1. Climate change refers to substantial changes in weather patterns due to human activities that release greenhouse gases into the atmosphere.
2. The earth has warmed over 0.5°C in the last century and models predict further warming of 1.8-4.0°C by 2100, with rising sea levels and more extreme weather.
3. Human activities like burning fossil fuels and deforestation are the main causes of increasing greenhouse gas emissions like carbon dioxide in the atmosphere.