The ongoing global warming is setting off changes in global climate-what has come to be known as climate change-with dire consequences on the ecosystem of the earth and on human life, being experienced by the world for over the last many decades in the form of climatic extremes, erratic rainfall, floods, droughts, cyclones, having adverse impact on water resources, agriculture, health, human settlements, biodiversity, loss of glaciers, rise in sea level, ocean acidification, etc. All these have been scientifically established through the Assessment Reports of the Intergovernmental Panel on Climate Change. The causes of this rising threat are mainly indiscriminate human activities of burning of fossil-fuels, deforestation, intensive agriculture, and animal husbandry, industrial emissions, etc., causing continual rise of emissions of greenhouse gases. The general perception is that decision making and action is slow, and the threat is increasing by the day. There is lack of public awareness toward the danger. Since human activities are the cause, it is through modification of human activities that the danger can be averted. The purpose of this book is to explain the whole phenomenon of climate change in easy language and lucid style, for creating public awareness. Aware people can prevail upon the governments and authorities to take up the mitigation and adaptation efforts in right earnest, and also on their part, they can conduct their daily activities with thought of abating the challenge.