Jawaharlal Nehru Technological University Hyderabad B.Tech III FUNDAMENTALS OF MECHANICAL ENGINEERING Previous Question Paper (October - 2020 - R16)

Global warming refers to the long-term increase in Earth's average surface temperature due to the greenhouse effect. This phenomenon is primarily driven by the accumulation of greenhouse gases (GHGs) such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide in the atmosphere, which trap solar heat that would otherwise escape into space.

Key contributors include the burning of fossil fuels for power generation and transportation, large-scale deforestation, and industrial processes. The consequences of global warming are significant, including the melting of polar ice caps, rising sea levels, increased frequency of extreme weather events, and disruption of global ecosystems and agricultural productivity.

Ozone depletion is the gradual thinning of the ozone layer in the Earth's stratosphere, which serves as a protective shield by absorbing harmful ultraviolet (UV) radiation from the sun.

The primary cause of this depletion is the release of ozone-depleting substances (ODS), most notably chlorofluorocarbons (CFCs), halons, and carbon tetrachloride. When these chemicals reach the stratosphere, they are broken down by UV radiation, releasing chlorine or bromine atoms. These atoms act as catalysts that break down ozone molecules (O₃) into oxygen (O₂), significantly reducing the concentration of ozone.

The thinning of this layer allows higher levels of UV-B radiation to reach the Earth's surface, leading to increased risks of skin cancer, cataracts, and immune system suppression in humans, as well as damage to marine life and terrestrial plant growth. International efforts, such as the Montreal Protocol, have been instrumental in phasing out the production and use of these harmful substances to facilitate the recovery of the ozone layer.