That's basically what you're alluding to with the seaweed and food thing.
Cultural and ideological hangups will go right out the window in a hurry when there's a real crisis and a culturally incompatible solution. People aren't gonna let things truly go to shit over something as trivial as what they eat or where their water comes from.
The primary danger in the first world as I see it is from the moneyed and empowered people F-ing it over for large enough other groups to cause probems. Doesn't take much of a stretch of the imagination to imagine how climate change might F-over downstate Illinois (because farms) but Chicago won't let them do anything about it because they hold all the cards and they make their money a different way. They'd probably figure it out eventually but with how unequal our society is I'm not gonna bet money on eventually happening before the shooting starts.
I actually can't envision what you mean by "Chicago won't let them do anything about it". Isn't Chicago the more liberal area that wants to fight climate change?
>Isn't Chicago the more liberal area that wants to fight climate change?
Right up until you have to take some other controversial step in order to do it.
I'm sure you can imagine how things would go if downstate farmers wanted to all apply some sort of fertilizer that would make their farming economically viable but the beta and the v1 versions of the chemical also killed some sort of visible wildlife.
It sounds like you're referring to herbicides and pesticides that kill bees and other pollinators. People have an obvious problem with pesticides that kill bees. It's not an acceptable level of collateral damage for dirt cheap corn and soybeans.
How about a desalination plant now? Even nuclear?
The water system has a storage capacity of 550 billion US gallons (2.1×109 m3) and provides over 1.2 billion US gallons (4,500,000 m3) per day of drinking water to more than eight million city residents, and another one million users in four upstate counties bordering on the system. Three separate sub-systems, each consisting of aqueducts and reservoirs, bring water from Upstate New York to New York City.
https://en.wikipedia.org/wiki/New_York_City_water_supply_sys...
My idea is that a real need makes people reconsider their opinions which they held dear as long as they did not have a skin in the game.
It is an interesting question if a new world war is more likely than a major cultural change in our diet.
If traditional food sources go away and technology provides an alternative food source, that is what people will eat. Culture will follow technology, if that's what people have to do to survive.
EDIT:That mostly applies to the population in the developed world with access to capital, technology and industrial resources that we can use to adapt our food supply. Not everywhere in the world has those resources to fall back on though.
Societal collapse in for example India or Brazil would make things awkward real fast for a large chunk of the world
The military does not even play a role here. All the poorer countries need to do is a) not prevent their own young people from leaving, b) not prevent activity of smuggler gangs, c) complicate deportations by refusing to issue passports to their citizens who destroyed their papers underway. None of those actions need guns, much less superior guns.
[0] ... India and Brazil aren't really in the "top population growth" league. Look up population pyramids of Niger, Ethiopia, Nigeria, Yemen. Those graphs promise future mass migration streams. (https://www.populationpyramid.net)
[1] ... https://ec.europa.eu/eurostat/statistics-explained/index.php...
Your parent was suggesting that the developed world could not deal with a collapse of India or Brazil or several populous African countries.
What would happen if 20% of India decided that their society has collapsed and they should migrate at any cost to some developed country?