In the 21st century, many environmental issues cause concern. Climate change, or global warming, is one of the biggest problems.
Scientists say the planet is getting warmer, and it’s happening faster than at any other time in history. While the cause is debated, most experts agree human activity is the source. Industry, automobiles, and other human-made sources emit carbon dioxide and other greenhouse gases. Released into the atmosphere, the gases trap heat. As the oceans warm up, glaciers melt and sea levels rise. Then habitats shrink for some animals, like polar bears . . . and people. Eventually, global warming could affect all life on Earth.
In 2015, representatives from 195 countries met in Paris, France, for the United Nations Climate Change Conference. There, they worked out the Paris Agreement, a global plan to reduce pollution. After enough governments approved the agreement, it went into force in November 2016. To celebrate, the mayor of Paris had two major monuments, the Eiffel Tower and the Arc de Triomphe, lit up with green lights. In 2025, President Trump began the process of the United States withdrawing from the agreement.
