A More Easily Evaluated Problem?

According to John Holdren (quoted here, seen via Greenie Watch):

A more easily evaluated problem is the tremendous quantity of waste heat generated at nuclear installations (to say nothing of the usable power output, which, as with power from whatever source, must also ultimately be dissipated as heat). Both have potentially disastrous effects on the local and world ecological and climatological balance.

The above quote appears to be real. On the other hand, it's from an article hidden behind a paywall. On the gripping hand, a search using Google Scholar will bring one to the same article.

I'll say it's a “more easily evaluated problem.” The above quote can be easily evaluated to be a heaping load of bullbleep. If we assume that the world population is 6.8 billion (almost enough to stand on Zanzibar), that a future advanced civilization uses 1.5 kilowatts per person (the same as the current U.S.), and that the power is generated at a thermal efficiency of 33%, then the total heat output (from both the power generators and the eventual dissipation of the electric power as heat) is about 3×10¹³ watts. The sunlight hitting the Earth is about 1.8×10¹⁷ watts, 6000 times greater. The extra heat won't be noticed.

If the human population rises to over a trillion, we might start to see some problems. On the other hand, by that time we will be spread all over the Solar System, which will increase the heat-dissipation area by a factor of billions.