PAST OIL FORECASTS



Oil Forecasts, Past and Present

R.W. Bentley, c/o Department of Cybernetics,

The University of Reading, Reading RG6 6AY, UK.

(Tel: +44 118 931 6796; E-mail: r.w.bentley@reading.ac.uk)

International Workshop on Oil Depletion, Uppsala, Sweden, May 23-24, 2002.

Introduction

One of the reasons that people are inclined to ignore current global oil depletion calculations is their impression that past oil forecasts have been wrong, particularly those made in the 1970s. This view sees the present forecasts as just another example of ‘crying wolf’. 1

This paper summarises a range of global oil production forecasts made between 1972 and the present day. On examination, most reputable oil forecasts made in the 1970s look like they will be substantially correct.

This paper also discusses the forecasts contained in the Club of Rome’s report: The Limits to Growth.

Past Forecasts

From as early as the nineteenth century there have been warnings of oil exhaustion that have proved premature. Many of these, however, (including some enumerated by the U.S. DoE) correctly indicated that production from a particular region or country would decline, but overlooked the scope for new discoveries elsewhere.

The 1970s and early 1980s produced their own crop of erroneous forecasts. Some predicted oil exhaustion based only on proved reserves, ignoring the existence of probable and possible reserves, and of oil yet to be discovered; while others assumed a continuation of the high demand growth-rates of the 1950s and 60s. Other erroneous forecasts included one from the CIA that assumed structural decline in the Soviet Union; and the UK’s UKOOA which forecast UK production based only on areas then-licensed.

In general, oil forecasts made in the 1970s fit into one of four categories:

(a). Non-quantitative fears of global supply scarcity, based on the experience of shortages that occurred during the oil shocks.

(b). Predictions that global oil would run out (i.e., reach exhaustion) in 30 years or so, based on the then-proved oil reserves of about 30 years’ worth of current production.

(c). Predictions of oil global exhaustion on a shorter timescale, based on the then proved oil reserves (or some larger amount), but with demand assumed to rise at a fast exponential rate.

(d). Predictions that global oil production would rise substantially, reach a resource-limited maximum production rate around the year 2000, and decline thereafter. This was a very different view to predicting near- or medium-term oil exhaustion.

Nearly all reputable organisations of the time took this fourth view: that world oil production would continue to grow rapidly until reaching a resource-limited physical peak some time around the turn of the century. This view was also expressed in many energy textbooks and monographs of the day. (See Table, below.)

This fourth, ‘production peaking’, forecast was based on:

- the then well-accepted estimate for the World’s original endowment of recoverable oil (the conventional oil ‘ultimate’) being roughly 2000 billion barrels;

- the knowledge that the global production peak would not occur until something like half of this, 1000 billion barrels, had been used;

- the knowledge that only about 300 billion barrels had been consumed at that date (i.e., it would need the consumption of an additional 700 billion barrels before the ‘mid-point’ was reached);

- the assumption that production would follow an ‘unconstrained’ logistic (‘Hubbert’) production profile.

On this basis, the global ‘midpoint’, i.e. the point at which global oil production would reach its maximum, was calculated to lie around the year 2000, (a precise calculation by Hubbert gave the date as 1996).

In the event, global demand was substantially curtailed by the price rises of the oil shocks, and the unconstrained logistic profile was not followed. This pushed the global conventional oil production peak out to around 2010 (see Figure, below).

Current Forecasts

To-day, there is a wide range of estimates for the World’s original endowment of conventional oil (i.e., recoverable oil excluding the tar sands, etc.). These vary from about 2000 Gb (including deepwater and polar oil, but excluding NGLs) up to about 4000 Gb. The majority of estimates, however, are close to the 2000 Gb figure (see the Table, below). Moreover, detailed analysis shows that oil producing regions reach their maximum production levels at about the mid-point (50%) of the estimates that make up the 2000 Gb number, and at much lower percentages for the higher estimates of ultimate. 2

The conclusion is that the global peak in the production of conventional oil is most realistically forecast by taking the mid-point of an estimate for the original endowment of conventional oil of about 2000 Gb, i.e., in agreement with the majority of the reputable forecasts made in the 1970s.

This is illustrated in the Table, which lists and comments on a range of forecasts up to the present day.

[pic]

Figure. World Oil: ‘Logistic Curve’ Forecast; and Actual Demand.

This graph is for ‘narrowly-defined’ conventional oil (i.e., excludes oil with API < 17.5,

oil in waters deeper than 500m, oil in polar regions, and NGLs).

Left-hand scale:

- Vertical bars: Global oil discovery by year: finds prior to 1930 shown in 1930.

(The discovery in 1948 of the world’s largest field, Saudi Arabia’s Ghawar, is

clearly visible.)

Right-hand scale:

- Small squares: An unconstrained logistic (‘Hubbert’) curve with an area of 1800 Gb.

- Large diamonds: Actual production up to 1999.

- Dots: Estimated future production.

N.B. The total area under the (actual + forecast) production curve is also 1800 Gb.

The short plateau in production, ~2000 to 2008, is based on the assumption that

price will curb demand.

As can be seen, the high prices from the oil shocks cut the top off the unconstrained

curve, and shifted the date of peak by about 10 years.

Source: C.J. Campbell. [Gb: Billion barrels; Gb/a: Gb per year.]

The ‘Club of Rome’ Report: The Limits to Growth

Because of its importance in many people’s perception of resource limits, it may be useful here to also discuss the Club of Rome report: The Limits to Growth. 4

This report was a key contributor to the 1970s understanding that resources are finite; that man’s use of these could reach limits within comprehensible time-spans; and that the complex interactions between resources, population, capital and pollution require system thinking if a proper understanding is to result.

Prior to the report, oil use had been growing at around 7% per year, and the calculations of the Club of Rome correctly showed that if this sort of growth rate were to continue, a resource base of almost any feasible size would be exhausted in a surprisingly short time-span.

The authors gave a table (p 58) listing the then-current proved reserves of various minerals, including oil at 455 billion barrels. The authors recognised that the figure they gave for each mineral represented only the resource discovered so far, and suggested that a larger amount, up to perhaps six times as much, might represent the total useful quantity of that mineral. (In oil’s case, co-incidentally, six times 455 Gb is roughly correct for conventional oil’s original endowment, i.e., ‘ultimate’).

But the authors made no use of these then-current resource numbers in their modelling. Instead they assumed, in their 'standard computer run', that all non-renewable resources, lumped together, had a resource base in 1970 of 250 years' supply at 1970 rates, (p 126). The standard run then showed that society would collapse in less than a hundred years due to resource depletion, itself driven by:

- population growth,

- compounded by an increasing per capita use of non-renewable resources,

- and further compounded by the assumption that the material capital to extract the

resources increases as the resources themselves are depleted.

Finally a point is reached where too little capital is left for future growth, as investment cannot keep up with depreciation (p 125), and the industrial base collapses, taking food and service production with it. If the authors doubled the resource base (p 127), society still collapsed, now primarily due to pollution limits, but also to severe restraints on resource availability.

Interestingly, in the sequel: Beyond the Limits,5 estimates are given for oil's ultimately recoverable reserves (as opposed to then-current proved reserves given in the previous book), with an acceptable range of 1800 - 2500 billion barrels (Table 3-2, p 71). But the authors appeared unaware of the dramatic implication of applying a logistic curve to these data (i.e., of applying the Hubbert 'decline from the mid-point' argument).

Overall, to-day, many people’s perceptions of the Club of Rome’s report (unaware of the details of its simulations) are that: since no major resource shortages have appeared, the report was fundamentally flawed; forecasting resource limits is a fool's game; and that man's ingenuity and skill will always overcome the outdated Malthusian nightmares of resource depletion. The report would seem to be due for re-consideration.

Conclusions

Nearly all the global oil forecasts made by reputable organisations in the 1970s combined ‘mid-point peaking’ arguments with realistic estimates for the World’s original endowment of conventional oil. Hence these forecasts gave, in quantitative terms, exactly the same warnings of the ‘wolf’s’ approach as given by to-day’s oil depletion calculations; namely, that global production of conventional oil will peak, and then inexorably decline, when roughly 1000 Gb have been produced.

Taken together, past and present oil forecasts based on estimates of the recoverable oil resource base thus constitute a consistent 30-year series of warnings of oil supply difficulties that it would be wise to heed.

Table: Some Forecasts of World Oil Supply based on Recoverable Resource

|Date of |Source |Forecast Date of Conventional Peak |Ultimate assumed* |Notes |

|Forecast | | | | |

|1972 |ESSO |“Oil to become increasingly scarce | 2100 Gb |[1] |

| | |from about the year 2000.” | | |

|1972 |Report for the UN |“ likely that peak production will | 2500 Gb |[2] |

| |Confr. on Human |have been reached by the year 2000.” | | |

| |Environment | | | |

|1974 |SPRU, Sussex | n/a | 1800 – 2480 Gb |[3] |

| |University, UK | | | |

|1976 |UK Dept. of |Peak: “about .. 2000.” | n/a |[4] |

| |Energy | | | |

|1977 |Hubbert |Peak: 1996. | 2000 Gb (Nehring) |[5] |

|1977 |Ehrlich et al. |Peak: 2000. | 1900 Gb |[6] |

|1978 |WEC / IFP | n/a | 1803 Gb |[7] |

|1979 |Shell |“.. plateau within the | n/a |[8] |

| | |next 25 years.” | | |

|1979 |BP (Oil Crisis … |Peak (non-communist world): 1985. | n/a |[9] |

| |again?) | | | |

|1981 |World Bank |“.. plateau around the | 1900 Gb |[10] |

| | |turn of the century.” | | |

|1995 |Petroconsultants |Peak: 2005. | 1800 Gb, (excl. NGLs) |[11] |

|1997 |Ivanhoe |Peak: 2010. |~ 2000 Gb |[12] |

|1997 |Edwards |Peak: 2020. | 2836 Gb |[13] |

|1998 |IEA: WEO 1998 |Peak: 2014. | 2300 Gb refnce. case |[14] |

|1999 |USGS (Magoon) |Peak: ~2010. |~ 2000 Gb |[15] |

|1999 |Campbell |Peak: ~2010. | 2000 Gb (incl. polar |[16] |

| | | |and deepwater oil) | |

|2000 |Bartlett |Peak: 2004, or 2019. | 2000, or 3000 Gb |[17] |

|2000 |IEA: WEO 2000 |Peak: “Beyond 2020.” | 3345 Gb (from USGS) |[18] |

|2000 |US EIA |Peak: 2016 - 2037. | 3003 Gb (from USGS) |[19] |

|2001 |Deffeyes |Peak: 2003 - 2008. |~ 2000 Gb |[20] |

|2002 |Smith |Peak: 2011 - 2016 | 2180 Gb |[21] |

|2002 |‘Nemesis’ |Peak: 2004 - 2011 | 1950 - 2300 Gb equiv. |[22] |

* ‘Ultimate’ is an estimate of the world’s original endowment of conventional oil; i.e., the amount of recoverable oil present before extraction started. Conventional oil is generally taken to exclude very heavy oils, tar sand and shale oils, and natural gas liquids. (Gb = billion barrels.)

Notes to Table

[1]. The Ecologist. A Blueprint for Survival, Penguin, London, 1972; see pp 18 and 130. This report looked at the impact of continued exponential demand growth on oil’s lifetime, but also presented the ESSO forecast given here. As mentioned above, the calculations of the 1970s did not foresee the global demand reduction from the oil shocks, so assumed production would rise to peak at about 100 million barrels per day, (36 Gb/a). This put the conventional oil peak earlier than if based on actual demand.

[2]. B. Ward & R. Dubos, Only One Earth: the Care and Maintenance of a Small Planet, Penguin Books, UK, 1972, p 184. This was a landmark report. Its status was ‘an unofficial report commissioned by the Secretary-General of the United Nations Conference on the Human Environment’, Stockholm, 1972. A committee of 158 extraordinarily eminent ‘scientific and intellectual leaders from fifty-eight countries served as consultants’ in the report’s preparation. The full extract (p184) is: “One of the most quoted estimates for usable reserves [of oil] is some 2500 billion barrels. This sounds very large, but the increase in demand foreseen over the next three decades makes it likely that peak production will have been reached by the year 2000. Thereafter it will decline.”

[3]. H.S.D. Cole et al., Eds. Thinking about the Future: A Critique of 'The Limits to Growth', Science Policy Research Unit, Sussex University, Chatto & Windus, 1974. This quotes a variety of estimates of ultimately recoverable oil reserves made mostly in the 1960s, including those of Hubbert in 1969 and Warman in 1971.

[4]. W. Marshall. Energy research and development in the United Kingdom, Energy paper No. 11, UK Department of Energy, 1976; p 12.

[5]. M.K. Hubbert. Project Interdependence: U.S. and World Energy Outlook Through 1990. Congressional Research Service, Washington, 1977, p 624; quoted in: ‘The Global 2000 Report to the President’, Penguin’, 1982, p 353. Hubbert took Nehring's world ultimate oil reserves estimate of 2000 billion barrels, and assumed that oil production would be limited only by resource availability. On this basis, he calculated that world production would reach a peak at about 100 Mb/d, around the year 1996.

[6]. P.R. Ehrlich, A.H. Ehrlich and J.P. Holden. EcoScience: Population, Resources, Environment. W.H. Freeman, San Francisco, 1977, ISBN 0-7167-0567-2, pp 400-404. A widely-quoted textbook. 3 The authors calculated a ‘Hubbert’ peak based on the ‘high-estimate’ for global conventional oil endowment of 10900 trillion MJ (~ 1900 Gb). (Interestingly, the book also draws attention to the then-controversy which led to the USGS revising down, by a factor of 3, its estimates for US undiscovered recoverable oil and gas.) [As an aside, it is probable that the famous Simon vs. Ehrlich, Harte and Holdren ‘commodity price bet’ failed in large measure because of the more than two-fold fall in the real-terms oil price (reflected also in other energy prices) between 1980 and 1990; energy being a large component of mineral extraction costs. Since the high price of 1980 was driven, fundamentally, by the US oil peak nearly a decade earlier, the conclusions generally drawn by economists from the outcome of that bet probably merit revision.]

[7]. J. Kiely. World energy in the 21st century. The Fourth Wilson Campbell Memorial Lecture. Reported in CME (Chartered Mechanical Engineer?, IMechE., UK) May 1980, pp 26-32. This paper reports the outcomes of a major study from a Commission established by the World Energy Conference (now the World Energy Council), whose report: World Energy: Looking Ahead to 2020 was to ‘study energy resources, conservation, demand and possible strategy to supply energy to the year 2020.’ “Arrangements were made for individual nations with particular expertise to make the resource based study. The French Petroleum Institute prepared the Petroleum Resources and Production study, …..”

Kiely’s article very presciently opens with: “The world can have the energy it needs for the rest of the 20th century. … But herein lies the real problem. With a false sense of security, many will not look over the horizon to the early part of the 21st century. … It is only by looking beyond the early 2000’s that we can see how fast the change will come.”

[Note that for oil and gas the report evaluated the potential for unconstrained supply; and compared these figures to anticipated demand. For the year 2000, the report estimated potential supply of oil to be 34 Gb/yr.; of gas, 143 Tcf/yr. (Actual production in 2000 was oil: 27 Gb; gas: 85 Tcf.)]

[8]. A.F. Beijdorff. Energy Efficiency, Group Planning, Shell International Petroleum Company, London, April 1979; p 1. (Current modelling suggests the world peak may be fairly sharp, rather than the long plateau suggested in this Shell study.)

[9]. BP report Oil crisis ... again ?, published in 1979. In terms of UK views, this report is one of the more significant of the examples of erroneous forecasts that people (e.g., J. Mitchell, P.R. Odell) choose to quote. It indicated that non-communist world oil production would peak in 1985. However, this forecast bears examination. The first step is to add back in communist production. Then, like other forecasts of that time, the report assumed rising production when high prices were in fact reducing demand. Adjusting for this, and for the subsequent increases in production of NGLs and non-conventional oil, makes the resulting prediction look reasonable; forecasting a fall in global conventional oil production from around the year 2000.

[10]. The World Bank. Global Energy Prospects, World Bank Staff Working Paper No. 489, 1981. See pp 37, 46. The report said: "The bulk of the world's reserves, principally in the Middle East, was built up in most part during the 1960s. Despite increased incentives to explore for oil provided by higher prices, conventional oil production is projected to reach a plateau around the turn of the century.” (Note that by the early 1980s, the impact of the demand reduction was becoming visible, and hence the calculated global peak date, for a given assumed ‘ultimate’, fell later.) Elsewhere, p 46, the report quotes ultimate recoverable oil reserves as being 1900 billion barrels, and says: "According to some estimates, the world's ultimate recoverable gas reserves are at least equal to [those of oil]".

[11]. C.J. Campbell and J.H. Laherrère. The World’s Supply of Oil, 1930 – 2050. Report from Petroconsultants S.A., Geneva, 1995. (See also: C.J. Campbell & J.H. Laherrère, The End of Cheap Oil, Scientific American, March 1998, pp 59-65.) This is one of the more detailed studies to date. It used full access to the standard industry oil resource database to carry out analyses of hydrocarbon reserves, with those in particular countries requiring adjustment. It also used a range of statistical approaches to assess the yet-to-find, and the logistic model to generate future hydrocarbon production. As critics have pointed out, this study did not explicitly include the effects of technology or price on the assessments of regional and global ‘ultimates’. But the authors maintain, with considerable supporting evidence, that price and technology have only a limited effect on the size of these ‘ultimates’, at least as they affect calculations of production peak date.

[12]. L.F. Ivanhoe. Updated Hubbert Curves Analyze World Oil Supply. World Oil, Vol. 217, No. 11, November, 1996, pp 91-94. Used USGS discovery data, and the fact that production has to largely mirror discovery. A clear and well-written warning of the problems to come.

[13]. J.D. Edwards. Crude oil and alternative energy production forecasts of the Twenty-First Century: The end of the Hydrocarbon Era. AAPG Bulletin, vol. 81 pp 1292-1305, 1997. A reasonable study, but limited by lack of access to industry data, so arrives at a high global ultimate.

[14]. The International Energy Agency ‘World Energy Outlook’; published Nov. 1998; ISBN 92-64-16185-6. Used the 1994 USGS mean estimate for global conventional ‘ultimate’, of 2300 Gb, for its reference case. It also used a low case of 2000 Gb, (based on the Petroconsultants report) and a high case of 3000 Gb (based perhaps on Odell’s data). The rate of discovery that would support the high case ‘ultimate’ was not examined. The study did not specifically account for the impact of likely price and technology developments, though it did examine the scope for non-conventional oils to come on-stream.

[15]. L. Magoon. USGS Open File Report, 00-320 Version 1. The main USGS 2000 survey (Ahlbrandt et al.) examined total oil available (basin ‘oiliness’), but did not look in detail at the rate at which these resources can be discovered. Magoon of the USGS endorsed data in the Scientific American article by Campbell & Laherrère on the rate at which the resources can become available.

[16]. C.J. Cambpbell. Oil Reserves and Depletion. PESGB Newsletter, Petroleum Exploration Society of Great Britain, March 1999, pp 87-90. A partial update of the 1995 Petroconsultants report. It analysed polar & deepwater oil separately, but added these back in the full analysis.

[17]. A.A. Bartlett. An analysis of US and world oil production patterns using Hubbert-style curves. Mathematical Geology, 32/1, pp1-17, 2000. Bartlett does not have access to the industry data, so simply predicted peak based on these two assumed values for the conventional ‘ultimate’.

[18]. The International Energy Agency. World Energy Outlook, 2000. Used the USGS 2000 survey mean oil-plus-NGLs ‘ultimate’, including reserves growth, of 3345 Gb. The IEA state that such data are “authoritative”, but, as mentioned above, the data pay no attention to the rate that such oil can be discovered. Note that USGS 2000 data include a large allocation for reserves growth, contrary to the decision of Masters for the previous survey. The USGS team has subsequently re-evaluated its approach of basing global reserves growth on the US’ experience.

[19]. US Energy Information Administration website, 2001. Uses the USGS 2000 mean ‘ultimate’ of for conventional oil (excluding NGLs, but including reserves growth), of 3003 Gb. If the world decline rate is taken as 2% p.a., this puts peak at 2016. If a much steeper (probably unrealistic) decline rate of 10% p.a. is assumed, this puts the peak later, at 2037.As with the IEA 1998 World Energy Outlook above, this study uses USGS 2000 survey results in an uncritical manner, both on the rate of discovery of oil, and on the scope for reserves growth outside the U.S.

[20]. K.S. Deffeyes. ‘Hubbert’s Peak’, Princeton University Press, 2001; ISBN 0-691-09086-6. Uses a range of statistical techniques, based, essentially, on the discovery trend curve indicating the likely ‘ultimate’. As Laherrère has shown, this basic approach is robust, and correctly captures the discovery/production behaviour of most basins and regions. However, Deffeyes’ study has no direct access, we believe, to the industry database.

[21]. M.R. Smith. Analysis of Global Oil Supply to 2050. Consultancy report from The Energy Network, March 2002. Production estimates are based on detailed country by country exploration analyses, and use individual depletion curves to meet calculated ‘ultimates’, rather than simple ‘mid-point peaking’. Includes data on the non-conventionals, and expected oil price forecasts. Global ultimate is 2180 Gb, making the global peak in 2011 if global demand is assumed to rise by 2%/yr.; or 2016 at 1%/yr. growth.

[22]. ‘Nemesis’, in a contribution in ASPO/ODAC Newsletter, Issue 15, March 2002. This study generates a range for the dates of peak production, based on cumulative production to-date; plus reserves and ‘net discovery’ data from Campbell and BP’s Schollnberger. This approach avoids the need to use specific estimates of ‘ultimate’, but yields the approximate ‘equivalent ultimates’ listed in the Table.

References

1. For recent examples see:

- Peter Davies (Chief Economist, BP): “There is always a series of geologists who are concerned about imminent depletion of world supplies, they have been wrong for 100 years and I would be confident they will be wrong in the future. As of today there are very adequate supplies of oil and gas. With the proven reserves and today’s technology there is 40 years of oil and 60 years of gas plus. I think there is every reason to believe that technology will continue to exceed the forces of depletion and we have continually replaced both oil and gas reserves over the past 30-40 years, … I would be very confident on the availability of fossil fuels for the foreseeable future.” Evidence to the UK House of Lords Select Committee on the European Union, considering the EU’s Green Paper (Nov. 2000) ‘Towards a European Strategy for the Security of Energy Supply’. Select Committee’s Report: Energy supply: How secure are we?, Session 2001-02 14th Report, HL Paper 82, published 12th February, 2002, page 79.

- T. Emerson: “Bush warns of ‘worst energy-supply crisis since the 1970s’. … The global view suggests, in fact, that there is no supply crisis.” The Thirst for Oil; article in Newsweek, April 8/15, 2002, p 32-35.

2. The explanation is that the global oil production peak date is driven almost entirely by the existing reserves in known fields. This is because the global conventional oil discovery to-date of about 1800 Gb (excluding NGLs) is being augmented so slowly by the discovery of oil in new fields (around 10 Gb/year) that the oil assumed in the high estimates for global conventional ultimate (i.e., estimates much above 2000 Gb) simply cannot be found until after the peak date.

It is easy to verify this by comparing estimates of conventional ultimate from the USGS year 2000 survey of the world’s oil resources with the cumulative production at the production peak points of the many countries and regions that are now clearly past peak.

Many also still think that improved recovery in existing fields also contributes large volumes of oil to the total available, but detailed analysis shows that most of such apparent ‘reserves growth’ is due to the conservative method of reporting reserves.

For more information, see: R.W. Bentley. Global oil and gas depletion: an Overview. Energy Policy, Vol. 30, No. 3, pp 189-205, Elsevier, February 2002; and: R.W. Bentley, R.H. Booth, J.D. Burton, M.L. Coleman, B.W. Sellwood, G.R. Whitfield. Perspectives on the Future of Oil. Energy Exploration and Exploitation, Vol. 18, Nos. 2 & 3, pp 147-206, Multi-Science Publishing Co. Ltd., 2000.

3. Other influential books from the 1970s, at least on this side of the pond, include:

- G. Foley, with C. Nassim. The Energy Question, Penguin Books, Middlesex, ~1975. This contains a fascinating discussion of the then-generally available data on oil resources; including an early understanding of apparent discrepancies in the data from Professor Odell.

- J.G. McMullan, R. Morgan and R.P. Murray. Energy Resources and Supply, Wiley, 1976. This has an excellent graph, Figure 1.3, showing the possible future production from a wide range of fuels, including fission and fusion. For conventional oil it shows a peak soon after the year 2000. (Professor John McMullan is now at Ulster University, and was Chairman of the DTI’s ‘Foresight Programme’ Energy Futures Task Force).

- G. Leach et al. A Low Energy Strategy for the United Kingdom, Science Reviews, London, 1979, ISBN: 0-905-927-20-6. Page 9 has: “Forecasts show energy needs rising implacably, with widening energy gaps appearing around the turn of the century as oil and gas production begin to decline.” (Gerry Leach is now with the Stockholm Environment Institute, and is based in London.)

4. D.H. Meadows, D.L. Meadows, J. Randers and W.W. Behrens III. The Limits to Growth, Earth Island, 1972.

5. D.H. Meadows, D.L. Meadows, J. Randers. Beyond the Limits, Earthscan, 1992.

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