Explain the Bering Land Bridge being exposed.
Continental drift. Land mass and continents rise and fall. Ocean height, a function of the topography and volume of water, can only change if the land mass underneath it changes, or if the water volume changes. If you want to go back to millions of years ago, then you might be able to theorize a forming earth where the temperature was hot enough and the crust/core still hot and elastic enough to generate that kind of change in ocean height. But in the last 250,000 years, not a chance.