3.1.1 Debate over Climate Change 2001

Castles and Henderson asserted that the IPCC has been using inflated economic growth rates, which result in increased emission estimates. [10] This was incorrect because IPCC growth and emissions rates were based upon several factors and not only GDP, as rebutted by Nebojsa Nakicenovic et al.

A few participants in IPCC Working Group I (Science) do not agree with the IPCC reports (of the 120 lead authors, 2 have complained [11]). A particularly active critic, MIT physicist Richard Lindzen, expressed his unhappiness about those portions in the Executive Summary based on his contributions in May 2001 before the United States Senate Commerce Committee :

"The summary does not reflect the full document... For example, I worked on Chapter 7, Physical Processes. This chapter dealt with the nature of the basic processes which determine the response of climate, and found numerous problems with model treatments – including those of clouds and water vapor. The chapter was summarized with the following sentence: 'Understanding of climate processes and their incorporation in climate models have improved, including water vapour, sea-ice dynamics, and ocean heat transport.'"

The "Summary for Policymakers" of the WG1 reports does include caveats on model treatments: Such models cannot yet simulate all aspects of climate (e.g., they still cannot account fully for the observed trend in the surface-troposphere temperature difference since 1979) and there are particular uncertainties associated with clouds and their interaction with radiation and aerosols. Nevertheless, confidence in the ability of these models to provide useful projections of future climate has improved due to their demonstrated performance on a range of space and time-scales. [12].

These statements are in turn supported by the executive summary of chapter 8 of the report, which includes:

• Coupled models can provide credible simulations of both the present annual mean climate and the climatological seasonal cycle over broad continental scales for most variables of interest for climate change. Clouds and humidity remain sources of significant uncertainty but there have been incremental improvements in simulations of these quantities.

• Confidence in the ability of models to project future climates is increased by the ability of several models to reproduce the warming trend in 20th century surface air temperature when driven by radiative forcing due to increasing greenhouse gases and sulphate aerosols. However, only idealised scenarios of only sulphate aerosols have been used.

3.2 IPCC Second Assessment Report: Climate Change 1995

Climate Change 1995, the IPCC Second Assessment Report (SAR) was finished in 19961996 was a leap year starting on Monday (see link for calendar), and was designated the International Year for the Eradication of Poverty''. Events January January 5 Hamas operative Yahya Ayyash is killed by an Israeli-planted booby-trapped cell phone Jan. It is split into four parts:

• A synthesis to help interpret UNFCCC article 2.
• The Science of Climate Change (WG I)
• Impacts, Adaptations and Mitigation of Climate Change (WG II)
• Economic and Social Dimensions of Climate Change (WG III)

Each of the last three parts was completed by a separate working group, and each has a Summary for Policymakers (SfP) that represents a consensus of national representatives. The SfP of the WG I report contains headings:

1. Greenhouse gas concentrations have continued to increase
2. Anthropogenic aerosols tend to produce negative radiative forcings
3. Climate has changed over the past century (air temperature has increased by between 0.3 and 0.6 oC since the late 19th century; this estimate has not significantly changed since the 1990 report).
4. The balance of evidence suggests a discernible human influence on global climate (considerable progress since the 1990 report in distinguishing between natural and anthropogenic influences on climate, because of: including aerosols; coupled models; pattern-based studies)
5. Climate is expected to continue to change in the future (increasing realism of simulations increases confidence; important uncertainties remain but are taken into account in the range of model projections)
6. There are still many uncertainties (estimates of future emissions and biogeochemical cycling; models; instrument data for model testing, assessment of variability, and detection studies)

3.2.1 Debate over Climate Change 1995

Most scientists involved in climate research believe that the IPCC reports accurately summarise the state of knowledge. A few scientists have objected and made public comments to that effect, in fact so few that no-one can find any suitable quote to add in here.

The report formed the basis of negotiations over the Kyoto ProtocolThe Kyoto Protocol is an amendment to the United Nations Framework Convention on Climate Change (UNFCCC), an international treaty on global warming. It also reaffirms sections of the UNFCCC. Countries which ratify this protocol commit to reduce their emis.

A December 20December 20 is the 354th day of the year (355th in leap years) in the Gregorian calendar. There are 11 days remaining. Events 1803 Louisiana Purchase completed 1860 South Carolina becomes first state to secede from the United States 1915 Last Australian t, 19951995 was a common year starting on Sunday (see link for calendar). It has a Golden number of 1, and was the first year of the International Decade of the World's Indigenous People (1995- 2005): http://www. org/culture/indigenous . Events January events Ja, Reuters report quoted British scientist Keith ShineKeith Shine is the head of the and a professor at the University of Reading's meteorology department, which is recognised by the World Meteorological Organization as "one of the world's principal centres for advanced training of meteorologists. Professor, one of IPCC's lead authors, discussing the Policymakers' Summary. He said: "We produce a draft, and then the policymakers go through it line by line and change the way it is presented.... It's peculiar that they have the final say in what goes into a scientists' report." It is not clear, in this case, whether Shine was complaining that the report had been changed to be more skeptical, or less, or something else entirely.

Dr. Frederick SeitzFrederick Seitz ( July 4, 1911-) says his research interests "center on general science, both physical and biological. Formerly, he was a solid state physicist. He served as the president of the National Academy of Sciences from 1965 until 1968, when he b, president emeritus of Rockefeller University and past president of the National Academy of Sciences, has publicly denounced the IPCC report, writing "I have never witnessed a more disturbing corruption of the peer-review process than the events that led to this IPCC report". He opposed it in the Leipzig DeclarationThis article is about the climate change declarations, not the Leipzig Declaration on Conservation and Sustainable Utilization of Plant Genetic Resources for Food and Agriculture The Leipzig Declaration on Global Climate Change is a statement signed by 80 of his Science and Environmental Policy Project.

3.3 IPCC supplementary report, 1992

The 1992 supplementary report was an update, requested in the context of the negotiations on the Framework Convention on Climate Change at the Earth Summit (United Nations Conference on Environment and Development) in Rio de Janeiro in 1992.

The major conclusion was that research since 1990 did "not affect our fundamental understanding of the science of the greenhouse effect and either confirm or do not justify alteration of the major conclusions of the first IPCC scientific assessment". It noted that transient (time-dependent) simulations, which had been very preliminary in the FAR, were now improved, but did not include aerosol or ozone changes.

3.4 IPCC First Assessment Report: 1990

The IPCC first assessment report was completed in 1990, and served as the basis of the United Nations Framework Convention on Climate Change (UNFCCC).

The executive summary of the policymakers summary of the WG I report includes:

• We are certain of the following: there is a natural greenhouse effect...; emissions resulting from human activities are substantially increasing the atmospheric concentrations of the greenhouse gases: CO2, methane, CFCs and nitrous oxide. These increases will enhance the greenhouse effect, resulting on average in an additional warming of the Earths surface. The main greenhouse gas, water vapour, will increase in response to global warming and further enhance it.

• We calculate with confidence that: ...CO2 has been responsible for over half the enhanced greenhouse effect; long-lived gases would require immeadiate reductions in emissions from human activities of over 60% to stabilise their concentrations at today's levels...

• Based on current models, we predict: under [BAU] increase of global mean temperature during the [21st] century of about 0.3 oC per decase (with an uncertainty range of 0.2 to 0.5 oC per decade); this is greater than that seen over the past 10,000 years; under other ... scenarios which assume progressively increasing levels of controls, rates of increase in global mean temperature of about 0.2 oC [to] about 0.1 oC per decade.

• There are many uncertainties in our predictions particularly with regard to the timing, magnitude and regional patterns of climate change, due to our incomplete understanding of: sources and sinks of GHGs; clouds; oceans; polar ice sheets.

• Our judgement is that: global mean surface air temperature has increased by 0.3 to 0.6 oC over the last 100 years...; The size of this warming is broadly consistent with predicion of climate models, but it is also of the same magnitude as natural climate variability. Thus the observed increase could be largely due to this natural variability; alternatively this variability and other human factors could have offset a still larger human-induced greenhouse warming. The unequivocal detection of the enhanced greenhouse effect is not likely for a decade or more.

Notice that the report did *not* attribute the observed warming to human influence.

In 1991, the SEPP surveyed IPCC contributors and researchers, along with a comparison group of global warming skeptics who had not contributed. [13]

4 See also

• Climate change

5 External links

• The IPCC web site
  • IPCC organisation
  • Second Assessment Synthesis Report (pdf)
  • Second Assessment Summary for Policymakers from the Working Group 1 (Science) Report.
• Third Assessment Report
• The IPCC Controversy - from the SEPP
• climate change - What is the IPCC by Jean-Marc Jancovici

International environmental organizations Climate change

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