1: Flood risk assessment and control

The biggest implication of climate change for the Northern Areas is in the field of flood risk assessment. Such assessment is necessary to guard dams and other hydropower schemes. It is also necessary to protect human populations that would become vulnerable to greater damages from the increased frequency of floods.

Archer (2001) gives the following causes of floods in the Karakorams:

• melting of snow and glacier ice which usually produce the annual maximum,
• summer monsoon rainfall which are more significant in the southern areas,
• dam breaks following landslides into rivers can produce high magnitude floods,
• outbursts of glacial lakes can similarly produce sudden, big floods.

Therefore climate change will affect flood risk through its effect on the above four factors.

• Snow and glacier melt - Higher summer temperatures would lead to more melting of snow and glaciers and may lead to a change in the seasonality and magnitude of the flood. In the high, glacier-fed Shyok river Fowler and Archer (2004) have found that a 10C rise in temperature produces a 17% increase in runoff. But this paper also contends that temperature and runoff are negatively correlated in middle altitude, snow-fed catchment areas. Here, increased temperatures result in increased evaporation and, since snow cover is limiting, in reduced runoff. The estimate is a reduction of about 18% for a 2oC rise in temperature.

Increased winter temperatures, as observed in the region, could lead to more rainfall where previously there was snowfall, and this could lead to less snow available for melt in summer. If warming is significant and continues in the near future, then glaciers will retreat and change the hydrology of the region on a big scale.

• Floods from monsoon rains - In spite of the fact that monsoon intrusion into this region is sporadic and not very strong, there have been years when summer monsoons have been heavy, such as in 1992, and have led to significant flooding. If climate change raises the intensity and frequency of monsoons here, then flood risk may also be elevated, especially flash floods in the drier regions (Ahmed, 2001; Archer, 2001).

• Dam breaks following landslides into rivers – Global warming would affect the frequency of intense rainfall which contributes to landslides. Thus more frequent and intense rain in the area would produce more slides and enhance the danger of flooding.

• Outbursts of glacial lakes - These, also known as GLOFs, can be generators of big floods downstream. There were many outbursts on the upper Shyok between 1926 and 1932 causing great flooding along the Indus river. In recent years there have been no major outbursts, however, even though Nepal and Bhutan have experienced a number of them in the last half century. With changing climate the GLOF phenomenon may change its frequency and intensity too.

Additionally, it has been reported in a UN study that the vulnerability of the high mountains environments of Central Asia (which would include the Northern Areas) to changes in water resources due to climate change is very high (FAO, 2004).

2: Forest resources

Climate change would also affect the forest resources and alter biomes in the region:

In non-temperate climates such as the Northern Areas, climatic warming may exceed the ability of present day forests to withstand these changes. According to Siddiqui (1997) a change of 30C can lead to an elevational shift of forests of about 500 meters. And even though species have been adapting to warming since the last Ice Age 10,000 years ago, the predicted change (2.50C for a doubling of CO2) is very high and will exceed their rate of “migration” to keep up. He says that a rate of change of 0.010C is a threshold for many species.

Since at high altitudes temperature is the main climatic control on crop and vegetation growth, a rise in temperature may have a significant impact on high value fruit trees and vegetable production in Pakistan’s mountain zones.

Further desiccation of arid areas due to warming would endanger food production in the plains unless a lot of trees are planted there.

3: Land use and ecology

Additionally, melting or advancing of glaciers would also affect the land use patterns around the glacier, e.g., agriculture or herding near the glaciers, and alter the habitat of animals and plants that have become adapted to existing close to the glacier.

If rains were enhanced, then increased land slides and soil erosion would make lives and livelihoods more vulnerable in the northern mountains of the country.

If temperature increases are significant in the next 20-30 years, that might affect the migratory pattern and spread of bird species in the region, which in turn could have consequences for the food web and also for the geographical spread of diseases such as the avian flu (FAO, 2004).