Cutting fossil fuel emissions is not enough to avoid dangerous climate change. Too much carbon is already in the atmosphere, and the oceans are continuing to heat. The Intergovernmental Panel on Climate Change stated in 2007 that "Complete elimination of CO2 emissions is estimated to lead to a slow decrease in atmospheric CO2 of about 40 ppm over the 21st century" (about 9% to 1985 levels; see IPCC's 7 Mb pdf file here, section 10.3).
In other words, the strategy of reducing carbon dioxide emissions, by itself, has little effect or leverage on the atmospheric concentrations. By treating global heating as a problem of energy, emissions, or technology alone, we only get to decide whether to wreck our climate slightly faster or slightly slower.
There is a biological side to global warming and the carbon cycle. Carbon is a main ingredient of all life, and of its remains. While planting trees is rightly discounted as a way to reduce atmospheric carbon, we could increase soil organic matter (58% carbon by dry weight) rapidly and cheaply. This will pull excess carbon out of the atmosphere while also enhancing soil fertility, water quality, food quality and human health, and also reducing floods, droughts, and agriculture's dependence on fossil fuels and chemicals.
How it works
Biological processes, such as photosynthesis and respiration, drive 99% of the carbon cycle. There is more carbon in soils than in vegetation and the atmosphere combined. Soil carbon can be more stable than plant carbon (less subject to oxidation or burning).