The pioneering scientist known for research on the impact of climate change is James Hansen. As a former director of the Nahional Aeronautics and Space Administration's (NASA) Goddard Institute for Space Studies, Hansen became a leading voice in climate science. His testimony before Congress in 1988 was pivotal, informing the public and policymakers about the realities of global warming. Hansen’s advocacy for immediate action to address climate change highlights the urgency of the issue. His influential research continues to shape environmental discussions and policies worldwide.