Climbing routes and difficulties

There are a number of routes on K2, of somewhat different character, but they all share some key difficulties: First is the extreme high altitude and resulting lack of oxygen: in fact there is only one third as much oxygen available to a climber on the summit of K2 as there is at sea level. Second is the propensity of the mountain to extreme storms of several days' duration, which have resulted in many of the deaths on the peak. Third is the steep, exposed, and committing nature of all routes on the mountain, which makes retreat more difficult, especially during a storm.

Abruzzi Spur

The standard route of ascent, used far more than any other route, is the Abruzzi Spur, first attempted by Luigi Amedeo, Duke of the Abruzzi in 1909 (see the history above). This is the southeast ridge of the peak, rising above the Godwin Austen Glacier. The spur proper begins at an altitude of 5,400 m, where Advanced Base Camp is usually placed. The route follows an alternating series of rock ribs, snow/ice fields, and some technical rock climbing on two famous features, "House's Chimney" and the "Black Pyramid." Above the Black Pyramid, dangerously exposed and difficult to navigate slopes lead to the easily visible "Shoulder," and thence to the summit. The last major obstacle is a narrow couloir known as the "Bottleneck," which places climbers dangerously close to a wall of seracs which form an ice cliff to the east of the summit. (It was partly due to the collapse of one of these seracs around 2001 that no climbers summited the peak in 2002 and 2003.

North Ridge

Almost opposite from the Abruzzi Spur is the North Ridge, which ascends the Chinese side of the peak. It is rarely climbed, partly due to very difficult access, involving crossing the Shaksgam River, which is a hazardous undertaking. In contrast to the crowds of climbers and trekkers at the Abruzzi basecamp, usually at most two teams are encamped below the North Ridge. This route, more technically difficult than the Abruzzi, ascends a long, steep, primarily rock ridge to high on the mountain (Camp IV, the "Eagle's Nest", 7,900 m), and then crosses a dangerously slide-prone hanging glacier by a leftward climbing traverse, to reach a snow couloirs which accesses the summit.
Besides the original Japanese ascent (see the History section), a notable ascent of the North Ridge was the one in 1990 by Greg Child, Greg Mortimer, and Steve Swenson, which was done alpine-style (though using some fixed ropes already put in place by previous teams).

Other routes
Northwest Ridge (finishing on North Ridge), first ascent 1991.
West Ridge, 1981.
Southwest Pillar or "Magic Line", very technical, 1986.
South Face, 1986.
South-southeast spur (finishing on Abruzzi route; a possibly safer alternative to the Abruzzi), 1994.
Northeast Ridge (long and corniced; finishes on uppermost part of Abruzzi route), 1978.
Northwest Face, 1990.
 Topographic characteristics

Climbing history
The mountain was first surveyed by a European survey team in 1856 headed by Henry Haversham Godwin-Austen. Thomas Montgomerie was the member of the team who designated it "K2" for being the second peak of the Karakoram range. The other peaks were originally named K1, K3, K4 and K5, but were eventually renamed Masherbrum, Broad Peak, Gasherbrum II and Gasherbrum I respectively.
The first serious attempt to climb K2 was organized and undertaken in 1902 by Oscar Eckenstein and Aleister Crowley, but after five serious and costly attempts, no member of the team actually reached the summit, possibly due to a combination of questionable physical training, personality conflicts, and poor weather conditions — of 68 days spent on K2 (the then-record for longest time spent at such an altitude) only eight provided clear weather.
Subsequent attempts to climb the mountain in 1909, 1934, 1938, 1939 and 1953 also ended in failure. The 1909 expedition, led by Luigi Amedeo, Duke of the Abruzzi, reached an elevation of 6,666 m on what is now known as the Abruzzi Spur (or Abruzzi Ridge). This is considered part of the standard route today;
An Italian expedition finally succeeded in ascending to the summit of K2 on July 31, 1954. The expedition was led by Ardito Desio, although the two climbers who actually reached the top were Lino Lacedelli and Achille Compagnoni. The team included a Pakistani member, Colonel Muhammad Ata-ullah. He had been a part of an earlier 1953 American expedition which failed to make the summit because of a storm which killed a key climber, Art Gilkey.
In 1977, 23 years after the Italian expedition, Ichiro Yoshizawa led the second successful ascent to the top. The Japanese expedition ascended through the Abruzzi Spur route traced by the Italians, and used more than 1,500 porters to achieve the goal.
The year 1978 saw the third ascent of K2, via a new route, the long, corniced East Ridge. (The top of the route traversed left across the East Face to avoid a vertical headwall and joined the uppermost part of the Abruzzi route.) This ascent was made by an American team, led by noted mountaineer James Whittaker; the summit party were Louis Reichardt, James Wickwire, John Roskelley, and Rick Ridgeway. Wickwire endured an overnight bivouac about 150 m below the summit, the highest that anyone had spent a night up to that date. This ascent was emotional for the American team, as they saw themselves as completing a task that had been begun by the 1938 team forty years earlier.
Another notable Japanese ascent was that of the difficult North Ridge, on the Chinese side of the peak, in 1982. A team from the Mountaineering Association of Japan led by Isao Shinkai and Masatsugo Konishi put three members, Naoe Sakashita, Hiroshi Yoshino, and Yukihiro Yanagisawa, on the summit on August 14. However Yanagisawa fell and died on the descent. Four other members of the team achieved the summit the next day.
The peak has now been climbed by almost all of its ridges. Although the summit of Everest is at a higher altitude, K2 is considered a more difficult climb, due in part to its terrible weather and comparatively greater height above surrounding terrain. The mountain is believed by many to be the world's most difficult and dangerous climb, hence its nickname "the Savage Mountain." As of August 2004, only 246 people have completed the ascent, compared with 2,238 individuals who have ascended the more popular target of Everest. At least 56 people have died attempting the climb;13 climbers from several expeditions died in 1986 in the K2 Tragedy during a severe storm.
Legend once had it that K2 carried a "curse on women." The first woman to reach the summit was Wanda Rutkiewicz, of Poland, in 1986. The next five women to reach the summit are all deceased — three of them died on the way down. Rutkiewicz herself died on Kangchenjunga in 1992. However, the "curse" was broken in 2004 when Edurne Pasaban summitted and descended successfully, and again in 2006 when Nives Meroi of Italy and Yuka Komatsu of Japan became, respectively, the seventh and eighth women to summit K2, both descending successfully.
For most of its climbing history, K2 was not usually climbed with bottled oxygen, and small, relatively lightweight teams were the norm. However the 2004 season saw a great increase in the use of oxygen: 28 of 47 summiteers used oxygen in that year.