140 Climate changein the twenty-firstcenturyand beyond
The changes that are likely to have the greatest impact will be changes
in the frequencies, intensities and locations of climate extremes, espe-
cially droughts and floods.
Sufficient fossil fuel reserves are available to provide for continuing
growth in fossil fuel emissions of carbon dioxide well into the twenty-
second century. If this occurred the climate change could be very large
indeed and have unpredictable features or ‘surprises’.The next chapter will look at the impact of such changes on sea level,
on water, on food supplies and on human health. Later chapters of the
bookwill then suggest what action might be taken to slow down and
eventually to terminate the rate of change.Questions
1 Suggest, for Figure 6.6,an appropriate temperature scalefor a place you
know. Define what might be meant by a very hot day and estimate the per-
centage increase in the probability of such days if the average temperature
increases by 1, 2 and 4◦C.
2 From Figure 6.9, compare the maximum length of periods in the summer
with less than 1 mm, 2 mm, 5 mm of total rainfall under normal climate
conditions and under conditions with increased carbon dioxide.
3 It is stated in the text describingextremes that in convective regions, with
global warming, as the updraughts become more moist the downdraughts
tend to be drier. Why is this?
4 Look at the assumptions underlying the full range of SRES emission sce-
narios in the IPCC 2001 Report. Would you want to argue that some of the
scenarios are more likely to occur than the others? Which (if any) would you
designate as the most likely scenario?
5 It is sometimes suggested that northwest Europe could become colder in the
future while most of the rest of the world becomes warmer. What could cause
this and how likely do you think it is to occur?
6 How important do you consider it is to emphasise the possibility of ‘surprises’
when presenting projections of likely future climate change?
7 Estimate the effect on the projected carbon dioxide concentrations for 2100
shown in Figure 6.2, the projected radiative forcing for 2100 shown in Figure
6.4(a) and the projected temperatures for 2100 shown in Figure 6.4(b), of
assuming the climatefeedback on the carbon cycle illustrated in Figure 3.5
(note: first turn the accumulated atmospheric carbon in Figure 3.5 into an
atmospheric concentration).Notes for Chapter 6
1 Nakicenovic, N.et al. 2000.Special Report on Emission Scenarios (SRES).
A Special Report of the IPCC. Cambridge: Cambridge University Press.