Science Academies: Climate Evidence is Strong & Credible

Australian Academy of Science along with several other national science academies – including the Royal Society of Britain and US National Academy of Science – have produced statements detailing the extent of consensus and uncertainty about climate change science. Together, they show that evidence for climate change in response to human activity is strong and credible and that urgent action is required to cut greenhouse gas emissions significantly and quickly. To improve our understanding, extensive research and rigorous debate must continue among scientists. Importantly, communicating this research to the wider public must be effective. This from Professor Kurt Lambeck, immediate past president of the Australian Academy of Science.

Kurt Lambeck In National Times
December 28, 2010 – 8:31AM

The rains have come but that is not a reason to ignore the scientific evidence on climate change. The US National Climatic Data Centre issued figures for the year to the end of October that indicate global average surface temperatures for 2010 are heading for one of the warmest years on record. Climate change is about trends that operate on time scales longer than that of individual human memory.

Ever since it became apparent the atmosphere was warming, people have been questioning the evidence and the nature of the likely causes. This questioning of evidence and of the underlying causes is an essential part of the scientific process.

Understanding what drives climate, and predicting how it may change under a combination of natural and anthropogenic forcing, is possibly one of the most challenging problems for the science community. No single scientist or group of scientists can successfully claim to understand all, free of all doubt. It becomes even more of a challenge for the wider public to understand the science and, in the face of uncertainties, to be able to make informed decisions about how to respond. That challenge becomes even more difficult in the face of seemingly conflicting messages about the science.

It is therefore important for scientists to take stock periodically and focus on the key scientific questions, on what the consequences are of specific uncertainties, and on what is required to resolve remaining uncertainties.

Recognising that the consequences of climate change are potentially global, serious and irreversible on human time scales, the Australian Academy of Science has published such an assessment, The Science of Climate Change: Questions and Answers.

In the past few months several other national science academies have produced statements detailing the extent of consensus and uncertainty about climate change science too. These include the Royal Society in Britain, the US National Academy of Sciences and the French Academy of Sciences. In addition, other science bodies, including the Geological Society of London, have expressed their views.

A scientist is not usually elected to a national academy for doing consensus science. These recent academy statements express views that have been robustly debated both by experts in areas of climate science and by eminent scientists with extensive research experience in related fields.

The independent messages from the four academies and the geological society are consistent and urgent. They include that the role of greenhouse gases in the atmosphere is well understood, and that increasing the atmospheric concentration of the principal anthropogenic greenhouse gas, CO2, leads to higher mean global surface temperatures. It is accepted that CO2 has increased substantially during the past century, to the highest levels seen in 800,000 years, and that this increase is primarily from human activity as a result of burning fossil fuels, with a lesser contribution from other activities such as the manufacture of cement and deforestation.

They recognise that some of the greenhouse gases from human activities will remain in the atmosphere for a very long time and that, unless these emissions are significantly reduced now, the rise in the global average surface temperature will continue. The importance of the potential effects of CO2 and temperature increases on sea level and ocean acidification are also recognised.

All reports recognise that natural processes have also contributed to past climate change but they also underline, for example, in the words of the geological society, that ”it is not possible to relate the Earth’s warming since 1970 to any . . . geological cause”.

Climate change science is no different to any other experimental science, with the attendant uncertainties, and policy decisions have to be made taking them into account. For example, accurate values cannot yet be given for the likely range of future warming because of current uncertainties in climate sensitivity to small disturbances. But climate models and evidence from past climate change do provide a plausible range of values, and all point in the same direction: the current levels of greenhouse gas emissions are such that they can only lead to global mean surface temperatures that have not been experienced in the present interglacial period.

Likewise, predicting accurate rates for future rises in sea level remains difficult without new information on the responses of ice sheets and mountain glaciers to rising temperatures, but all models and observations point to the same direction of a globally averaged rise in sea level at rates where it is already affecting land use in low-lying coastal areas. Regional climate remains difficult to assess with accuracy, particularly for changes in regional rainfall patterns.

The reports identify where work needs to be done to reduce the uncertainties in the present knowledge but they also stress that these uncertainties do not affect the major conclusions, although they may impinge on precise time scales or magnitudes of change and on the nature of the regional impact.

Together, the statements show that evidence for climate change in response to human activity is strong and credible and that urgent action is required to cut greenhouse gas emissions significantly and quickly.

To improve our understanding, extensive research and rigorous debate must continue among scientists. Importantly, communicating this research to the wider public must be effective.

Scientists have the responsibility of providing the best evidence to help policy makers reach conclusions that are founded in science, that are based on the best current understanding.

The academies’ findings provide a firm basis for understanding the science of climate change, and contribute to the understanding of the science on which any policy response must be debated and constructed.

Professor Kurt Lambeck is a climate scientist and immediate past president of the Australian Academy of Science

Source: www.nationaltimes.com.au