Notes 141
2 For details of IS 92a see Leggett, J., Pepper, W. J., Swart, R. J. 1992. Emission
scenarios for the IPCC: an update. In Houghton, J. T., Callender, B. A.,
Varney, S. K. (eds.)Climate Change 1992: the Supplementary Report to
the IPCC Assessments. Cambridge: Cambridge University Press, pp. 69–
- Small modifications have been made to the IS 92a scenario to take into
account developments in the Montreal Protocol.
3 This summary is based on the Summary of SRES in the Summary for pol-
icymakers. In Houghton,Climate Change 2001,p.18.
4 The+30% amounting to an addition of between 200 and 300 ppm to the
carbon dioxide concentration in 2100 (see box on carbon feedbacks on
page 40).
5 The World Energy Council ReportEnergy for Tomorrow’s World. 1993. Lon-
don: World Energy Council. In its most likely scenario this report projects
that global sulphur emissions in 2020 will be almost the same as in 1990,
although with a different distribution (more over Asia but less over Europe
and North America). An extension of this study (Global Energy Perspec-
tives to 2050 and Beyond. London: World Energy Council, 1995) projects at
2050 global sulphur emissions that are little more than half the 1990 levels.
6 Detailed values listed Ramaswamy, V.et al. 2001. Technical summary. In
Houghton,Climate Change 2001, Chapter 6.
7 Note that because the response of global average temperature to the in-
crease of carbon dioxide is logarithmic in the carbon dioxide concentration,
the increaseof global average temperaturefor doubling of carbon dioxide
concentration is the same whatever the concentration that forms the base for
the doubling, e.g. doubling from 280 ppm or from 360 ppm produces the
same rise in global temperature. For a discussion of ‘climate sensitivity’ see
Cubasch, U., Meehl, G. A.et al. 2001. In Houghton,Climate Change 2001,
Chapter 9.
8 See Houghton,Climate Change 2001.
9 See Harvey, D. D. 1997. An introduction to simple climate models used in
the IPCC Second Assessment Report. InIPCC Technical Paper 2. Geneva:
IPCC.
10 Note that the uncertainty ranges in Figure 6.4 do not include those that arise
from lack of knowledge concerning climate feedbacks on the carbon cycle
(see box in Chapter 3 on page 40).
11 The assumption that greenhouse gases may be treated as equivalent to each
other is a good one for many purposes. However, because of the differences
in their radiative properties, accurate modelling oftheir effect should treat
them separately. More details of this problem are given in Gates, W. L.
et al. 1992. Climate modelling, climate prediction and model validation. In
Houghton, J. T., Callander, B. A., Varney, S. K. (eds.)Climate Change 1992:
the Supplementary Report to theIPCC Scientific Assessments. Cambridge:
Cambridge University Press, pp. 171–5.
12 Related through the Clausius Clapeyron equation,e–^1 de/dT=L/RT^2 ,
whereeis the saturation vapour pressure at temperatureT,Lthe latent
heat of evaporation andRthe gas constant.
