Dennis Ojima has conducted research and assessments on global change impacts on ecosystems around the world and in the US Great Plains, including research on adaption to climate change in Mongolia, China, and in the Central US. He has led National Climate Assessment reports on the Great Plains. Dennis served as the CSU director of the USGS North Central Climate Adaptation Science Center (2011- 2018) and served as the president of the Ecological Society of America in 2022. Dennis shared in the recognition for contributions to the 2007 Noble Peace Prize for the International Panel on Climate Change (IPCC). In 2013, he was honored as a champion of the environment by the Mongolian Minister of the Environment and Green Development.