The Qori Kalis Glacier snakes out of the Peruvian Andes. It is one of the few tropical glaciers left in the world and one of the most studied.
According to the National Snow and Ice Data Center in the US, the ice has retreated by almost 50 percent since 1963 when measurements began, making it a symbol of global warming.
With warnings that the glacier could completely disappear within 20 years, a team of researchers from Ohio State University has returned to study it.
The retreating ice has revealed fossilised plants dating back 6,300 years.
According to Dr Lonnie Thomson, a paleoclimatologist at Ohio State University, this means the ice cap has not been smaller in over 63 centuries.
The team collected 17 fossilized plant specimens on their latest outing and took them back to their lab in Ohio for identification and carbon dating.
“Each plant was taken at a different location, getting successively closer to the glacier,“says Don Kenny, a senior researcher on the team. “So hopefully it will tell us the date it was captured by the glacier, because at that point it was no longer taking in nutrients, it was no longer taking in CO2 (carbon dioxide) from the atmosphere and that carbon 14 concentration in there was locked in, and then we can see what that concentration is via the analysis.”
As scientists sound the alarm for global warming, the results show that it took the glacier 1,600 years to advance just 300 metres, but it has taken only 25 years for the ice to retreat that same distance.