Climate change means that the Earth's temperature is getting warmer and warmer over time. The scientific consensus on climate change is that it is real, it is happening and it is caused by people. A scientific consensus is when most scientists agree that something is true.
To get to this consensus, scientists study the environment and all the different things that can cause the temperature to go up. They measure how much carbon dioxide and other gases are in the atmosphere and how much the Earth's temperature has changed over time. They also look at things like land use and how much of forests are being cut down, which can also affect the temperature.
By looking at all of this data and analyzing it, scientists have come to the conclusion that climate change is real, it is happening and it is caused by people. This means that while climate change is a natural process, humans have made it worse by putting too many gases into the atmosphere.