In March 2008, University of Iowa professor Greg Carmichael published new findings revealing a striking connection between soot (aka "black carbon") and global warming. The research was published in the journal Nature Geoscience with co-author V. Ramanathan. Within days, publications worldwide picked up on the development, hailing Carmichael's work as a major addition to the climate change dialogue. In this video, watch Carmichael discuss why black carbon is "the second most important greenhouse gas" at a symposium on climate change and human rights. The event was organized by the Journal of Transnational Law and Contemporary Problems, the Center for Global and Regional Environmental Research (CGRER), and the International Law Society at the University of Iowa February 15, 2008. For more information, contact Greg Carmichael at gregory-carmichael@uiowa.edu, or Soheil Rezayazdi at soheil-rezayazdi@uiowa.edu