Who's who in the carbon zoo?

Every year, BP produces a "Statistical Review of World Energy".  It is a wonderful resource, not least because it comes complete with a database which allows you to draw your own graphs (and your own conclusions).

This year's edition has just been published.  It includes a listing of the carbon emissions from burning fossil fuels over the past 57 years:

Zowie! We have been told the world is heading for disaster; that we will fry if we don't mend our ways; that eternal damnation awaits us if we continue to burn fossil fuels.  Yet what does this show?  The "Evil US" has actually cut back its emissions, without any guff about signing the Kyoto Protocol.  Europe cut back at the beginning of the nineties - nothing to do with Kyoto, and everything to do with the arrival of North Sea gas. And Asia/Pacific is going absolutely bananas, now nearly half the total fossil-fuel-derived emissions.

The thin brown stripe is the whole of Africa.  For those of us in South Africa who think we can save the world by cutting our emissions, building windmills and huge solar plants, please think again.  In the scheme of things, we are truly insignificant.

The case for nuclear power in South Africa

There has recently been a meeting in Stellenbosch where some energy modellers tried to plan South Africa's energy future.  They had some interesting concepts, not least of which was that the most important driver of any plan should be a reduction in our carbon emissions.

If you or I tried to make a plan, we would probably recognise that what South Africa needs, and needs as soon as possible, is enough power at as low a price as possible.  It goes without saying that the power should be reliable, available on demand 24 hours a day, and that the source of power should have a reasonably long life, so that we had some hope of achieving a return on the considerable investment needed to provide us with the power we need. 

Most people would think, if they stopped to consider a basis for planning our energy future, that this was a reasonable set of requirements.  However, they may also be moved by the fact that our President offered massive reductions in our carbon footprint at Copenhagen in 2009. Surely this should also be taken into account?

If they were so moved, they might also remember that the President’s generous offer was conditional upon large-scale aid from the developed nations, those nations that have done most of the carbon emitting for the past few generations. There is not one sign of any such aid.  There have been several conferences since Copenhagen, and none of the meetings has made any progress towards making aid commitments.  Accordingly, our armchair planners would probably reject reducing our carbon footprint as an additional requirement.  They would say that it is a constraint that can wait until we see the money.

However, the Stellenbosch planners believed that we should still strive for lower carbon emissions.  They believe lower emissions can be achieved while still producing cheap reliable power by using renewable energy such as wind or solar power.  They are wrong.

It is true that the costs of renewable power have fallen in recent years.  However, that does not mean that renewable energy is economic.  Remember, we need sufficient reliable power at as low a price as possible.  Our experience to date with wind power alone is sufficient to cause major concerns.  Eskom installed three large wind turbines at Klipheuvel.  One of them has failed already, and the other two have produced about 10% of their potential output. 

The Darling wind farm was launched in 2008 to great fanfare.  The four turbines have the potential to generate 5.2MW.  The power is bought by the City of Cape Town, which recently reported that the farm had generated 30.8GWh since inception.  Its average output is therefore about 720kW, less than 14% of its potential. It cost R70 million to construct. I have a 2litre diesel car that has 120kW output. It cost just over R100 000 in 2008. The wind farm produces six times more power, but costs about 700 times more.

In Europe, North America and China, all of which have been sold tens of thousands of wind turbines, the story is similar.  This is not yet an established technology.  You need ordinary power to ensure continuity of supply when the wind doesn’t blow.  You need to be able to dump the wind power somewhere when the wind does blow and there is no demand for the energy. Denmark, the home of wind turbines, has to send over half of what it generates annually out of the country at a loss.  The result is that Danish power is presently the most expensive in Europe.

Surprisingly, the technology is comparatively untested.  The large units presently being favoured have only been in operation for about seven years.  Mechanical and electrical failures are still very much more common than the tried and tested conventional alternatives. A recent European report has shown how output falls as the installation ages, until after about 12-15 years it has to be replaced because maintenance costs exceed revenue. In many places there is a realisation that, in the haste to set up a wind farm, they forgot how much it might cost to take it down.

Siting is critical, and the technology of selecting the optimum site has improved in recent years. However, there remain mistakes – one US wind farm was recently hit by a tornado.  Skittles, anyone?

Wind power is the cheapest of the renewables.  The lowest offer under our Integrated Resource Plan IRP2010 was 89c/kWh.  This is impressive, but it has to be remembered that it is private capital at risk.  There is no guarantee that the project will yield investors a reasonable return.  The wind may not be quite as good as the developers had hoped, or the turbines may need somewhat more maintenance than assumed, or maintenance technicians may cost more than budgeted. 

And while 89c/kWh may be impressive, it has to be seen against Eskom’s present costs of 32c/kWh, projected Medupi costs of 53c/kWh, and present independent power producer costs of 77c/kWh.  The recent Eskom price increase includes a significant allowance for the extra cost of the renewables that IRP2010 will bring.

The other renewables are even more expensive.  Solar PV costs have also fallen, but are still over R1.20/kWh at the MW scale.  Solar thermal power is really expensive, around R2.50/kWh, but it is a really unproven technology – last year it made about 0.01% of the world’s electricity.

So what does this leave us? We need sufficient, reliable power at as low a price as possible. The best bet by far is natural gas.  The average global economy gets about a third of its primary energy from gas.  We get about 2%.  There is a strong indication of gas in the Karoo, but it still requires exploration.  We should not be dithering.  There is gas in Mozambique, and, reports to the contrary, it is clearly economic to pipe it into South Africa to generate power.  Sasol is already doing that on a 200MW scale at Sasolburg. Liquefied natural gas is a widely traded commodity, and all it requires is a regassing station.  Gas turbine power stations are cheap and can be built rapidly.  Siting them at the coast would allow sea water to be used for cooling.

Gas would even contribute to a reduction in carbon dioxide emissions.  In the US, thanks to shale gas, the price of natural gas has fallen by a factor of four, coal-fired power stations have been shut down, and the US now emits less CO₂ than it did in 1990. Even Canada has been affected – the increase in energy supply in the US has meant that Canada has been saddled with excess oil.  Recently you could buy tar-sands product at $53/barrel.

But we don’t yet have our own gas, and we are clearly running out of coal, if only because the rest of the world has started to value the rubbish we are presently burning.  Coal mines can get better prices on the international markets than Eskom is prepared to pay.

That leaves us with nuclear.  There is a belief that nuclear is expensive.  It is not much more expensive to build than conventional thermal plant, and with low fuel costs and a long life, the costs of electricity are low.  Indeed, today Koeberg produces the cheapest electricity in South Africa.

Part of the erroneous belief in the high cost of nuclear power arises from the fact that it comes in large units, 900MW upwards.  But that is reliable, continuous power. Koeberg will shortly be delivering 2100MW 80% of the time.  To do that with Darling wind farm technology would require over 9300 wind turbines and would cost about R200 billion today.  For that money you could build quite a few Koebergs.

The case for nuclear in South Africa could hardly be stronger.  Models that show otherwise are driven primarily by the reduction in carbon dioxide emissions, not by our need for cheap reliable power. They rely on assumptions about the possible reduction in renewable energy costs that have little basis in reality. There seems to be a belief that policy should determine our energy future.  The cost of power and the reliability of its supply are far more important. That should be the basis for the next IRP.

The *!@%$ carbon tax

In 1912, Alice, Lady Hillingdon, wrote “When I hear my husband’s steps outside my door, I lie down on my bed, close my eyes, open my legs and think of England.” South African business appears to be taking the same approach to the impending carbon tax.

The arguments for the tax are specious in the extreme. There is a belief that we have voluntarily committed to reduce our emissions by 34% by 2020.  Nothing could be further from the truth.  We have made an offer provided, and only provided, international funds and technology are made available to pay for any reduction.  As of today, not one brass farthing has appeared. Meanwhile we are already paying an extra 3.5c/kWh for coal-derived electricity. The electricity price is being further inflated by Eskom paying an average of over R2/kWh for ‘renewable’ energy; its own production costs are 32c/kWh.  We can expect further price increases as even more ‘renewables’ are thrust upon us by this insane pursuit of the unattainable.

“Insane pursuit of the unattainable”? Yes, the idea that any reduction we make will affect global carbon dioxide emissions is risible.  Worldwide, they have grown 50% in the last 17 years.  The annual growth exceeds our total output. Any reduction we made would be invisible against the background of surging fossil fuel use. A 34% reduction would devastate our economy and give nil benefits – zilch, zero.

Has rising carbon dioxide had any measurable impact?  No! Global temperatures have been flat for the last 17 years. The evidence for impending disasters is slender in the extreme. The sea level rise has slowed since we came out of the last Ice Age.  It is now only about 3mm per year, almost imperceptible against the background of tides and storms. The Arctic has shrunk to levels last seen in the 1920’s. Glaciers only 400 years old are shrinking again. And for the rest, everything is as variable as it has always been. 

But surely a carbon tax will change our behaviour?  It is unlikely to reduce our incomes to the point where we starve and turn cannibal, to be true.  But it is equally unlikely to change any other behaviour.  If you doubt this, think of the tax on gas-guzzlers.  Have you seen any fewer Sandton tractors on the streets of late? The parking spaces at the private schools are being lengthened to enable the mothers to get in and out.

Has Government given us any indication of what it intends to do with the billions it will suck out of our economy? No! It wants to continue to distribute revenue as it sees fit, which is increasingly being seen as a means of buying votes. 

The time has come to reject any notion of a carbon tax.  It will bring no benefits, and will damage the economy. Stronger reasons for rejection are difficult to imagine.

A climate of scepticism - Part III

In this final part of my climate paper, I talk about extreme events and other scare stories, and about how some scepticism is the result of the excessive zeal of climate change proponents.

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. Nothing illustrates this aspect of the debate better than the ongoing accent on “extreme events.” A violent storm, such as the recent Sandy that struck New York, is immediately seized upon as evidence of “climate change.”

Weather is ever variable. The vigour of every natural phenomenon has a wide range. Many phenomena, for example rainfall, are best described by a distribution which is very strongly skewed.  Such distributions are quite counterintuitive when it comes to trying to define what constitutes “extreme”.

The problem is how to decide the width of the ‘normal’ range, a decision essential for describing an event as abnormal or ‘extreme’, that is, lying outside the normal range.   A lot of data is necessary to define ‘normal’, which implies that data must be collected over a long period. The long period may exceed a human lifetime.  If so, then few living individuals can have experienced the truly “extreme” events – and an event much less than extreme may be seized upon as an example of an extreme event when in fact it is no such thing.

In the case of storm Sandy, there has been an assessment of the intensity of all hurricanes and “post-tropical storms” (of which Sandy was one) that made landfall on the continental United States between 1900 and 2012. The data are shown in Figure 8[i].

A person born in 1900 would probably have experienced their most extreme event in 1936.  However, that person might have lived to the age of 106, and would have seen two stronger storms. That might have convinced him/her that the world was getting worse.  He/she would have been wrong, of course – the random nature of extreme events would have fooled them. 

Figure 8.  Power dissipation index of storms which made landfall on the US, 1900-2012

This illustrates quite nicely how long one must wait before one can determine even the 100-year event – and how just because there has been such an event, another nearly as bad can turn up in less than 100 years after that! The statistics of extreme events are counterintuitive, and very long baselines are needed before it is possible to decide if something is extreme or not.

There has been extensive concern about extreme events, partly because almost every day somewhere on the globe there will be an event that might be describable as ‘extreme’. The IPCC has issued a special report on the subject[ii]. It can probably best be described as ‘delphic’ – a series of very cautious pronouncements that can be interpreted in different ways, depending on your viewpoint. Probably the best measure of the extent to which extreme events should be viewed as likely to be caused by climate change comes from a study of deaths caused by severe weather[iii].  The results are shown in Figure 9.

It is clear that the absolute number killed each year has dropped since the 1920’s.  In relative terms, the drop has been even more dramatic, from a peak of 241 per million to 5 per million.  At this low rate, extreme weather no longer presents the same risks as faced previous generations.

Figure 9. Deaths and death rates per million people from extreme weather events

 The reasons for this steep decline are several.  One is vastly better weather prediction, so that there is now adequate warning about possible extreme weather conditions.  Secondly, there is much better communication of impending severe weather. Finally, with improved knowledge of severe conditions, mankind has learned to design structures that protect us from the hazards. If ‘climate change’ is having any effect, it is invisibly by this measure.

The final scare story that needs to be laid to rest is that of species extinction as a result of climate change. The popular press reports this regularly. “’Climate change now represents at least as great a threat to the number of species surviving on Earth as habitat-destruction and modification,’ said Chris Thomas, a conservation biologist at the University of Leeds in the United Kingdom. - - the predicted range of climate change by 2050 will place 15 to 35 percent of the 1,103 species studied at risk of extinction. The numbers are expected to hold up when extrapolated globally, potentially dooming more than a million species. ”[iv] 

However, science prefers predictions that are testable. A recent serious study concluded that “Surprisingly, [there is no] straightforward relationship between local extinction and limited tolerances to high temperature.” [v] Indeed, this follows from common sense.  Figure 10 shows the average monthly conditions for Cape Town. The boxes show the average daily maxima and minima, the lines show the highest and lowest temperatures ever recorded, and the lower and upper horizontal lines reflect the annual average temperature in 1900 and 2000 respectively. 

Figure 10. Monthly temperatures in Cape Town, and annual averages in 1900 and 2000

It is reasonable to ask how the relatively small average temperature change can be detected by organisms that every year are likely to be exposed to changes some 50 times larger, to which they seem perfectly adapted.

The final reason for ongoing scepticism is the behaviour of some of the proponents of the climate change thesis.  It starts with the Intergovernmental Panel on Climate Change.  It has become a political body rather than a technical body.  The best illustration of this is the publication of the Panel’s reports.  It is preceded by the publication of a summary for policy makers. This summary often differs in material respects from the findings of the main report, and invariably puts a politically correct slant on what is supposed to be a dispassionate review of the scientific literature[vi]. 

The IPCC’s work is not aided by the fact that much of the work reported is not scientific, but reproduced from activist literature.  The Canadian journalist Donna Laframboise has documented this problem in detail[vii].

For example, she tracks how a relatively unknown professor of epidemiology, Anthony McMichael, who had written a polemic in 1991, became a lead author of the chapter on malaria and the health effects of climate change, even though he had no professional publications about malaria and even though some of his conclusions were rejected by members of the Panel who were world experts on the subject. 

Sections of McMichael’s book appeared almost verbatim in the IPCC’s Assessment Report in 1995. This led directly to the thesis that global warming will increase the spread of malaria. There is no evidence that this is likely, because malaria has been known in cold climates for centuries. Moreover, the spread of malaria is known to be almost entirely a function of social conditions and public health.

The fight against malaria is not helped by those who claim that climate change is part of the problem. If they had their way, the accent would be on addressing climate change rather than fighting malaria. This illustrates a danger of accepting a possibly flawed thesis too uncritically – resources may be diverted from essential activities affecting the lives of millions in the hope that there will be a positive impact on putative risks that might possibly affect billions.  Before taking such a decision, one needs to be very certain indeed that the putative risks can be avoided by the diversion of resources.

Another reason for scepticism is that the debate about climate change has revealed some major imperfections in the scientists themselves. Some players on the human-induced climate-change playing field have shown themselves to be only too human in the defence of the indefensible. For example, two scientists did what scientists are supposed to do – they peer-reviewed the work of some 200 other scientists[viii].  They reported that:

“Across the world, many records reveal that the 20th century is probably not the warmest nor a uniquely extreme climatic period of the last millennium.”

This was totally contrary to the thesis that today’s warming was exceptional. Accordingly the believers in human-induced change forced the editor of the journal that had published the review to resign, and went out of their way to try to destroy the reputations of the two authors.  All this (and more) was revealed when a series of emails found its way into the public domain from the Climate Research Unit at the University of East Anglia[ix].

The world is slightly warmer than a century ago.  The carbon dioxide levels of the atmosphere are increasing.  Plants are doing better than before because of the higher carbon dioxide[x]. The sea is rising in a barely detectable way. Climatic disasters are no worse than previously. The animal kingdom is being squeezed by the growth of a single species, us, but that has nothing to do with global warming.

And that is why there is a climate of scepticism.

---

[i] http://rogerpielkejr.blogspot.com/2012/11/us-hurricane-intensity-1900-2012.html Accessed January 2013

[ii] IPCC, 2012: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change [Field, C.B. et al (eds.)]. Cambridge University Press, Cambridge

[iii] Goklany, I.M. Wealth and Safety: The Amazing Decline in Deaths from Extreme Weather in an Era of Global Warming, 1900–2010. Reason Foundation, Washington DC and Los Angeles, CA, 2011

 http://reason.org/files/deaths_from_extreme_weather_1900_2010.pdf Accessed January 2013

[iv] http://news.nationalgeographic.com/news/2004/01/0107_040107_extinction.html Accessed January 2013

[v] Cahill, A.E, Aiello-Lammens, M.E., Fisher-Reid, M.C., Hua, X., Karanewsky, C.J., Ryu, H.Y., Sbeglia, G.C, Spagnolo, F., Waldron, J.B., Warsi, O. and Wiens, J.J. How does climate change cause extinction? Proc. Royal Soc. B 2012 doi: 10.1098/rspb.2012.1890

 http://rspb.royalsocietypublishing.org/content/early/2012/10/15/rspb.2012.1890.full Accessed January 2013

[vi] http://www.publications.parliament.uk/pa/ld200506/ldselect/ldeconaf/12/1207.htmAccessed January 2013

[vii] Laframboise, Donna The Delinquent Teenager who was mistaken for the world's top climate expert. Ivy Avenue Press, Toronto 2011. ISBN: 978-1-894984-05-8

[viii] Soon, W. and Baliunas, S. Proxy climatic and environmental changes of the past 1000 years. Climate Research Vol. 23, pp89–110, 2003

[ix] http://www.assassinationscience.com/climategate/1/climactic-research-unit-foi-leaked-data.zip Accessed January 2013

[x] http://www.co2science.org/data/plant_growth/plantgrowth.php Accessed January 2013

A climate of scepticism - Part II

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 3^oC. 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 1^oC[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 1.2^oC of warming if doubling the CO₂ caused a 3^oC rise.  Figure 1 in the previous posting showed that the actual warming over this period has only been about 0.4^oC. Has the globe cooled by 0.8^oC 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 1.5^oC above today’s ground level temperatures. By 2046-2065 it is expected to be about 3^oC warmer, and by 2080-2099 about 5^oC warmer. Thus this region is expected to warm by about 0.6^oC 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 0.6^oC 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.

doi: http://dx.doi.org/10.1175/1520-0442(1992)005<0847:parvos>2.0.CO;2 Accessed January 2013

[vii] http://climexp.knmi.nl/data/pHadEWP_monthly_qc.dat Accessed January 2013

[viii] http://www.psmsl.org/data/obtaining/rlr.monthly.data/12.rlrdata Accessed January 2013

[ix] http://sealevel.colorado.edu/ Accessed January 2013

[x] Fischetti, M. Drowning New Orleans. Scientific American, October 2001, pp34-42