Global Warming from waste heat? I was surprised and intrigued by David McRobert's post on LinkedIn, and so read the three papers that sit behind this piece posted at Aeon. Here's why I take some issue with the implication of David's chosen headline that "waste heat will pose a problem that is every bit as serious as global warming from greenhouse gases."
1. The papers involved can be characterized as thought experiments, not in-depth studies. It's sort of equivalent to some of the conjectures about CO2 warming 100+ years ago.
2. The timeline here is long, on the scale of 200-300 years. Just to be clear, the amount of waste heat produced today is trivial in Earth's energy budget.
3. Assuming global warming can come from waste heat assumes that global energy demand continues to increase exponentially, and that energy is supplied from sources that result in waste heat -- most specifically, fossil fuels (even with CO2 capture and storage), nuclear, or geothermal.
4. One of the biggest problems with CO2 induced warming is that the CO2 sticks around for a long time. But getting rid of waste heat, e.g. by replacing fossil or nuclear with renewable energy, is immediate in its impact. So even if we were to build a lot of geothermal or nuclear, replacing that generation over time would solve the waste heat problem.
All of that said, the papers do raise interesting cautionary points (and one hopeful one):
Bottom line, there are some interesting ideas here, with some potential near-term implications. But in no way does this detract from the urgency of tackling GHG-induced warming -- on which all of the papers agree.