Climate change refers to changes in long-term weather patterns due to an increase in temperature worldwide. The climate is the usual weather in an area over many years, while weather refers to short term conditions. The Earth's climate is currently changing, with the planet's average temperature having increased about 1 degree Fahrenheit in the last 100 years. This warming is caused by human activities like burning fossil fuels, which release greenhouse gases that trap heat in the atmosphere. If current trends continue, scientists expect further warming over the next century that will raise sea levels and cause more extreme weather events.