Ancient Tools Revealed by Melting Ice

This is interesting:

Warming temperatures are melting patches of ice that have been in place for thousands of years in the mountains of the Canadian High Arctic and in turn revealing a treasure trove of ancient hunting tools.

Ice patches result from layers of annual snow that, until recently, remained frozen all year. As Earth’s temperature has warmed in recent decades due to the accumulation of heat-trapping greenhouse gases in the atmosphere, some of the ice patches have begun to melt away, sometimes revealing ancient artifacts to the surprise of archaeologists.

So if the melting ice reveals ancient artifacts doesn’t that mean it was warmer during those ancient times? Why does the author of the article blame the recent warming on “heat-trapping greenhouse gases”? Is that what caused it to be warmer in those ancient times? Where would such greenhouse gases come from in ancient times? Maybe the temperature of the earth has a natural variance? Just a thought….