The document discusses the role of natural and industrial sources of greenhouse gases, specifically carbon dioxide (CO2), highlighting the impact of the industrial revolution around 1850 when fossil fuel burning began. It emphasizes that deforestation and pollution from vehicles are stressing the ocean's capacity to act as a carbon sink, leading to ocean acidification. With forests covering 31% of the planet, their loss contributes to approximately 15% of greenhouse gas emissions, further compromising this essential carbon sink.