Penner has contributed to multiple reports from the Intergovernmental Panel on Climate Change (IPCC), which was awarded the 2007 Nobel Peace Prize for its series of assessment reports. Penner was the coordinating lead author for chapter 5 on "Aerosols, their Direct and Indirect Effects" within the 2001 Assessment Report 3, Working Group 1 (AR3 WG1), and one of 18 lead authors for the technical summary of that same report. In 2007, she was one of 7 lead authors for chapter 9 on "Understanding and attributing climate change" (). In 2013, she served as a review editor for chapter 7 (Clouds and aerosols, ) and for the technical summary (). She was also one of the contributing authors for the 1995 IPCC report.