Climate scenarios overhaul – Nature

A proposal for the next generation of climate scenarios for projecting future change features in this week’s Nature. This paper, which is the culmination of four years of work by IPCC scientists, is co-authored by Prof Marting Manning of the NZ Climate Change Research Institute, Victoria University of Wellington.

An excerpt from the Editor’s summary of the research:

“Climatologists use model-based ‘scenarios’ to provide plausible descriptions of how the future might unfold when evaluating uncertainty about the effects of human actions on climate. The traditional method of establishing these scenarios was a time-consuming sequential process, each discipline taking turns to add data and complexity. … These ‘next generation’ scenarios should make for faster, more rigorous assessment of proposals for climate mitigation and adaptation.”

The SMC asked Prof Martin Manning to explain the work and it’s significance. He prepared the following background Q & A:

“The Next Generation of Scenarios for Climate Change Research and Assessment”, Richard Moss et al, Nature, 11 February 2010.

Questions & Answers

1. What are scenarios?

Scenarios are possible pathways into the future that can be used as a basis for detailed analysis of what could happen, and they have been used over many years for both military planning and by Shell and others for industrial planning. They need to cover a broad range of what may happen for the things that we can’t make definite predictions about. Scenarios have become the key for studying how climate change may evolve in the future because future emissions of greenhouse gases are not simply predictable. That is also why future climate changes generated from scientific analysis and computer models are called projections, not predictions

2. Climate science already has scenarios, why set up some more ones?

Detailed scenarios that have been used in climate science for more than twenty years have covered a range of things that could happen if the world’s development was not strongly influenced by attempts to reduce climate change. The new scenarios now cover detailed analyses of the rates at which current increases in greenhouse gas emissions might be turned around if climate becomes a key factor in technological development and social response.

3. Why do these scenarios need to be detailed?

The science of climate change has to cover a broad range of issues going from the changes in weather patterns and ice sheets to the full range of responses in biological systems around the world. We also need to be able to consider the social and economic implications of these changes. A simple global scenario can be useful, but much more detailed ones are more relevant for specific regions, like New Zealand, and can provide a closely coordinated way of considering all the different factors.

4. What is the parallel process now being planned?

Research into the effects of climate change has considered: the range of future technological changes for greenhouse gas emissions, then the effects on the atmosphere and climate, and then the responses for natural and human systems. This has taken many years to develop a consistent analysis across all the science areas. The new parallel process has been developed over the last four years, by experts in all the relevant areas, so as to set up a framework in which the ongoing research can now be kept closely consistent across all of the areas involved.

5. So how does this help people who aren’t scientists?

Governments agreed in 1992 that they should stabilise the increasing levels of greenhouse gases in the atmosphere at a level that would prevent dangerous interference with the climate system. The new scenarios provide the basis for very detailed consideration of the implications of stabilisation at different levels. The lowest scenario will provide a more detailed analysis of how to keep global warming to 2°C, which is widely supported by governments, but it already shows that much more rapid uptake of new technology is needed than is occurring so far.

The SMC also approached  scientists for comments on the proposed climate scenarios:

Dr Andy Reisinger, Senior Research Fellow, NZ Climate Change Research Institute, VUW comments:

“The new set of scenarios reflect many years of work and will provide the basis for much of climate change research over the next decade. The scenarios represent a wide range of alternative futures and will help researchers explore many interconnected “what-if?” questions that link environmental with social, technological and economic outcomes. Such an approach, which has a strong tradition in climate science, is essential if we want to reflect adequately the very real choices that human society has to make with regard to climate change and its implications.”

Dr James Renwick, Principal Scientist NIWA National Climate Centre, comments:

The “RCP” approach is a significant step forward in the quest to improve our vision of the future, especially the effects of climate changes upon natural systems and humanity. Not only is the new approach more efficient in terms of gaining new understanding, it also takes explicit account of possible mitigation strategies (political action), something that was not taken account of in the previous generation of (SRES) scenarios. The RCPs are an excellent result from years of hard work.”