KARACHI: The Siachen Glacier has been reduced by 5.9km in longitudinal extent between 1989 and 2009 because of rising temperatures, says a study published recently.

Human presence at Siachen may also be affecting the neighbouring glaciers of Gangotri, Miyar, Milan and Janapa which feed Ganges, Chenab and Sutlej rivers.

The study, Climate Data and Modeling Analysis of the Indus Ecoregion, has been written by Dr Ghulam Rasul of the Pakistan Meteorological Department as part of a project titled Building Capacity on Climate Change Adaptation in Coastal Areas of Pakistan. It was a European Union-financed project of World Wide Fund for Nature-Pakistan.

According to the study, Himalaya, Karakoram and Hindukush together make the largest mountain chain on earth and they are the custodian of the third largest ice reserves after the Polar Regions. The glaciers in these mountain ranges feed 1.7 billion people through seven large Asian river systems, including the Indus, Ganges, Brahmaputra, Mekong and Yangtze.

These ranges are a blessing for South Asia as they protect it from the cold surges in winter associated with northerly winds.

“Since temperature maxima have been increasing at a greater rate, the thinning of ice and retreat of glacial extent has taken place simultaneously at an alarming rate. The decay estimates calculated by remote sensing techniques show that Siachen Glacier has reduced by 5.9km in longitudinal extent from 1989 to 2009. Thinning of its ice mass is evaluated at 17 per cent,” the study says.

A sharp decline in the mass of all glaciers has been seen since the 1990s. Accelerated melting process of seasonal snow and that of glacier ice from mountain glaciers have been adding to greater volume of water into the sea than normal discharges, it says.

Both precipitation and thermal regimes in Pakistan have suffered changes, especially in the recent two decades in line with a sharp jump in global atmospheric temperatures. Visible changes in hydrological cycle have been observed in the form of changing precipitation patterns, cropping patterns, droughts, water availability periods, frequency and intensity of heatwaves, precipitation events and weather-induced natural disasters.

According to the study, both minimum and maximum temperatures have increased in summer and winter almost throughout Pakistan.

Late onset and early winter ending will reduce the length of growing season for crops which will complete their biological life quickly causing reduction in yields as plants will gain accelerated maturity without reaching proper height and size. Early winter means that temperatures will start rising in February when wheat crop reaches the grain formation stage.

“Sharp rise in temperature will cause forced maturity of grains as a result neither grains will attain their proper size or weight nor will they accumulate optimum levels of starch thereby reducing the grain yield; pollination in banana, another important crop of the Indus delta, will be affected due to early winter and high spring temperatures. Thermal stress will result in a poor fruit set and dwarf yields.

“Such adverse effects are already visible and there is a dire need for adaptation strategies by introducing crop varieties which require shorter span and are resistant to stress conditions,” the study says.

The study lists recent extreme weather events which caused great losses to the socio-economic sector. They are: cloudburst events (2001, 2003, 2007, 2008, 2009, 2010, 2011), prolonged droughts (1999-2002), historic river flooding (2010), tropical cyclones (1999, 2007, 2009, 2010, 2011), severe urban flooding (2001, 2003, 2007, 2008, 2009, 2010, 2011), heatwaves in spring (2006, 2007, 2010), snowmelt flooding (2005, 2007, 2010) and drought at sowing stage (2004, 2006, 2007, 2009, 2010, 2011).

About the floods of 2010 and 2011, the study says that such back-to-back occurrence of the history’s worst flooding is at least a unique phenomenon in case of Pakistan. In 2010, intense precipitation concentrated over the elevated plains of Khyber Pakhtunkhwa due to interaction of three weather systems from east, south and north.

“Such interactions are very rare in the pre- and post-partition meteorological history of this region. Nor was it the heavy precipitation zone of monsoon season,” it says.

Similarly, another historic climatic anomaly occurred in 2011 when the monsoon axis set its orientation from head of Bay of Bengal to southern Sindh which was commonly found parallel to the Himalayas in case of heavy precipitation in Pakistan.

“Rains storm persisted for a couple of weeks over the Indus delta and adjoining areas experiencing arid climatic conditions.

Generally, this region receives less than 200mm rain during the year but in a couple of weeks some eastern parts gathered precipitation exceeding 1000mm. Poor slope of land, heavy soil and abandoned drainage infrastructure exaggerated the situation and a disaster occurred in the area,” the study says.