Coupled Model Intercomparison Project (CMIP) is like a big science experiment where scientists try to figure out what will happen to the earth's climate in the future. It's like predicting the weather, but for a really long time - like 100 years or more!
To do this experiment, scientists use special computer programs that simulate the earth's climate. These programs are called Earth System Models (ESMs). They can be very complicated, with lots of different parts like the atmosphere (the air), the ocean (the water), and the plants and animals on land.
But because there are so many different parts of the climate, and so many different ways that they can interact with each other, it's hard to say for sure what's going to happen in the future. So, scientists from all over the world work together on the CMIP project to compare their simulation results and see what they agree on.
Using lots of different ESMs and comparing their results helps scientists figure out which parts of the climate are most important for predicting the future, and which parts we still don't understand very well. By working together, they can make better predictions and help us prepare for what might happen to our planet in the years to come.