The July 2011 issue of Scientific American Magazine contains an article describing what is now known about a period of global warming that occurred about 56 million years ago.
During that period:
"in the course of a few thousand years—a mere instant in geologic time—global temperatures rose five degrees Celsius, marking a planetary fever known to scientists as the Paleocene-Eocene Thermal Maximum, or PETM.
"Climate zones shifted toward the poles, on land and at sea, forcing plants and animals to migrate, adapt or die. Some of the deepest realms of the ocean became acidified and oxygen-starved, killing off many of the organisms living there. It took nearly 200,000 years for the earth’s natural buffers to bring the fever down."
The article's authordescribes how the researchers went to the island of Spitsbergen in the
The fossils in the mineral records indicate that absorption of carbon dioxide by the ocean caused significant acidification which happened then much slower than is happening now. Even so, something like 30 percent of all species of ocean flora and fauna die out.
- "Global temperature rose five degrees Celsius 56 million years ago in response to a massive injection of greenhouse gases into the atmosphere.
- That intense gas release was only 10 percent of the rate at which heat-trapping greenhouse gases are building up in the atmosphere today.
- The speed of today’s rise is more troubling than the absolute magnitude, because adjusting to rapid climate change is very difficult."
"[the] evidence suggests the pace of Earth's most abrupt prehistoric warm-up paled in comparison with what we face today. The episode has lessons for our future."