Why did it take so long to recognize global warming

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The key reasons for the delay in recognizing the global warming threat were, first, the power of the global mean temperature data set and, second, the need for the emergence of global environmental awareness. The global mean temperature data set is calculated using the land-air and sea-surface temperature. From 1940 till the mid-1970s the global temperature curve seems to have had a general downward trend. This provoked many scientists to discuss whether the Earth was entering the next great ice age. This fear developed in part because of increased awareness in the 1970s of how variable global climate had been in the past. The emerging subject of palaeoceanography (study of past oceans) demonstrated from deep-sea sediments that there were at least 32 glacial-interglacial (cold-warm) cycles in the last two and a half million years, not four as had been previously assumed. The time resolution of these studies was low, so that there was no possibility of estimating how quickly the ice ages came and went, only how regularly. It led many scientists and the media to ignore the scientific revelations of the 1950s and 1960s in favour of global cooling. As Ponte (1976) summarized:

Since the 1940's the northern half of our planet has been cooling rapidly. Already the effect in the United States is the same as if every city had been picked up by giant hands and set down more than 100 miles closer to the North Pole. If the cooling continues, warned the National Academy of Sciences in 1975, we could possibly witness the beginning of the next Great Ice Age. Conceivably, some of us might live to see huge snow fields remaining year-round in northern regions of the United States and Europe. Probably, we would see mass global famine in our life times, perhaps even within a decade. Since 1970, half a million human beings in northern Africa and Asia have starved because of floods and droughts caused by the cooling climate.

It was not until the early 1980s, when the global annual mean temperature curve started to increase, that the global cooling scenario was questioned. By the late 1980s the global annual mean temperature curve rose so steeply that all the dormant evidence from the late 1950s and 1960s was given prominence and the global warming theory was in full swing. What is intriguing is that some of the most vocal advocates for the global warming theory were also the ones responsible for creating concern over the impending ice age. In The Genesis Strategy in 1976, Stephen Schneider stressed that the global cooling trend had set in; he is now one of the leading proponents of global warming. In 1990 he stated that 'the rate of change [warming] is so fast that I don't hesitate to call that kind of change potentially catastrophic for ecosystems'.

Why the hysteria? John Gribbin (1989) describes the transition very neatly in his book In Hothouse Earth: the Greenhouse Effect and

In 1981 it was possible to stand back and take a leisurely look at the

3 record from 1880 to 1980 ... . In 1987, the figures were updated to 1985, chiefly for neatness of adding another half a decade to the records ... . But by early 1988, even one more year's worth of data justified another publication in April, just four months after the last 1987 measurements were made, pointing out the record-breaking warmth now being reached. Even there, Hansen [James Hansen, head of the NASA team studying global temperature trends] and Lebedeff were cautious about making the connection with the greenhouse effect, merely saying that this was 'a subject beyond the scope of this paper'. But in four months it had taken to get the 1987 data in print, the world had changed again; just a few weeks later Hansen was telling the US Senate that the first five months of 1988 had been warmer than any comparable period since 1880, and greenhouse effect was upon us.

It seems, therefore, that the whole global warming issue was driven by the upturn in the global annual mean temperature data set. This in itself is interesting because some scientists in the early 1990s believed that this was a flawed data set because: (1) many of the land monitoring stations have subsequently been surrounded by urban areas, thus increasing the temperature records because of the urban heat island effect, (2) there have been changes in the ways ships measure the sea-water temperature, (3) there was not an adequate explanation for the cooling trend in the 1970s, (4) satellite data did not show a warming trend from the 1970s to the 1990s, and (5) the global warming models have overestimated the warming that should have occurred in the northern hemisphere over the last 100 years. Since the early 1990s the urban heat island and variations in sea-temperature measurements have been taken into account. We now know that the cooling trend of the 1970s is due to the decadal influence of the sunspot cycle. It turns out that the satellite results were spurious for a number of reasons and a e greater understanding of the system and recalibrated data shows a a significant warming trend. Lastly, it was discovered that other w pollutants, such as sulphur dioxide aerosols, have been cooling | industrial regions of the globe, and as the models of the early 1990s J'

did not take them into consideration, they were overestimating the p o amount of warming. So the latest IPCC 2001 Science Report has j reviewed and synthesized a wide range of data sets and shows that, ? essentially, the trend in the temperature data is correct, and that this warming trend has continued unstopped until the present day (see Figure 6). In fact we know that 1998 was globally the warmest year on record, with 2002 the second, 2003 the third, 2001 the fourth and 1997 the fifth warmest. Indeed the ten warmest years on record have all occurred since 1990.

The upturn in the global annual mean temperature data was not the sole reason for the appearance of the global warming issue. During the 1980s there was also an intense drive to understand past climate change. Major advances were made in obtaining high-resolution past climate records from deep-sea sediments and ice cores. It was, thus, realized that glacial periods, or ice ages, take tens of thousand years to occur, primarily because ice sheets are very slow to build up

1860 1880 1900 1920 1940 1960 1980 2000 Year

6. Variation of the Earth's surface temperature

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6. Variation of the Earth's surface temperature and are naturally unstable. In contrast, the transition to a warmer period or interglacial, such as the present, is geologically very quick, in the order of a couple of thousand years. This is because once the ice sheets start to melt there are a number of positive feedbacks that accelerate the process, such as sea-level rise, which can undercut and destroy large ice sheets. The realization occurred in the palaeoclimate community that global warming is much easier and more rapid than cooling. It also put to rest the myth of the next impending ice age. As the glacial-interglacial periods of the last two and half million years have been shown to be forced by the changes in the orbit of the Earth around the sun, it would be possible to predict when the next glacial period will begin, if there were no anthropogenic effects involved. According to the model predictions by Berger and Loutre (2002) at the Université catholique de Louvain in Belgium, we do not need to worry about another ice age for at least 5,000 years. Indeed, if their model is correct and atmospheric carbon dioxide concentrations double, then global warming would postpone the next ice age for another 45,000 years. Palaeoclimate work has also provided us with worrying insights into how the climate system works. Recent work on the ice cores and deep-sea sediments demonstrate that at least regional climate changes of 5°C can occur in a matter of decades. This work on reconstructing past climate seems to demonstrate that the global climate system is not benign but highly dynamic and prone to rapid changes.

The next change that occurred during the 1980s was a massive grass-roots expansion in the environmental movement, particularly in the USA, Canada, and the UK, partly as a backlash against the right-wing governments of the 1980s and the expansion of the consumer economy and partly because of the increasing number of environmental-related stories in the media. This heralded a new era of global environmental awareness and transnational

NGOs (Non-Governmental Organizations). The roots of this growing environmental awareness can be traced back to a number e of key markers; these include the publication of Rachel Carson's

Silent Spring in 1962, the image of Earth seen from the moon in W

1969, the Club of Rome's 1972 report on Limits to Growth, the |

Three Mile Island nuclear reactor accident in 1979, the nuclear J'

accident at Chernobyl in 1986, and the Exxon Valdez oil spillage in p o

1989. But these environmental problems were all regional in effect, j i.e. limited geographically to the specific area in which they ?

occurred.

It was the discovery in 1985 by the British Antarctic Survey of depletion of ozone over Antarctica which demonstrated the global connectivity of our environment. The ozone 'hole' also had a tangible international cause, the use of CFCs, which led to a whole new area of politics, the international management of the environment. There followed a set of key agreements, the 1985 Vienna Convention for the Protection of the Ozone Layer, the 1987 Montreal Protocol on Substances that Deplete the Ozone layer, and the 1990 London and 1992 Copenhagen Adjustments and Amendments to the Protocol. These have been held up as examples of successful environmental diplomacy. Climate change has had a slower development in international politics and far less has been

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7. Global warming and the media

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7. Global warming and the media achieved in terms of regulation and implementation. This is, at its most simplistic level, because of the great inherent uncertainties of the science and the greater economic costs involved.

The other reason for the acceptance of the global warming hypothesis was the intense media interest throughout the late 1980s and 1990s. This is because the global warming hypothesis was perfect for the media: a dramatic story about the end of the world as we know it, with important controversy about whether it was even true. Anabela Carvalho, now at the University of Minho (Braga, Portugal), has done a fascinating study of the British quality press coverage of the global warming issue between 1985 and 1997. She concentrated particularly on the Guardian and The Times and found throughout this period that they promoted very different world-views. Interestingly, despite their differing views, the number of articles published per year by the British quality (broadsheet) papers followed a similar pattern and peaked when there were key IPCC reports published or international conferences on climate change (see Figure 7). But it is the nature of these articles that shows how the global warming debate was constructed in the media. From the late 1980s The Times, which published most articles on global warming in 1989, 1990, and 1992, cast doubt on the claims of climate change. There was a recurrent attempt to promote mistrust in science, through strategies of generalization, of disagreement within the scientific community, and, most importantly, discrediting scientists and scientific institutions. A very similar viewpoint was taken by the majority of the American e media throughout much of the 1990s. In fact it has been claimed a that this approach in the American media has led to a barrier w between scientists and the public in the USA. In the UK the |

Guardian newspaper took the opposite approach to that of The J'

Times. Although the Guardian gave space to the technical side of p o the debate, it soon started to discuss scientific claims in the wider h context. As scientific uncertainty regarding the enhanced s greenhouse effect decreased during the 1990s, the Guardian coherently advanced a strategy of building confidence in science, with an emphasis on consensus as a means of enhancing the reliability of knowledge. This was because the Guardian understood and promoted one of the fundamental bases of science, which is that a theory, such as global warming, can only be accepted or rejected by the weight of evidence. So, as evidence from many different areas of science continues to support the theory of global warming, so correspondingly our confidence in the theory should increase. Far from painting science as 'pure' or 'correct', instead the Guardian politicized it to demonstrate the bias that is inherent in all science. This clearly showed that many of the climate change claims were being eroded by lobbying pressure, mainly associated with the fossil-fuel industry. This politicizing of science allowed the

Guardian to strengthen their readers' confidence in science. Moreover, they clearly conveyed the uncertainties that the science of the global warming hypothesis contains and were and still are in favour of the precautionary principle. It was through this media filter that scientists attempted to advance their particular global warming view, by either making claims for more research or promoting certain political options. From the late 1980s onwards, scientists became very adept at staging their media performances, and it is clear that the general acceptance of the global warming hypothesis is in part due to their continued effort to communicate their findings. Indeed, both the sceptical and the supportive stances of The Times and Guardian, respectively, so legitimized the debate over global warming that the public became aware that this was not an overnight news story but something that has become part of the very fabric of our society.

•E It seems that the media has also influenced our use of words. From

| 1988 onwards the use of the phrase 'global warming' and 'climate j| change' gained support, while 'greenhouse effect' lost its appeal and u by 1997 was rarely mentioned. The change in terminology is reflected in this book. The title is Global Warming, as everyone knows what it means, and the major discussions in this book are about the climate change it might induce.

So by combining (1) the science of global warming essentially carried out by the mid-1960s, (2) the frightening upturn in the global temperature data set at the end of the 1980s, (3) our increased knowledge of how past climate has reacted to changes in atmospheric carbon dioxide in the 1980s, (4) the emergence of the global environmental awareness in the late 1980s, and (5) the media's savage interest in the confrontational nature of the debate, we are led to the final recognition of the global warming hypothesis. This has culminated in thousands of scientists turning their attention to the problem to try to prove it right or wrong. Landmarks since then have been the setting up of the Intergovernmental Panel on Climate Change (IPCC) in 1988 by the United Nations Environmental Panel and World Meteorological Organization; the publication of key reports by the IPCC in 1990, 1996, and 2001; the formal signature of the United Nations Framework Convention on Climate Change (UNFCCC) at the Rio Earth Summit in 1992; the subsequent Conference of the Parties (COP) at Kyoto in 1998, where the UNFCCC Protocols were formally accepted, and then in Bonn in July 2001, where the so-called 'Kyoto' Protocols were agreed by 186 countries.

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    Why did it take so long to recognize global warming?
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    Why did it take so long to air pollution?
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