Okay kiddo, you know how when we drive cars or use electricity, it creates smoke and other things that can be bad for the environment? Well, there are a bunch of people called scientists who study how all of this affects the earth.
The IPCC (which stands for Intergovernmental Panel on Climate Change) is a group of scientists from all around the world who come together to study climate change. They made a big report called the Fourth Assessment Report to explain what they found.
They basically found that because of all the things we humans do, like driving cars and burning coal, there are a whole bunch of gases (like carbon dioxide) that get released into the air. And these gases trap heat from the sun in the earth's atmosphere, which makes the earth warmer.
This can cause a lot of problems for us and for the planet, like sea levels rising and more extreme weather like hurricanes and floods.
The scientists in the IPCC report said that we need to start doing things different to help stop this from happening, like using less energy and finding cleaner ways to make electricity. They also said that if we don't start making changes soon, things could get a lot worse for all of us.
So basically, the IPCC Fourth Assessment Report is a big report that tells us about how human actions are causing climate change, and what we can do to try and stop it before things get even worse.