Geog. 143 -- Global Environmental Change

Exercise 3:  Reading the IPCC Assessment Reports

The Intergovernmental Panel on Climate Change (IPCC) is the principal international body with a focus on understanding and projecting future climate change.  It is sponsored by the U.N. Environment Program (UNEP) and the World Meteorological Organization (WMO).  The assessment most recently issues (2007) is the fourth such assessment, and is sometimes referred to as the "AR4" (Assessment Report 4).  Previous assessments appeared in 2001, 1995, and 1990.

The aim of this exercise is to review the structure and content of the IPCC assessments using the web pages that present the Third Assessment.  The questions below focus on particular features of this assessment, but it would be a good idea to get a broad overview of the assessments, including the parts that aren't explicitly focused on here.  As you'll see, although quite massive, the IPCC Assessments boil down a large amount of information from the peer-reviewed scientific literature and present it in a useful way, and an important objective of this exercise is to see how that's done.

Key web pages and information links:

There are several different web pages that provide the entire Fourth Assessment online, as well as other links that describe the way in which the IPCC works.

• Main IPCC web page:  http://www.ipcc.ch
• Fourth Assessment (AR4) and IPCC Special Reports web page:
            http://www.ipcc.ch/ipccreports/index.htm
  Note that this page includes a graphical depiction of how an individual assessment report is done.
• The "IPCC Reports" web page includes links to:
  • the WG I Report (The Scientific Basis)  http://www.ipcc.ch/ipccreports/ar4-wg1.htm 
  • the WG II Report (Impacts) http://www.ipcc.ch/ipccreports/ar4-wg2.htm 
  • the WG III Report (Mitigtation) http://www.ipcc.ch/ipccreports/ar4-wg3.htm 
  • the Synthesis Report  http://www.ipcc.ch/ipccreports/ar4-syr.htm 
  • the Emissions Scenario Special Report http://www.ipcc.ch/ipccreports/sres/emission/index.htm 
• The "Information for the Press" page contains some "Fact Sheets" that describe how the Assessment Reports are put together and approved:"
  • The IPCC and Assessment Reports http://www.ipcc.ch/press/ar4-factsheet1.htm 
  • How the individual SPMs are approved http://www.ipcc.ch/press/ar4-factsheet2.htm

Note that the Assessment volumes and special reports are available as both .pdf and .html (web page) versions.

1.  The Emissions Scenarios

The projection of future climate change is a multi-step process that begins with projecting the future emissions of greenhouse gasses and aerosols and their future concentrations (e.g. ppm CO₂) or loadings, which are required as inputs for the climate models used to make the climate projections.  The IPCC Special Report on Emissions Scenarios makes such projections for greenhouse gasses and aerosols.  Browse the Emissions Scenarios report web page (see the link above), and in particular find the "2. Emissions Scenarios and Their Purposes" section in the Technical Summary.  Here's a direct link to that section:

• http://www.grida.no/climate/ipcc/emission/010.htm

Q1:  What are emissions scenarios?  What are the basic kind of information required to make a projection of greenhouse gas emissions sometime in the future?  Does the approach used by the IPCC strike you as reasonable, or as a naive shot-in-the dark?

2.  The Working Group Reports

The three Working Group Reports share a common structure.  Take a look at the individual report outlines and web pages (see the links above).

Q2:  What is the common structure of the Working Group Reports, or in other words, what are the  particular sections that each report  has in common?  What kind of strategy do you think is implemented by this structure?

3.  The Synthesis Report

Despite the great amount of information concentration that takes place in the individual assessments, there is still a need for a concise overall summary.  This is done in the Synthesis Report

Q3:  What are the five main topic sections in the Synthesis Report Summary for Policymakers?  To what extent does this structure parallel the overall IPCC assessment effort?

4.  The report approval process

Although assembled by scientists and reviewed by scientists and other specialists, the Summary for Policymakers must be "approved" at a plenary session (everybody meets) of the IPCC that includes "government delegations".  Take a look at the two fact sheets listed above to get an idea of how that approval process works.

Q4:  Reading between the lines, what do you think the role the fairly cumbersome approval process is?  Does it enhance the scientific credibility of the reports?

(For a perspective of what happened at last year's WG II Plenary Meeting, see the NY Times article at:  http://www.nytimes.com/2007/04/07/science/07cside.htm   This article is also in Readings section of the Course Documents area on Blackboard.)