To kick things off, an introduction by Kurt Lambeck, president, Australian Academy of Science May 2006 – May 2010:
The science of climate is at the intersection of a number of science disciplines and sub-disciplines. At its heart are physics, chemistry, biology and mathematics — each with their sub-disciplines of atmospheric physics and chemistry, oceanography, hydrology, geology etc — and each of which can be considered as mature within the framework required to discuss climate.
It is at this intersection of the disciplines where uncertainty can and will arise, both because of the yet poorly understood feedbacks between the different components of the climate system and because of the difficulty of bringing these components together into a single descriptive and predictive model.
This would include, for example, the biological consequences of how increasing carbon dioxide (CO2) feeds back into climate and into the climate model, or how the consequences of atmospheric warming on water vapour, cloud cover, ocean warming and circulation feedback can be described and quantified in a coherent and integrated theory.
It is these feedbacks and interactions that make it difficult to realistically quantify the uncertainty in the outputs of climate models at levels that the experimental scientist is usually accustomed to. In a process as intrinsically complex as climate it should not be surprising that the path to understanding is long and arduous.
In many other areas of experimental science the paths to full understanding are equally complex. What makes climate change different is that the consequences are not only potentially global and serious but also that they occur over long time scales (decades to centuries) so that actions need to be contemplated before full understanding is achieved.
These actions themselves are built on economic, social and political models each with their own inherent assumptions and difficulties with data and observations. In the presence of uncertain scientific uncertainty, it should not be surprising that, when it comes to recommendations about how to respond to a threat of climate change, the spectrum of opinions is broad indeed.
The Australian Academy of Science is strongly committed to enhancing public understanding of scientific issues and how these may impact on society and the planet. Through its members and through its National Committees for Science it is able to draw on expertise from across a broad sector of the Australian science community to report on important scientific issues.
This includes climate science. The Academy recognises that decisions on how to respond to climate change will have to be made by our society as a whole. These decisions need to consider the findings of climate change together with many considerations that go beyond the science and must include, amongst others, ethics and equity, economics, risk management and politics. The purpose of this document is to contribute to the public understanding of the state of the science and to attempt to tread a path through the often contradictory public commentary on the science.
It is not a formulation of a policy response but an attempt to improve the public understanding of the science upon which any policy response should be constructed. To this effect the Academy’s Council established two committees to address some of the major questions that are frequently asked about climate change science.
First, an expert Working Group carefully formulated the questions and answers about the science of climate change. This group consists of internationally recognised scientists who have contributed extensively to the underpinning science, including contribution to the successive IPCC assessments.
Seven “big” questions were identified within each of which “lower-level” questions have also been addressed. Second, an Oversight Committee comprehensively reviewed the answers provided to ensure that they are authoritative within the current state of knowledge. This Committee consists of eminent Fellows of the Academy and other experts with both extensive research experience in related fields and in the leadership of climate-related programs and organisations.
While it is important to emphasise that it is not possible to provide definitive answers to many of the questions that are being asked about climate change, it is also important to stress that considerable progress has been made in understanding climate change and why it occurs. The role of greenhouse gases in the atmosphere is qualitatively well understood.
It is known that increasing the atmospheric concentration of the principal anthropogenic greenhouse gas, CO2, leads to higher mean global surface temperatures. It is known that CO2 has increased very substantially during the last century, to the highest levels seen in the past 800,000 years, and that this increase is primarily of anthropogenic origin. It is also beyond serious question that some CO2 from human activities remains in the atmosphere for a very long time, as is the message that unless greenhouse gas emissions are reduced, an upward trend in global temperature will continue.
The uncertainties in the science do not affect such major conclusions but they will affect the precise timescales or magnitudes of the change and they will affect the global distribution of its impact. It is important therefore that extensive research and rigorous scientific debate continue within the expert scientific community and that the communication of that research to the broader community be effective.
The Academy therefore hopes that this work will provide a firmer basis for understanding the science of climate change and its implications.
The Australian Academy of Science, which represents Australia’s foremost scientists, provides scientific advice to policy makers and promotes excellence in Australian science, has devoted considerable resources to untangling the science of climate change and presenting it in a simple and easily understood format.