The Central Karakoram National Park area is ca.10557.73 km2, and roughly 40% of it is covered by ice (30% of the glacier surface of the entire Karakoram range in Pakistan). There are some glaciers that intersect the
park boundary, and therefore including all glacier outlines CKNP boundary covers an area of 13,199 km2.
The attention paid to this area is increasing, because the evolution of its glaciers recently depicted a situation of general stability, known as “Karakoram Anomaly” and more recently the “Pamir-Karakoram
Anomaly”, in contrast to glacier retreat worldwide.
An inventory, based on 2001 satellite images, displayed 711 glaciers within the CKNP region spanning a broad range of size, geometry, type, and surface conditions. Most of the glaciers are typical debris covered glaciers, that is glaciers with the largest part of their tongue or ablation zone continuously covered by rock debris; moreover for most glaciers there is lack of real accumulation basins and they are nourished largely or wholly by snow and ice avalanches.
Some glaciers are more than 60 km long (for instance Hispar, Biafo, Baltoro).
The Baltoro Glacier, one of the most prominent, most walked and known all over the world glaciers in the park, is one of the largest debris covered glaciers worldwide (604 km2).
The glacier gives rise to the Shigar River, which is a tributary of the Indus River. Several large tributary glaciers feed the main Baltoro glacier, including the Godwin Austen Glacier, flowing south from K2; the Abruzzi and the various Gasherbrum Glaciers, flowing from the Gasherbrum group of peaks; the Vigne Glacier, flowing from Chogolisa, and the Yermandendu Glacier, flowing from Masherbrum. The confluence of the main Baltoro Glacier with the Godwin Austen Glacier is known as Concordia; this location and K2 base camp are popular trekking destinations.
The trough of this glacier is very wide. Small valley glaciers form icefalls where they meet the trunk glacier. The sidewalls vary from very steep to precipitous. The glacier has carved striations on the surrounding country rocks. Moving ice has formed depressions, which serve as basins for numerous glacial lakes.
Baltoro glacier has been studied for more than one century, within several scientific expeditions, among others those led by Ardito Desio, a most renowned Italian scientist and explorer. In a more recent inventory, based on 2010 satellite images, the number of glaciers is slightly lower than in 2001, with 707 glaciers (due to some individual glaciers advancing to merge with neighboring glacier bodies), covering an area of 4,613 km2 (±38 km2). Then the total glacier surface increased slightly, by ca. +27 km2 during 2001-2010. The relative area change is not remarkable (+0.6% of the 2001 area), thus suggesting rather stable conditions. Moreover, 40 glaciers (over the whole sample of more than 700) are found with changed area, i.e. only 0.06% of the CKNP glaciers varied its surface, confirming the stability of this glacierized region. In spite of the overall stable situation, when focusing upon those 40 glaciers witnessing surface change (i.e. due to advance or surge events), noticeable variations are found. In some cases they even advanced on top of their bigger neighboring glaciers.
MAIN KARAKORUM GLACIER OUTSIDE THE PARK
The Biafo Glacier is a 63 km (39 mi) long glacier which meets the 49 km (30 mi) long Hispar Glacier at an altitude of 5,128 m (16,824 ft) at Hispar La (Pass) to create the world’s longest glacial system outside the polar regions. This highway of ice connects two ancient mountain kingdoms, Nagar (immediately south of Hunza) in the west with Baltistan in the east. The traverse uses 51 of the Biafo Glacier’s 63 km and all of the Hispar Glacier to form a 100 km (62 mi) glacial route.
Biafo glacier, the world third longest glacier (63 kilometers) is also found in the same region, which meets the Hispar glacier at the famous snow lake at the height of 5,128 m, creating the longest glaciated highway in the world from Shigar valley to Nagar Valley in Gilgit Baltistan.
The Biafo Glacier presents a trekker with several days of very strenuous, often hectic boulder hopping, with spectacular views throughout and Snow Lake near the high point. Snow Lake, consisting of parts of the upper Biafo Glacier and its tributary glacier Sim Gang, is one of the world’s largest basins of snow or ice in the world outside of the polar regions, up to 1,600 m (0.99 mi) in depth. The Hispar River, a tributary of the Hunza River, rises from the meltwater of the glacier.
Siachen Glacier is the world second-longest glacier in the world’s non-polar areas (75 kilometres), located in the eastern Karakoram range. It falls from an altitude of 5,753 m (18,875 ft) above sea level at its head at Indira Col on the China border down to 3,620 m (11,875 ft) at its terminus.
The glacier lies between the Saltoro Ridge immediately to the west and the main Karakoram range to the east. The Saltoro Ridge originates in the north from the Sia Kangri peak on the China border in the Karakoram range. The crest of the Saltoro Ridge’s altitudes range from 5,450 to 7,720 m (17,880 to 25,330 feet). The major passes on this ridge are, from north to south, Sia La at 5,589 m (18,336 ft), Bilafond La at 5,450 m (17,880 ft), and Gyong La at 5,689 m (18,665 ft). The average winter snowfall is 10.5 m (35 ft) and temperatures can dip to −50 °C (−58 °F). Including all tributary glaciers, the Siachen Glacier system covers about 700 km2 (270 sq mi).
Batura Glacier (58 kilometres) is just north of the massifs of Batura, at 7,795 metres (25,574 ft), and Passu, at 7,500 metres (24,600 ft). It flows west to east. The lower portions can be described as a grey sea of rocks and gravelly moraine, bordered by a few summer villages and pastures with herds of sheep, goats, cows and yaks and where roses and juniper trees are common.