Global warming is caused by an increase in greenhouse gases like carbon dioxide that are released through burning fossil fuels and deforestation. These gases trap heat in the atmosphere and warm the Earth's surface above natural levels. Some key causes of increased greenhouse gases are burning fossil fuels for energy and transportation, deforestation, increased population leading to higher food and resource demands, farming practices, and industrial waste. While the greenhouse effect is a natural process, human activities have increased the levels of greenhouse gases and strengthened the effect, contributing to global warming.