The first part of this piece described the weakness of the hypothetical link between increasing carbon dioxide and increasing global temperatures. In this part, I consider the question of whether there are models which can strengthen the hypothesis and whether those models can tell us anything about other aspects of climate such as rainfall.
The proponents of the anthropogenic warming thesis claim to have models that
show how added carbon dioxide will lead to a warmer world[i]. There are major problems with these models,
not least of which is the fact that the proponents claim that doubling the CO2
in the atmosphere will increase the temperature by over 3oC. This is
well above any physical reason[ii].
It results from arguments about the effect of water vapour in the atmosphere,
which is supposed to exacerbate the effect of increased CO2.
The
doubling effect is so far invisible.
Other estimates have suggested that doubling the CO2 may
increase the global temperatures by less than 1oC[iii]. The evidence for this is building. For
instance, there has been about a 40% increase in atmospheric CO2
since 1945, which would imply perhaps 1.2oC of warming if doubling
the CO2 caused a 3oC rise. Figure 1 in the previous posting showed that the actual warming over
this period has only been about 0.4oC. Has the globe cooled by 0.8oC
while the added CO2 has been warming us? It seems unlikely.
There are
further reasons to doubt the models. For
instance, Figure 5 reproduces Figure 10.7 from the IPCC Fourth Assessment
Report[iv]. The
sections are from the South Pole on the left to the North Pole on the
right. In the atmosphere, altitude is
expressed in terms of pressure, with sea level at 1000hPa and 11km being about
200hPa. Stippling on the figures shows regions where all the models agree
within narrow limits.
 |
| Figure 5. Model predictions of global temperature changes: atmospheric upper, oceanic lower |
The area of
particular interest is the ‘blob’ in the atmosphere over the equator and
centred at about 200hPa. In 2011-2030 it is just less than 1.5oC
above today’s ground level temperatures. By 2046-2065 it is expected to be
about 3oC warmer, and by 2080-2099 about 5oC warmer. Thus
this region is expected to warm by about 0.6oC per decade, if the
models are to be believed.
For about
the last 60 years, balloons carrying instruments have been flown into this
region to obtain data for weather forecasts.
Examination of the temperature records has failed to reveal any heating
whatsoever[v]. Satellites have been flown since the late
1970’s, and some of their views through the atmosphere can be interpreted as
average temperatures of particular regions[vi]. The satellites show very slight warming – but
nothing like 0.6oC per decade.
In science,
a single experiment can suffice to disprove a theory. Any theory whose predictions fail
experimental tests must be abandoned without further ado. In the present case,
the anthropogenic warming hypothesis has led to theoretical models, but those
models have failed experimental proof.
Such is the strength of belief in the anthropogenic thesis, however,
that the modellers are most reluctant to abandon – or even revise – their
models. This is one of the strongest reasons for scepticism.
The anthropogenic
thesis has also led to many predictions of the possible conditions in a warmer
world. Some, such as the impact on the
cryosphere, seem to be borne out. However, the models which, as noted earlier,
are highly suspect, suggest such things as dramatic changes in
precipitation. The evidence is
negligible.
For
instance, there is a very long record of rainfall for England and Wales, shown
in Figure 6[vii].
There is absolutely no sign of any change in the rainfall pattern over the last
60 years. Over the entire period, the annual average over 25 years is 913 ±42mm.
The 42mm is the maximum deviation, not the standard deviation!
 |
| Figure 6. A 240-year rainfall record |
Similarly,
there are repeated suggestions that the sea level will increase rapidly due to
the melting of ice and the warming of the oceans (warm water is less dense than
cold, so it occupies a larger volume).
It is true that the sea level is rising, but you seek in vain for any
evidence that it has risen significantly faster since 1945 than before. Figure 7 illustrates this, using the tide
gauge data from New York which extends back to 1858 with a gap from 1879 to
1892[viii].
The regression line for all the data from 1870 to 2011 has a slope of
2.947mm/a; that from 1945 to 2011 has a slope of 2.948mm/a. There has been no significant increase in the
rate of sea level rise at New York for the past 140 years.
 |
| Figure 7. A 150-year sea-level record. |
Many of the
fears about sea level rise are unfounded.
Yes, the sea is rising slowly.
Satellite measurements since the early 1990’s confirm a rate of rise of
about 3mm/a[ix].
However, there are already defences against the sea. It is necessary to allow
for tides, storm surges and even tsunamis.
The existing defences are measured in metres, not mm. An increase in the
average level of 3mm/a can be offset by raising the defences by an additional
brick every 30 years or so. The rising sea level is not a threat.
Of course,
there are events where the defences prove inadequate. This was the case when Hurricane Katrina
struck New Orleans. Several years
previously, it had been reported that the levees were likely to fail[x].
They were old, and lacked modern design features. They failed, as anticipated, when
the storm surge arrived. Their failure had nothing to do with ongoing rise in
sea levels, and everything to do with weak defences.
However, there are repeated references in the
literature to the New Orleans levee failure being the result of “climate
change.” This illustrates a feature of the debate that reinforces
scepticism. Disasters that have nothing
to do with a changing climate are ascribed to “climate change” as a means of
raising awareness about the supposed threats. Do we need to have our awareness raised? Or isn't it better just to be sceptical?
[i]
Randall, D.A., R.A. Wood, S. Bony, R. Colman, T. Fichefet, J. Fyfe, V. Kattsov,
A. Pitman, J. Shukla, J. Srinivasan, R.J. Stouffer, A. Sumi and K.E. Taylor,
2007: Climate Models and Their Evaluation. In: Climate Change 2007: The
Physical Science Basis. WG1, Fourth Assessment Report of the Intergovernmental
Panel on Climate Change [Solomon, S. et al, (eds.)]. Cambridge University
Press, Cambridge
[ii]
See Randall, D.A. et al, op cit p.
640: “A number of diagnostic tests have been proposed…but few of them have
been applied to a majority of the models currently in use. Moreover, it is not
yet clear which tests are critical for constraining future projections (of
warming). Consequently, a set of model metrics that might be used to narrow the
range of plausible climate change feedbacks and climate sensitivity has yet to
be developed.”
[iii] Spencer,
R.W. and Braswell, W.D Potential Biases
in Feedback Diagnosis from Observational Data: A Simple Model Demonstration, J
Climate 21 5624-5627, 2008 DOI:
10.1175/2008JCLI2253.1
[iv]
Meehl, G.A., T.F. Stocker, W.D. Collins, P. Friedlingstein, A.T. Gaye, J.M. Gregory,
A. Kitoh, R. Knutti, J.M. Murphy, A. Noda, S.C.B. Raper, I.G. Watterson, A.J.
Weaver and Z.-C. Zhao, 2007: Global Climate Projections. In: Climate Change
2007: The Physical Science Basis. WG1, Fourth Assessment Report of the
Intergovernmental Panel on Climate Change [Solomon, S., et al (eds.)].
Cambridge University Press, Cambridge
[v]
Douglass, D. H., Christy, J. R., Pearson, B. D. and Singer, S. F. (2008), A
comparison of tropical temperature trends with model predictions. Int. J.
Climatol., 28: 1693–1701. doi: 10.1002/joc.1651
[vi]
Spencer, R.W. and Christy, J.R. 1992: Precision and Radiosonde Validation of
Satellite Gridpoint Temperature Anomalies. Part I: MSU Channel 2. J. Climate, 5,
847–857.
[x] Fischetti, M. Drowning New Orleans.
Scientific American, October 2001, pp34-42
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