Original sentence: "  There are thousands of papers published about model-based studies in peer reviewed journals - and a part of this research is work improving the models.Barnett of the Scripps Institution of Oceanography observed in 2001 that he didn't know that they reproduced climate any better than they did 5 years earlier.Climate modeler Jeffrey Kiehl of the National Center for Atmospheric Research stated that "we have made progress, but sometimes progress means you learn you need to know more.However, climate modeler Tim P.Much has yet to be learned, as cloud physicist Robert Charlson observes: "To make it sound like we understand climate is not right.Thousands of climate researchers around the world use climate models to understand the climate system
Edited sentence: Thousands of climate researchers around the world use climate models to understand the climate system, and publish thousands of papers about this in peer reviewed journals - and a part of this research is work improving the models