AIDS and climate change (CC) are two of the most important "long wave" global issues of the recent past, the present and the future. They share similarities, interactions, and present possibilities for a more united response. Yet these links have received little analysis. This paper seeks to address that gap. It first focuses on scientific issues, identifying major, minor, and speculative pathways by which AIDS and CC are likely to interact. These interactions are, here, called the HIV and Climate Change Complex (HACC).