To combat Anthropogenic Global Warming (AGW), emissions of Greenhouse-Gas (GHG) from human activities must be eliminated. The breakdown of GHC emissions is show in the figure below, taken from the book by the late David MacKay: Sustainable Energy - without the Hot Air.
Roughly 74% of GHC come from "Energy" in the form of carbon dioxide and it is this fraction which can be eliminated with greatly increased nuclear generation of electricity. Fossil fuels are the main source of carbon dioxide emissions and to obtain a "Carbon Neutral" environment all must be eliminated from electricity generation; heating; transport and industry. In the medium term, much decrease in emissions can come directly from increased total electricity generation using nuclear power, in the long term some processes will require that fossil fuels are replaced with hydrogen made indirectly from electrolysis using nuclear power.
Different types of electricity generation have varying intensities of CO2 emissions as indicated in the figure below. Nuclear power generation has 20 times lower emissions than generation by natural gas and 30 times lower than coal generation. Hydroelectric, Wind, Solar and Biomass generation also have low emissions. Wind and Solar generation are weather dependent and, alone, cannot give a dependable supply of electricity.