Klaus Hasselmann is a German oceanographer and climate scientist known for his work in understanding climate change. He was awarded the Nobel Prize in Physics in 2021 for his contributions to the development of models that link weather and climate, helping to predict how human activities affect the Earth's climate. Hasselmann's research has significantly advanced the field of climate science, particularly in the area of ocean-atmosphere interactions. His work has provided valuable insights into the complex systems that govern climate patterns, making it easier to understand and address the challenges posed by global warming.