Abstract: Global warming is not only a hot research area in atmospheric sciences and even all Earth sciences but is also a controversial topic in the international community.The purpose of this paper is not to clarify these controversies, but instead, to address the physical basis on which our understanding of global warming is founded, and to briefly review the nearly 200\|year history of global warming sciences.We hope the paper will help readers, who have no background in the atmospheric and climate sciences, understand scientific issues of global warming.