This is a present day map of Glacier Bay in Alaska. There are lines in the Bay with dates on them. (you may need a magnifying glass to read the dates)
In 1750 when the area was first mapped the glacier extended right to the end of Glacier Bay (down near the bottom) and you can track the extent of the ice over the years by checking the dates. Clearly the ice has receded and the Bay is now mainly water.
So, the glaciers have been retreating for
at least 250 years and possibly longer for all we know. So maybe there is some global warming but it CANNOT be man made if it goes back that far.
Also, if you look closely you will see that in two of the inlets the ice is ADVANCING over more recent years! Which, surely, is an indication that we do not know all the mechanics of glaciation and climate change.
My feeling is that it is a cyclical thing and man's influence is minute. Despite this I feel that it is sensible to reduce CO2 emissions as much as possible but I am very much against green taxes.