Saul Griffith has an old talk entitled "Climate Change Recalculated." The gist is that he converts everyday energy consumption into averaged watts over a day, and then looks at the energy area density of renewables. The resulting picture is rather daunting. If we go 100% renewable--If we even could!--all of our lifestyles would be radically curtailed, and this is after a construction binge of enormous scale.

We absolutely need fission and/or fusion. Of this there is no doubt.