Yes, tidal energy should be a major part of plans to fight global warming, because tidal energy is a green energy that can make a big impact with very little negative effects on the environment. There is a small impact on fish, but on the whole, harvesting tidal energy is a good way to reduce dependence on fossil fuels.
While there are many benefits to tidal energy, it should not be a major part of plans to fight global warming yet because it costs too much and there is limited availability. There are other types of energy that could work equally as well or better, are more readily available, and cost less. Additionally, tidal power turbines can kill sea life and if the goal is to improve the environment, it seem that it would be antithetical to use tidal energy for this purpose.