What changed? The timing of The Enhanced Greenhouse Effect, at a critical juncture in the climate change debate, suggests one possible answer. When Climate of Concern was released in 1991, the UN Framework Convention on Climate Change (UNFCCC) was still being negotiated, with the two most powerful nations on the planet actively working to slow or weaken the deal. By 1994, however, the UN Climate Convention was a reality, and demand was already rising for a new, stronger deal to turn the treaty commitments from words into action. The Enhanced Greenhouse Effect appears a year before the first Conference of Parties to the United Nations Framework Convention on Climate Change, where nations would gather to begin negotiating how to collectively confront the challenge of climate change. Perhaps this why the 1994 report marks an inflection point in Shell’s treatment of the subject, with the company thereafter increasingly focusing public attention on scientific uncertainty. “confidential,” there is no indication that The Enhanced Greenhouse Effect was as well. The Greenhouse Effect from 1988 acknowledged uncertainties, but made clear that the key research questions lay in how to address growing emissions and climate impacts, not what the precise impacts would be. The Enhanced Greenhouse Effect, in comparison, contained a long discussion of those uncertainties. In its section on “Areas of Controversy and Alternative Scientific Views,” the report addressed alternative carbon sinks,55 the reliability of temperature records,56 defects in global climate models,57 the possibility that actual climatic changes might not be as bad as expected,58 and the uncertain impacts on agriculture.59 It concluded that “[i]t is thus not possible to dismiss the global warming hypothesis as scientifically unsound; on the other hand any policy measure should take into account explicitly the weaknesses in the scientific case.”60 While the 1988 report was marked A Shell Management Brief from February, 1995 restated many of the points in the 1994 report – acknowledging the potential consequences of climate change, but emphasizing the uncertainties in climate science. Shell again acknowledged that “an increase in atmospheric greenhouse gas concentrations… must have some effect on the radiation balance which ultimately determines global climate. However, it is not possible to quantify the consequences for global climate.”61 This brief was not marked as classified.62 EXHIBIT 6 Atmosphere Concentration for Total Resource Use Presentation from Royal Dutch Shell Group, Climate Change: What Does Shell Think and Do About It? 6 (Mar. 1998), available at http://www.climatefiles.com/shell/1998-shell-report-think-and-do-about-climate-change/. A Crack in the Shell | 10 | Another report in 1995, entitled Is Climate Change Occurring Already? and not marked as classified, addressed whether the human signal could be found in the climate system.63 It bears recognition that this 1995 report diverged from Shell’s own earlier analyses and disregarded the explicit testimony by Dr. James Hansen of NASA to the US Congress in June 1988 that the signal of anthropogenic climate change had, by that summer, clearly emerged from the background noise of natural variation. In other words, climate change was no longer an abstract hypothesis; it was an emergent reality. Seven years after Hansen’s testimony and four years after Shell released Climate of Concern, the company’s 1995 report proved remarkably – unjustifiably – equivocal about climate science. Although Shell did not deny that climate change was happening or that it was the caused primarily by fossil fuel combustion, it argued that only “a slow accumulation of evidence, rather than a ‘smoking gun’, will indicate man-made emisCenter for International Environmental Law