Posts Tagged ‘IPCC’

RCPs, SSPs, SPAs, …. what????

At the latest with the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) a number of new acronyms started spilling out of the climate change research community to policy makers and the broader interested public. Centrally among them are RCPs, SSPs and SPAs, meaning Representative Concentration Pathways, Shared Socio-economic Pathways and Shared climate Policy Assumptions, respectively.

But what is this all about? And where do I have to look if I need more detailed information?

A nice and user-friendly introduction to the scenario framework is given at the IIASA website.

A first more detailed reference certainly is the article on A new scenario framework for Climate Change Research which forms part of a special issue A Framework for the Development of New Socio-economic Scenarios for Climate Change Research of the journal Climatic Change. The paper describes the basic concept how scenarios  that take into account the two dimensions of future climate change and socio-economic development can be formulated by combining alternative levels of radiative forcing of the climate system, described by RCPs, with alternative trajectories of future global development, described by the SSPs.

It also lines out that givens levels of radiative forcing may be attained through different climate policy designs and that different pathways of socio-economic development may require different sets of policies. This is the point where the SPAs come in, which complete the three-dimensional scenario framework.

For descriptions of the Shared Socio-economic Pathways (SSPs), another paper in the same special issue is worth reading. Details on the narratives that underlie each of the SSPs can be found in a workshop report on The Nature and Use of New Socioeconomic Pathways for Climate Change Research. The core data sets with pathways of economic growth and population growth for each SSP are accessible through the SSP Database.

The Representative Concentration Pathways (RCPs)  are dealt with extensively in another special issue on The Representative Concentration Pathways in Climatic Change. The articles in this collection give an overview on the RCPs and details on each of the RCPs that are used for the scenario framework.

The concept of Shared Policy Assumptions (SPAs)  is introduced  in a paper, which provides details on the concept and how it links into the general scenario framework.

As a nice feature, most of the information is open access.

The scientific consensus on anthropogenic climate change

The latest assessment report of the Intergovernmental Panel on Climate Change (IPCC) states that

Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system.

This statement reflects a scientific consensus on anthropogenic climate change. But how does this scientific consensus actually look like and how strong is it? Two studies explore this question more in detail.

In a first paper, Scientific Historian Naomi Oreskes at the University of California at San Diego analyses 928 papers on global climate change published between 1993 and 2003 to see how many of them endorse the consensus that climate change is real and is influenced by human activity and how many disagree with the consensus position. Her results show that none of the papers disagrees with the consensus.

A second paper by a team around John Cook of the Global Change Institute at the University of Queensland extends the analysis by Oreskes and examines abstracts of 11 944 scientific papers from 1991–2011 matching the topics ‘global climate change’ or ‘global warming’.  Of the abstracts that express a position on anthropogenic climate change, 97.1% endorse the consensus position. Less than 2% of the papers reject the consensus.

The two studies show in a convincing manner that there is virtually no disagreement within the scientific community on the reality of anthropogenic climate change. Disagreement or discussion rather exist about the speed and magnitude of climate change and on the measures required to tackle it.


Cook, J., Nuccitelli, D., Green, S.A., Richardson, M., Winkler, B., Painting, R., Way, R., Jacobs, P., Skuce, A., 2013. Quantifying the consensus on anthropogenic global warming in the scientific literature. Environ. Res. Lett. 8, 024024.

IPCC, 2013. Summary for Policy Makers, in: Stocker, T., Qin, D., Plattner, G.-K., Tignor, M., Allen, S., Boschung, J., Nauels, A., Xia, Y., Bex, V., Midgley, P.M. (Eds.), Climate Change 2013: The Physical Science Basis. Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Switzerland.

Oreskes, N., 2004. The Scientific Consensus on Climate Change. Science 306, 1686–1686.

[This blog post was inspired by the course Climate Change in Four Dimensions at]