Loki wrote on Jun 1
st, 2012 at 12:59pm:
I'm just going to go back to the original post instead of adding to the stream of argument... Localised climate change is different from global climate change (it can be a massive contributing factor if enough localities are having this change). Local climate change due to human action bringing down a civilisation is not just relevant to that single case.
Take for example the original inhabitants of Easter Island. Archeological evidence (note, climate scientists didn't discover this or add CO2 emissions stuff to it) suggests that the island was once covered in large trees and supported a large civilisation.
Obsession with building moai meant cutting down trees to make logs. The same trees were used for fishing, sea-faring and burning for fuel. When the people arrived, they also brought rats with them (most likely as a food source), this decimated the forest at a fast rate as the seeds are eaten by the rats. Once the forest lost protection around the coast, the wind and salt did further damage and eroded once fertile soil. The island became barren, society broke down but there were no more trees for boats. People starved and fell to disease and war amongst the tribes. This is a clear case of man-made localised climate change.
It's idiotic to speak as if the localised climate change of the past is an indication that localised climate change cannot cause global climate change. We live in an industrialised age for those who haven't noticed. Industrial techniques are used all over the globe now rather than at a few 'hotspots' of activity. We are also doing much more over all, and we can see modern examples of localised climate change (destruction) at mining outposts and felled forests in Africa. The drought and soil erosion leading to desertification in Africa is not simply the result of sunlight.
The quote from the initial post about forcing is complete pseudo-scientific drivel. It makes absolutely no sense, and shows a distinct lack of understanding of over all global climate change effects. By saying that the sun provides the only 'forcing' in climate change, the poster ignores the fact that the Earth also regulates its weather patterns through currents and winds as well as the lay of the land and cloud formation. We live in a complex system, and it's at our own peril if we choose to misunderstand it.
You make it sound like the cities of today cant farm, so cant feed themselves and should have died off.
There is no doubt that what you speak of would have been slow. They would have moved to where they could farm, harvest the forest or whatever. If it were too far from the city, they would have moved and stayed.
You make it sound like they just sat there and waited to die. That is looniville assumptions.
You take away the major drivers and leave CO2, we would die. Other way around, the empirical evidence says we will survive. CO2 does stuff all.
The sun, the rays, the magnetic field of the earth and sun. the forces from the moon, the wind, the sea, the current ,jetstreams and cloud cover are what makes our climate. Not CO2.