The study looked at what causes changes in streamflow around the world. They found that factors other than just rainfall and evaporation are the main reasons for changes in streamflow at almost half of the locations studied. When using reconstructed data, rainfall was the main factor at most locations. This suggests that using reconstructed data may overemphasize the role of rainfall and underestimate the impact of other factors like vegetation and human activities. The study shows that different factors affect streamflow changes in different regions, emphasizing the importance of using real observed data to understand these changes accurately.