Agriculture is the main source of food security in Nepal. It shares 31.1% of total GDP and provides employment to 70.6% of total employed population. Climate change has serious impact on agriculture and livelihood of farming community. Moreover, it has challenged food security and overall livelihood options. Developing countries have been hurt more seriously and face the great difficulties in adaptation to the impacts of climate change. The climate is changing and farming community has already experienced the impacts of climate change in their crops, environment and livelihoods.

Nepal is in vulnerable position with regard to climate change due to the fragile ecosystem, which is very sensitive to even slight changes in natural climate, weaker geological situation and complex topography. Moreover, Nepal posses less coping and adaptive capacity to address the additional impacts of climate change. Because of the subsistence agricultural production, depends heavily in nature, and based on the traditional knowledge and practices, any changes in climatic condition, therefore, will affect a lot in the food security in Nepal.

Unequal land distribution, traditional farming system and micro-climatic adversities perpetuated by the climate change brings additional challenge to food security in Nepal. About thirty-one percent of people in Nepal are living below the poverty line and are struggling to secure year round food supply to sustain their lives and livelihoods. The vulnerability of people and their agricultural systems is very complex due to interacting direct and indirect climate related stresses. The agricultural sector, with the low productivity increases and high rate of population growth, climate change is likely to have serious consequences for sustainability of Nepalese agriculture. In addition the livelihood assets of poor community such as land, water, forest, economic and social system are experiencing the risk from changing climate.

Climate change involves, perhaps most seriously, changes in the frequency of magnitude of extreme weather events. In the agricultural sector, impacts are associated with the crop yields, altering the cropping pattern, reducing productive capacity of livestock, loss of valuable Agro-biodiversity, change in forest composition and cover, loss of ecosystem, increase in river discharge, flash flooding and riverbank erosion, disaster shifting of Eco tone, change in water navigation, lower water table, cold wave and hot winds, long dry spells and ultimately resulted in lower  agricultural production and threatening food security. Climate change will have impact on the extinction of biodiversity species and shift in habitat is likely to occur. The uniform rise of rainfall will have positive impact on overall agriculture but extreme event will have negative impact on soil nutrient loss, flood damage and erosion. Increase in temperature and occurrence of erratic rainfall are expected to lead to a 30% decrease in crop yields in central and south Asia by the mid-21st century. However at a higher latitude, crop yields should increase because there will be a decrease in frost and cold damage. A case study conducted in Manang and Mustang shows that farmers are benefited to the changing climatic condition for the short time as they are growing new vegetables like Cauliflower, Cabbage, Chili, Tomato, Cucumber and the new plant species that grow previously at lower altitude can be grown at present day.

Due to the excessive drought and high temperature, there was drying of almost 50% of rice seedlings, maize, millet and soybean in most part of the country during the year 2009, Eastern Terai faced rain deficit in the year 2005/06 by early monsoon and crop production reduced by 12.5% on national basis. Nearly 10% of agri- land were left fallow due to rain deficit but mid western Terai faced heavy rain with floods, which reduced production by 30% in the year 2007. Currently also due to shifting of the monsoon the transplantation of the rice has not been able to complete in maximum of the cultivated land of the Nepal. The change in the climatic pattern and also shifting of climatic zones has been observed in the country. Extinction of local basmati rice varieties, some local wheat, maize and other agricultural crops was also observed.

Thus climate change has caused the serious impact on the agriculture of the country and thereby reducing the production and productivity at the tremendous amount and causing the serious threat of the food insecurity in the country. So, the necessary adaption and mitigating strategies should be adopted so as to avoid the great impact of climate change in agriculture.