It is commonly accepted that the current global warming is caused by humans, especially by anthropogenic emission of carbon dioxide. It is justifiably considered to be one of the biggest threats for life on the planet and human civilization. However, since millennia humans have been changing the climate locally and globally. Especially after the development of agriculture and animal husbandry people have been progressively increasing the albedo of the planet. The cooling of the climate that took place since the Neolithic Revolution and lasted until the onset of the Industrial Revolution corresponds better with the growth of human population than with any other factor. The current global warming threatens with drought, hunger, migrations and inundation of coastal areas. However, throughout the human history, it was the cooling that was related to drought and hunger. The cooling and drought that occurred about 4.2 thousand years ago (the 4.2 ky event) were the most severe. It resulted in the collapse of all Neolithic civilizations. Its reason is still not explained. This paper presents a hypothesis how people could unwillingly cause change in monsoons' strength and direction as well as global climate catastrophe that occurred 4.2 thousand years ago.