Ocean rise already is worsening the floods and high tides sweeping California this stormy winter, climate experts say, and this month’s damage and deaths highlight that even a state known as a global leader in fighting climate change has yet to tackle some of the hardest work of dealing with it. The critical steps yet to come include starting to decide which low-lying cities, airports and highways, along with threatened landmarks like San Francisco’s Embarcadero, to hoist above the rising water and which to abandon — and where to start getting the many billions of dollars for those climate rescues.