Predicting future global temperatures
It was almost entirely due to the apparent link between the temperature and CO2 levels over the past few hundred thousand years, revealed by the analysis of ice cores drilled in the ice caps, that the present concern about the effect of human activity on the CO2 levels in the atmosphere has been given some scientific credence (see Figure 3.3).
Figure 3.3: Ice-core date from Vostok, Antarctica (after Raynaud et al., Science 259, 1993)
The indirect information obtained from the ice-core samples in the Antarctic give us a picture of the CO2 levels and temperatures over the past 600,000 years. However, they can tell us only about the CO2 levels and temperatures locally; they do not tell us what was happening to the rest of the world. While it is likely that the CO2 levels measured in one place, such as Mount Mauna Loa in Hawaii, will not differ significantly from that in the rest of the world, the same cannot be said for the temperature. It would be a nonsense to suggest that a period of hot summers in Manchester meant that there was also a period of excessive heat in Botswana. It is unlikely that the relative hot and cold spells found in the Antarctic ice-core samples accurately reflect what was happening in the rest of the world.
Although the results are largely reproducible, their absolute accuracy cannot be verified, as there are no standard measurements with which to compare them. However, we have direct and anecdotal historical evidence of the temperature changes in the past 1,000 years from various areas around the world (see Figure 3.4).
Figure 3.4: Over 1,000 years there is little change in the temperature of northern Europe
Nevertheless, it is only in the past 50 years that advances in technology have allowed us to measure the change in CO2 levels accurately and record temperatures continuously. In the past 15 years, thanks to the use of Earth-orbiting satellites, we are now able to obtain accurate, reproducible data on ocean levels, global temperatures and the behaviour of clouds.
Global-warming predictions
It is largely due to the gaps in our knowledge and the indirect nature of the information about events in the remote past that people have interpreted the same information in different ways. There is no doubt that some have seen political and personal advantage in filling in these gaps with the most absurd, scary guesses and projections; others have minimised their importance or ignored the potential problem; while some have used the information selectively in order to advance a preconceived hypothesis. The information has been misinterpreted and wildly exaggerated by some in order to make political points. Some pressure groups justify this as being necessary to alert the public to the perceived dangers of global warming. They echo St Paul, who in his letter to the Corinthians appeared to license such scare tactics when he wrote, ‘If the trumpet give an uncertain sound who shall prepare himself for battle?’ Indeed, Sir John Houghton, the first chairman of the International Panel on Climate Change (IPCC), is reported to have said, ‘Unless we announce disasters no one will listen to us.’
There is no doubt that the evangelical nature and the scary exaggerations of many who claim the environmental banner – and their insistence that ‘all reputable scientists agree with them’ when, clearly, many do not (the Oregon petition had more than 33,000 signatures of scientists disagreeing with the theory of manmade global warming, more than 9,000 of whom have PhDs) – has done a grave disservice to science and made many question the basis of all the work linking anthropogenic CO2 to global warming.
The most alarming suggestion of the doomsday environmentalists, that the oceans are rising at an alarming rate, has been proved wrong. Islands that were due to be submerged, according to their forecasts, are actually seeing the seas receding. Their prophecies have been shown to be wrong by information from orbiting satellites. Over the past eight or nine years the measurements from ERS1 and ERS2 (European remote sensing satellites) have demonstrated that there has been a rise in sea level of 0.5–0.1mm a year (within the margin of scientific error) and that the increase is not accelerating! Although there is some evidence that the levels of the oceans have risen slowly, possibly by about 5cm over the past 150 years, it is a process that started long before industrialisation produced an increase in atmospheric CO2. So confident are the owners of property in the Maldives that the sea is actually receding that lavish seafront hotels are being built, yet the prophets of doom assure us that they will soon be under water. The island of Tuvalu in the Pacific, which was predicted to become submerged, has actually seen the sea level fall (it may be that the island is rising). The acceleration in the rate at which some glaciers in Greenland have been melting, adding to the ocean mass, started long before the motor car and industrialisation.
Not every drought or flood, hurricane or volcanic eruption, change in the climate or in the population of an animal species is due to global warming. There have been many such occurrences in the past and there is no evidence that their incidence is increasing (see Figure 3.5). Although the Arctic ice cap has probably been getting smaller since the Little Ice Age, most evidence points to an increase in the amount of ice in the Antarctic ice.
Figure 3.5: Number of hurricanes on the east coast of America over the past 150 years (National Weather Statistics)
Climate modelling
All the predictions of the future behaviour of the climate are produced from models that are based on past events. Most of the data used to construct these models comes from the same sources. If there are errors in this information it will be copied and exaggerated in all the models. Models of this kind have been likened to pop art, because, like the paintings of Andy Warhol, they project only the most obvious features on to a larger or longer picture. They are bound to reflect a personal interpretation of information rather than solid, verifiable evidence. They inevitably ignore some subtle details and they exaggerate others. They are limited by the impossibility of knowing every feature of a complex, multifaceted, ever-changing picture.
Many parameters, such as the exact contribution of water vapour and of the clouds to global warming, are immeasurable or unknown. The practice, used in some of the scariest models, of labelling years as either warm or cold from the size of the rings in tree trunks has been shown to be so grossly inaccurate that the predictions based on them are considered fraudulent. The best model is only as good as the weakest information used in its construction. Many of the factors that might determine the global weather pattern, such as cosmic radiation and solar-magnetic effects, are omitted because they are uncertain or unpredictable.
In response to the criticism that instead of the predicted increase in global temperatures in the past nine years there has been a 0.4ºC fall, and the failure of all the models to predict past events, such as ‘The Little Ice Age’. A senior scientific adviser to the IPCC (International Panel on Climate Change), Dr Trenberth, admitted that the models were not intended to be predictions but were designed to cover a range of possibilities. They are meant only to be what-if scenarios. Unfortunately they have been treated as proven facts by the media, by politicians and by environmentalists who do not appreciate the level of uncertainty in their predictions.
Few weather stations equipped with the most sophisticated monitoring techniques would confidently predict the weather next year, let alone 50 years hence. The longer the timeframe of these projections, the greater will be the magnification of any initial error. It is little wonder that these models produce