Climate change is a phenomenon due to emissions of greenhouse gases from fuel combustion, deforestation, urbanization and industrialization (Upreti 1999) resulting variations in solar energy, temperature and precipitation. It is a real threat to the lives in the world that largely affects water resources, agriculture, coastal regions, freshwater habitats, vegetation and forests, snow cover and melting and geological processes such as landslide, desertification and floods, and has long-term effects on food security as well as in human health.
In Nepal, majority of the population are small land holding farmers. The nature of agriculture is subsistence and depends on natural climate. Once the climate is disturbed, the whole agriculture system is affected. As the farmers cannot predict the weather that they were accustomed to, the adverse impact of climate change in agriculture is highly significant. The impacts are multiplied by the fact that there a lack of awareness on climate change at different levels, and lack of capacity to cope with adverse impacts of climate change.
The impacts of climate change on agriculture are both direct and indirect. Rise in temperature and temporal and spatial change in rainfall pattern have direct impacts while disturbances in water resources for irrigation and incidences of pests and diseases are the indirect impacts of climate change on agriculture. The rainfall is becoming more and more unpredictable which has negatively affected in the agriculture production since the farmers are planting and harvesting crops within certain dates of the year. The yield and cultural practices depend on timely rainfall. When the sowing and planting activities are not done on time, the crop fails, leading to fallowing of land for season. The farmers are not prepared to cope with such weather uncertainties because they still believe that rainfall will occur on certain dates of the year.
The annual mean temperature trend over Nepal ranged from -0.04 to 0.06⁰ C in far western, 0.02 to 0.04⁰ C in mid western, 0.02 to 0.08⁰ C in western, -0.04 to 0.08⁰ C in central and -0.06 to 0.09⁰ C in eastern region during period showing a range of variations in the temperature trend (Practical Action 2009). Nevertheless, the temperature trends on Nepal are high when compared to global average temperature rise of 0.74⁰ C in the last 100 years (1906 to 2005) and 0.13⁰ C per decade in the last 50 years (1956 to 2005) (IPCC 2007).
Baidhya et al (2008) found a general increasing trend in the extreme events with a consistent higher magnitude in the mountains than in the plains. The study has reflected that both days and night are becoming warmer with less frequent cold days and cold nights. It may be due to solar radiation absorbed by glacial lakes as well as radiation absorbed by land because of snow melting in the Himalayan region.
In Nepal there is more erratic pattern of precipitation in the country. Rainfall was recorded minimum in the year 1972, 1977, 1992 and 2005 and maximum in the year 1975, 1985 and 1998 respectively. However, a clear decreasing trend has been seen in the number of annual rainy days during the last four decades (APN 2007). 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. Such events increase possibility of climatic extremes like irregular monsoon pattern, droughts and floods. For example, there were rain deficit in eastern terai and western regions, normal rain in far western region and heavy rain in the mid western region creating flood, landslide and inundation. The average annual precipitation trend ranged from -10 to 20 mm in the eastern region, -40 to 20 mm in the central region, -30 to 40 mm in the western, -20 to 10 mm in the mid western and -10 to 20 mm in the far western region between 1976 to 2005 (Practical Action 2009).
These are some statistical data showing that contributing to the changing climate and climate change is a global issue and every country trying to adapt or mitigate in vulnerability on climate change. Knowingly or unknowingly, Nepal also made efforts to mitigate the effect of climate change. To mitigate the effect of climate change, forest management practice is one of them. I think adaptation is more important aspect in case of Nepal than mitigation due to our physiographical situation. Same-wise farmers perceive more problem of change in rainfall than change in temperature which was shown by our recent survey on “Ecological impact of climate change on agriculture and livelihoods in the Giruwari catchment, Nawalparasi, Nepal”.
The declining trends of river discharge have direct adverse impacts on agriculture mainly with inadequate water for irrigation. Moreover, the water availability for irrigation has also been affected by landslides and debris flow which have washed away the irrigation channels and sub ducted the water under the debris making it inaccessible for use. This problem is becoming severe in the foothills of Churiya ranges of Makawanpur, Chitwan, Nawalparasi, the soil erosion and landslides have also increased on the slope land cultivated areas (Practical Action 2009).
In high mountains the small glaciers are disappearing resulting into drying up of water for irrigation. However, in the higher altitude areas, there are some positive impacts of increase in temperature through increase in growing seasons for the crops. Farmers in the hills are now able to grow crops that used to grow in lower altitudes earlier, but there are emergence of new pests and diseases in higher altitudes and local people perceive the climate warming as the cause.
Climate change is real and underway, so there is a need of impact identification and adoption to cope with vulnerabilities in agricultural sector. Nepal being a least developed country, it is moving towards vulnerable situation due to climate change. As it is known, its effects cannot be completely controlled but effective planning and change in human habit towards a low carbon economy can slower down possible disasters. Enriched CO2 has shown positive impact on yield of major crops in all geographical zones. However, some research findings from other countries showed reduction in grain and food quality. Increase in temperature and CO2 levels is also threatening to bring hidden-hunger problem in human by lowering essential nutrients contents in food crops. It is concluded that overall impact of climate change in agricultural sectors will have negative impacts in the long run.
APN. 2007. Enhancement of national capacities in the application of simulation models for the assessment of climate change and its impacts on water resources and food, and agricultural production. Final Report of APN Capable Project, 2005-CRP1CMY-Khan.
Baidhya, SK. Shrestha, ML. and Sheikh, MM. 2008. Trends in daily climatic extremes of temperature and precipitation in Nepal. Vol 5 (1), Journal of Hydrology and Meterology, Society of Hydrologists and Meterologists, Nepal.
Bajracharya, et al. 2007. Impact of climate on Himalayan glaciers and glacial lakes. ICIMOD/ UNEP,
IPCC. 2007. Climate change 2007: Climate change impacts, adaptation and vulnerability: Summary for Policy makers. A report of the Working Group II of the Intergovernmental Panel on Climate Change, Fourth Assessment Report. pp7-19.
Practical Action Nepal Office. 2009. Climate change and adaptation in Nepal. A field report submitted by Small Earth Nepal (SEN) to Practical Action Nepal Office.
Upreti, D.C. 1999. Rising Atmospheric CO and crop response. SASCOM Scientific Report, pp1-8.
Note: This concept was shared by author (Dinesh Panday) as participant in e-Conference on Sustainable Mountain Development in the Southeast Asia, June 1-30, 2011.