Geo-Joint: Glaciers in the Tropics

When you think of the equatorial tropics, chances are the first thing that comes to mind is a beach—a warm, breezy, sea-level scene, complete with coconut palms. Or maybe a lush rainforest, soaking wet and humid, with a steamy heat that makes you break into a sweat just thinking about it. Less likely is the thought of high mountain peaks, cold and windy, with glaciers gracing their upper reaches. Though such harsh landscapes are more common in latitudes distant from the equator, like the Himalaya, New Zealand’s Southern Alps, or the mountains of Alaska, the equator sits quite close to some high-elevation places. Glaciers there are in a rather tenuous position, islands of frigid weather in a sea of baking humidity. For thousands of years, despite the nearby heat, they managed to maintain their isolated, icebox climates.

Lately, however, as any aware person knows, glaciers are receding worldwide, and the ice in equatorial locales is going especially fast. It’s happening in South America’s Andes, where the peaks of Ecuador’s Chimborazo and Cotopaxi are less than a degree of latitude from the equator, and the same is true on Indonesia’s Puncak Jaya, at only 4 degrees south. In East Africa, Mt. Kenya is seeing its glaciers dwindle, as are those in Uganda’s Rwenzori Mountains. Mt. Kenya is a mere 10 miles from the equator, and the Rwenzoris less than 30. Climate change is most pronounced in Arctic regions, where temperatures that get above freezing for longer and longer periods are reshaping the very surfaces that people and wildlife depend upon. In most of the tropics, incremental heat increases are not as noticeable because it’s always hot. But the peaks of these tall mountains are susceptible to just a few degrees of warming, or longer periods of heat. Locals are worried about their future sources of drinking water as the meltwater from high above will, in the not too distant future, be gone. And scientists are rushing to study these rare locations because their ice documents climate history going back centuries or millennia.


Kilimanjaro’s glaciers are disappearing rapidly.


There is another equatorial glacial location, perhaps more well known than all the others, which is slipping away as well. This is Tanzania’s Mt. Kilimanjaro, itself only about three degrees away from the world’s centerline. Accessible enough to have been climbed by many travellers, and photographed by thousands more, the gently sloping profile of this famous mountain may soon lose its icy crown. In the case of Mt. Kilimanjaro, it is not only the general rise in Earth’s temperature that is making the glaciers disappear. Kilimanjaro’s ice is not melting in great pools, or sending overflowing streams down its sides as the solid ice turns to water. Rather, its ice is sublimating, which means it is going from a solid directly to a gaseous state as it disappears. Between 1912 and 2011, about 85 percent of the ice on Kilimanjaro went away in an accelerating fashion, and what’s still there likely has only a few years left. Ice climbers trying to experience the dwindling opportunities there in 2014 found that in a scant few days, a particular location would go from climbable to crumbling. It was vanishing before their eyes.

What is causing Kilimanjaro’s unique style of ice loss? The sublimation is apparently resulting from deforestation occurring on the mountain’s lower slopes. Without the humidity once provided by the wooded areas, upslope winds have become much drier, and the high altitude ice has succumbed to the air’s hunger for moisture. And any ambient warming that may also be present (up to the melting point) acts to accelerate the sublimation process. Part of climate change crusader Al Gore’s mountain of evidence for a warming planet in his movie, An Inconvenient Truth, was the example of Kilimanjaro’s waning glaciers. When researchers determined the cause was more to be laid to this loss of forest biome, deniers howled that the whole concept of a warming planet was a sham. The unique circumstances on Kilimanjaro, which happen also to have been set in motion by human activity, do not in any way negate the overwhelming evidence that we have destabilized the planet’s climate through excessive production of CO2 and other greenhouse gases. But it is a lesson that generalizations can be inaccurate. Fortunately, science is all about testing assertions and getting to the root causes of phenomena. Kilimanjaro’s ice may be going away for a complicated set of reasons, but worldwide, by any measure, glaciers are feeling the heat and turning to water.

Mt. Kilimanjaro rising high above the plains.

Ecuador’s Chimborazo, sitting high and near the equator.

Cotopaxi, close by and also glaciated, is a more recently active volcano.


Want to see the glaciers of Kilimanjaro, Mt. Kenya, and the Rwenzoris before they get any smaller? Start planning your trip with this Northeastern Africa Wall Map by National Geographic, available only through



caption: Ecuador’s Chimborazo, sitting high and near the equator.
source: Wikimedia Commons: Dr. Carlos Costales Terán (CC by SA 4.0)
caption: Cotopaxi, close by and also glaciated, is a more recently active volcano.
source: Wikimedia Commons: Cesár Muñoz/Andes (CC by SA 2.0)
caption: Mt. Kilimanjaro rising high above the plains.
source: Flickr: Tambako the Jaguar (CC by ND 2.0)
caption: Kilimanjaro’s glaciers are disappearing rapidly.
source: Flickr: Cristoph Strässler (CC by SA 2.0)

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