Posted 11 February 2012 - 20:47
Somewhat not surprised by this, given the anthro-meteorological happenings of the past 25 years.
We appear to have forgotten about the first Gulf war in early 1991, which ended by the Iraqis torching all the Kuwaiti oil wells, such that much of southeast Asia, including the Himalaya were covered in an acrid oily smoke. Some of this blackened the Himalayan snow, this causing a more rapid thaw of snow than normal during the summers of 1991 and 1992. Such was the rate of melting during 1991, that some serious flooding occured on some of the rivers leading southwards out of the main Himalayan chain during the monsoon season of 1991. The village of Tatopani in the Annapurna region of Nepal was almost swept away by a flood. By the time I visited the Annapurna region in central Nepal in October and November 1992, much of the non consolidated snow had melted. Normally, the last few thousand feet of the climb up Chulu East, a trekking peak, would have been on snow, but a weak monsoon and ablating snow due to altered albedo meant that only the highest few hundred feet were snow covered. During the following years, there was a perceived reduction in glacier ice due to further hot summers and low rainfall.
During the past few years, there has on occasions been strong southward movement of the polar front jet, by blocking of the temperate westerlies and negative NAO, or even a serious weakening of the polar front jet such that the subtropical jet has played a more active part during the winter half of the year. This has meant that atmospheric mobility has been much further south than normal, and therefore more able to tap into subtropical warmth and moisture. Although the Himalaya gets 'westerly' storms during the winter, during the past few, these have been on occasions particularly active, with the jet driving moisture eastwards from the Med to the Karakorum and further east. There have been significant rains in Pakistan during the winter months during the past two winters especially with corresponding high rates of snowfall across the mountains.
There have also been some significant monsoon storms during the past few years too, the near inundation of Pakisan by the Indus river being a very tangible event in this respect. Altough freezing levels in such storms are generally in the order of 4000 to 5000 metres, with some of the peaks exceeding 8000 metres in this region, there must have been the propensity for further significant snow accumulations above this level during the monsoon season.
Therefore, looks like the losses of snow allegedly caused by the first Gulf War may be being recharged and therefore correcting an initially perceived over rapid depletion of Himalayan ice.