The existence of a Bering straight land bridge is indisputable. During the last glacial maximum, the extent of the Laurentide ice sheet is well documented and understood. A calculation of ice volume allows for a calculation of how much sea level would have dropped to accomodate the amount of ice on the continents. The Bering straight was dry.
As far as human migration goes, native north americans have asian and european roots. asians crossed the Bering straight land bridge, and europeans crossed the Atlantic from France. Remember, the latitude of central France would have been at the southern limit of the ice sheet, and would have extended across the atlantic. To cross, people would have made their way across the ice at the southern margin, hunting seals and catching fish along the way.
Modern Inuit people of northern Canada carry a majority dna of asian descent, but also carry european dna as well.
For more info on the last glacial maximum, google laurentide ice sheet, or wisconsin glaciation.
If you read closely you will also find lots of evidence that made made global warming is unsubstantiated.\
Have fun.