A combination of insulation, thoughtful design (south-facing glass, adjustable awnings, solar water heating, heat pumps vs. resistive electrical heat, etc.) and renewably sourced electricity go a long ways towards the heating issue. I live in a cold-ish city in a 2 bed apt with only electric storage heaters (which are awful) and pay for supposedly 100% renewable (wind/solar/geothermal) energy and my bill peaks at €65 a month in the winter.
Commuting:
There are also thousands of businesses within a 30 minute walk from my home. Not turning cities into parking lots and skidpads with a building dropped here and there helps. If I cycle, the number of businesses in that range increases by about a factor of 9. (I cycle around 3 times as fast as I walk, so can cover a distance roughly three times as far, or area ~9 times as great). If I don't like pedaling, an e-bike or 50-150cc scooter/motorcycle will get me even farther.
Food:
I'm not well informed enough on this to comment. Where I live already has pretty bland food with loads of bread and potatoes. Good burritos, though. I'd miss that. We'd probably eat a lot less meat. I could do with a better supply of soyrizo, anyway.
Effects:
Sea level rise is far from the only concern. Stronger storms, drought, the displacement of peoples and an ensuing refugee crisis as their crops fail and water supplies dwindle, ocean acidification, and changing weather systems from the loss of the Arctic ice cap (and possibly a chunk of Greenland) are just a few of them. Also, I suppose this makes me impossibly impractical but hey, the loss of polar bears would make me sad. Maintaining the civilisation we built at the cost of the natural world we inherited isn't fantastic; watching the forests of my home (California) be completely devastated by drought, heat, and beetles is a bummer, to put it mildly.