We're going to have sea level rise in the region of 1-2 metres by end of the century, and 5-10 longer term.
Levees are expensive, and not always viable. It depends on the geography, the wealth of the city / county, the porosity of the ground, etc.
Some places will be sure to use levees, some won't.
With regards to crops, we don't know the outcome. If the Gulf stream stops or some regions dry out it could greatly affect crop yield, especially over the short-term. And that's all that matters for starvation to occur. The term year average yield isn't as important as this year's harvest.
Levees are expensive, and not always viable. It depends on the geography, the wealth of the city / county, the porosity of the ground, etc.
Some places will be sure to use levees, some won't.
With regards to crops, we don't know the outcome. If the Gulf stream stops or some regions dry out it could greatly affect crop yield, especially over the short-term. And that's all that matters for starvation to occur. The term year average yield isn't as important as this year's harvest.