When should we panic?

The evidence for human-driven climate change is compelling. If you doubt this then this blog is not for you. (Perhaps you should read the latest IPCC report.)

A rise of two degrees now seems inevitable and much larger rises entirely possible. The consequences of a two degree rise will be serious. We, I speak globally, will lose agricultural production and human habitat. People will migrate in unprecedented numbers and come into conflict with their luckier neighbours. People will starve and some will, with justice, blame the developed nations.

It is, probably, possible to restrain temperature growth so that we experience no more than two degrees of warming. This is technically difficult because of the delays in the climate system and politically difficult because it requires real sacrifices from so many people.

But this is irrelevant because we really aren't trying. No government of a developed country has yet committed itself to a sufficient degree of emissions reduction and several governments of developing countries seem committed to increased emissions. The only relevant international agreement, the Kyoto treaty, would be inadequate even if the US had joined - which it hasn't.

We need significant action within the next decade yet itstead of applying the brakes on climate change we are currently using the accelerator.

So my question is this. How long must be wait before concluding that saving the climate is a lost cause? When should we panic?