An Inconvenient Truth presents Al Gore's campaign to educate people about global warming through his slide show, which he has presented over 1,000 times to audiences worldwide since 1989. The film features a comprehensive presentation replete with detailed graphs, flow charts and stark visuals, including photographs of the Earth taken from multiple space missions. Gore shares personal anecdotes that inspired his interest in the issue, including his college education with early climate expert Roger Revelle at Harvard University and his sister's death from lung cancer, before discussing the scientific consensus on global warming and its consequences. The film includes segments intended to refute critics who say that global warming is unproven or that warming will be insignificant, while also presenting solutions such as reducing CO2 emissions and planting more vegetation to consume existing CO2.