With respect to Niven, I don't think this is a valid claim.  There's too much technology in Known Space for dumping planetary waste heat to be a serious problem.

In one of the Peace Corben stories, "War and Peace", the kzin Buckminster suggests using transfer booths to take hot gases from the surface of Plateau and dump them into local space for refrigeration.  Cooled, the gases would fall back to the planet.  Massively scaled up, a project like this could cool the surface of the planet to habitable levels after a few centuries.  Start with a planet whose surface isn't a furnace already and such cooling could maintain the climate indefinitely.  The Puppeteers would use stepping discs instead of transfer booths, but the principle is the same.

Sinclair time compression fields could also be used to shift long wave IR up to higher frequencies where it could be more efficiently radiated away.  Stepping disc technology would be useful here as well, as the discs have been shown capable of passing electromagnetic radiation as well as matter.  So instead of pumping UV (frequency shifted long IR) through your atmosphere out to space, you pump it directly to space via stepping discs.