Volcanoes can change the weather. They can cause rain, thunder and lightning. Volcanoes can also have long-term effects on the climate, making the world cooler.
Fast-moving lava can kill people and falling ash can make it hard for them to breathe. They can also die from famine, fires and earthquakes which can be related to volcanoes. People can lose their possessions as volcanoes can destroy houses, roads and fields.
Lava can kill plants and animals too. The Mount St Helens volcano in 1980 killed an estimated 24,000 animals including 11,000 hares, 6,000 deer, 300 bobcats, 200 black bears and 15 mountain lions.