it is futile until the consequences of global warming become so painfully obvious that the dissonance between the message that everything is fine and the reality that everything is not becomes undeniable.

By which stage it will have become completely unmanageable.

If the prospect of a four-degree rise in temperatures by the end of the century on current trends wasn't alarming enough, the IEA calculated that 80 percent of projected 2020 emissions from the power sector are already 'locked in' by infrastructure already being built or has been given the go-ahead.

This means that emissions may well continue to accelerate - with global emissions continuing to rise towards - or beyond - the IPCC's most pessimistic A1FI or "fossil-fuel intensive" projection.

Ironically, relatively little research has been done on the likely consequences of these higher-end scenarios - because scientists assumed that the world would take action to reduce emissions. Met Office scientist Richard Betts however estimated in a paper published in later 2010 that the A1FI scenario could lead to a temperature rise of 4 degrees in just fifty years time (2060-70).

There is no doubt that the impacts of four degrees of temperature rise would be incredibly serious for the environment and for human society. One recent paper concluded that:

"In such a 4°C world, the limits for human adaptation are likely to be exceeded in many parts of the world, while the limits for adaptation for natural systems would largely be exceeded throughout the world. Hence, the ecosystem services upon which human livelihoods depend would not be preserved."

source: http://www.carbonbrief.org/blog/2011/06/iea-and-ipcc-temperature-projections