Not sure if this is the right place to post but my friend and I were talking about how a bit of terraforming could change the climate of Socal. So what I thought was that if there was a sort of barrier in the pacific (like in the picture), then sea temperatures within the barrier would be much warmer. Because of this, there would be much less fog, warmer winter temps, and summer thunderstorms because of the large difference in water temperature along the seawall (80f vs 60f for example).
Am I right about these conclusions or am I missing something? I know there aren’t any examples in nature of hot and cold seawater being separated by an artificial barrier, but hypothetically what do you think would happen?