How much should we reduce greenhouse gas emissions in order to combat the global warming problem?

Climate stabilization is one of the most serious problems that humanity faces this century. National climate policies in some European countries consider an increase of 2"C in the global mean temperature on that of the pre-industrial era to be a level of dangerous climate change. These countries have established action plans for the next 50 years in order to avoid overshooting this target. I reviewed the research on dangerous levels of climate change and analyzed the required reduction rates for greenhouse gas emissions. Based on this review, I discuss the required counter-measures and their feasibilities in order to overcome the global warming problem and to get through the first half of this century.