Michael Mann is an author and climatologist known for his work in the field of paleoclimatology, a branch of climate science that studies the changes in climate by analyzing historical data such as ice cores, tree rings, sediment, and other sources. He is perhaps most famous for his work on the "hockey stick" graph, which illustrates the rise in global temperatures over the past century. Mann's research has contributed significantly to the scientific understanding of human-induced climate change and has been influential in public policy debates about global warming and environmental policy. He has written several books and many peer-reviewed scientific papers, advocating for climate change mitigation and better understanding of climate science among the public and policymakers.