Since we’re apparently not going to do much about global warming for at least a few years, we might as well examine past events for some insight into what our own immediate future may hold. There is no shortage of climate-linked catastrophes to go by. Mass extinctions, regardless if they coincide with giant volcanoes or space rock impacts, always involve massive changes in global climate. But many climatologists zero in on one geologically recent event, called the Paleocene-Eocene Thermal Maximum or PETM, as the best analogue to the loaded smokestacks the planet is breathing through now.
The PETM starts about 55.5 million years ago, just 10 million years after the more well-known K-T event that signaled the end of non-avian dinosaurs and about every other animal over 50 pounds in weight on land or by sea. The latter part of the Paleocene was a strange time, both in terms of biota and climate. Before the changes all started, the temperature was comparable to today, everywhere except the polar regions. Mammals had emerged from their hidey-holes and evolved into more diverse forms. Some clear precursors of modern grazers and predators are seen in the fossil record, but very few blades of anything like modern grass yet exists to support later, more familiar ice-age megafauna. Raptors were long gone, but a new family of giant, carnivorous flightless birds had evolved to fill a most similar, terrifying niche. Early primates diversified and prospered, some living comfortably beyond the Arctic Circle. Even the geography was getting recognizable, as tectonic forces slowly guided the major continents toward their current destinations and shapes.
But all those plants and animals are in trouble: the temperature is set to spike and the climate about to change, quickly and dramatically. It will come in two rapid-fire pulses, one of which seems to have happened almost overnight by the patient standards of geology. When it’s all over, the average global temperature will be 5 to 8 °C (9 to 14 °F) warmer. Which is about where we may be headed in the next century or two.
from Daily Kos http://ift.tt/2nMjfP5
0 التعليقات:
Post a Comment