First, there is the extermination of species. We could drive half of the plant and animal species on the planet to extinction. Humans are already placing stresses on many species as we take over the land, and climate stress is being added on top of these others. Now a given mean temperature line is moving poleward, northward in the Northern Hemisphere, by 50-60 km per decade, about 35 miles per decade. That rate will accelerate under business-as-usual. Many species cannot migrate that fast. Besides, there is no place colder for polar species to go, and there is no place higher for mountain species to go. In effect, we will push these species off the planet. Many species are interdependent, so there is danger of mass extinctions.

Second, there is potential instability of the ice sheets. If additional global warming exceeds two degrees Fahrenheit, the West Antarctic ice sheet and part of Greenland surely will become unstable, causing eventual sea level rise of several meters. The disaster in New Orleans will be small potatoes compared with world wide catastrophes due to rising seas. Iowa won't be under water but impoverishment of our country will affect everyone, and hundreds of millions of refugees will create global turmoil.

Third, there will be a noticeable increase in climate extremes, at both ends of the hydrologic cycle. Heavy rains and floods will increase, but so will extreme droughts and forest fires, especially in subtropical regions such as the American West, the Mediterranean, Australia and parts of Africa. Early stages of increased drought and fires are already beginning in the American West.

Then he proposes his Declaration of Stewardship:

1. Moratorium on Dirty Coal
2. A Price on Carbon Emissions
3. Increased energy efficiency and no-carbon energy sources.

Kudos again to Hansen for telling it like it is.