The average annual temperature trend of Nepal for the period of 1971-2005 has indicated to be continuous warming at the rate of 0.06°C/yr (INDC, 2016). According to Nepal’s second communication report, 2014; overall seasonal maximum temperature in the country is found to have the largest increase of 4.5?C in spring and smallest increase of 3.3?C in summer, whereas minimum temperature in the country is found to have the largest increase of 5.4?C in winter and smallest increase of 3.4?C in summer by the end of the 21st century. Signi?cant warming trends in the Himalayan, generally higher than the global average, are reported in the literature (Raut, 2004).
Figure 4: Annual average temperature of Nepal (Sharma, 2009)
2.4 Precipitation Change:
Data on trends of Nepal from 1975 to 2005 showed mean rainfall has significantly decreased on an average of 3.7 mm (-3.2%) per month per decade (INDC, 2016). Rainfall was recorded minimum in the year 1972, 1977, 1992 and 2005 and maximum in the year 1975, 1985 and 1998 respectively which can be shown in the figure 2. Erratic rainfall events (i.e. higher intensity of rains but less number of rainy days and unusual rain) with no decrease in total amount of annual precipitation have been experienced. No change in precipitation pattern in western part but up to 5-10 % change in eastern Nepal for winter. In summer, precipitation increased by 15-20% for the whole country both in number of rainy days and increase in rainfall magnitudes.
Figure 5: Trend of precipitation (Baidya and Karmacharya, 2009
2.5 Impact on different sectors and its priority impact
2.5.1 Impact on water resources and Hydropower
Water resources and hydropower rank significantly higher than any other sector for several reasons. Nepal has 6000 rivers which are flowing from Himalaya to plain and mainly glacier fed and less are rain-fed. We dependents on these rivers for mainly irrigation, generating hydropower and water supply. A remarkable impact of warming can be seen in glacier and snow and they are melting at accelerating rate. If there is a warming of 0.06ºC/year, there will be no glacier left in the Nepal Himalayas by 2070. Such a situation will substantially reduce the total water availability in the Nepal Himalayas from 176.08 km3 /year to 128.44 km3 /year by 2200 at an assumed warming rate of 0.06ºC/year ( Chaulagain, 2006).
Nepal is producing 90% of electric power from water. Dry season are increasing which has major impact on the variability flow of the rain-fed rivers which are being insufficient to generate electricity. But for the glacier- feed rivers, increased flow variability causing floods, erosions and GLOFs activities. This has major impact on Hydropower and its generation rate. The impacts of climate change on water are: