Dr. Jeff Masters, a scientist, hurricane watcher, founder of a national Internet weather site, and as respected as any meteorologist in the public eye known to this journalist, predicts when climate stability will collapse:
There were 88 presentations on arctic sea ice at the 2008 AGU [American Geophysical Union] conference. None of the presenters expressed the view that the current long-term decline in arctic sea ice was almost entirely natural, or that we can expect the decline to reverse this century. Sea ice experts do blame part of the decline on natural variability in the weather, but we wouldn't be where we are now without the warming caused by human-emitted greenhouse gases. One view (Stroeve et al., 2007) is that human-emitted greenhouse gases are responsible for 47 - 57% of the arctic sea ice loss since 1979. Heat-absorbing black soot from fires and pollution settling on the white ice is thought to also be a significant contributor.
The consensus I heard at the AGU conference among arctic sea ice experts was that the summertime sea ice will be gone by 2030. If they are correct, we can expect a period of significantly accelerated global climate change to begin 10 - 20 years from now. Arctic sea ice is one of the critical components maintaining the stability of our current climate. Once the the ice is gone, the climate will become unstable, with highly unpredictable results. It is true that Earth's past has many examples of warmer climates that evolved due to natural causes where life flourished, and we shouldn't fear the new, stable climate we will eventually arrive at centuries from now. However, life on Earth is adapted to the current climate. The changes that will occur during the transition will be extremely disruptive to Earth's ecosystems and the humans that rely on them for life. If one were to rate the destructive capability of climate change the way we rate hurricanes, I would rate current climate change at the "Invest" or "tropical disturbance" stage--the climate change storm is just beginning to organize. But the coming climate change storm is destined to hit our children with the full fury of intensifying hurricane.
If Masters is right we have about ten years to get ready for a different planet.