The change in weather parameters in a large area for an extended period of time is called climate change. It is caused by various factors. Certain human activities contribute to it. The variation in monsoon, rising temperatures, drought and changed hydrological cycle are some forms of climate change seen in Nepal. Variation in weather pattern causes variation in agriculture output, which in turn affects people's living standards.Climate-related disasters can be caused by rapid-onset events and slow-onset events. Rapid-onset events include landslides, avalanches and floods, while drought, rising temperatures sedimentation and accelerated melting of snow and glaciers come under slow-onset events.
There are many recent evidences of climate change in Nepal. Extremely foggy conditions have repeatedly been observed during winter in the Tarai region. Late or early monsoon, unusual precipitation, decreasing rainy days and intense rainfall events are causing more runoff and low groundwater recharge. Shifting of climatic zones has been observed in many parts.
Research shows that Nepal's average temperature is increasing at an annual rate of 0.04-0.06°C. Warming is more pronounced in higher altitudes than in the Tarai and Shiwalik region. This may be due to solar radiation absorbed by glacial lakes as well as radiation absorbed by land because of melting snow in the Himalayan region.
The rainfall pattern is not uniform in Nepal. Sometimes there is heavy rainfall and sometimes severe drought. The average annual rainfall is increasing by 168 mm and the days of rainfall are decreasing by 0.16 days a year. It means heavy rainfall occurs over a shorter period causing landslides and soil erosion. The recent landslides in Kaski, Baglung, Myagdi and Chitwan are the results of such erratic rainfalls, the resulting landslides and flash floods killing more than 50 people in these districts last year.
As a result of climate change, there is less land available to cultivate. Agricultural lands in Tarai are becoming less productive while such lands are being lost due to landslides in hilly and mountainous regions.
However, rising temperature and CO2 emission are helpful, to an extent, in increasing agricultural production as they accelerate photosynthetic process, reduce water use and boost soil microbial activities. Early maturity of crops, due to increase in temperature, boost productivity. However, traditional rainfall in May and June has been shifted to July and August. This has negative effect on paddy production.
Another affected area is irrigation. According to the Agriculture Development Strategy report, an increase in temperature by 3ºC would increase irrigation water demand by 11 percent, if other parameters remain constant. Nepal is already experiencing water deficit in the four or five non-monsoon months. Further warming may worsen the situation.
Loss of local crop variety is another visible impact. Furthermore, the shift in agro-ecological zones, high incidence of pest and diseases, emergence of new alien and invasive species, early sprouting, flowering and fruiting, and decline in the productivity of some herb and grass species have also been seen. Many vector-borne and water-borne diseases result from climate change. Landslides and floods are also causing loss of market and service infrastructures.
Only 17 percentage of total land in Nepal is cultivable. Access to irrigation is poor. Soils are of low fertility. Hence understanding the interaction among forest, agriculture and water management and their relation to climate change can help us develop effective strategies to adapt to both long and short term impacts of climate change on agriculture.
The government has recently completed its national-level adaptation plan (NAPA) which has identified different priority projects and recognized the need for local-level adaptation. But the implementation is weak.
Nepal, already a least developed country, is getting more vulnerable due to climate change and recent earthquake. Agricultural sector is badly affected by natural disasters. Food costs are increasing and the population under poverty is growing. So the government should bring adaptation packages including crop diversification, promotion of local C4 crops varieties and establishment of seed bank for sustainable solution to food insecurity.
C3 crops include rice, wheat and barley while C4 crops include sugarcane, corn, sorghum, and millet. As C4 plants can tolerate higher temperatures and their CO2 compensation point is higher than C3 plants, we should prioritize their commercial plantation in hilly areas. Local fruit crops tolerant of extreme weather conditions should also be promoted.
There is a strong link between crop production and seed accessibility, especially in case of climate change and earthquake. Hence, local institutions and farmers' organizations, such as community seed banks can be key allies for local seed system under such conditions. The seed banks in Tanahun and Nawalparasi, for example, quickly provided rice seeds to farmers of earthquake affected districts upon the request of the District Agriculture Development Offices (DADOs). Such productive cooperation must be promoted.
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