[sbierwagen]

As stronglikedan said, spaceflight propulsion/institutional inertia. (Stationary space facilities will use solar, just like on Earth. Space transport, unlike Earth transport, will be an awful combo of slow and expensive. Space stations will need to be simple. One type of computer. One type of microcontroller board. Maybe three sizes of screw. Solar panels are simple, identical, and interchangeable. And not radioactive! (Fun fact: every bolt on the outside of the ISS uses the exact same head size: 7/16" hex))

Seasonal variation with solar is a bit of a bummer. If we need to fully electrify everything, (Transport and heating) then winter will be a problem. Either we massively overprovision solar in order to still have heat on the shortest day of the year, or we run thousand mile cross-country transmission lines and enormous battery banks.

Even so, the economics are such that heavy industry might become a seasonal job. Right now we run aluminum smelters 24/7 because baseload power is fairly consistent, but if solar power is free in July but dear in January you might see multi-month shutdowns. This gives headaches to central planners, and makes them inclined to pour billions into fusion if it can preserve some of the status quo.

[pfdietz]

> Even so, the economics are such that heavy industry might become a seasonal job.

Or it will move to locations where seasonality is not as important.

[sbierwagen]

Something of a question mark of how long the tropics are going to remain habitable. We're still on the "business as usual" emissions curve, with no signs of meaningfully changing that. That puts us 5C higher by the century, and will keep going up after that.

Many equatorial regions will either be too hot for human life, (https://advances.sciencemag.org/content/6/19/eaaw1838) or be active combat zones as a result of refugees escaping heat. Some cities in India are now routinely hitting 50C during the summer, and we've only had 1C of warming.

[pfdietz]

If the tropics threaten to become uninhabitable countries like India will go ahead with direct climate engineering by dispersing fine particles in the stratosphere to reflect sunlight. This need not be at all expensive, even for them. No credible threat from other countries would deter them, as they'd face mass destruction otherwise.