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CHANGING CLIMATE; KATHMANDU "NO FAR FROM IT"

By: Ms. Anushiya Shrestha, Nepal Engineering College (NEC)

Inter governmental Panel for Climate Change (IPCC) defines climate change as a change in the state of the climate that can be identified (e.g using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. It refers to any change in climate over time, whether due to the natural variability or as a result of the human activity. The 1990s was the warmest decade of the millennium and 1998 was the warmest year on record (IPCC 2001).

IPCC (2007) reported there is an "Increase in intensity or frequency of the extreme weather events. Climate change is expected to cause an increase in the mean annual temperature up to 5*C by 2080 in Asia. The total amount of the precipitation and the number of rainy days in South-Asia has decreased (Cruz et al. 2007). According to NASA (2009), in total average global temperature have increased by about 0.8*C (1.4*F) since 1880, the year that modern scientific instrumentation became available to monitor temperatures precisely. According to the World Meteorological Organization (2011) the year 2010 ranked as a warmest year on record, together with 2005 and 1998, and global temperatures in 2010, 2005 and 1998 show no statistically significant differences.

Nepal Engineering College under the research grant of International Development Research Center, Canada, analyzed various attributes of rainfall and temperature for seven stations (Khumaltar, TIA, Godawari,  Changu Narayan, Naikap, Panipokhari and Sankhu) selected considering their proximity to the peri-urban research sites of the projects.

Based on the analysis, temperature record showed a clear decrease in number of days below 0*C and increase in the number of the hot days (>30*C). The highest and the lowest temperature of the both daily Tmin (Minimum Temperature) and daily Tmax (Maximum Temperature) showed and increase suggesting that both the days and the nights have become warmer. The increase temperature was the lowest for summer season and strongest for fall and winter season. Tmin showed an average increase of 0.04*C per year and Tmax showed on average an increase of 0.05*C per year. Similarly the number of days with temperature below 0*C showed a decrease while the number of hot days (Temperature >30*C) increased.

In case of rainfall, no clear increasing or decreasing trend was found in the number of days with rainfall nor the total annual rainfall showed any significant increasing or decreasing trend. Four out of above mentioned seven stations have a decrease in number of rainy days in non-monsoon period. Four monsoon period only three out of seven stations have a decrease in number of rainy days. There is no recognizable pattern to draw any conclusions concerning the Standard Daily Intensity Index (SDII=Total Rainfall/No. of rainy days) of Kathmandu valley as conducted for monsoon period in the study. The analysis showed an increase in the number of extreme rainfall events (daily rainfall >50mm) in most of the stations.

Due to the data gaps in the evaporation and humidity while availability of wind speed data only for the shorter period (available only for TIA for 1993-2008 and Khumaltar for 1999-2008), these data could not be used for the analysis.

The earlier studies conducted for understanding the trend of Climate Change in Nepal are comparable to these findings. (Shrestha et al 1999) temperature observation in Nepal from 1977 to 1994 showed a general warming trend and increased in average annual temperature was 0.06*C. A Study made by Practical Action Nepal (2009) on the temporal and spatial variability of temperature and rainfall, based on the observed meteorological data for the period 1976-2005, shows increasing trend in temperature over Nepal. The maximum temperature was found to be increasing at a greater rate (0.05*C/year) than the minimum temperature (0.03*C/year). Similarly Shrestha et al. (2000) did not find any changing precipitation pattern over the period 1970-2000. Also study Baidya et al. (2008) for rainfall data throughout Nepal also did not any significant trend for the daily intensity of precipitation while found an average increase of  0.001 for the number of days with more than 50 mm rainfall.

The Peri-Urban areas of Kathmandu include hill slopes and are vulnerable to land slide and soil erosion. Literature's show the relation of daily rainfall threshold to destabilize a hill slope (Larsen and Simon 1993, Gabet et al. 2004) and an increase in extreme rain events can trigger land slide. This finding can be an important caveat to the ongoing unplanned land pooling and rampant sand mining activities in the Peri-Urban areas of Kathmandu.

Several studies point out that the variability of the temperature also plays an important role in crop growth. Dukes and mooney (2000) suggested the invasive weeds will probably be the fastest to migrate with increasing temperature. Higher temperatures have also been associated with an increase in diarroeha, mind winters tend to increase rodent- borne diseases and can also increase dengue-fever transmitted by mosquitoes (Kovats et al. 2003). Lal (2011) described how a significant part of the stagnation in rice and wheat yield can be assigned to the rising temperatures during the cropping season. Joshi et al. (2011) found a significant negative relation between increase in maximum summer temperature and maize yield, the second major summer crop in Nepal after paddy.

Rapid urbanization expanding towards the peripherals has resulted increasing competition over the available land and the water resources in the Peri-Urban areas of Kathmandu. Additionally, increasing temperature and though not clear, changing rainfall as perceived by local people has resulted increased pest occurrences and invasion of unidentified weeds. These have been major causes of decline in agricultural yield and in increase in the production cost. Consequently, the net benefit to the farming communities in the peri-urban areas has reduced, and more over extended the threat of food insecurity.

   

Ms. Shrestha is currently involved in the research on "Water Security in the Peri-Urban South Asia; Adapting to Climate Change and Urbanization" underway at Nepal Engineering College (NEC) supported under the research grant of International Development Research Center (IDRC).




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3 comments:

  1. This is a part of 'Himalayan Dilemma' ... after all the world is suffering because of climate change. Change must happen from core of attitude of all people, most importantly so called climate champions.

    BTW, your article , if had included educational aspects of CC, would be more appreciated. You have done good. Keep it up and keep the genuine spirit.

    ReplyDelete
  2. Dear Preeti jee,

    You have been reading the articles genuinely in the website. Please continue the spirit.

    ReplyDelete
  3. Thank you preeti for your effort.

    ReplyDelete

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