How do we know earth is changing

Scientists utilize both contemporary and historical images to monitor the evolving conditions of Earth over time. Given that Earth is our home, and it is the sole known planet where life can thrive, scientists engage in continuous observations of its terrestrial, aquatic, and atmospheric features.
Through the acquisition of images from terrestrial and satellite perspectives, we gain valuable insights into the transformations Earth has undergone compared to its earlier states.
This is a good video from NASA that gives you the view about our earth over time.