sentence: Some people try to stop global warming, usually by burning less fossil fuel.
sentences_after: Many people have tried to get countries to emit less greenhouse gases. The Kyoto Protocol was signed in 1997. It was meant to reduce the amount of greenhouse gases in the atmosphere to below their levels in 1990. However, this has not happened. Carbon dioxide levels today are the highest they have been since the start of the Industrial Revolution.
concept_name: people
headings: Global warming Some responses
categories: Energy Climate change Air pollution