Global warming is caused by greenhouse gases trapping heat in the atmosphere, causing the Earth's temperature to rise. This warming harms many plants and animals by changing their environments. Some signs of global warming include rising sea levels submerging islands, killing coral reefs and algae in oceans, and more severe wildfires destroying forests. The primary cause of increased greenhouse gases is human activities like burning fossil fuels for energy and transportation, cutting down trees, and producing garbage. To reduce global warming, people are taking actions like carpooling, conserving energy, planting trees, and reducing waste.