Seaweed farms have the capacity to grow huge amounts of nutrient-rich food, and oysters can act as an efficient carbon and nitrogen sink.
You Can Cool Your City
A few days ago, Treehugger reported that New York City has already experienced climate change. Temperatures are up and expected to rise higher--up to nine degrees above the norm. Water levels will also be higher, endangering the subway system and low-lying areas.
As noted here before, we'll have to adapt and change our behavior if we're going to thrive. Architects are also proposing workarounds for the future. Cities are also working to reduce their carbon footprints--and when they do that, they greatly contribute to improving our world, because the fate of our environment will be decided in the cities.
Meanwhile, it may seem like a small thing, but you can plant a tree. In New York, you can arrange to have one planted on your street, or if you've access to a backyard, you can plant one yourself. You can also get involved with community groups that work to cool their cities through other means.
City trees are more valuable than they seem. In fact, they have turned out to be more useful to the environment than scientists had assumed. Because of trees, it turns out cities actually absorb a lot more carbon than anyone had figured--by a factor of ten. Trees aren't a cure-all (they work best when planted in tropical areas and once you burn them, they pollute) but with their shade they do manage to cool the street and with their roots, absorb rainwater.
Also--and this was only recently discovered--as the world gets warmer, trees should become better at storing carbon and cleaning the air--over time, they will become more useful.
At least one answer is simple for the future: plant more trees.