Population and Environment

, Volume 27, Issue 2, pp 117–149

On Development, Demography and Climate Change: The End of the World as We Know it?

Authors

    • London School of Economics
    • Development Studies InstituteLondon School of Economics
Article

DOI: 10.1007/s11111-006-0017-2

Cite this article as:
Dyson, T. Popul Environ (2005) 27: 117. doi:10.1007/s11111-006-0017-2

Abstract

This paper comments on the issue of global warming and climate change, in an attempt to provide fresh perspective. Essentially, five main arguments are made. First, that the process of modern economic development has been based on the burning of fossil fuels, and that this will continue to apply for the foreseeable future. Second, that in large part due to momentum in economic and demographic processes, it is inevitable that there will be a major rise in atmospheric CO2 during the present century. Third, that available data on global temperatures suggest strongly that the coming warming will be appreciably faster than anything that humanity has experienced during historical times. Moreover, especially in a system that is being forced, the chance of an abrupt change in climate happening must be rated as fair. Fourth, that while it is impossible to attach precise probabilities to different scenarios, the range of plausible unpleasant climate outcomes seems at least as great as the range of more manageable ones. The consequences of future climate change may be considerable; indeed, they could be almost inconceivable—with several negative changes occurring simultaneously and to cumulative adverse effect. There is an urgent need to improve ways of thinking about what could happen. Fifth, the paper maintains that the human response to other difficult ‘long’ threats—such as that posed by HIV/AIDS—reveals a broadly analogous sequence of social reactions (e.g. denial, avoidance, recrimination) to that which is unfolding with respect to carbon emissions and climate change. Therefore the view expressed here is that major behavioral change to limit world carbon emissions is unlikely in the foreseeable future, and that the broad sway of future events is probably now set to run its course.

Key words:

climate changeeconomic developmentpopulation growth

Introduction

Global warming and climate change receive a huge amount of attention. Whether the world is heating up, the implications for the climate, and the possible long run consequences for humanity, are all topics that are never far from the newspaper headlines. It is clear that the issues involved are uncertain, complex, and often the object of controversy. Therefore it might be thought that little can be gained from a general social scientific consideration of the subject—one that starts from a concern with development and demography.

The view taken here, however, is that looking at global warming and climate change in historical perspective, examining the subject in the round (i.e. drawing on material from both the social and the environmental sciences), treating scientific study of it as a form of social activity, comparing human responses to it with those evidenced in relation to broadly analogous issues, and, above all, standing back from the subject—so as not to miss the wood for the trees—can yield fresh insights both about what is happening and about what may happen.

Accordingly, the present paper—which in large part is commentary—is an attempt to provide fresh perspective on global warming and climate change. It adopts an holistic approach, and essentially forwards five main points. First, that since about 1800 economic development has been based on the burning of fossil fuels, and that this will continue to apply for the foreseeable future. Although there will doubtless be increases in the use of renewable energy sources, and rises in the efficiency with which energy is used, there is no real alternative to the continued use of coal, oil and natural gas for the purpose of economic development. Second, that mainly due to momentum in economic and demographic processes, it is inevitable that there will be a major rise in atmospheric CO2 during the 21st century. Demographic and CO2 emissions data will be presented to help substantiate this point. Third, that the available data suggest that the coming rise in global temperatures, which itself will result partly from momentum in climate processes, will be appreciably faster than anything that human populations have experienced during historical times. Moreover, particularly in a system that is being forced, there must be a reasonable chance of the occurrence of an abrupt change in climate. Fourth, that while it is impossible to attach precise probabilities to different scenarios, the chances of an unpleasant climate outcome occurring are at least as great as the chances of a more manageable one. The agricultural, political, economic, demographic, social and other consequences of future climate change could be very considerable. In a more populous world of eight or nine billion people, adverse developments could well occur on several fronts simultaneously, and to cumulative adverse effect. Related to this, it will be argued here that there is a pressing need to improve our ways of thinking about what may happen—because current prognostications tend to be routine, predictable and restricted. Finally, the paper argues that humanity’s experience of another difficult ‘long’ threat—HIV/AIDS—reveals a broadly analogous sequence of human reactions. In short: (i) scientific understanding advances rapidly, but (ii) avoidance, denial, and recrimination characterize the overall societal response, therefore (iii) there is relatively little behavioral change, until (iv) evidence of damage becomes plain. Apropos climate change, however, the opinion expressed here is that major behavioral change to limit world carbon emissions is unlikely to happen in the foreseeable future.

There certainly is uncertainty about what will happen. But the basic data on trends in atmospheric CO2 and world temperature—presented here—are fairly easy to understand and not in serious dispute. Moreover, despite impressions to the contrary, there is a scientific consensus on the reality of human-induced climate change. It is suggested here that the broad course of future events is probably now set to run its course.

Development, Demography and Energy Use

The modern processes of economic and demographic development both have their origins in the European Enlightenment. It was in the second half of the 18th century that the first glimmerings of the demographic transition occurred in countries like France, England, Denmark and Holland. And this period also saw the birth of the so-called ‘Industrial Revolution’ in Britain—with the associated, momentous new phenomenon of ‘modern economic growth’ (Kuznets, 1966).

Before the Industrial Revolution all economies everywhere were extremely constrained in what they could produce. Borrowing a term from Wrigley (1988), pre-industrial economies were ‘organic’—in that virtually all of their products were ultimately dependent upon capturing solar energy through the exploitation of wood and other vegetative matter that grew on the land.

The Industrial Revolution transformed this situation through the mass exploitation of coal, which in turn spurred a host of cumulative economic interactions. Britain’s annual production of coal in 1800 was about 15 million tons—when the combined output for the rest of Europe was probably under 3 million tons. Burning 15 million tons of coal provided the British economy with roughly the same amount of heat as the wood that could have been harvested, on a sustainable basis, from about 6 million hectares of land (Wrigley, 1988:54–55). This revolution in industrial production, however, could not be constrained to one country, and by the middle of the 19th century the use of coal was rising steeply elsewhere in Europe. The United States came to coal a little later—mainly because it had plentiful supplies of timber to burn. But by the mid-1880s coal had become the main source of energy in the US. And, as a result of these developments, it is estimated that the world’s annual production of coal reached about 701 million tons in 1900 and 1454 million tons by 1950 (Cipolla, 1967:55). Today the annual coal production figure is roughly 4.1 billion tons (i.e. about 2,778 million tons in oil equivalent) and rising (British Petroleum, 2005).

With the United States in the vanguard, the 20th century saw rapid rises in the exploitation of oil and natural gas. The US had large reserves of oil. And from early in the 20th century its oil industry expanded fast—spurred by the development of oil-burning furnaces, the spread of car ownership, the rise of aviation, and growth in the production of petrochemicals. The mass exploitation of natural gas (e.g. in electricity generation, and for household heating and cooking) had to await the development of high pressure pipeline technologies in the US during the 1930s. In both Europe and Japan the diversification away from coal, towards oil and gas, occurred several decades later (Ponting, 1993).

The implications of these trends for world energy use are shown in Table 1. Oil has been the most important fuel since the 1960s. By 2004 oil accounted for about 37% of global energy use, followed by coal and gas in roughly equal proportions (about 27 and 24% respectively). Nuclear and hydro each accounted for around 6%. By 2004 global use of fossil fuels was equivalent to the burning of about 8.96 billion tons of oil each year. Notice that growth in the world’s annual consumption of fossil fuels shows little sign of waning. Thus during 1980–1990 the combined use of coal, oil and natural gas rose by an estimated 1115 million tons of oil equivalent (mtoe); and during 1990–2004 it rose by a further 1743 mtoe (see Table 1). Except for those countries in eastern Europe and the former Soviet Union (FSU) that have experienced economic decline following the collapse of communism, only a handful of countries were burning smaller quantities of fossil fuel energy (expressed in terms of mtoe) in 2004 compared to 1994, and then by only small amounts (British Petroleum, 2005). The overwhelming picture is one of expansion. For example, Brazil, China, India and Indonesia experienced rises in their use of fossil fuels of 47, 69, 63, and 62% respectively during 1994–2004. And even in the world’s most advanced economies any changes in fuel mix, or rises in energy use efficiency, were significantly outweighed by increased levels of fossil fuel consumption. Thus during the same time period, fossil fuel energy use rose by 8.5, 12.0, and 5.8% respectively in the US, the European Union (as it is presently constituted, i.e. the EU24) and Japan (British Petroleum, 2005).
Table 1

World Energy Supplies, 1950–2004

Year

Coal production (mtoe)

Oil production (mill. tons)

Natural gas production (mtoe)

Total fossil fuels (mtoe)

Nuclear energy consumption (mtoe)

Hydro consumption (mtoe)

Total (mtoe)

1950

884

518

187

1589

1589

1960

1271

1049

458

2778

2778

1970

1359

2355

919

4633

17

269

4919

1980

1708

3088

1311

6107

161

387

6655

1990

2254

3168

1800

7222

453

494

8169

2000

2112

3604

2190

7906

584

614

9104

2004

2778

3767

2420

8965

624

634

10,223

Notes: All figures are in million tons of oil equivalent (mtoe) and should be regarded as only broadly indicative. One million tons of oil equivalent equals approximately 1.5 million tons of hard coal. World nuclear generating capacity was insignificant in 1960, but the total figures given above for 1950 and 1960 are slight underestimates because they contain no allowance for hydro. There were minor discrepancies between some of the time series used above, but they can safely be ignored for present purposes.

Principal data sources: Coal 1950–1980 (Kane, 1996), 1990–2004 (British Petroleum, 2005); Oil 1950–1960 (Flavin, 1996a), 1970–2004 (British Petroleum, 2005); Natural gas 1950–1960 (Flavin, 1996b), 1970–2004 (British Petroleum, 2005); Nuclear (British Petroleum, 2005); Hydro (British Petroleum, 2005).

The huge degree to which differences in levels of per capita fossil fuel energy consumption underpin differences in living standards in the world today is shown by Figure 1. It illustrates the relationship for 63 countries for which recent data are available. Virtually all of the countries which lie far below the fitted line (e.g. Uzbekistan, Kazakhstan, Ukraine, and the Russian Federation) were part of the FSU, and their use of fossil fuel energy is generally very inefficient. The two points which lie furthest above the line are France and Japan—both of which rely heavily on nuclear energy. Notice that about half (n=32) of all the countries are crammed together in the bottom left hand corner of the diagram. These countries have levels of fossil fuel energy consumption of less than one metric ton per person per year. The economies of all these poor countries are severely constrained because they are still largely ‘organic’. The basic message is extremely clear: countries have been unable to escape from conditions of material poverty in the absence of having access to supplies of fossil fuel energy. As the economic historian Carlo Cipolla succinctly stated:
[H]igh per capita consumption of energy not only means more energy for consumption, heating, lighting, household appliances, cars, etc., but [it] also means more energy for production, i.e., more energy available per worker and therefore higher productivity of labour. (Cipolla, 1967:57, emphasis in the original)
https://static-content.springer.com/image/art%3A10.1007%2Fs11111-006-0017-2/MediaObjects/11111_2006_17_Fig1_HTML.gif
Figure 1.

Fossil fuel energy consumption as a determinant of per capita gross domestic product around the year 2000. Notes: Data on both variables were found for 63 countries, all with estimated populations in 2002 of 10 million or more. The trend line shown is a simple linear regression. The GDP data are expressed in purchasing power parity (i.e. ppp) terms, and the energy use data are expressed in kilograms of oil equivalent (kgoe). As well as the various factors discussed in the text, some of the scatter around the trend line undoubtedly reflects inadequacies in the data. Principal data source: World Resources Institute (2003:Tables 4 and 8).

In concluding this section it is worth stressing that while the current size of the world’s population is certainly an important factor conditioning the total quantity of fossil fuels that is being burnt each year—i.e. around 8.96 billion tons of oil equivalent in 2004—it is modern economic growth that has been the main engine of growth in humanity’s use of fossil fuel energy. Thus between 1950 and 2000 the world’s population increased by roughly 140%, but the rise in fossil fuel energy consumption during the same period was almost 400% (see Table 1).

Trends in Atmospheric Co2 and the Earth’s Surface Temperature

The idea that the burning of fossil fuels might lead to a build-up of CO2 in the atmosphere, and so prevent heat escaping from the Earth, stems from scientific work in the 19th century. It was Joseph Fourier who first saw that the atmosphere acts to retain heat radiation, and John Tyndall who recognized the important role that CO2 plays in this process (Weart, 2003:2–4). However, it was the chemist Svante Arrhenius who in 1896 published a famous piece on how the Earth’s surface temperature might be raised by increased levels of atmospheric CO2 produced from the burning of coal. His initial estimate was that a doubling of atmospheric CO2 would produce a rise in temperature of about 5 degrees Celsius (deg/C). However he later amended this to 4 deg/C—a figure that is well within the range that is estimated today with the help of much greater knowledge and modern computers (World Meteorological Organization, 2003:29).

For most of the 20th century the idea received little attention. Yet by the early 1980s it was becoming apparent that the Earth was probably warming. And concern that this might partly be due to human activities led to the creation of the Intergovernmental Panel on Climate Change (IPCC) in 1988. The mandate of the IPCC—which specifically excludes making policy recommendations for governments—is to assess research on climate change and to provide relevant information to the global community. The IPCC has now gone through three assessment rounds (e.g. see IPCC, 1990, 1995, 2001a). The fourth assessment is due in 2007. Successive IPCC reports have concluded with growing confidence (i) that the Earth’s climate is indeed warming, and (ii) that this is mainly due to anthropogenic (i.e. human-induced) causes—particularly the burning of fossil fuels which releases CO2 into the atmosphere. It is important to stress that, contrary to popular impressions, these key conclusions are accepted by virtually all of the world’s climate scientists; there is no substantive disagreement on the matter (see Oreskes, 2004).

The most recent IPCC assessment, released in 2001, concluded that during the final two decades of the 20th century about three-quarters of the CO2 released into the atmosphere came from burning fossil fuels, with most of the rest coming from land use changes—especially deforestation. Other greenhouse gases (GHGs) resulting from human activities that have made significant, though lesser, contributions to ‘positive radiative forcing’, and hence global warming, are halocarbons such as chlorofluorocarbons (CFCs), methane (CH4), and nitrous oxide (N2O). It is notable that a sizeable part of the release of both CH4 and N2O derives from agriculture and the need to produce food and sustain livelihoods—so, again, the current size of the world’s population is a pertinent consideration. Some anthropogenic influences have had a cooling effect—notably the release of sulfate aerosols (i.e. tiny airborne particles), many of which also emanate from fossil fuel burning. However, the net effect is very much one of positive radiative forcing (IPCC, 2001b:7–9).

Measures of atmospheric GHG concentrations for most past periods come from the analysis of ice core samples. The resulting time series suggest that levels of atmospheric CO2 started to rise from about 1800 i.e. the time of the Industrial Revolution. Moreover, similar trends are evident for CH4 and N2O—suggesting that humanity’s influence on the global environment entered a distinctly new phase from about that time. Estimates of the world’s surface temperature for most past periods in history are less accurate than those available for levels of atmospheric CO2. This is because temperature estimates have to be imputed from the analysis of materials like tree rings and coral reefs. Nevertheless, the available estimates suggest a slight cooling trend in the centuries before about 1910. But the temperature has risen sharply since. The IPCC considers that the temperature rise during the 20th century was about 0.6 deg/C with a 95% confidence figure around this estimate of ±0.2 deg/C. The rise was irregular—with comparatively rapid warming before 1940, and again since the mid–1970s (IPCC, 2001b:3–9). Interestingly, much of the plateau in temperature between the 1940s and the 1970s is now thought to have reflected the cooling influence of sulfate aerosols coming from the burning of fossil fuels.

Clearly, imputed estimates of past surface temperature are less satisfactory than those based on direct measurement. However, prior to the 20th century regular measurements of temperature were only made at a small and unrepresentative number of geographical locations. And, prompted in part by concern among some scientists regarding the results of the calculations made by Arrhenius, systematic and direct measurement of levels of atmospheric CO2—good enough to provide reasonably reliable estimates of trends over time—date only from 1958 to 1959, with observations made at the Mauna Loa Observatory in Hawaii.

Table 2 gives the Mauna Loa measurements. The level of CO2 in the Earth’s atmosphere has risen from about 317 parts per million (ppm) in 1959–1961 to around 377 ppm in 2004 (the level prevailing before 1800 is thought to have been about 280 ppm). Figure 2 shows that although the size of the annual increment in CO2 fluctuates substantially, it has tended to increase. It is notable that 2002 and 2003 were the first consecutive years with increments exceeding 2 ppm. However in the past some analysts have claimed that there has been no significant upward trend in the increment since 1977 (Hansen & Saito, 2001). The world’s oceans and terrestrial vegetation are major ‘sinks’ (i.e. absorbers) of CO2. And there are reasons to believe that, with rising levels of the gas in the atmosphere, and rising temperatures, these sinks may have increased their absorption. According to the IPCC (2001b:7) about half of all CO2 currently released into the atmosphere by human activity is absorbed by the oceans and vegetation. And there is evidence of increased plant growth because of the fertilizing effect of higher levels of carbon dioxide in the atmosphere (e.g. see Nemani et al., 2003). Nevertheless, according to the observations in Table 2 the average increment for years 1959–1976 was +0.95 ppm, whereas for 1977–2004 it was +1.61 ppm. There are certainly no signs that the size of the annual increment is diminishing. And it is certain that the concentration of CO2 in the atmosphere will rise appreciably during the present century, although it is uncertain by how much.
Table 2

Global Atmospheric CO2 Concentrations and Surface Temperature Anomaly Estimates, 1959–2004

Year

CO2 (ppm)

Annual increment (ppm)

Temp. anomaly (deg/C)

Year

CO2 (ppm)

Annual increment (ppm)

Temp. anomaly (deg/C)

1959

316.00

 

0.01

1982

341.09

1.14

0.02

1960

316.91

0.91

−0.03

1983

342.75

1.66

0.23

1961

317.63

0.72

0.02

1984

344.44

1.69

0.03

1962

318.46

0.83

0.01

1985

345.86

1.42

0.01

1963

319.02

0.56

0.04

1986

347.14

1.28

0.10

1964

319.52

0.50

−0.23

1987

348.99

1.85

0.25

1965

320.09

0.57

−0.17

1988

351.44

2.45

0.24

1966

321.34

1.25

−0.08

1989

352.94

1.50

0.16

1967

322.13

0.79

−0.09

1990

354.19

1.25

0.31

1968

323.11

0.98

−0.11

1991

355.62

1.43

0.25

1969

324.60

1.49

0.04

1992

356.36

0.74

0.12

1970

325.65

1.05

−0.03

1993

357.10

0.74

0.18

1971

326.32

0.67

−0.19

1994

358.86

1.76

0.23

1972

327.52

1.20

−0.04

1995

360.90

2.04

0.37

1973

329.61

2.09

0.09

1996

362.58

1.68

0.23

1974

330.29

0.68

−0.17

1997

363.84

1.26

0.41

1975

331.16

0.87

−0.12

1998

366.58

2.74

0.58

1976

332.18

1.02

−0.20

1999

368.30

1.72

0.34

1977

333.88

1.70

0.06

2000

369.47

1.17

0.29

1978

335.52

1.64

−0.04

2001

371.03

1.56

0.42

1979

336.89

1.37

0.07

2002

373.07

2.04

0.47

1980

338.67

1.78

0.10

2003

375.61

2.54

0.47

1981

339.95

1.28

0.13

2004

377.38

1.77

0.45

Notes: The CO2 concentrations are derived from air samples collected at the Mauna Loa Observatory. The temperature series are combined global land and marine surface temperatures relative to the average temperature recorded for the period 1961–1990. They are taken from the ‘Global average temp 1856–2005’ dataset (taveGL2v) of the Climate Research Unit at the University of East Anglia, UK.

Principal data sources: CO2 (Keeling et al., 2004; Keeling & Whorf, 2005); Temperature anomaly data (Palutikof, 2004; Jones & Palutikof, 2005).

https://static-content.springer.com/image/art%3A10.1007%2Fs11111-006-0017-2/MediaObjects/11111_2006_17_Fig2_HTML.gif
Figure 2.

Annual increments in atmospheric CO2 (ppm) as measured at the Mauna Loa Observatory, 1959–2004. Note: Increments are expressed in parts per million (ppm). Principal data source: See the notes to Table 2.

Table 2 also gives corresponding annual estimates of the Earth’s surface temperature. The particular time series shown is that compiled by the Climate Research Unit (CRU) at the University of East Anglia in the UK. However, time series produced by other bodies—such as the World Meteorological Organization (WMO) or the Goddard Institute for Space Studies (GISS)—provide a reasonably similar picture. By convention, the CRU estimates shown in Table 2 are expressed relative to the average temperature holding during 1961–1990. The resulting mean temperature ‘anomaly’ for 1959–1961 is zero i.e. the average temperature for these 3 years is equal to the average for 1961–1990. In contrast, the estimated mean temperature anomaly for the 5-year period 2000–2004 is 0.42 deg/C, and the estimate for the year 2004 itself is 0.45 deg/C higher than the reference level (see Table 2). The 1990s were the warmest decade since a reasonable quantity of direct records became available (around the middle of the 19th century). According to this time series, the ten warmest years globally have been, in ascending order: 2000, 1990, 1999, 1995, 1997, 2001, 2004, 2002 and 2003 (joint), and then 1998—the hottest year recorded, 0.58 deg/C above the average for 1961–1990.

Clearly, and unlike the level of atmospheric CO2, the world’s surface temperature can fall from one year to the next because of specific events. For example, the eruption of Mount Pinatubo in 1991 led to a reduction in temperature in 1992 and 1993. And a major El Niño event—which involves significant oceanic warming—contributed to the record temperatures of 1997 and, especially, 1998 (see Table 2). However, Figure 3 shows clearly that the temperature trend has been firmly upwards since the mid-1970s. Notice that the moving average reveals the existence of a fairly regular fluctuation to the rise, linked in part to the El Niño/Southern Oscillation (ENSO) climate phenomenon. There is some suggestion that the next peak in the moving average might occur around the year 2010. Finally, at the time of writing (i.e. in late 2005) it is virtually certain that 2005 will turn out to be either the second or third warmest year yet recorded according to the CRU time series (UK Meteorological Office, 2005). Indeed, there is a good chance that 2005 will be the hottest year on record according to the GISS time series—a fact that is especially striking because it will have happened in the absence of a large El Niño event (see Hansen, Sato, Ruedy, & Lo, 2005).
https://static-content.springer.com/image/art%3A10.1007%2Fs11111-006-0017-2/MediaObjects/11111_2006_17_Fig3_HTML.gif
Figure 3.

World surface temperature anomaly estimates, 1959–2004. Notes: Temperatures are in degrees Celsius (deg/C). The trend line is a 3 year moving average. Principal data source: See the notes to Table 2.

As previously intimated, the causal relationships linking levels of atmospheric CO2 and world surface temperature are extremely complex. A vast amount is unknown about how intermediary mechanisms operate. However it is known that the level of CO2 at any one moment implies a higher temperature over the longer run—what the IPCC terms a ‘commitment’ to future warming. Also, while it is generally agreed that increasing levels of atmospheric CO2 are bringing about a rise in surface temperatures, it is also agreed that in some circumstances the rise in temperature can lead to the release of CO2 i.e. the direction of causation can work both ways. For instance, as temperatures rise the process of ‘respiration’, whereby soils and decaying plant matter release CO2 into the atmosphere, tends to increase. In addition, CO2 respiration can occur through forest fires and forest dieback, both of which could also become more frequent as temperatures rise further (e.g. see Pearce, 1999; Houghton, 2004:37–42).

In concluding this section, it is worth underscoring that the data in Table 2 have the advantages of being comparatively straightforward and reliable. There is no reasonable doubt that levels of atmospheric CO2 and surface temperatures are on a distinctly upward path. Accordingly, this is an appropriate place to present a personal interpretation of the various social responses that have occurred with respect to this growing body of information.

Social Reactions to the Evidence on Global Warming

That modern economic growth has raised levels of atmospheric CO2—leading to a rise in the Earth’s surface temperature and the threat of climate change—is patently unwelcome news. It raises difficult issues about the basis of economic growth. It highlights huge—and morally awkward—disparities in energy use, CO2 emissions, and living standards between rich and poor. It rears the prospect that some extremely difficult changes in behavior may be required. Indeed, inasmuch as it suggests the need for big cuts in energy consumption, it strikes at the very heart of the modern conception of ‘development’.

The view taken here is that the human response to this news has been characterized by a mixture of denial, avoidance and recrimination, and that these reactions are fairly predictable. The social response has been complicated because climate change is commonly seen as a phenomenon which—if indeed it is real—lies far off in the distant future. Most people are preoccupied with the events of their daily lives, they are increasingly distrustful of official sources of information, and they tend to be relatively unconcerned with what may happen over the very long run. Political leaders too have more immediate concerns to occupy their time. They usually avoid difficult issues, being chiefly concerned with the short run—often the period until the next election.

Accordingly, this section comments briefly on selected reactions to the consensus on global warming that now exists among climate scientists. The point is not to be critical of such reactions. Rather, it is to propose that they are to be expected in the context of the dawning of unwanted news. On the present view, they are social phenomena that often have little direct bearing on the CO2 and temperature data to which they supposedly relate.

No one doubts that there have been significant rises in levels of atmospheric CO2, but a small, vocal minority still question whether the world is heating up. For example, in a paper still used in the United States to petition the government to reject the Kyoto Protocol, Robinson and others state:

The empirical evidence—actual measurements of Earth’s temperature—shows no man-made warming trend. Indeed, over the past two decades, when CO2 levels have been at their highest, global average temperatures have actually cooled slightly. (Robinson, Baliunas, Soon, & Robinson, 1998:1)

A key part of this position—replicated by a host of internet websites—is that the indicated recent rise in surface temperature is spurious. It is contended that, instead, the rise reflects urbanization. That is, it is claimed that direct temperature measurements are being increasingly biased upward over time by the so-called ‘urban heat island effect’—as more and more of the measurements take place in urban areas, or areas close by. Also important to this position are satellite-based estimates of the temperatures prevailing in the lower troposphere (i.e. at altitudes of about 2–4 km) which are interpreted as suggesting that there has been little change in the Earth’s temperature.

However, both of these points have been considered and largely rejected by climate scientists. The research teams that compile the estimates of surface temperature—such as those at the WMO, GISS, and CRU—are well aware of the potential bias coming from urbanization, and much work has gone into gauging it. The conclusion is that any distortion is small—probably no more than 0.05 deg/C for the entire period before 1990 (see IPCC, 2001a:Box 2.1). Time series, such as that in Table 2, are adjusted downwards to allow for it. The temperature estimates for the lower troposphere are also open to question. Satellites do not gauge temperature directly. Rather, they measure molecular microwave emissions which are then converted into temperatures—a process that involves making many assumptions. Furthermore, the satellite data are only available from the late 1970s—a fairly short length of time that makes trend estimation tricky. Recent work on the microwave data concludes that the temperature of the lower troposphere has probably risen by more than was previously thought. And, when the revised estimates are combined with radiosonde (i.e. balloon-borne) temperature measurements, differences in trend between them and the surface temperatures largely disappear (World Meteorological Organization, 2003:198; see also National Research Council, 2000). In short, significant progress has been made in reconciling temperature estimates for the surface and the lower troposphere. And in both locations the evidence is that the Earth is heating up.

Of course, questioning and skepticism are integral to science. But the present view is that statements such as that shown above border on denial. That such statements are made by a minority of non-climate scientists tends to be diminished by the media—which in the interest of providing ‘balance’ strives to provide equal space to opposing views. Beyond these concerns lie issues of interest, on both sides. Some of the work of the IPCC has involved specialists who could have potential conflicts of interest with their commercial work (see Lohmann, 2001:22–23). Scientific research on climate change is certainly affected by political and economic considerations (Demeritt, 2001). And the provision of advice on how to adapt to, or help mitigate, climate change is big business. On the other hand, many industries (e.g. in power generation, manufacturing, transport, etc) have considerable commercial interest in the continuing exploitation of sources of fossil fuel energy. And prominent skeptics on global warming have received generous funding from the corporate sector (e.g. see Pearce, 1997; van den Hove, Le Menestrel, & de Bettignies, 2003; Weart, 2003:165–166). Furthermore, national governments—invariably with close links to industry—have found it extremely hard to confront the issue head on.

This brings us to the international political response—because reducing global CO2 emissions would certainly require international agreement. The United Nations Framework Convention on Climate Change was initiated in 1992 to start the process towards stabilization of GHGs. But the Convention specifically avoided the issue of the level at which CO2 (and other GHGs) should be stabilized. This matter remains largely unresolved—although a figure of 550 ppm (i.e. about twice the pre-industrial level) is sometimes discussed. That said, other bodies, such as the Global Commons Institute, argue for a limit no higher than 450 ppm (Hillman, 2004:119).

Following publication of the IPCC’s second report, world leaders met in Kyoto in 1997. However in some respects the ensuing ‘Kyoto process’ can itself be interpreted as one that is partly concerned with ways of avoiding making significant reductions in CO2 emissions. At least, that is the position that is taken here. Examples of this tendency towards avoidance include the discussion of ‘carbon sequestration’ i.e. the planting of trees and other vegetation to help ‘neutralize’ CO2 emissions. It took considerable time for the limitations of this approach to be appreciated fully—for example, that over the long run the areas of forest required are very great, that as temperatures rise so it may prove difficult to stop the ‘respiration’ of some of the sequestrated carbon back into the atmosphere, that especially at high latitudes increased forest cover may actually lead to increased absorption of solar radiation, and, perhaps most important, that the overall net benefit of such sequestration efforts is likely to be small compared to the probable scale of future human-induced CO2 emissions (e.g. see Lohmann, 1999; Houghton, 2004:249–253). Another approach which can be viewed as having a sizeable element of avoidance involved—one that has occupied armies of negotiators, lawyers, economists, consultants, etc, the very stuff of Weberian bureaucratization (Prins, 2003)—is the construction of ‘carbon markets’. By enabling ‘emissions trading’ such markets will allow some countries (usually richer ones, with high emissions) to pay others (usually poorer ones, with low emissions)—essentially as a way of easing the requirement of richer countries to make greater reductions in emissions themselves. Carbon markets are controversial, and their ability to bring about significant reductions in world CO2 emissions has been questioned on many grounds (e.g. see Mobbs, 2005:79–86). Moreover, Lohmann has commented that:

None of Kyoto’s market measures ... tackle directly the physical root of global warming: the transfer of fossil fuels from underground, where they are effectively isolated from the atmosphere, to the air. (Lohmann, 2001:5)

It was noted above that in the last decade or so virtually all countries have continued to burn greater amounts of fossil fuel. This also applies to those that have arguably been most prominent in supporting the Kyoto process—notably Canada, Japan and those of the European Union (EU). Many of these countries are unlikely to meet their CO2 reduction targets agreed under the Kyoto treaty (which finally came into force in 2005). Thus comparing 1990 and 2002, it is estimated that Canada’s emissions increased by 22% and Japan’s by 13 (see Zittel & Treber, 2003). While the CO2 emissions of the 15 countries that comprised the EU before 2004 (i.e. the EU15) remained roughly constant, this was mainly due to reductions in Germany and Britain—both of which gained fortuitously from a move away from coal towards natural gas (which emits less CO2 per unit of energy). Of the remaining countries in the EU(15), only Sweden—which relies heavily on hydro and nuclear—registered a fall in CO2 emissions between 1990 and 2002. Of the 36 ‘Annex B’ countries of the Kyoto treaty (i.e. the industrialized countries, including former eastern bloc nations), only 12 experienced declines in emissions: the three in the EU(15), plus nine former eastern bloc nations. If one excludes these, then CO2 emissions among the remaining 24 Annex B countries rose by 13% during 1990–2002 (Zittel & Treber, 2003). Of course, the United States, the world’s largest emitter of CO2, is not a signatory to the Kyoto treaty. And, to complete the list of social reactions that are regarded here as fairly predictable, the ‘Kyoto process’—and the 2005 UN Climate Change Conference in Montreal—have involved no shortage of recrimination between representatives of the US, the EU, and other countries.

The present view is that the prospects for an enforceable international agreement that will bring about a sustained and significant reduction in annual global CO2 emissions are very poor. While it may be in the interest of the world as a whole to restrict the burning of fossil fuels, it is in the interest of individual countries to avoid making such changes (i.e. there are elements of a classic isolation paradox). Really major nations, such as the US and China, have considerable capacity to circumvent or ignore international agreements when it suits them. Moreover, the enormous complexities involved—many of them created and informed by matters of interest—will also hinder agreement. Doubtless there will be gains in energy use efficiency, shifts towards less carbon intensive fuels, and greater use of renewable energy sources (e.g. solar, biomass, wind and tidal power). But except for a massive shift towards nuclear—which has many serious problems attached, and would in any case take decades to bring about—there are limits to what such changes could possibly achieve in terms of CO2 reduction. Other technological ideas—like the extraction of CO2 from coal and its sequestration underground (so-called ‘carbon capture and storage’) or, still more, the development of the so-called ‘hydrogen economy’—are remote ideas as large scale and significant solutions to the problem during the foreseeable future (Smil, 2003). Indeed, such notions can themselves be regarded as providing some basis for avoidance inasmuch as they suggest that something is being done. Understandably, poor countries are unlikely to put great effort into constraining their CO2 emissions—especially in the face of massive discrepancies between themselves and the rich.

In sum, the view taken here is that for the foreseeable future the basic response to global warming will be one of avoidance and, at most, modest change. That the absolute amount of CO2 emitted into the atmosphere each year is almost certainly going to rise in the coming decades is shown by an examination of basic demographic and emissions data in the next section.

Illustrative Calculations on Future CO2 Emissions

Demographic growth is a useful place to begin when considering future trends in CO2 emissions. At the start of the 21st century the world’s population was about 6.1 billion. The United Nations projects that by 2050 it will be around 9.1 billion (United Nations, 2005). This represents growth of 49% in 50 years. Although this projection is approximate, considerable further demographic growth is inevitable—because of population momentum. Moreover it is worth remarking that the UN has a good record of forecasting the world’s total population.

By itself an increase in the world’s population of roughly one half (i.e. 49%) will not lead to a similar proportional rise in CO2 emissions from the burning of fossil fuels. The reason is that most of the coming demographic growth will occur in poor countries, which—almost by definition—burn relatively small amounts of coal, oil and natural gas. In this context Table 3 summarizes the situation at the start of the 21st century and provides a way of exploring the future. Column (i) shows the distribution of the world’s population in the year 2000. Columns (ii) and (iii) give the corresponding levels of per capita and total CO2 emissions by region. Notice that in 2000 the world’s population of 6.09 billion was releasing about 23.2 billion tons of CO2 through the combustion of fossil fuels—implying an average annual per capita emissions figure of about 3.8 metric tons. However, the statistics in column (ii) also underscore the enormous variation that exists around this average. Thus in North America (i.e. the United States and Canada) the average level of emissions was about 20.0 tons of CO2 per person per year, whereas in both sub-Saharan Africa and South-central Asia it was only around 0.9 tons. Column (iii) shows that around the year 2000 the largest absolute regional contribution to total world CO2 emissions came from North America, followed closely by Europe. Together these two developed regions contained only about 17% of humanity, but at the start of this century they accounted for around 54% of all CO2 emissions from fossil fuel burning.
Table 3

Estimates of Regional and Global Emissions of CO2 Produced by the Combustion of Fossil Fuels for around the year 2000, with Illustrative Calculations for 2050

Region

Population (millions)

Per capita CO2 emissions (metric tons)

Total CO2 emissions (million metric tons)

Projected population (millions)

Total CO2 emissions (million metric tons)

2000

2000

2000

2050

2050

(i)

(ii)

(iii)

(iv)

(v)

Developing regions

Sub-Saharan Africa

670

0.9

613.8

1692

1550.1

North Africa/West Asia

335

4.3

1430.8

628

2682.2

Eastern Asia

1479

3.4

5044.6

1587

5412.9

South-central Asia

1485

0.9

1368.2

2495

2298.8

South-eastern Asia

519

1.3

696.1

752

1008.6

Central America and Caribbean

174

2.8

481.2

256

707.9

South America

349

2.2

771.9

527

1165.6

Subtotal

5011

2.1

10,406.6

7937

14,826.2

Developed regions

Europe

729

8.4

6106.2

653

5469.6

North America

315

20.0

6294.5

438

8752.3

Oceania

31

11.8

365.0

48

565.1

Subtotal

1075

11.9

12,765.7

1139

14,787.0

World

6086

3.8

23,172.2

9076

29,613.2

Notes: All the figures given above are approximate—especially those relating to CO2 emissions. The per capita and total emissions statistics shown for 2000 actually pertain to 1999. The regional groupings of countries used are those employed by the World Resources Institute, but with Asia (excluding West Asia) being broken down according to the standard groupings of the United Nations. Here Sudan forms part of sub-Saharan Africa. The regions are designated above as either ‘developing’ or ‘developed’—perhaps the main qualifications being that Japan falls in Eastern Asia, and that Melanesia is part of Oceania. The World Resources Institute provides no regional statistics on CO2 emissions for sub-Saharan Africa. In 1999, however, South Africa had estimated per capita and total CO2 emissions of 8.1 tons and 346 million tons respectively. To get the figures shown above for sub-Saharan Africa for the year 2000 it was arbitrarily assumed that per capita emissions for the remainder of the region averaged 0.4 tons (about the levels indicated for Angola and Senegal). Several modest adjustments were required to produce the relatively consistent regional and global picture given above, and therefore some of the figures on CO2 emissions differ slightly from those published by the World Resources Institute on which they are based. The figures in column (v) are the product of those in (ii) and (iv).

Principal data sources: World Resources Institute (2003: 258–259); United Nations (2005).

Turning to the future, column (iv) of Table 3 summarizes UN population projections for the year 2050 by region. During the period 2000–2050 the population of sub-Saharan Africa is projected to rise by around 1022 million, and that of South-central Asia (which includes India, Pakistan, and Bangladesh) by 1010 million. Taken together, these two very poor regions are projected to account for about two-thirds of the growth in world population over this time period. Note too that the populations of North America and Oceania are projected to rise by about 123 and 17 million respectively. Only Europe’s population is expected to decline in size.

Column (v) of Table 3 shows the total CO2 emissions that will apply in 2050 if the projected regional populations in column (iv) are combined with the corresponding per capita CO2 emission figures for 2000 given in column (ii). On this simple and unrealistic assumption (i.e. that of holding per capita emissions in each region constant at the level that prevailed around the year 2000), it can be seen that global CO2 emissions would rise to about 29.6 billion tons i.e. by 28%. Also, the average level of per capita emissions for the world as a whole would fall from about 3.8 to around 3.3 metric tons per person (i.e. 29,613/9076). The explanation for this fall is that most of the coming demographic growth will occur in poor regions with low per capita emissions—thereby weighting the global per capita emissions figure downwards over time. Precisely the same consideration explains why the projected population increase of 49% leads to a rise in global CO2 emissions of only 28%. Note from the sub-totals in columns (iii) and (v) that the projected population growth in the developing regions leads to a 42% rise in their total emissions (i.e. from 10.4 to 14.8 billion tons). And for the developed regions too demographic growth produces a 16% rise in total emissions (i.e. from 12.8 to 14.8 billion tons)—despite the projected decline in Europe’s population. This helps to underline the fact that in North America, especially, immigration could play a significant role in the growth of future CO2 emissions.

The rise in annual world CO2 emissions in the next 50 years may well be appreciably greater than 28%. The huge differentials in current per capita emission levels shown in column (ii) of Table 3 account for this. Although, as comparative newcomers, the developing regions can expect to benefit from rises in the efficiency with which energy is derived from fossil fuel sources, it is nevertheless virtually inevitable that most of these regions will experience significant rises in their per capita emission levels as they develop economically. Consider, for example, that during 1990–1999 the level of per capita CO2 emissions rose appreciably in all the developing regions for which data are available. Thus for Asia (excluding West Asia) the increase was about 19.3%; for North Africa/West Asia it was around 19.7%; and for South America it was about 22.5% (World Resources Institute, 2003:258–259). Conservatively, these figures imply a 20% rise in per capita emissions per decade. And, cumulated across five decades, this would translate into an increase in per capita emissions of very roughly 150%. That said, no one knows by how much these per capita emission levels will increase. The degree of uncertainty is substantially greater than that regarding the scale of future demographic growth.

However, the figures in column (v) of Table 3 can be adjusted in a straightforward manner to explore the broad implications of different hypothetical trajectories in future per capita emissions. For example, if during 2000–2050 per capita emissions in the world’s more developed regions were to fall by 40% (which many might regard as optimistic) then the total volume of their emissions in 2050 would be about 8.9 billion tons (i.e. 0.6*14,787), and—assuming no change in per capita emissions for the developing regions—then the total volume of world emissions in 2050 would be about 23.7 billion tons (compared to the 23.2 billion that was being emitted around the year 2000). This suggests that a 40% reduction in per capita emissions in the developed regions would be outweighed solely by the effects of demographic growth elsewhere in the world. Alternatively, if per capita emissions were to double (i.e. increase by just 100%) in the developing regions over the same period then their total emissions in 2050 would be around 29.6 billion tons (i.e. 2.0*14,826), and—assuming no alteration in the per capita emission levels of the developed regions—then the total volume of global emissions in 2050 would be about 44.3 billion tons i.e. a 90% rise compared to the 23.2 billion tons being emitted around the year 2000. This calculation underscores the big influence that increased fossil fuel burning to support economic growth in the developing regions is likely to have on the volume of world CO2 emissions. Finally, consider the case in which per capita emissions in the developed regions fall by 40% while those in the developing regions double. This combination would produce global CO2 emissions in 2050 of 38.5 billion tons (i.e. 8.9+29.6)—an increase of about 66% compared to the year 2000.

Several conclusions arise from these simple illustrative calculations. First, the period 2000–2050 will see substantial demographic growth—forcing total world CO2 emissions to rise. Because most of this growth will occur in poor regions, the implied proportional growth in total CO2 emissions (here 28%) is appreciably less than the population increase (49%). Second, the influence of population growth on future CO2 emissions will not be confined to the developing world. North America, and to a lesser extent Oceania (which here effectively means Australia/New Zealand), both have very high per capita emission levels and are expected to experience significant demographic growth—much of it due to migration. Consider, for example, that in Table 3: the population of South-central Asia increases by 1010 million in 50 years, which implies the emission of an additional 931 million tons of CO2; and the population of North America rises by only 123 million, which implies an additional 2458 million tons of CO2. Third, even should the developed regions make big cuts in their emissions, these will be more than offset by rises elsewhere. Thus the effect of population growth in the developing regions alone would outweigh a 40% reduction in CO2 emissions in the developed regions. Yet economic development will likely mean that the total emissions of the developing regions will rise by much more than is implied just by demographic growth. Finally, as a consequence, it is virtually certain that there will be a significant rise in global CO2 emissions. This will happen due to population growth, but it will happen much more because of the fueling of economic growth.

Of course, there is great uncertainty about just how big the coming rise in annual world CO2 emissions will be. The IPCC, for example, has developed many different scenarios for future CO2 release (both from fossil fuel burning and changes in land use) and explored scenarios for other GHGs and sulfur emissions. This work underscores the critical importance of economic and technological changes for the future evolution of emissions. But the resulting range of variation in emissions between the different scenarios is huge. Thus, towards the extremes, over the period 2000–2050 annual CO2 emissions from fossil fuel use could increase only slightly or quadruple. Furthermore the IPCC is careful not to assign probabilities to any scenario, nor does it express any preferences with regard to them (IPCC, 2001c).

Particularly in relation to oil—and perhaps natural gas—it seems possible that limits to the available reserves may operate to curb the expansion of their use for energy production in the coming decades (World Energy Council, 2004). However, global reserves of coal are ample, and with China and India investing massively in new coal-fired power stations, growth in world coal use is currently much greater than that for either oil or natural gas (British Petroleum, 2005). It is especially difficult to gauge the extent to which per capita CO2 emissions from fossil fuel burning will rise with the anticipated future economic expansion of Eastern Asia and South-central Asia. And, to reiterate, there is much uncertainty regarding whether, and to what extent, developed countries will be able to reduce their CO2 emissions. Even with much greater use of renewable energy sources, and greater use of nuclear, there is little doubt that world use of fossil fuels will rise significantly in the coming decades and that they will continue to dominate in world energy production (e.g. see Bodansky, 2001; International Energy Agency, 2005; Smil, 2003; World Energy Council, 2004). Given the numbers in Table 3, and some simple assumptions, it seems reasonable to hazard that global CO2 emissions from fossil fuel burning could easily rise by somewhere between a quarter and two-thirds during the first half of the 21st century. But we saw too that a combination of constant per capita CO2 emissions in the developed regions, and a doubling in the developing regions, would raise annual emissions by 90%—which would imply an average annual growth rate in emissions of about 1.3% during 2000–2050. In this context it is worth noting that projections made by the International Energy Agency (2005) suggest that between 2005 and 2030 energy-related CO2 emissions may rise by 52%—implying an annual growth rate of 1.7%.

In concluding this section the main point is surely very clear: the absolute amount of CO2 being emitted into the atmosphere each year is almost certainly going to rise appreciably in the coming decades.

Prospects for the Earth’s Temperature and Climate

The coming major rise in CO2 emissions will occur on top of levels of fossil fuel burning that have already helped to raise the level of CO2 in the atmosphere by about 33% (compared to the pre-industrial era) and contributed to an estimated rise in the world’s surface temperature of around 0.6 deg/C. There is little doubt that these trends will continue—and that the Earth’s climate will alter significantly as a result.

Of course, the interconnections between trends in fossil fuel use, CO2 emissions, levels of atmospheric CO2, increases in the world’s temperature, and climate change, are incredibly complex. The elaborate computer general circulation models (GCMs), on which the IPCC draws to make statements about possible future trends, have a lot of limitations (Houghton, 2005:77–114). The GCMs find the task of simulating many of the interconnections very challenging. This is particularly true in relation to the incorporation of feedback mechanisms—the nature and strength of which may change in the future in ways that cannot be readily anticipated. Moreover, the models are especially restricted in their ability to predict sudden shifts. Nevertheless, despite such limitations, in certain key respects—perhaps most notably in relation to global temperature change during recent centuries—the models do provide a reasonable fit to past trends. And this is the more impressive since the results from the models are not tuned to provide a reasonable fit to the data; rather, they stem from established physical principles that are incorporated into the GCMs themselves (Burroughs, 2001:263).

In its most recent assessment, published in 2001, the IPCC underscored that fossil fuel burning will probably remain the dominant influence on the level of atmospheric CO2 during the present century. Furthermore, it is certain that the stock of CO2 in the Earth’s atmosphere will rise. Indeed, the IPCC projections suggest a range of atmospheric CO2 for the year 2100 of somewhere between 540 and 970 ppm (IPCC, 2001b:14). It was noted above that the level in the year 2004 was about 377 ppm, and that during 1977–2004 the average annual increment was +1.61 ppm (Table 2). A continuation of this increment for the rest of this century would produce a level of 531 ppm by the year 2100. It is clear, then, that the latest IPCC projections envisage that the size of the annual CO2 increment may well rise significantly, compared to the general order of the increments conveyed in Table 2. This could happen partly because of the likely coming rise in the volume of anthropogenic CO2 emissions. But it could happen too because there are reasons to think that the net absorptive capacity of the world’s oceans, soils, and terrestrial vegetation (as ‘sinks’ for CO2) may weaken in the future—for example, due to increased microbial activity in soils, forest die-back and forest fires, and changes in seawater chemistry (O’Neill, Landis MacKellar, F., & Lutz, 2001:31; Hadley Centre, 2005:6–7).

The IPCC’s projections of global average temperatures incorporate an allowance for ‘commitment’ to future warming deriving from past CO2 emissions. The most recent assessment of the IPCC is that the average world surface temperature may rise by between 1.4 and 5.8 deg/C over the period 1990–2100. In presenting this range, the IPCC notes that these projected temperatures are higher than those contained in its previous reports. The main explanation for the rise in projected temperatures is that the projections for future sulfate aerosol emissions—which can have a significant cooling influence—have been reduced (IPCC, 2001b:13).

In trying to assess the implications of these IPCC temperature projections, it is worth recalling that the Earth’s surface temperature is thought to have risen by about 0.6 deg/C during the 20th century. Therefore the lowest figure of the latest IPCC range—i.e. an increase of 1.4 deg/C—implies that during the present century the average temperature will rise at roughly twice the rate it did during the 20th century. A temperature increase that lies in the center of the IPCC’s range—i.e. a rise of 3.6 deg/C—means that the Earth’s temperature will increase by about six times as much as it did during the 20th century. Finally, a trajectory that took us to 5.8 deg/C by the year 2100 would mean that the rise in temperature would be roughly nine times as great. In contemplating these figures it should be borne in mind that the rate of temperature increase experienced during the 20th century was itself quite unprecedented in history. Those who maintain that there have been equally warm periods in history—such as during the medieval climatic optimum (e.g. see Avery, 2003)—tend to base their arguments on data that pertain to only certain parts of the world. In fact, it is not possible to deduce that the Earth’s temperature in previous historical times has been higher than that which now prevails (see Burroughs, 2001:104).

The IPCC’s temperature projections tend to evolve in a comparatively smooth way. However, in its various reports the IPCC has also noted the possibility of a major, possibly abrupt, climate ‘surprise’—an unpleasant fact that has tended to be overlooked in commentaries on IPCC reports (Weart, 2003:187). But when any system is being forced the chances of a sudden discontinuity occurring are likely to be raised. For example, it is at least conceivable that at some point in the future the rise in temperature could lead to the cumulative, large-scale release of methane (CH4) from underground or undersea deposits of methane hydrate. In turn, this could contribute to further warming—so stimulating the release of still more CH4. Another conceivable, anticipated, ‘surprise’, albeit one that would unravel over centuries, might involve accelerated ice sheet melting—e.g. of the West Antarctic or Greenland ice sheets—about which there is considerable uncertainty.

However, perhaps the most likely possible ‘surprise’ scenario for the present century is that the rise in temperature could lead to a sudden collapse of the thermohaline circulation system in the world’s oceans. This would probably cause a rapid and major alteration of the global climate. Sudden collapses of the thermohaline system have occurred in the distant past. It seems that a key component of such a collapse would be a shutdown of the Gulf Stream in the North Atlantic. This might lead to a major cooling of northwestern Europe should it occur earlier rather than later in the present century (if it occurred later then the cooling effect might be offset by general warming). That said, it is important to underline that the climatic ramifications of such an event would almost certainly extend worldwide. Such a shutdown could be triggered by decreases in the salinity of the ocean to the east and south of Greenland—itself caused by the melting of Artic ice and increased discharge of fresh water from northern rivers. There is evidence of falls in salinity in these areas of ocean (Calvin, 1998; Palmer, 2003) and of some slowing of water circulation in the North Atlantic (Bryden, Longworth, & Cunningham, 2005). However, most climate scientists believe that the thermohaline system will not collapse during this century (e.g. see IPCC, 2001b:16; Osborn, 2004; Hadley Centre, 2005:4–5)—although no one can be sure.

It is impossible to attach probabilities to the four highly stylized future trajectories that have been raised in this section—namely that Earth’s temperature in the coming century might rise at twice, six, or nine times the rate that happened in the 20th century, or that there might be some sort of ‘surprise’. It should also be stressed that increases of twice or nine times the 20th century rate represent extremes at the ends of an envisaged range. Nevertheless it seems reasonable to conclude that the chances of humanity facing a very difficult situation sometime during this century are considerable—at least, that is the view taken here. A doubling of the rate of temperature rise experienced during the 20th century might well be manageable. But a rise approaching six times the rate would surely be extremely demanding. And any much greater temperature increase—in the direction of the top of the range—would doubtless be disastrous; moreover the same probably applies in the event of a major ‘surprise’. Therefore the range of future temperature trajectories varies from the tractable to the disastrous. The next section considers what could happen, and makes some comments about conventional thinking on the subject.

Thinking on the Consequences of Climate Change

Mainstream thought on the effects of a rise in temperature for the world’s climate, and its people, has at one and the same time been valuable, yet restricted. The temperature rises discussed in the previous section may seem small, but their implications could be immense.

So far as the consequences for the climate are concerned, and with reference to its projected range of temperature increase for the year 2100 (i.e. 1.4–5.8 deg/C), the IPCC valuably summarizes the essentials as follows: the land surface temperature rise will probably be greater than the ocean surface temperature rise; there will probably be more hot days and fewer cold days, but with a reduced diurnal temperature range over most land areas; there will be increases in water vapor in the atmosphere, and rainfall will increase in most locations; in many places there will be more intense rainfall events; in many places there will be an increased risk of drought (e.g. such as those associated with El Niño events); it is likely that there will be increases in the frequency of extreme weather events—like thunderstorms and tornadoes; it is likely that there will be an increase in variability of the rainfall associated with the Asian summer monsoon; glaciers and ice caps will continue to melt; and sea levels will probably continue to rise as the ocean expands due to thermal expansion and the melting of snow and ice—a global mean sea level increase of anywhere between 9 and 88 centimeters over the period 1990–2100 is projected (IPCC, 2001b:13–16). In relation to all these effects there will be variation by world region, and the effects will generally vary directly with the extent of the coming temperature rise.

The task of gauging what the numerous consequences of these possible changes in climate might be for humanity is probably even greater than that of determining the nature of the likely climate changes themselves. This is partly because of the existence of both regional and socioeconomic variation, and because of the multitude of dimensions both of the environment and of human life. However, key elements of the IPCC’s assessment of the implications and consequences of coming changes in climate for human populations include: that natural systems are often limited in the extent to which they can adapt, and that changes in such systems can sometimes be irreversible; that although adverse impacts will probably tend to predominate there will also be beneficial impacts—thus, for example, while the overall effect for world agriculture may be negative, in some locations levels of agricultural production might be raised from some climate changes (e.g. increases in temperature and rainfall); that in most settings—whether between or within countries—the adverse effects of climate change will fall disproportionately upon the poor—for example, ‘[t]he effects of climate change are expected to be greatest in developing countries in terms of loss of life and relative effects on investment and the economy’ (IPCC, 2001d:8), and ‘squatter and other informal urban settlements with high population density, poor shelter, little or no access to resources ... and low adaptive capacity are highly vulnerable [to urban flooding]’ (IPCC, 2001d:13); that there will probably be appreciable increases in the geographical areas and human populations that are subject to water stress, to flooding and to food insecurity as a result of climate change; that disaster losses due to extreme weather events are likely to rise substantially; that the adverse impacts of climate change will be greater with more rapid warming; and, lastly, that adaptation is a necessary strategy to complement efforts at climate change mitigation—thus, ‘[f]or each anticipated adverse health impact there is a range of social, institutional, technological, and behavioral adaptation options to lessen that impact’, and ‘[a]daptation to climate change presents complex challenges, but also opportunities, to the [insurance and financial services] sector’ (IPCC, 2001d:12 and 13).

Given the sheer magnitude of the task, the IPCC’s exploration of the likely consequences of the coming change in the world’s climate is commendable. However it is open to criticism in several key respects. For example, questions arise about the vocabulary that is used. The single most important theme is usually that of ways of adapting to climate change. But ‘adaptation’, and similar words like ‘coping’, are not neutral. They presuppose changes to which it will be possible to adjust. Likewise, the analytical perspectives that tend to be employed—for example, that there will be ‘winners’ as well as ‘losers’ (echoed in some of the preceding extracts), can be criticized in that they presume an element of symmetry—yet it could be that on the basis of some future trajectories of temperature and climate, conditions might deteriorate for almost everyone.

Again, and as one might expect, studies of the consequences of climate change tend to proceed sector by sector—for example, examining the possible implications for agriculture, industry, the service sector, health, etc. Almost inevitably this means that it is hard to do justice to the manifold possible interactions between different sectors. In fact, in broad terms, the IPCC’s assessment of the implications of future climate change starts from a consideration of possible ecological changes—for example, relating to water resources, coastal zones, and marine ecosystems—and then proceeds to discuss the implications for the production of goods and services, human settlements, energy, industry, financial services, and health. While this is a reasonable direction in which to proceed, it is not the only possible one. Thus it is arguably less people-centered than, for example, the recent Millennium Ecosystem Assessment—which more specifically considers ecosystems in terms of the benefits that they provide to people (e.g. in terms of timber, clean air, fibers, food, etc). Moreover, and predictably, the dominant social science perspective in these studies is that of economics. Input from, for example, sociologists or political scientists is negligible in the published IPCC reports. Unfortunately this means that some potentially important effects of future climate change receive virtually no consideration at all—for example, as to how people’s views of the world might alter (e.g. in terms of religious beliefs) or the ways in which the behavior of nation states in the international arena might change (e.g. towards positions that are even more dominated by instrumentalism and national self-interest than applies now).

A common thread behind the issues raised in the preceding paragraphs is that study of the possible consequences of future climate change tends to shy away from contemplating circumstances that incline in the direction of a rapid and sustained temperature increase or the occurrence of a major ‘surprise’ (for exceptions see National Research Council (2002) and Stipp (2004)). It has been argued here, however, that there is a good chance that such circumstances might arise. This is not the place to consider the possible consequences of more rapidly warming climate scenarios or those involving a major unexpected happening, but a few observations are relevant by way of conclusion.

First, consider that the world’s population later in this century will probably be around nine billion. The addition of an extra three billion people will mostly be those who are poor and relatively vulnerable. Second, the continuing process of urbanization will mean that extremely large numbers of people—probably several billion—will be living in low lying, densely populated, coastal areas of the developing world, and their situation is likely to be particularly exposed. Third, probably the most important consequence of future climate change for human populations relates to agricultural production in the world’s tropical and semi-tropical regions (IPCC, 2001d). Food production in such regions is an activity that is unlikely to be able to adapt to a rapid rise in temperature, and it will almost certainly not be able to cope with any abrupt change in climate. Perhaps no economic generalization is sounder than that small declines in food production can produce big rises in food prices—often with very significant sociopolitical ramifications. Fourth, more thought needs to be given to circumstances in which several adverse changes occur simultaneously and to cumulative adverse effect. This is the matter of how various potential harmful developments might interact. For example, flooding of coastal areas, which might result partly from sea level rise and partly from increased rainfall, could lead to the simultaneous loss of cropland and urban infrastructure, producing food price rises, large scale migration, and possibly significant sociopolitical disruption.

Finally, any really major or abrupt change in the world’s climate could well lead to a situation in which virtually everyone loses and nobody wins. This could happen, for example, through the likely severe adverse effects on agriculture everywhere. In such circumstances it would be especially naive to believe that only poor countries would be badly affected. Indeed, it is worth considering the notion that the very interdependent complexity and high degree of specialization that characterize the world’s most economically advanced countries could well be a potential source of significant vulnerability for some of them. A rapid rise in temperature or sudden change in climate would have consequences that may be almost inconceivable to those of us who have grown up in a generally improving world, one underpinned by massive increases in the use of fossil fuel energy.

Conclusions

The view taken in this paper has been that there is a very appreciable chance of major climate change occurring at some point during the present century. To have this view is not to deny that there is scope for technological change to reduce CO2 emissions per unit of energy; nor is it to deny that changes in human behavior could alter the volume of global CO2 emissions, and therefore the world’s future temperature and climate trajectory over the longer run. Furthermore, it is quite possible that future change in the world’s climate will be modest, manageable, and perhaps even beneficial for many people. That said, the chance of some sort of large-scale ruinous development happening—such as global warming at a quite unmanageable rate, or the occurrence of some kind of abrupt climate change—appears to be just as great.

It is all too easy to get distracted by detail. Accordingly, as was intimated at the paper’s start, the approach adopted here has been to step back, look at the big picture, and try to focus on the essentials. With this in mind, the paper has brought together material on per capita CO2 emissions and population projections, and it has presented data on levels of atmospheric CO2 and measures of the world’s surface temperature. The purpose of doing this is so that, to some extent at least, the reader can make up his or her own mind regarding past and future trends.

It can be predicted with considerable confidence that levels of anthropogenic CO2 emissions are going to rise significantly. It is virtually certain that the level of CO2 in the Earth’s atmosphere will continue to increase monotonically in the coming decades. It is very hard to envisage that the figure will not exceed 530 ppm by the end of this century. It is likely that the world’s surface temperature will continue to rise at a pace that is quite unprecedented during human history. Looking at the more immediate term, it seems very likely that the first decade of the 21st century will supplant the 1990s as the warmest decade since reasonable direct measurement began. There seems to be fair reason to expect that the next secondary peak in the temperature cycle may occur around the year 2010. Indeed, Hansen et al. (2005:4) observe in relation to 2005 that: ‘the trend of global temperatures toward global warming is now so steep that in just 7 years the global warming trend has taken temperatures to approximately the level of the abnormally warm year of 1998.’ Anyhow, the time series presented in this paper can be updated—since just how these measures change during the coming years should be extremely interesting, and help us to determine just where the world is heading.

Denial and avoidance have also been very significant themes in the opinion that has been expressed here. Understandably, people don’t like to confront difficult issues, nor do they like to change their behavior much. As was intimated at the start, there is a broad parallel here with respect to HIV/AIDS. Within 5 years of its identification, all the main transmission routes of this disease were known, the virus was isolated, tests had been developed, and the first antiretroviral drug was available. It is perhaps worth adding that there was also some optimism among the scientific community about developing a vaccine and ‘conquering AIDS’ (Curran, 2001). Yet any such optimism was to see things in much too narrow, clinical-medical terms; it was to massively underestimate the human, the social side. Denial, avoidance and recrimination were rife with respect to HIV/AIDS—they still are—and, partly as a result, perhaps some 60 million people have either died of the disease or are currently infected. There is much evidence that people only really change their sexual behavior when evidence of damage becomes plain. Similarly, the thrust of the position taken here with respect to global warming and climate change is that people will only really alter their behavior with respect to energy use when they experience serious effects from these phenomena for themselves. That said, the purpose of this piece has been to try to comment objectively on the subject, rather than to try to alter behavior.

That modern economic growth and the demographic transition both began at around the same time in history is hardly coincidental. Population growth, migration, and urbanization all play significant roles in the subject of global warming and climate change. However, the most important part, by far, is that played by fossil energy—coal, oil and natural gas—in fueling economic development. It is important to remember that what still locks so many people in conditions of material poverty is their reliance upon economies that remain overwhelmingly ‘organic’ i.e. they have no real access to the energy supplied by fossil fuels. If there are major changes to the world’s climate in the coming century then the agricultural, economic, political and wider social repercussions could be so great that they impact on the future growth trajectory of the human population. While our children or grandchildren may not face the end of the world, they could well face the end of the world, at least as we have known it.

Copyright information

© Springer Science+Business Media, Inc. 2006