It can be very cold during winter. But even so, average temperatures on Earth are rising. It's happening around the world. This is known as global warming. Almost all scientists agree that global warming is real. They also agree that humans are causing it.

How can we still have cold weather and global warming? It's because weather and climate are two different things.

Weather Is What's Happening Right Now

Weather is what happens in the air closest to Earth. It can be hot and sunny or rainy and cold. It can be cloudy, windy and stormy. It can rain or snow.

The sun heats the air. Warm air rises, or goes up. Cold air rushes in to fill its place. This causes wind. Air also holds water gas called water vapor. The wind and the water in the air cause clouds, rain, and snow. It causes storms to form and move.

The weather is always changing. Scientists study the weather. They look at satellites, weather stations, and instruments that float in the ocean. They try to tell what weather is coming in the next few days or weeks. This is called a forecast. Weather forecasts are very important. They warn people. Big storms can cause floods. Dry winds can spread forest fires.

Climate Describes Conditions over a Long Time

Weather can last for days or weeks or months. Climate is what the weather is like over a long time. This is usually 30 years or more. A very cold winter can happen even when the world is getting warmer.

Climate is different around the world. Different types of plants and animals live in different climates.

Weather and climate are connected. A change in climate can lead to changes in weather patterns.

This Time, Humans Are Changing Climate

Climate change is not new. The climate has changed many times in Earth's history. Now, it is changing much faster. Humans are causing the change.

People burn coal, gas, and oil. These are called fossil fuels. They formed from plants and animals that were buried a long time ago. We use fossil fuels to power our cars, trucks, buses, and trains. We use them to turn on the lights, heat our homes, and run factories.

Burning fossil fuels puts carbon dioxide into the air. Carbon dioxide is a kind of greenhouse gas. These gases are like the glass roof in a greenhouse. They allow heat from the sun to come into the atmosphere. They trap the heat. Earth gets warmer.

Earth Is Getting Warmer

Global warming is already happening. In the last 100 years, Earth has warmed by more than one degree Fahrenheit. Sea ice is melting. Glaciers are shrinking. Sea levels are rising. Events, like floods, wildfires, and hurricanes, happen more often. When they do, they are stronger. Animals and plants are moving to cooler areas.

Scientists first learned about how greenhouse gases affect the atmosphere in the 1800s. In the late 1930s, scientists found that Earth was already getting warmer. In the 1980s, people started to do something about the warming.

In 1988, the United Nations formed a group. It is called the Intergovernmental Panel on Climate Change. Since then, countries have agreed to lower how much carbon dioxide they put out.

In 2015, almost 200 countries agreed to lower the greenhouse gases they make. This is called the Paris Agreement. In 2017, the United States left the agreement. On a list of countries that put out greenhouse gases, the United States is second.