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Intergovernmental Panel on Climate Change (IPCC)

The Intergovernmental Panel on Climate Change is not a policy-making body, but falls under the category of climate policy because its scientific recommendations are used to draft international climate treaties. Furthermore, the IPCC does not do research of its own, but rather draws upon research done by other organizations and individuals. The IPCC also offers no oversight of the research it draws upon, though it does review work before including it in its Assessment Reports. Currently, governments from more than 120 countries are members of the IPCC and have line-item approval rights over what does or does not go into an Assessment Report.

The IPCC was established in 1988 with the goal of providing scientific guidance regarding climate change and the technical and socio-economic issues that accompany it. The IPCC does not pay contributors and all efforts are made on a voluntary basis. Despite the lack of direct payment, it is clearly recognized that a prestigious position on the IPPC or recognition for a contribution is helpful in securing future funding. Thus, the indirect benefits of being a contributor to the IPCC are substantial.

Assessment Reports (ARs)

Assessment reports are not published on any kind of regular basis, but rather are compiled and published as scientific consensus changes or when important discoveries are made. These reports are intended to summarize the current state of climate science for use by policy makers. To date, four official reports and one supplement have been published. A fifth report is pending and due in 2014.

In general assessment reports follow a three stage review process as follows:

  1. Expert Review – This is similar to peer review carried out for other scientific publications. Research and other material that is being considered for an AR is made available to scientists in various fields who review the data, methods, and validity of the work to determine if it is fit for inclusion
  2. Government Review – At this stage, member countries review the recommendations made by the experts and determine whether they feel the science should or should not be included. They also propose policy recommendations to be included.
  3. Policy Review and Editorial Review – At this stage, policies from the previous step are reviewed and amended, overviews are written, and a summary is constructed. The final publication occurs after this step.

All comments from the steps above are publicly available for at least five years after a report is published. This effort at transparency helps to provide integrity to the report and gives non-member countries that opportunity to review the process and reach their own conclusions.

Of the four reports published, the major themes and findings cam be summarized as follows:

  • First Assessment Report (FAR) – 1990
    • Basis for United Nations Framework Convention on Climate Change
    • States the certainty that human emissions of greenhouse gases (GHGs) are increasing the average temperature of the Earth’s surface
    • A range of 0.3-0.6 degrees Celsius is given as the human-caused (anthropogenic) temperature increase since 1890
    •  A prediction of 0.3oC of temperature rise per century is made if GHG emissions remain at 1990 levels
  • Supplementary Report (SR) – 1992
    • Confirms that research has not changed the findings from the FAR
    • Noted that models were improved from 1990, but that ultimate conclusions remained the same
  • Second Assessment Report (SAR) – 1996
    • States that GHG concentrations have increased in the atmosphere
    • Concludes that anthropogenic aerosols have produced negative forcing (a cooling effect)
    • Reconfirms that the temperature change in the last century is 0.3-0.6oC
    • Reports improved models that take into account aerosols and indicates that these models confirm that humans are changing the climate
    • Makes predictions about future climate change, but provides few specifics
  • Third Assessment Report (TAR) – 2001
    • Pegs warming at 0.6oC over the 20th century
    • Reports improved models that project continued warming of (1.5-5.8oC) over the next century if emissions remain unchained
    • Provides projections regarding sea level rise that amount to 0.1 to 0.9 meters through the year 2100
    • Admits that while models used in the above projects are the best available at the time, they have many uncertainties

The Third Assessment Report was widely criticized for what many scientists considered to be serious physical modeling problems. In particular, MIT scientist Richard Lindzen spoke to the U.S. Senate regarding problems with clouds and water vapor and how they affect warming trends. Lindzen’s criticism was authoritative because he had worked on generating the TAR and, as a result of its final status, and resigned from the IPCC in protest. The impact of water vapor on greenhouse warming is known to be significant, but is poorly understood. For this reason, Lindzen considers all climate models to be severely limited. While the IPCC estimates climate sensitivity to be on the order of 1.5-4.5oC, Lindzen has said the value is likely closer to 0.5oC.

The Third Assessment Report was also criticized for its reliance on a graph by Dr. Michael Mann that became known as the “hockey stick graph.” The hockey stick, officially called the “Millennial Northern Hemisphere Temperature Reconstruction,” used proxy data (tree rings and ice cores) to estimate temperatures from roughly 1000 CE to about 1850. After that, Mann graphed instrument data on to the graph to show temperatures from 1850 to 2000. The problem with the method is that proxy data and instrument data diverge and no satisfactory explanation for this divergence is given. The concern is that if temperature data and proxy data do not match now, how can we be certain that they ever would have and thus how can proxies be used to accurately estimate temperature? The other problem with the graph was suppression of what is known as the Medieval Warm Period (MSP), which is deduced from reports of wine grapes growing in northern latitudes where they currently cannot due to cold weather. These two controversies led to skepticism of the conclusion that the world is warmer now that at any time in the past 1000 years. If the MWP was as warmer or warmer than current conditions and occurred prior to significant GHG production by humans, then it undermines the conclusion that warming is due to human activity and that we can do anything about it.

  • Fourth Assessment Report (AR4) – 2007
    • States that warming has occurred and that there are no doubts about it
    • States that the likelihood that warming from the mid-20th century onward is human-caused is >90%.
    • The probability that warming is all natural is estimated at <5%
    • Levels of carbon dioxide, methane, and nitrous oxide are higher than in the previous 650,000 years due to human activity
    • Indicates that warming and sea level rise will continue for centuries (perhaps a millennium), regardless of current intervention, due to the timescales associated with climate feedback
    • Gives the following estimates of temperature and sea-level rise through 2100
      • >90% confidence that there will be increased warm spells and heavy rain
      • >66% confidence that there will be increased droughts, high tides, and tropical cyclones (hurricanes)
      • 18 to 59 centimeters of seal-level rise
  • Fifth Assessment (AR5) – Pending 2014

Final Notes

Due to the controversies that became widespread with the Third Assessment Report, the U.N secretary-general requested a review of IPCC procedure by the InterAcademy Council. The findings indicated a number of things, but chief among them was the suggestion that the IPCC refrain from supporting or criticizing policy and that it stick to reporting science and facts only. The UNFCCC will handle policy in the future while the IPCC will remain dedicated to reporting the best available science and nothing else.

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