The term extreme weather or climate event refers to ‘an occurrence of…a weather or climate variable beyond a threshold…,’ Intergovernmental Panel on Climate Change, (IPCC) 2012. It includes very high (and low) temperatures, very heavy rainfall (and snowfall in cold climates) and very high wind speeds. By definition, extreme weather events occur only rarely and are noticeable as they are so very different from the usual (Fig 1). They are however, associated with adverse impacts on humans, infrastructure and ecosystems. In many cases, the most severe impacts are felt when several extreme events occur simultaneously. Examples include: (i) the impacts on agriculture when a combination of drought and a heat wave occur; and (ii) high bush fire danger weather, which can be a combination of high temperature, low humidity, high wind and drought.
Indian agriculture and extreme weather events: The challenges facing agriculture in India are ever increasing. In the present global climate change debate the sustainability of intensive agriculture using current technologies is being questioned. Long-term changes and the increasing frequency of extreme weather events are likely to adversely impact the agricultural sector. Recurring failure of rains and occurrence of natural disasters such as floods and droughts could lead to crop failures, food insecurity, famine, loss of property and life, mass migration, and negative national economic growth.
The 2001–2010 decade witnessed the intensification of climate and weather extremes such as destructive flooding, severe droughts, heat waves, heavy downpour and severe storms. The number of extreme events of rainfall (very heavy rainfall) has almost doubled in the country in the last 50 years and the observed trends suggest enhanced risks associated with extreme rainfall over India in the coming decades.
Trends of extreme weather events in India: With respect to cyclones, India is particularly vulnerable because of its relatively large percentage of the population living in coastal districts that lie in the path of cyclones.
Climate information and loss minimisation: Beyond doubt, climate information services will be one of the tools to meet the challenges of the future particularly with reference to extreme events. The provision of need-based climate information to farmers can support the management of agricultural resources (land, water and genetic resources). Better understanding of climate in a location provides opportunities to design various measures to reduce its impact on natural resources. Climate information services are needed for landuse planning, agroecological zoning, sustainable land and forest management. Recent improvements in the provision of advance climate information allow the earliest identification of areas likely to be affected by a specific climate risk.
Drought monitoring: In the case of drought, for example, a combination of traditional and more innovative technological approaches are being used to manage risks. Technological drought management (e.g. development and use of drought tolerant cultivars, shifting cropping seasons in agriculture, and flood and drought control techniques in water management) is combined with model-based seasonal and annual to decadal forecasts. Model results are then translated into an early warning in order to take appropriate drought protection measures.
Aridity anomaly index is used to monitor the incidence, spread, intensification and recession of drought. With the help of aridity anomalies, crop stress conditions in various parts of the country is monitored during the monsoon season. These anomalies are used for crop planning and in the early warning system during drought/desertification. The Standard Precipitation Index (SPI) is a relatively new drought index based only on precipitation (Fig 2). Its an index based on the probability of precipitation for any time scale. Depending on SPI values and categories of rainfall situation, drought condition for a particular period is determined. Along with the prediction of cyclonic storms issued by the Cyclone Warning Division of India Meteorological Department (IMD), during ‘THANE’ and ‘NILAM’, Agromet Field Unit simultaneously issues Special Agromet Advisory Bulletin for fisheries, animal husbandry and horticulture crops.
Forecast for extreme events: Special weather forecast for agriculture provides the necessary meteorological input to assist farmers in making decisions. The requirements for these special forecasts will vary from season to season and from crop to crop and are normally issued for planting, chemical application, forestry etc. Special extreme event forecast issued are as follows:
- Tropical cyclone (North Indian Ocean) track, intensity, structure changes and landfall process (wind and gust, rainfall and storm surge);
- Heavy rain and strong winds triggered by tropical cyclones, SW and NE monsoon, troughs and ITCZ migration and orography;
- Thunderstorms and hail associated with severe convection; and,
- Extreme hot and cold conditions and frost.
The IMD is operating an Integrated Agro-Meteorological Advisory Services (IAAS) at the district level in India—a small step towards agriculture management in rhythm with weather and climate variability, leading to weather proofing for farm production. The network for assessing extreme events in the nation includes the conventional observational network, automatic weather stations (AWS), buoys/ship observations, cyclone detection radars, Doppler weather radars and satellites observations. Satellite and radar observations are very crucial for the assessment of hazards, especially in the Himalayan region and the North Indian Ocean. Under IAAS, IMD has started issuing quantitative district level weather forecast upto 5 days from June, 2008. In the current plan period IMD is venturing into block level forecast.
The IAAS is also disseminating advice to the Indian farming community through SMS messaging and Interactive Voice Response Technology (IVR). In a public-private partnership arrangement, AMFUs are preparing and sending district AAS bulletins twice weekly to private companies including IFFCO, Kisan Sanchar Limited (IKSL), NOKIA, Reuter Market Light, Handygo, state department of agriculture and comprising weather forecasts and advisory on extreme events along with crop, pest, disease, seed and fertilizer information. Sixteen states (Delhi, Uttar Pradesh, Punjab, Haryana, Rajasthan, Madhya Pradesh, Odisha, West Bengal, Gujarat, Karnataka, Kerala, Tamilnadu, Andhra Pradesh, Bihar, Maharashtra and Himachal Pradesh) have been covered by this service, with around 3 million farmers receiving updates and advisories.