Some things global warming makes worse (clockwise from top left): Wildfires, droughts, and dead coral killed by the ocean getting more hot and acidic.

Earth's average temperature, shown by measurements from various scientific organizations, has increased since the Industrial Revolution.

Places that have become warmer (red) and cooler (blue) over the past 50 years

Global warming is the rise in temperature of the air and oceans globally. It is happening mainly because humans burn coal, oil, and natural gas; and cut down forests. Average temperatures today are about 1 °C (1.8 °F) higher than before people started burning a lot of coal around 1750. In some parts of the world it is less, and in some, more. Most climate scientists say that by the year 2100, temperatures will be 2 °C (3.6 °F) to 4 °C (7.2 °F) higher than they were before 1750.