In the climate change negotiations the thirteen countries that are members of OPEC obstruct progress towards reducing emissions of greenhouse gases. Although these actions undermine sustainable development in developing countries, the larger Group of 77 (G-77) coalition nevertheless tacitly supports its OPEC members in the climate regime. This article explains the connection between OPEC's interests in oil exports and its inaction on climate change, and the divergence of these interests with those of the G-77. It argues that OPEC's influence within the G-77, and therefore the climate regime, stems from the desire to maintain unity within the G-77. This unity has and is likely to continue to cost the majority of developing countries in the form delayed assistance for adaptation, the possibility of inadequate reduction in emissions under the second commitment period under the Kyoto Protocol, and continued dependence on increasingly expensive oil imports.