But Hansen and his co-authors argue this
emissions» limit must be cut in half to draw
carbon dioxide levels down to 350 parts per million from their current level
of 395 ppm (the highest they have been in 3 million years) and to
stabilize global temperatures.
«
global emissions of carbon dioxide have to be reduced to very low levels, well below half
of levels in 2000, in order to
stabilize their concentrations in the atmosphere» Decision FCCC / KP / AWG / 2006 / L.4