Scientists from universities in Wales, England and Sweden reached that conclusion after mapping changes in 270 of the largest glaciers between Chile and Argentina and finding they have lost volume at an average of 10 to 100 times faster in the last 30 years, the BBC reported Sunday.
Calculations show the glaciers that cover the area have lost 145 cubic miles of ice.
The researchers analyzed remotely gathered images of glacier outlets in Patagonian ice fields straddling the Andes, on the border between Chile and Argentina, but used a longer timescale for the analysis than previous studies had.
"Previous estimates of sea-level contribution from mountain glaciers are based on very short timescales," Neil Glasser of Aberystwyth University in Wales said.
"They cover only the last 30 years or so when satellite images can be used to calculate rates of glacier volume change.
"We took a different approach by using a new method that allows us to look at longer timescales," he said.
Their analysis revealed that the mountain glaciers have rapidly increased their melt rate in recent years and thus their impact on rising global sea levels.
The Patagonia glaciers are located at a latitude in the Southern Hemisphere equal to the Alps in the Northern Hemisphere, researchers said, and suggest the same calculations there would reveal a similar pattern of loss rate increase.
"The work is significant because it is the first time anyone has made a direct estimate of the sea-level contribution from glaciers since the peak of the industrial revolution [between 1750-1850]," Stephen Harrison of the University of Exeter in England said.