CHANGING RAINFALL CLIMATOLOGY OF NORTH INDIA: IMPLICATIONS FOR RAINFED AGRICULTURE IN CLIMATE ZONE 4, 5, 7 IN NORTH INDIA

The Earth‘s climate is a complex interactive aggregate of physio-chemical and biological systems. Climate in a narrow sense is usually defined as the ‗average weather‘, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system. In this contest, it is relevant to look into the climate variability/change scenarios in different agro climatic zones (4,5 and 7) as it will throw light to take up impact of climate variability with reference to plantation crops, which is one of the objectives of the present study. The trends in rainfall scenarios over the zones have been examined zone-wise viz., 4, 5 and 7. Over the last five decades of the 20th century, the major and minor rainy seasons have undergone varying degrees of drying. This reduction in rainfall is not uniform, either temporally through the rainy seasons or spatially across the study area. Most locations had significant reductions in rainfall during the minor rainy season and at the beginning of major rainy season, and often an increase in rain during the short dry spell. The universal decline of mean rainfalls totals and number of rainy days during the minor rainy season, often associated with greater inter-annual variability, is particularly threatening to the production of a second crop during this time of the year. Meanwhile, increases in means of both variables and reduction in their standard deviations during the short dry spell, only exacerbates these problems. as this season has traditionally been used to store the first crop and to perform slash and burn in preparation for the second crop. A humid condition during the short dry spell increases the likelihood of losses from fungi and hinders the successful burning of cleared vegetation. In India, the projected impact of climate change on agriculture varies across regions because India has immense climatic/geographic diversity. In the arid regions, where the agricultural crops face the heat stress, even small changes in temperature (increase) will have a devastating effect (decline) on agricultural production. However, the same rate of increase in temperature in cooler places such as near the Himalayas could have a positive effect on agricultural production