Current World Environment

Significant variation in mean state of the climate or in its variability persisting for an extended period (typically decades or longer) is referred as climate change. It may be due to natural internal processes or external forcing or persistent anthropogenic changes in the composition of the atmosphere.¹Greenhouse gases like CO₂, CH₄, N₂O, water vapours and ozone re-emit some of solar radiations in the form of short wave radiations to the earth surface and responsible for its warming.²If they did not perform this useful function, most of the heat energy would escape, leaving the earth cold (about – 18^oC) and unfit to support life.³However, since the Industrial Revolution began about 150 years ago, man-made activities have added significant quantities of GHGs to the atmosphere. The atmospheric concentrations of CO₂, CH₄, N₂O have grown by about 31%, 151% and 17%, respectively, between 1750 and 2000.¹Twenty years ago snowfall was regular phenomenon in high hills of Himachal Pradesh but in the last 20 years, only 2-3 instances of snowfall have been recorded.⁴It has been recorded that the average maximum temperature rose by 0.58^oC from the year of 1963 to 2007, whereas, the average minimum temperature rose by 2.75^oC.⁵Though, Kullu in northern Himachal Pradesh is well known for apple cultivation, but due to inadequate snowfall and improper chilling hours survivaling affected the cultivation of apple in the region.⁶Chilling affects the flowering and subsequent fruit setting qualitatively as well as quantitatively.⁷have indicated that irregular bearing behavior of Starking Delicious is largely influenced by climatic conditions. The rain and hails during flowering adversely affects the fruit set, whereas, moderate temperature of 20^oC with relatively low rains during flowering results in the good fruit set.⁸The plants mortality rate due to drought was higher. The plants mortality rate due to drought was higher. About 80% of reduction in yield was estimated due to irrigation water shortage and 20% due to high evaporation rate in apples.⁴reported decrease in chill unit hours in the apple growing areas of Himachal Pradesh. Most of the apple varieties require 1000-1600 hours (at or below 7.2⁰C) of chill units depending upon the variety.⁹