today. It was part of what let them grow (or "acquire" from others) enough food to raise armies to do all that conquering. The Fall coincided with lowering temperatures. (Which was far from the only factor, but that couldn't have helped.)
It's natural for the world's climate to change. Sometimes it has even changed rapidly. (Though the current warming is still extreme in its pace.) Rising temperatures release CO2 from decaying plant matter, including that in thawing tundra, adding a positive feedback. Then the plants start to catch, producing new growth, and CO2 levels drop. There's no simple cause and effect in any of this, of course, but rather a complicated interaction.
So what is the "normal" temperature for the Earth? That depends on what period you pick. The world has been somewhat warmer... and much cooler. And then back again. In multiple, overlapping cycles.
The Roman Warm Period was another time when Europe - and the entire world - was much warmer than today. It was part of what let them grow (or "acquire" from others) enough food to raise armies to do all that conquering. The Fall coincided with lowering temperatures. (Which was far from the only factor, but that couldn't have helped.)
It's natural for the world's climate to change. Sometimes it has even changed rapidly. (Though the current warming is still extreme in its pace.) Rising temperatures release CO2 from decaying plant matter, including that in thawing tundra, adding a positive feedback. Then the plants start to catch, producing new growth, and CO2 levels drop. There's no simple cause and effect in any of this, of course, but rather a complicated interaction.
So what is the "normal" temperature for the Earth? That depends on what period you pick. The world has been somewhat warmer... and much cooler. And then back again. In multiple, overlapping cycles.
