The Vanishing Glaciers of Puncak Jaya...

Carstensz Glacier.  Photo from Jakarta Globe.

When we think of the tropics many images come to mind....warm, sunny beaches and hot and humid rainforests probably being the most common.  Most of us don't think of snow-covered peaks and glaciers, and for a good reason: they just aren't very many of them in the tropical belt.  But there are a few, and amongst these are the glaciers of Puncak Jaya in the region of Papua in Indonesia. 

From Prentice and Hope, 2006.  See references.

Puncak Jaya is located in Lorentz national park, which is the largest terrestrial national park in Southeast Asia.  The glaciers in the mountains there represent the only tropical glaciers between Mt. Kilimanjaro in East Africa and the Andes mountains of South America. But the days of the Puncak Jaya glaciers are numbered; a study using high-resolution remotely-sensed imagery found that between 2000 and 2002 the total area of the glaciers decreased by 7.5% (Kincaid and Klein, 2004), which confirmed what previous studies had shown.

Glaciers can provide unique glimpses into the past because there are bubbles within the ice.  These air bubbles provide a snapshot of the composition of the atmosphere at the time when the bubble was trapped in the ice.  By drilling cores in the ice, glaciologists can study the air bubbles to understand how the earth's atmosphere and by extension its climate have changed.  Some core records go back further than 100,000 years!  It's thought that the Puncak Jaya glaciers are a lot newer than this, but for geographers, climatologists, and glaciologists the ice at Lorentz is special....the glaciers are at the western edge of the pacific warm pool, an important feature of the global atmospheric-oceanic circulation system (1). 

Chasing the Cores...

Glaciologist Lonnie Thompson, of the Byrd Polar Research Center at Ohio State University, has been studying tropical glaciers for years.  Thompson and his team made an expedition to Puncak Jaya last year to collect ice cores.  No one had ever collected cores from the Puncak Jaya glaciers before, and time was of the essence in this case.  The problem was actually getting to the glacier, though.  Puncak Jaya is located in a relatively isolated and hard-to-reach area of Papua, and the team had to hike for two days just to reach their base camp. 

A Short Introduction to Glacial Processes...

Glacial Cirque

Glaciers are thick masses of ice that originate on land from the accumulation, compaction, and recrystallization of snow.  They are fundamentally different from snow and ice in that it takes years and requires lots of pressure from weight for glacial ice to form.  About three-quarters of the world's freshwater is frozen in the form of glaciers, and these massive sheets of ice cover about 10% of the earth's land area.  Glaciologists and geographers classify glaciers into two categories: alpine glaciers (forming in mountains) and continental glaciers.  The glaciers at Lorenz National Park are alpine glaciers.  Alpine glaciers form at high altitudes

Notice the morraines...

and move down the slope under their own weight.  You might think of them as "rivers of ice".  Along the way they exert tremendous pressure on the landscape and scoop out pieces of the mountain.  Alpine glacial landscapes are really distinctive; at the top there's usually an amphitheater-shaped feature called a cirque.  As you follow the glacial flow downslope you'll notice along its sides trails of rocks that have been dislodged from the mountains.  These are called morraines.  You can tell where two glaciers have come together because there will be a medial morraine in the center of the new flow.  As you move further down the slope you'll eventually pass an equilibrium point past which snow is no longer accumulating; past this point melting exceeds accumulation.  This is referred to as the zone of ablation.  Ablation is a fancy word used to describe all the processes that remove ice or snow from a glacier.  You can see how it works in the diagram below.  

Diagram from Christopherson, 2010.  Geosystems.

Glaciers are pretty fascinating and we can learn a lot from them.  It is unfortunate that many tropical glaciers, including those at Puncak Jaya, are disappearing. Fortunately Dr. Thompson was able to make it to Puncak Jaya before the glaciers there are completely gone.  The cores are still being analyzed (in fact, two Indonesian graduate students at Ohio State are taking leading roles in this project), but they could potentially reveal a great deal that will help us understand in greater depth how the Earth's climate and atmospheric-ocean interactions work. 

Notes

(1)  The warm pool plays an important role in the El Nino-La Nina oscillation; look for a future post on this phenomenon.  

References and For Further Reading

Kincaid, Joni, and Andrew Klein.  2004.  Retreat of the Irian Jaya Glaciers from 2000 to 2002 as Measured from IKONOS Satellite Images.  Paper presented at 61st Eastern Snow Conference, Portland, Maine.

Prentice, Michael and Geoffrey Hope.  2006.  Climate of Papua.  Ecology of Papua.  Springer-Verlag: NY.  

Stone, Richard.  2010.  Arduous Expedition to Sample Last Virgin Tropical Glaciers.  Science 328, pp1084-5.

Thompson, Lonnie, Ellen Mosley-Thompson, Mary Davis, and Henry Brecher.  2011.  Tropical Glaciers, Recorders and Indicators of Climate Change, Are Disappearing Globally.  Annals of Glaciology 52(59): pp23-34.

Indonesia's official site for Lorentz National Park can be found here.