What's the worst scenario you imagine for earth if the global warming goes absolutely terrible?

Answer 1

Sea levels will rise by about 80 meters flooding many coastal areas. Populations will need to migrate to escape this flooding. Weather patterns will change forcing still more adaptation from various populaton groups. Non adaptive or poorly adaptive species will decline or become extinct. New species may arise to fill new niches in the echo system.

But, this is not going to happen in the next year or two or even in the next few decades. It is a slow process and those who can will adapt and adjust, just like in the past.

In truth, I think the worst scenario is that we (the human race) will expend all of our resources trying to stop global warming (which is simply not possible) and have none left to deal with the inevitable consequences.

Answer 2

The flooding of coastal areas because of rising seas (54% of Americans live within 50 miles of the coastline.), floods, droughts & other violent weather causing severe disruption of human activities, eradication of many animal species who cannot adopt to the new environment, famine, disease (Maleria has already been discovered in Italy), loss of material resources to the industrial economies, etc.
I am not a doomsayer, however, I see a worst case scenario happening re climate change and the tentative response of the world's burocracies to the crisis.
The world will never be the same and we will have a very tenuous grip on it.

Answer 3

Well, rise in sea level due to melting of polar ice as well as glaciers would cause massive inundation of coastal regions.

Another major effect would be on lifestyles of all lifeforms - animals and vegetation. The cropping season would be affected and availability of food would become scarce due to change in cycle. Water availability would change, rate of fluvial erosion would increase.
Energy requirements for cooling homes and office would increase manifold.

To sum up life style on earth would not be the same as it is today.

Answer 4

emos being the only survivors :S