International organizations should be formed to help relocate coastal communities that are affected by sea level rise. These communities cannot possibly organize a relocation of the entire city themselves, so they would need additional help from a highly trained organization. An organization formed to solve this issue would be the best option.
The coast is going to rise regardless if people step in or not. The best bet it would be to have intervention step in and solve the issue before it becomes a problem. Its better to have the situation handled by a international force than to have issues like Venice is having, keeping their city floating.
I do not feel like it is an international duty to perform this act. It is instead a thing that the individual countries should do or find a way to correct the dilemma. If it became an international matter then this could cause more conflict then is necessary and there could be people that fall through the cracks. Plus an individual country could perform this task faster than an international organization.
I do not think that international organizations should be formed to help communities that are affected by rising sea levels. I think that it would not be logical for funds and resources to be used for such a thing. Problems like that should be dealt with the countries that are affected by it.
Even if global warming is happening, and the effects of ocean levels rising is actually happening, it will not effect us for a few centuries. There is no reason at the moment to think about forming an organization that will help relocate people hundreds of years from now, if it even were to happen at all.