In 2011, the Intergovernmental Panel on Climate Change carried out a meta-study on CO2 emissions from various energy sources, summarising 296 individual studies.(Sathaye et al., 2011) [1
Here are the median values of this first meta-study:
A second meta-study followed in 2013 (Hertwich et al., 2013). [2 This time, the number of studies was limited to comparable life cycle values with similar assumptions.
Here are the median values of this second meta-study with Min/Max in the error bar:
But that is not a fair comparison.
Both meta-studies do not take into account storage for renewables.
However, wind and solar are not baseload capable, but “fidget current”.The CO2 values would be many times higher with the necessary storage.
A summary of all figures can be found here Life-cycle greenhouse-gas emissions of energy sources – Wikipedia
The exact CO2 balances of all energy sources are very controversial.This also applies to nuclear power.
You have to include all climate-damaging effects in the life cycle of a power plant, from construction and dismantling to the extraction and transport of raw materials.
Same answer as
- Are nuclear power plants really the cleanest way of producing energy?
- What is the carbon footprint of photovoltaic modules?