The diplomatic strategy followed by the EU in leading international negotiations over the global warming issue are based on its long and deep experience acquired through multilateral negotiations among European countries over the cross-border atmospheric pollution issue dating back to the 1970s. The issue of cross-border atmospheric pollution that the issue of global warming are very similar to each other in that they both entail, for example, (a) a fusion of scientific research and diplomatic negotiation, and (b) a determination of how much each country is to cut back. In Japan, the general assessment of the EU emissions trading system (EU-ETS) tends to be excessively high; here, we must keep in mind that EU-ETS has two aspects, one being to set a precedent for governance in line with EU eastern expansion, and the other being to put the entire EU within an emission reduction framework. In our research, we (a) examine the behavioral principles underlying EU environmental negotiation as they pertain to continuities between cross-border atmospheric pollution policy and global warming negotiation, and (b) extract strategic implications for Japanese diplomats as relate to global warming negotiations and, in Asia, environmental collaboration.