A new study shows that the Andes glaciers of South America are rapidly disappearing over the past four decades, with more ice lost than at any other time in the last 300 years.
The study published in The Cryosphere, a journal was made available to the Ghana News Agency on Wednesday.
The researchers combine on-the-ground observations with aerial and satellite photos, historical records and dates from core of ice extracted from the glaciers to survey an area of almost a thousand square kilometres, making the new study the most comprehensive review of Andean glaciers so far.
The study monitored about half of all Andean glaciers across Colombia, Bolivia, Peru and Ecuador to see how the volume of ice they contain has changed since the 1970s.
Its aim was to provide the community with a comprehensive overview of the studies of glaciers in the tropical Andes conducted in recent decades leading to the current status of the glaciers in the context of climate change.
In terms of changes in surface area and length, the study shows that the glacier retreat in the tropical Andes over the last three decades is unprecedented since the maximum extension of the Little Ice Age.
In terms of changes in mass balance, although there have been some sporadic gains on several glaciers, it shows that the trend has been quite negative over the past 50 years, with a mean mass balance deficit for glaciers in the tropical Andes that is slightly more negative than the one computed on a global scale.
According to the study, even if glaciers are currently retreating everywhere in the tropical Andes, it should be noted that this is much more pronounced on small glaciers at low altitudes that do not have a permanent accumulation zone, and which could disappear in the coming years/decades.
Monthly mass balance measurements performed in Bolivia, Ecuador and Colombia show that variability of the surface temperature of the Pacific Ocean is the main factor governing variability of the mass balance at the decadal timescale.
It said precipitation did not display a significant trend in the tropical Andes in the 20th century, and consequently cannot explain the glacier recession. On the other hand, the new Andean study shows that temperature increased at a significant rate of 0.10 C decade −1 in the last 70 years.
It said the higher frequency of El Ni'no events and changes in its spatial and temporal occurrence since the late 1970s together with a warming troposphere over the tropical Andes may thus explain much of the recent dramatic shrinkage of glaciers in this part of the world.
The Andes in South America are home to 99 per cent of the world's tropical glaciers - those located high up in mountain ranges around the equator.