While human beings have always been able to visualize and seemingly care about the entire globe, it is only recently that the world has come to know genuinely global problems. Global warming, ozone depletion, and threats to biological diversity represent the first, bona fide global challenges, because they threaten the fundamental organic infrastructure that supports life on earth. If they come to pass, they will have universal physical consequences, in contrast to the more circumscribed consequences of non-global issues. This understanding conflicts with much contemporary thinking, which tends to see all problems—from poverty and hunger to war and human rights abuses—as global in character and thus in need of globalist responses. Proper understanding of what constitutes a genuinely global challenge will work against this tendency, and thus encourage addressing problems at the most appropriate level of governance. This article tries to provide such an understanding. It delineates the global dimension of global warming, ozone depletion, and threats to biological diversity and—after differentiating local, regional, and global issues—argues against addressing all common, transboundary challenges at the global level.