The role of the IPCC is to assess climate change not advocate Kyoto

The Australian Senate's Environment, Communications, Information Technology and the Arts Legislation Committee has recently released its Report on the Kyoto Protocol Ratification Bill 2003 (No.2).

On the specific subject of the Inquiry, the Committee divided along party lines: the Report recommended that the Bill for ratification of the Protocol not be proceeded with, and a Dissenting Report from the Australian Labor Party, Australian Democrats and Australian Greens recommended that it be "proceeded with forthwith".

On the more fundamental issues, however, there was near-unanimity.

The Committee stated that the most recently accepted report by the Intergovernmental Panel on Climate Change (IPCC) had "predicted" a doubling or tripling of atmospheric levels of carbon dioxide by 2100 and had found that this "will" lead to global warming of between 1.4 and 5.8 degrees Celsius. There was bipartisan support for "the proposition that the problem of global warming is real and one that cannot be ignored", and for the concomitant need "to substantially reduce greenhouse gas emissions in order to stabilise atmospheric concentrations of those gases".

These views were shared by all groups that made submissions to the Inquiry. The Report said that those groups that opposed ratification of the Protocol were "united in the belief that climate change is a serious issue, warranting global attention, so that the impacts of climate change on humankind can be avoided or minimised"; and that the groups in favour of ratification "point to the enormity of the climate change scenario facing the world".

The general impression conveyed by the Report - and, to an even greater extent, by the Dissenting Report - is that it has been established that human-induced climate change poses an extremely serious problem which demands urgent countervailing action in the form of negotiated emissions reductions, either under the Kyoto Protocol or some successor instrument.

But this is far from being the case. To begin with, the IPCC's Third Assessment Report, which the Senate Committee Report describes as "the most recent generally accepted authoritative statement on climate change", produced "projections" - not "predictions" - of future greenhouse gas concentrations and global temperatures.

The distinction is crucial. Dr. John Zillman, Australia's Principal Delegate to the Panel since 1993, made clear in an address in March 2003 that the projections in the IPCC's Report are "nothing more than 'what if?' assessments", and "are not, in any sense, to be regarded as predictions of actual future climate".

In the same address, Dr. Zillman said the question of how global greenhouse warming will manifest itself at the national, regional or local level "is, at present, completely unanswerable". He recognised, however, that "we do have sufficient information ... to develop the techniques that would enable us to begin to evaluate the benefits and costs [of future climate change for individual states or regions of Australia] once we are in a position to produce estimates (i.e. predictions rather than scenarios) of global greenhouse gas concentrations for the century ahead".

Dr. James Hansen, Head of the NASA Goddard Institute of Space Studies (GISS), has recently produced a "lay person's emissions graph" in order to show that it is highly misleading to interpret the IPCC's projections of future carbon dioxide emissions as if they are predictions (see the second graph, labelled Figure 15). Hansen's comments on this Figure include the observation that "The IPCC scenarios that extend far off-scale (high) are impractical to show in entirety with a linear scale, but they do not need to be shown as they are unrealistic".

Dr. Hansen's previous graph (Figure 14) enables the Senate Committee's statement that the IPCC had "predicted" a doubling or trebling of carbon dioxide concentrations to be placed in a more balanced perspective. It shows that the build-up of these concentrations under the "alternative scenario" developed by Hansen and his colleagues at GISS would be substantially slower than under any of the IPCC scenarios.

James Hansen is not a climate sceptic. In fact, an extract from one of his recent papers (co-authored with 27 of his colleagues at GISS) was cited in the Australian Greenhouse Office publication Climate Change: an Australian Guide to the Science and Potential Impacts (December 2003) in support of the view that global warming is attributable to human influences: