A description is offered in layman language on the basic scientific principles of global warming induced by human activities. The impacts of climate change on various components of the Earth System (atmosphere, ocean, land, cryosphere, etc.) are reviewed. The scientific research tools and methodology used to understand the current state of the climate system, and to project its evolution in the coming decades, are introduced. The role of the United Nations Intergovernmental Panel on Climate Change (IPCC) in coordinating and documenting the efforts of the scientific community is explained. The experience and observations of the speaker in contributing to the work of the IPCC during the past two decades are shared with the audience. An account is given of the social controversies surrounding the IPCC reports, with reflections of the personal hardships faced by several climate scientists in these debates.