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| Titel |
On the relationship between metrics to compare greenhouse gases – the case of IGTP, GWP and SGTP |
| VerfasserIn |
C. Azar, D. J. A. Johansson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
2190-4979
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| Digitales Dokument |
URL |
| Erschienen |
In: Earth System Dynamics ; 3, no. 2 ; Nr. 3, no. 2 (2012-11-02), S.139-147 |
| Datensatznummer |
250001006
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| Publikation (Nr.) |
 copernicus.org/esd-3-139-2012.pdf |
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| Zusammenfassung |
| Metrics for comparing greenhouse gases are analyzed, with a particular focus
on the integrated temperature change potential (IGTP) following a call from
IPCC to investigate this metric. It is shown that the global warming potential (GWP) and IGTP are
asymptotically equal when the time horizon approaches infinity when standard
assumptions about a constant background atmosphere are used. The difference
between IGTP and GWP is estimated for different greenhouse gases using an
upwelling diffusion energy balance model with different assumptions on the
climate sensitivity and the parameterization governing the rate of ocean
heat uptake. It is found that GWP and IGTP differ by some 10% for
CH4 (for a time horizon of less than 500 yr), and that the relative
difference between GWP and IGTP is less for gases with a longer atmospheric
life time. Further, it is found that the relative difference between IGTP
and GWP increases with increasing rates of ocean heat uptake and increasing
climate sensitivity since these changes increase the inertia of the climate
system. Furthermore, it is shown that IGTP is equivalent to the sustained
global temperature change potential (SGTP) under standard assumptions when
estimating GWPs. We conclude that while it matters little for abatement
policy whether IGTP, SGTP or GWP is used when making trade-offs, it is more
important to decide whether society should use a metric based on time
integrated effects such as GWP, a "snapshot metric" as GTP, or metrics
where both economics and physical considerations are taken into account. Of
equal importance is the question of how to choose the time horizon,
regardless of the chosen metric. For both these overall questions, value
judgments are needed. |
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