© Fernando Caracena, 2018
Remember that Gore invented the Internet? Now he is also a climate expert, and a Nobel laureate. What height of human achievement he will reach next?
Global warming is a mixed bag. It exits, and there are a number of scientific issues surrounding it. When the politicians get hold of it then the exaggerations creep in--it becomes mostly a political issue.
Global warming follows every ice age, the last one ending about 10,000 years ago. Ever since then, the glaciers and ice caps have been shrinking. Early in the thaw, a huge ice dam broke up over Montana, and a flood of biblical proportions swept across Washington State producing the Scab Lands. The melting ice has given humanity fat times in water availability as fresh water stored in ice was added to natural precipitation.
Periodically, man has also catastrophically upset his local environment enough to make it a desert. The Sahara was once partially forested, and covered with savannas and grasslands. Satellites reveal ancient river beds that still contain water. The locals cut down the forests and kept sheep and goats that grazed grasses down to bare sand. The wind blew away the topsoil and exposed highly reflecting sand that changed the local radiation balance. As sunlight was reflected back into space during the day, a large area of atmospheric sinking developed over the area to compensate for net radiative cooling through the adiabatic contraction of sinking air. The new mode of atmospheric circulation generated a self perpetuating desert.
The thaw from the last ice age has not been monotonic. At one point, Greenland had become warm enough for the Vikings to colonize it, and they went on to colonize parts of Newfoundland. Then the ice rallied. Greenland become uninhabitable to people trying to live the way they were familiar with in Denmark. Most of the Vikings starved to death, and perhaps a remnant of them was either wiped out by the natives, or absorbed by them.
We are aware that since our great grandparents' time the climate has been getting warmer as the earth came out of the Little Ice Age.