I would like to think that the more intelligent any particular human is, the more likely they are to understand that very few problems have solutions. Instead, most bad situations must be avoided before they begin, or the most you can hope to do is mitigate impacts, and that only, if you try really really hard.
Global warming, and a commitment to very high fossil carbon consumption are already long past the "beginning" stage. An intelligent response is to first accept what *IS* and not what one might *WISH IT TO BE*. One might wish humans would reduce their consumption of fossil carbon (both energy and as concrete), but there is no indication any such thing is happening or will happen tomorrow. What is true, is that humans are accelerating the amount of carbon they put in the atmosphere; just as they have done for more than a century. That is what *IS*.
All the screaming in the world of scientists against CO2 emissions can not alter the behavior of that Chinese lower middle class guy who wants to buy his first airconditioner and dangle it on the outside of his apartment. And the Chinese authorities are not going to help either; they have huge excesses of metals and concrete production that need to find buyers.. and 300-500 million people who are potential customers for their first air conditioning units.
So, accepting what *IS*, we can see that IPCC "BAU" trajectory is not only likely, its conservative. Because reality is not BAU going into the future; reality is BAU Amplfied. So what does BAU Amplified give us with regard to climate? Full industrial collapse, starvation, wars, more starvation, and die off. In our world, you do not get to say the words "human die off" without being labeled with a tinfoil hat, and either disregarded, or tossed in the loonie bin if you're too annoying. You can't say it without folks thinking you're some kinda of nihilist looking forward to the end of everything. So the discussion dies instead.
Thus, denial of reality floats right along with denial of climate change itself. Both together sealing the fate of humanity to the worst possible results from the worst possible configuration of future events.
So what does ultra doomer AgentR11 suggest then, for trying really really hard for mitigating impacts?
Acknowledge reality.
Accept that we will burn all available carbon.
then..as policy,
Do not ever rebuild or repair any city or facility that is inundated by storm water. All flood insurance is paid in buyout-terms only.
Favor GMO research and optimization of grain lines to produce in ever higher latitudes, and higher tolerance of late season high temps.
Do not expand any infrastructure towards a coastline; build rail, electric distribution, and large roads that disperse inland, making it easier for new construction to pick locations further inland, and thus drag city centers along with them away from the drowning coast.
Walk port facilities inland so that they are usable and useful as new portions of the river channel become deep enough to handle shipping. Anticipate the rise, and be ready for it.
Place appropriate use fees on water in areas that are arid or modeled to become arid. And by appropriate, I mean cripplingly high for any use in excess of maybe 1000gal/person/month at a residential location; and no affordable breakpoint for other sectors. If it can't grow in your yard with rainfall alone, it doesn't belong there. Tax the every loving snot out of groundwater withdrawal. If a "taking" exists, then write the check, and then later crank the tax up even higher to pay for the check. A good place to start on the fee would be about $25/1k gal. after an affordable allowance for a dwelling.
Enact AgentR11's carbon tax amendment as noted in several posts on po.com; because I'm awesome afterall.
Expand the army, but pull a lot of it back to internal garrison duty, and be prepared to lock down our borders tight against huge numbers of climate refugees. Legalize EVERYONE here at that time; permanent residence status, regular path to citizenship. We have a nice mix of races and cultures in the US as is; and the numbers are well within our carrying capacity, well into the bottleneck. Where we all go together as a multi-ethnic country, we can not go with 600 million+.; And yes, this means shooting people who try to forcefully cross the border. Maybe make auto-cannons do most of the killing so we don't have to feel bad, and the potential refugee won't make an assumption about compassion. This is survival at this point forward; there is no right to economic refugee status. You could even expand the army concept a bit to separate between folks that are happy enough to fight overseas, and those feel guarding a home border is more just and honorable. Both types of folks exist, intense and appropriate training can be provided suitable to each distinct role. Border would be some LEO-light, marksmanship, crowd control; as opposed to the more typical infantry training for overseas combatants.
That is how AgenR11's mitigation plan would begin.