Editing IPCC Third Assessment Report (section)

==Projections==
Projections are used in the TAR as a guide to the possible future [[effects of climate change]], e.g., changes in global mean temperature and sea level.<ref name="tar projected climate change impacts">
{{citation
 | at=[http://www.grida.no/climate/ipcc_tar/vol4/english/009.htm Question 3]
 | title=Summary for Policymakers
}}, in {{harvnb|IPCC TAR SYR|2001}}
</ref> In the TAR, the word "projection" is favoured over "prediction".<ref>
{{citation
 | at=[http://www.grida.no/climate/ipcc_tar/wg2/104.htm 2.6.1. Treatments of Uncertainties in Previous IPCC Assessments]
 | title=2. Methods and Tools
 | author=Ahmad, Q.K.
|display-authors=etal}}, in {{harvnb|IPCC TAR WG2|2001}}
</ref>  This is because many future changes related to climate are highly uncertain.<ref>
{{citation
 | at=[http://www.grida.no/climate/ipcc_tar/vol4/english/204.htm Definitions of "climate projection" and "projection"]
 | title=Annex B. Glossary of Terms
}}, in {{harvnb|IPCC TAR SYR|2001}}
</ref>  For example, climate change projections are affected by highly uncertain changes in future GHG emissions.<ref>
{{citation
 | at=[http://www.grida.no/climate/ipcc_tar/vol4/english/026.htm Box 3-1]
 | title=Question 3
}}, in {{harvnb|IPCC TAR SYR|2001}}
</ref>

The TAR projects impacts according to possible future changes in global mean temperature.<ref>
{{citation
 | at=[http://www.grida.no/climate/ipcc_tar/wg2/686.htm 19.8.2. What does Each Reason for Concern Indicate?]
 | title=19. Vulnerability to Climate Change and Reasons for Concern: A Synthesis
}}, in {{harvnb|IPCC TAR WG2|2001}}
</ref>  Other projections are based on [[climate change scenario|scenarios]] that the IPCC has developed.<ref name="tar projected climate change impacts"/>  In 2000,<ref>
{{citation
 | at=[http://www.grida.no/climate/ipcc_tar/wg3/080.htm 2.5.1.1 IPCC Emissions Scenarios and the SRES Process]
 | title=2. Greenhouse Gas Emission Mitigation Scenarios and Implications
 | author=Morita, T.
|display-authors=etal}}, p.143 in {{harvnb|IPCC TAR WG3|2001}}
</ref> the IPCC published 40 different scenarios<ref name="SRES Approach to Scenario Development">
{{citation
 | at=[http://www.grida.no/climate/ipcc_tar/wg3/080.htm 2.5.1.2 SRES Approach to Scenario Development]
 | title=2. Greenhouse Gas Emission Mitigation Scenarios and Implications
 | author=Morita, T.
|display-authors=etal}}, pp.143-144 in {{harvnb|IPCC TAR WG3|2001}}
</ref> (the "[[Special Report on Emissions Scenarios|SRES" scenarios]]) which contain estimates of future changes in anthropogenic emissions of greenhouse gases and aerosols. The SRES scenarios project a wide range of possible changes in future social and economic development,<ref name="SRES Approach to Scenario Development"/> and projected climate change impacts vary according to the scenario considered.<ref name="SRES impacts figure SPM-3">{{citation
 | url=http://www.grida.no/climate/ipcc_tar/vol4/english/009.htm
 | title=Summary for Policymakers - Figure SPM-3
 | access-date=14 February 2012
 | archive-date=29 September 2012
 | archive-url=https://web.archive.org/web/20120929111305/http://www.grida.no/climate/ipcc_tar/vol4/english/009.htm
 | url-status=dead
 }}, in {{harvnb|IPCC TAR SYR|2001}}</ref>  The IPCC has not assigned probabilities to the 40 SRES scenarios.<ref name="SRES impacts figure SPM-3"/>  Some authors<ref>{{cite journal
 | year=2007
 | author=Dietz, S.
 | title=Reflections on the Stern review (1): a robust case for strong action to reduce the risks of climate change
 | journal=World Economics
 | volume=8
 | issue=1
 | page=164
 | issn=1468-1838
 | url=http://personal.lse.ac.uk/dietzs/Reflections%20on%20the%20Stern%20Review%20(1).pdf
 | display-authors=etal
 | access-date=2012-02-14
 | archive-date=2013-06-01
 | archive-url=https://web.archive.org/web/20130601072555/http://personal.lse.ac.uk/dietzs/Reflections%20on%20the%20Stern%20Review%20(1).pdf
 | url-status=live
 }}</ref><ref>{{citation
 | date=15 January 2005
 | author=Tol, R.S.J.
 | at=[https://publications.parliament.uk/pa/ld200506/ldselect/ldeconaf/12/5020107.htm Memorandum by Professor Richard S J Tol, Hamburg, Vrije and Carnegie Mellon Universities]
 | title=Economic Affairs - Minutes of Evidence (Tuesday 1 February 2005)
 | url=https://publications.parliament.uk/pa/ld200506/ldselect/ldeconaf/12/5020101.htm
 | access-date=31 August 2017
 | archive-date=29 October 2016
 | archive-url=https://web.archive.org/web/20161029081001/http://www.publications.parliament.uk/pa/ld200506/ldselect/ldeconaf/12/5020101.htm
 | url-status=live
 }}, in {{harvnb|Economic Affairs Committee|2005}}</ref> have argued that some SRES scenarios are more likely to occur than others.