The conflict over global warming

Sophisticated computer models have been employed by the United Nations Environment Programme’s Inter- governmental Panel on Climate Change (IPCC) to assess past variations of world climate and to project possible trends over the next century. Attention has focused on the growing concentration of carbon dioxide (CO,) and other greenhouse gases that contribute to global warming. Critics in scientific and policy professions hold that simulation models are not yet adequate to guide policy decisions. Many western governments dissent from this judgment and insist that a 20% reduction in CO2 emissions should be achieved within 15 years and that remedial policies must be adopted to prevent catastrophic climate change. The proposed remedies range from saving tropical rain forests to forced conservation of energy or taxation of fossil-fuel combustion. A consensus is emerging in the scientific community to endorse a ‘no regrets’ policy that involves buying various kinds of ‘insurance’ against future global warming.

The authors are with atmospheric science and public policy programmes in the State University of New York at Albany, 1400 Washington Avenue, Albany, NY 12222, USA.

The conflict over global warming

The application of scientific research to policy choices

Volker A. Mohnen, Walter Goldstein and Wei- Chyung Wang

The rise of ecological advocacy groups and green political parties in the 1980s took many western societies by surprise. It had been widely believed that public opinion would remain passive or confused when complex scientific issues were debated. To many scientists it was a matter of astonishment that public opinion responded with anxiety on learning that global average temperatures had risen in the past 150 years, and that they would continue to climb dangerously in the next century if remedial action were not started.

Concern about the habitability of Earth was voiced by the popular press, by governments’ enquiry panels, and in cautious reviews appear- ing in scientific and technical journals. Scientific advisers warned that a historic catastrophe was brewing and that irreparable damage would be done to the biosphere early in the next century. But there was another side to the debate. Scientists in several countries insisted that the ‘warming panic’ amounted to hysteria and scientific overkill. A worst- case scenario had been projected of the heat-trapping gases that were accumulating in the atmosphere; and projections of global warming had been broadcast that were neither reasonable nor accurate.

The debate intensified as scientists moved from analytical pursuits to campaigns of advocacy. An international group of experts submitted to the United Nations Environment Programme (UNEP) the results of two years of intensive study. Their reports were guilty either of scare- mongering or of excessively timid judgment, depending on which critics were to be believed. Basically it was agreed that emissions of human- made greenhouse gases would continue to warm the atmosphere, but opinion differed in predicting how far temperatures would rise and determining what remedial measures should be taken. A rapid increase in concentration of carbon dioxide in the atmosphere (and of other greenhouse gases too) was clearly developing. Simulation models and analytic teams still differed, however, in forecasting the degree of change that would appear in the global climate, sea levels, and weather patterns of the next century.

0959-3780/91/020109-15 0 1991 Buttetworth-Heinemann Ltd 109

The corzflicf over g/oh/ wurrning

Is there a greenhouse effect?

The scientific community accepts the proposition that the process of climate change and the variability of weather trends must be more closely studied; and that computer models of the earth’s climate system must be further refined. While this work proceeds over the next few years, three basic questions remain in contention:

0 Has the climate meusurably changed in the past 150 years, and will it continue to do so in the 21st century?

0 Can climate changes be attributed with certainty to a rise in greenhouse gases (especially carbon dioxide) and to the massive burning of fossil fuels?

0 Is it wise at this early phase of the enquiry to legislate high-cost measures to halt the process of global warming if the testing of climate models and greenhouse consequences is still at a prelimin- ary stage?

The first of a scholarly series of reports’ has been published in recent months by the Intergovernmental Panel on Climate Change (IPCC). The reports were commissioned by the World Climate Research Prog- ramme that is funded by two agencies of the United Nations: the World Meteorological Organization and UNEP. The IPCC reports rely upon mathematical modelling and projections derived from the fastest com- puters. Working with a novel set of general circulation models (GCMs), the IPCC effort has raised the level of sophistication in research on changes in global ecological systems.

The aim of the IPCC panel is to study the climate impact of increases in the concentration of atmospheric greenhouse gases (ie gases which absorb the infrared radiation that is emitted by Earth’s surface). The research methodology is still at a formative stage and doubts about climate assessment remain high. The assumptions plugged into the GCMs are tentative and varied. They posit that global average temperatures will rise as emissions of greenhouse gases increase, but they disagree about the timing, the geographic extent, or the degree of global warming that will occur in the next half century. Predictions range from an increase of 1.5”C to a catastrophic climb of 4.5”C of global warming. They are obviously inexact. It is hoped that a closer study will improve the predictive capacity and the modelling techniques that are now being

developed. No matter how strongly prediction models conflict, it is agreed that

concentrations of carbon dioxide (CO,) and other greenhouse gases are building up at an increasing rate. The human-made emissions of CO2 are running at the somewhat sensational rate of 22.4 gigatonnes (or 22.4 billion metric tonnes) per year. In addition, an accumulation of chlorofluorocarbons (CFCs), methane, and nitrous oxide could also alter the climate (Table 1). They are all potent greenhouse gases, but the primary threat is posed by CO*. The volume of CO2 entering the atmosphere has increased by 25% in the last century, and the rate could speed up

‘J.T Houghton, C.J. Jenkins and J.J. dramatically as the burning of fossil fuels and biomass accelerates.

Ephraums, eds, Climate Change: The It is accepted that a relatively small shift in global temperature could

/PCC Scientific Assessment, Report of the create major problems in large cities, on crop-growing prairies, and in United Nations Environment Programme, Intergovernmental Panel on Climate

poor countries dependent on subsistence agriculture. The heat energy

Change (IPCC), Cambridge University trapped in the atmosphere by radiatively active gases of human-made

Press, Cambridge and New York, 1990. origin creates an ‘enhanced’ greenhouse effect, pushing global tempera-

110 GLOBAL ENVIRONMENTAL CHANGE March 1991

The conj’icr over global warming

Table 1. The principal greenhouse gases.”

Concentration: Pre-industrial

Present

Lifetime in atmosphere (years)

Global warming

1

20 years potential 100 years relative to COzb 500 years

Contribution to total radiative effect 198&90 (%)

co2 280

ppmvC 353

ppmv

(50-200)

1

55 15 24 (all CFCs) 6

CH, 0.79 wmv 1.72

ppmv

10

63 21

9

CFC-11 CFC-12

0 0

280 484

PPt+? PPtv

65 130

NzO 280

ppbvd 310

ppbv

150

4500 7100 270 3500 7300 290 1500 4500 190

a Data from IPCC Working Group 1; b The warming effect of an emissron of 1 kg of each gas relative to CO, based on the present-day atmosphere: ’ Parts per million by volume; d Parts per billion by volume; e Parts per trillion by volume. Source: Global Climate Change, Briefing Paper Series, Royal Dutch Shell, London, 1990, p 1.

tures ever higher. It appears that the history of the 21st century will turn on the ability to hold global warming stable at 1990 levels.

The authors of the IPCC report express confidence in their findings. They call for a 20% reduction in global emissions of CO;, by the year 2005 and a 50% reduction at a later date. If this is not achieved, there could be increasing drought in the grain lands of the temperate zones, a significant rise in sea levels, and severe climate changes world-wide

(Table 2). The political and economic cost of arresting the process of global

warming could be astronomical. Economic growth might have to be curbed and industrial costs would soar if emission controls were rigorously enforced. Possibly 5% of GNP would have to be appropri- ated to execute corrective policies in the near future. Though allocations of this magnitude might be economically feasible in the USA, Western Europe, or Japan, they would be fiercely contested. The GNPs of the USA and of the 12-nation bloc of the European Community are each valued at $5000 billion. A diversion of 5% would roughly equal the price that each pays for its annual oil supplies or medical care, and it would

Table 2. Estimates for changes by 2030.

Central North America

Warming will vary from 2 to 4°C in winter and 2 to 3°C in summer. Precipitation increases will range from 0 to 15% in winter but there will be decreases of 5 to 10% in summer. Soil moisture will decrease in summer by 15 to 20%.

Southern Asia

Warming will vary from 1 to 2°C throughout the year. Precipitation will change little in winter and generally will increase throughout the region by 5 to 15% in summer. Summer soil moisture will increase by 5 to 10%.

Sahel

Warming will range from 1 to 3°C. Area mean precipitatron will increase and area mean soil moisture will decrease marginally in summer. However, throughout the region, there will be areas of both increase and decrease in both parameters.

Southern Europe

Warming will be about 2°C in winter and will vary from 2 to 3°C in summer. There is some Indication of increased precipitation in winter, but summer precipitation will decrease by 5 to 15%. and summer soil moisture by 15 to 25%.

Notes: (a) these projections are based upon the IPCC ‘Business-as-Usual’ scenano; (b) area Australia

averages hide large variations at the subcon- tinental level; (c) it is assumed that the rate of

Warming will range from 1 to 2°C in summer and will be about 2°C in winter. Summer precrpitation will

change from the pre-industrial era to the present increase by around 1 O%, but the models do not produce consistent estimates of the changes in soil morsture.

will roughly double.

GLOBAL ENVIRONMENTAL CHANGE March 1991 111

“The Economist, 15 September 1990, p 85. ‘S.H. Schnerder, ‘The global warming debate heats up: analysis and perspective’, Bulletin of the American Meteorologrcal Society, Vol 71, No 9, September 1990, pp 1292-I 304. %ee Stephen H. Schneider, ‘The greenhouse effect: science and policy’, Science, Vol 243, No 4892, 10 February 1989, pp 771-781. %obert M. White, ‘The great climate debate’, Scientific American, Vol 263, No 1, July 1990, pp 3643. ‘T.A. Boden. P. Kanciruk. and M.P. Fallell. Trends ‘90:’ A Compendium of Data on Global Change, ORNUCDIAC-36, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, TN, August 1990.

require considerable sacrifice. Nevertheless, an impressive start was made when the German government announced that it would cut CO* emissions by 20% over 15 years if others would follow suit. Nine countries agreed to enact similar measures but many more disagreed, either on principle or because they rejected the assessment of the costs involved.’ The dissidents argued that Draconian restraints and budget expenditures should be delayed until better data had been gathered and until the models’ simulation runs had been validated.

The greenhouse effect and climate change

One-third of the solar energy entering the atmosphere is reflected back into space, leaving two-thirds to be absorbed by Earth and eventually re-emitted as infrared radiation. The contribution to the greenhouse effect over the decade 198CL90 has been carefully estimated (Table 1): 55% came from carbon dioxide (CO?) emissions; 15% from methane (CH1); 24% from chlorofluorocarbons (mainly CFC-11 and CFC-12): and 6”/0 from nitrous oxide (N,O).

Even though greenhouse gases are natural components of the atmosphere. human-made emissions have prompted a sharp increase in their atmospheric concentrations. The accumulation of CO2 in the past decade alone has matched the total recorded between 1850 and 1950. If this rate does not slow down, CO2 levels could double within 25 years. Deep ice-core samples reveal that global temperatures were 7°C lower at the end of the last ice age (20 000 years ago) than they are today.’ Another minor ice age occurred between the 14th and 18th centuries when glaciers rapidly advanced and severe winters struck Western Europe. With the onset of the industrial revolution in the 19th century. measurements of surface temperature climbed 0.5”C. The historical record suggests that small changes in global temperature can provoke significant upheaval in ecosystems. It is in this light that scientists consider the news that the 1980s was the warmest decade known since temperatures were recorded.

Most of the GCMs indicate that average global temperature could rise between l.S”C and 4.5”C between 1850 and 2050 if atmospheric CO? concentrations were to double. Though this rate of increase would be largely attributed to industrial activity, the methodology and the assumptions used by model calculations are still at a tentative stage.” The first aim of the GCMs is to distinguish natural variations in climate from the consequences of fossil fuel combustion. Unfortunately, by the time that convincing proof can be assembled it might be too late to launch corrective measures. But as one noted observer put it, there is reason for hope: the IPCC simulation runs might justify the funding of a ‘no regrets’ package of remedial measures so that insurance can be bought against future risks of disaster.”

The combustion of fossil fuels discharges approximately 6100 million metric tonnes (6.1 gigatonnes) of carbon each year. This converts on a molecular weight basis to 22.4 gigatonnes of carbon dioxide a year.” The significance of these data appears in the alarming rate of increase of CO]. It mounted from 2.1% in 1986-87 to 3.7% in 1987-88. If this pace of acceleration holds, the crisis of global warming will come to a head long before 2050. The burning of liquid and solid fuels - largely oil and coal - accounted for 80% of the discharge, and the burning or flaring of natural gas for the rest. The US share of emissions declined



Table 3. 1988 carbon dioxide emission estimates (million tonnes of carbon).

USA USSR PRC

FRG India UK Poland Canada

TotaP Solid Percentage of total Liquid

Percentage of total Gas

1310.2 493.6 37.7 566.4 43.2 238.6 1086.0 425.3 39.2 334.4 308 302.6 609.9 487.9 80 86.9 14.3 7.5 269.8 82.9 30.8 152.8 56.6 23.5 182.7 78.0 42.7 75.0 41.1 25.1 163.8 117.4 71.7 35.3 21.6 3.5 152.5 66.7 43.7 55.0 36.2 27.0 125.3 106.0 64.6 11.9 9.5 5.4 119.4 26.9 24.2 54.9 46.0 32.5

Percentage of total

18.2 27.9 1.2 8.7 13.7 2.1 18.2 4.3 27.2

Per capitab

5.3 3.8 0.56 2.2 3.0 0.2 2.7 3.3 4.6

Source: T.A. Boden, P. Kanciruk, and M.P. Falleli, Trends ‘90: A Compendium of Data on Global Change, ORNUCDIAC-36, Carbon Dioxide Information Analysis Center, Oak Ridge Natronal Laboratory, Oak Ridge, TN, 1990. aAmounts from other categories are insignificant and have been omitted, thus row totals do not add up to 100%. ‘Tonnes of carbon.

from 42% (after 1950) to 21% of the total as other nations raced ahead to industrialize, but the US volume of emissions still stands unrivalled at 1.3 gigatonnes (Table 3). Difficult as it is to conceptualize, carbon emissions now equal about one tonne a year for each person on the planet. How much more, it must be asked, can the atmosphere take?

The sources of greenhouse gases

Carbon dioxide

Carbon dioxide emissions contribute heavily to the absorption of terrestrial radiation and the increased concentration of CO2 will lead to a perturbation of Earth’s radiation balance. This is known as ‘radiative forcing’ since it leads to a forced change of the global climate system. To the 22 billion tonnes of carbon dioxide each year that are derived from the burning of fossil fuels, biomass burning and deforestation add another seven billion tonnes.

CO* emissions from fossil-fuel combustion vary greatly by region and function. Power generation, industrial production, commercial activity, and transportation account for 75% or more of the carbon from fossil-fuel burning. Logically, the heaviest discharges come from the wealthy industrial countries. This prompts bitter arguments in international policy fora on the environment. If rich countries created so much of the mess, the poor nations ask, why do they insist that all countries must sacrifice resources to clean it up?

Only 4.8% of the world population lives in the USA, but it is the source of 21% of the CO;! derived from fossil-fuel burning (Figures 1 and 2). By contrast, with 15.8% of the world population, India contributes only 4% of global C02. Discrepancies of this order have been cited by countries that refuse to cooperate in environment control. They claim that their low per capita emissions of COZ and their low per capita GNPs justify a position of unconcern.

Yet the need for international action to curtail CO2 is difficult to deny. Projections of CO1 emissions (Figure 3) suggest that emission levels in the less developed countries (LDCs) will escalate more rapidly than in the USA and Western Europe. The two most populous nations, the PRC and India, will create the gravest difficulty. Like many of the LDCs, they argue ‘it is their turn’ to catch up with the pollution spawned by industrialization. They need to manufacture millions of cars, to build extensive power plants, and to exploit their abundant coal resources in a desperate bid to expand GNP. It would help, of course, if the wealthy



5-

Canada,

;i ?

5 4-

Czechoslovokla q

5 DAustrolio

5 -

i Poland

0

% 3- OWest Germany

?

; Romonla 0 OUK

B

$ South Africa c, aJapan

g 2-

Figure 1. 1988 per capita emissions z FranceDo Italy

of carbon and total emissions of car- & - bon. a Spa~nooKorea

I- O Mexico

Source: T.A. Boden, P. Kanciruk, and M.P.

USA q

q USSR

Global overage. q

1.2 per person

Fallell, Trends ‘90: A Compendium of Data on Global Change, ORNUCDIAC-36, Car- bon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, TN, August 1990.

Bra211 0 lndla

0 Chino

Y

I I1111111 I I I Illlll I I I IIIII 100 IO00 10000

Total carbon emwlons from fossll fuels (tonnes x IO61

countries simply gave them efficient power sources or energy conservation technologies without charge. But opponents object since such transfers breach the commerical rules of the marketplace.

Carbon dioxide is not the only contributor to global warming. Three other gases are also important. Methane (CH,) accounted for one-sixth of the change in radiative forcing in 1980-90. It is a chemically and radiatively active gas with a relatively brief lifetime in the atmosphere. Emissions are estimated at 525 million tonnes a year. Methane gas is produced by ruminant cattle, natural wetlands, rice paddies, landfills, and termites; from venting releases in coal mines, gas drilling, and transmission facilities; and from biomass burning. There is an additional anxiety about methane. It is feared that a slight rise in Earth’s surface temperatures could release vast quantities of methane gases that are now trapped under permafrost at high Arctic latitudes.

Of the remaining greenhouse gases, CFCs account for a quarter of the

change in radiative forcing. CFCs are widely used as retrigerants, propellants for aerosols and solvents, and insulating agents. When the

q North Amerxa

q USSR

Figure 2. Per capita energy consump- i 120

tion by region. s

=

Note: Global average - 53 million Btu per = 60

person (3412 Btu = 1 kWh). Source: World Resources 7990-91, Re- port of the World Resources Institute, Ox- + 0

ford University Press, New York and Ox- 0

ford, 1990, Table 21 .l , p 316.

East Europe 0

q West Europe

Latin Amerlca/Conbbeon 0 Asia/Middle East Chino

q 0 Afnca South Aslo

I I I q I 0 1200 2400 3600 4800

Population (mllllon)


The conflicr over global warming

Figure 3. Human origin of global COn emissions.

Source: K. Yeager, Electric Power Re- search Institute, Palo Alto, CA, 1990, personal communication.

7World Resources 7990-97, Report of the World Resources Institute, Oxford Uni- versity Press, New York and Oxford, 1990, Table 21 .l p 316. %.A. Houghton, ‘Emissions of greenhouse gases’, in N. Myers, ed, Deforesfa- tion Rates in Tropical Forests and Their Climate Implication, Friends of the Earth, London, 1989, pp 5362; R. Monastersky, Biomass burning ignites concern,’ report on Williamsburg conference, Science News, Vol 137, 1990, p 196; J. Shukla, C. Nobre, and P.J. Sellers, ‘Amazon deforestation and climate change’, Science, Vol 247, p 1322. ‘Houghton, Ibid.

0 1950 1985 2020 2060

USA

Other developed countrtes

Less developed countries

destructive impact of CFCs on the ozone ‘hole’ in the Antarctic was confirmed, a Protocol was signed by all major governments, pledging that the production of CFCs will cease within 10 years.

The last gas to note is nitrous oxide (N,O). It is a chemically and radiatively active trace gas that is produced by biological sources in soils, by the burning of biomass, and by fossil-fuel combustion. Global N20 emission estimates vary between 14.5 and 34.5 million tonnes per year, contributing to 6% of change in radiative forcing. All of these greenhouse gases are increasing in concentration and their persistence in the atmosphere will extend well into the next century.

How best to cope with CO2

Arguments over the reduction of CO:! emissions may not be resolved for many years to come, though a consensus is emerging that some form of remedial strategy will have to start soon. Two different types of strategy are available: one draws on biological measures to sustain the carbon cycle; the other requires extensive change in industrial technology, in social behaviour patterns, and in the burning of fossil fuels. The first relies upon the regenerative power of Earth’s forests and oceans. The second looks to a slowdown of global warming by curtailing energy consumption and the wasteful combustion of fossil fuels - it cannot possibly succeed until a radical switch is made to carbon-free fuels and renewable sources of energy.

Biological measures

Halting deforestation and biomass burning

Tropical forests stretch over 13% of Earth’s land surface and account for almost one-half of its forests. More importantly, their vegetation absorbs 40% of the world’s plant carbon.’ It is imperative that the cutting down and burning of these forests be stopped since the accumulation of CO2 in the atmosphere must be moderated by the storing of carbon in trees. The process of photosynthesis can take up XL60 billion tonnes of carbon per year.s If present levels of human-made CO2 emissions are eventually to be reduced by 20%) an additional 1.2 billion tonnes of carbon a year must be stored in the long-lived tree species of the tropical forests.

Tragically, the world is fast losing its forests. Tropical forests have been slashed and burned to make way for agricultural and grazing land.” The need for firewood and for land has become critical in countries


Table 4. Requirements for reforestation.

a J. Holowacz, ‘Forests of the USSR, The Fore- stry Chromcle, Vol 61, No 5, October 1985, pp 366373. b An Am/y.% of fhe Timber Situeffon in the United States, f952-2030, Forest Resource Re- port No 23, US Forest Servce, Department of Agriculture, December 1982. ‘V Smil, ‘Deforestation in China’, Ambio, Vol 12. 1983. DD 22&231. * lnfensive ~u~~ip/e-Use forest ~anagemenf in the Tropics, FAO Forestry Paper 55, Food and Agriculture Organization, Rome, 1985 e S. Brown, A.E. Logo, and J. Chapman, ‘Biomass of tropical tree plantations and its Im- plications for the global carbon budget’, Cana- dian Journal of Forest Research, Voi 76, 1986, pp 390-394.

Land area Forests (millions of hectares)

Carbon fixation defined as net annual forest growth (tons of carbon per hectare)

Temperate and boreal forests:

USSR 2227 Canada 922 USA 913 PRC 933 India 297 All Europe except USSR 472

Tropical forests:

Brazil Indonesia Zaire Mexico Total Africa Total Asia and Pacific Total Latin America

846 181 227 192

2190 945

1680

792 264 195 125 73

145

396 123 106 48

217 306 679

0.3a 0.44a 0 82-l .35b 0.39c

0 70-I 07d

i 1.56-3.90e

burdened with a rapidly growing population. Scientists have warned that the loss of tropical rain forests will reduce the biosphere’s carbon sink over the next century. Brazil has pledged to halt the destruction of the Amazon forest, and its deforestation has been successfully reduced by 70% since 1987. At the height of forest destruction, an area comparable to the size of (the former) West Germany was burned and cleared each year.“’ Then the warning was heeded that deforestation, particularly in Latin America and tropical Africa, could rapidly alter the

climate by lowering the region’s rainfall.

Biomass burning is widespread in tropical zones and boreal forests or savannas. The burning of agricultural waste and fuelwood today adds to the global threat. The total amount of carbon dioxide released to the atmosphere by biomass burning has been estimated at 14 billion tonnes a year. By origin, 2.2 billion tonnes comes from tropical forests, 6 billion tonnes from savannas (mainly Africa), 3.3 billion tonnes from agricultural wastes, and 2.3 billion tonnes from fuelwood.

Fuelwood provides one-sixth of world energy but one-half of the energy needs in the poorest of the developing countries. This depend- ence on wood cannot be sustained if consumption continues to exceed current yields in sub-Sahnran Africa or southern Asia.” The exhausting demand for fuelwood has already created a ‘ring of desolation’ around crowded popLllation centres. Too little concern has been given to the pillaging of this vital resource. If the LDCs began to use fuelwood more efficiently and to plant more trees, global emissions of carbon dioxide could be reduced by 4%) million tonnes.

Scientists find difficulty in calculating how much land must be found for reforestation because of uncertainties in the carbon uptake of forests. Rates vary with tree species, the quality of forest management (silviculture), soil and climate conditions. The land area now covered with

“‘World Resources institute, World Re- sources 198&89, Basic Books, New York,

temperate and boreal forests is roughly 1.65 billion ha (Table 4); this

1988, pp 69-88; J.S. Levine, ‘Burning compares with only 1.2 billion ha of tropical forests (a hectare is roughly

trees and bridges’, Nature, Vol 346, 1990, 0.45 acre). Extensive tracts of forest in temperate zones, such as the p 511. “J. Soussan et al, ‘Urban fuel wood: chal-

USA and Western Europe, are needed to absorb one ton of carbon (or

lenges and dilemmas’, Energy Policy, Vol 3.7 tonnes of carbon dioxide). Tropical forests grow in countries such as

18, No 6, August 1990, pp 35-43. Brazil, Indonesia, and Zaire, at a vigorous rate; and they require



considerably less area to absorb the same amount of carbon from the atmosphere. The area would be even smaller if reforestation programmes in tropical regions were developed in intensely managed plantations. They would then require only 0.1-0.27 ha as against 0.7-l .2 ha in temperate zones to take up each ton of carbon.

In the USA alone, 800 million ha of once-forested land could be replanted with productive forests if much of the land was not held for commercial and residential use. At best only about 200 million ha are available. With proper management and genetic engineering to foster growth, somewhere between 95 and 525 million tonnes of carbon could be removed each year. This would equal 7% to 40% of current US emission levels. The reforesting of 13 million ha of crop land set aside in the USA since 1986 under the Conservation Reserve Program could only absorb 65 million tonnes of carbon annually.”

Reforestation could be more cost-effective in tropical than in temperate climates because forest growth flourishes in warm moist climates. Half of the planet’s tropical rain forests are located in four countries - Brazil, Indonesia, Zaire, and Mexico. About 120 to 250 million ha would be required to store 20% of current global CO2 emissions from fossil fuels. The land to be set aside for managed forest growth would amount to a significant fraction of the existing rain forests, but substantial incentives might have to be offered to convert present land use to silviculture. It has been suggested that these countries could offer equity in their silviculture to offset billions of dollars of their foreign debt. Alternatively, they could trade forest rights for investments in their social and economic infrastructures.

Another strategy proposes to stimulate the biological ‘fixation’ or extraction of CO* from the atmosphere by nurturing marine organisms in the Arctic and Antarctic oceans. The Commission on Life Science of the US National Academies of Sciences and Engineering reviewed a proposal to spray iron pellets into the ocean.r3 The aim would be to create giant blooms of marine algae to soak up carbon dioxide dissolved in ocean water; the CO2 would be constantly replenished from the atmosphere. The hypothesis suggested that populations of tiny marine algae (phytoplankton) are limited in their growth by serious deficiencies of iron.‘” If iron were sprayed on the sea, in the form of powder or slow-release floating pellets, the phytoplanktonnes’ growth could be powerfully stimulated.

The Commission on Life Science suggested that 300 000 tonnes of high-grade iron should be dispersed each year into polar waters. They could possibly remove up to two billion tonnes of carbon per year, or well over 20% of human-made carbon from the atmosphere. The estimated cost would be less than $1 billion per year. The panel recommended that an international experiment should begin with an allocation of $5&$150 million; if it were successful, the cost could be as low as 50 cents per ton of carbon removed. Critics cautioned that intervention into biological cycles has produced mixed results in the

“G. Byrne, ‘Let 100 million trees bloom’, past, and further, that an extensive environmental impact analysis must Science, 21 October 1988; N.R. Samson, ‘Releaf for global warming’, American

first be completed since the Law of the Sea puts oceans under

Forests, November/December 1988. international jurisdiction.

‘3A.G. Davies, ‘Taking a cool look at iron’, Nature, Vol 345, 1990, pp 114-l 15. “‘J.H. Martin, M. Gordon. and SE. Fitz- Political and economic measures to halt global warming water, ‘Iron in Antarctic waters’, Nature, Vol345, 1990, pp 156-158. Biological measures can be harnessed to provide less expensive and less


The conjlicr over global warming

painful solutions to the CO2 problem. It will not be easy to halt the tearing down of forests or to finance reforestation and marine algae programmes. But these counter-measures will probably provoke less resistance than radical proposals to tax economic growth or to proscribe the burning of fossil fuels. The 160 countries in the global system are locked into a race for industrial expansion and economic power. Burdened with debt and exorbitant factor costs, few are willing to make sacrifices or retard GNP growth to protect the biosphere. Though scientists still argue over the technical findings of rival climate models, they agree that the capacity of the atmosphere to carry carbon dioxide is approaching exhaustion. By now some degree of global climate change is inevitable. If technology can be harnessed to ease the adjustment process, it may be possible to buy time or ‘climate insurance’ to cope

with a threatening future. If the world economy is to raise the efficiency of its energy production

and consumption schedules, it must turn to market forces and realistic pricing levels to promote conservation and fuel-switching programmes. Price incentives will have to be supplemented with punitive carbon taxes or differential fuel subsidies. Factor costs and aggregate consumption expenditures will have to move sharply upward, first to deter waste, and second to finance alternative energy programmes. Rich and poor countries will surely protest; so too will industrial, agricultural, and consumer pressure groups. Some will claim that rising cost schedules will stimulate inflation and hinder the pace of industrial development. Others will argue that a rise in energy outlays will impair their comparative advantage in the world marketplace; or that energy pricing strategies will widen the already desperate gap between the LDCs and the rich world economies.

The worst difficulties will be met in lowering the 22 gigatonnes a year of CO2 emissions that threaten to impair the biosphere. The most visible obstacles will be found in the USA since it is a disproportionate contributor to global emissions of CO*. In 1988 the USA generated 5.3 tonnes of CO2 per person, for a national total of 4.8 gigatonnes - or 21% of global carbon emissions. Of the US emissions 36% came from transportation, 34% from electric power generation, 16% from industrial users, and the remaining 14% from residential and commerical activities (Table 5). By contrast Japan, West Germany, and a number of industrial countries have realized an impressive economy in fuel costs and outlays by promoting energy-efficiency initiatives. For each unit of GNP produced they have lowered their energy input by one-third to one-half, thus achieving an input-output ratio which far exceeds the US or Canadian efficiency index.

The goal of cutting US emissions by 20% is certainly feasible. Energy-efficiency standards improved by 40% in the 1970s and 19XOs, when oil prices shot up from $2 to $40 a barrel, but they declined as

Table 5. 1988 US CO. emissions by fuel and sector (million tonnes COJyear).

Oil Gas Coal W)

Residenbal 136 274 6 8.6 Commercial 84 158 8.6 5.2 Industrial 183 347 231 15.7 Transportation 1777 _ 36.8

Source: New York State Annual Energy Review: Electric utilities 135 155 1341 33.7 Energy Consumption, Supp/y and Price Stafis- Totals 2315 934 1587 100.00 tics 1970-1988. New York State Energy Office, Albany, NY, 1990, p 85. (See Ref 18 in this Total 1988 COP emissions: 4835 million tonnes as COP (1319 million tonnes carbon). article.)



FRG 1973

FRG 1986

Japan 1970

m DomestIc airlines

eza Car

0 Rail (long datonce)

Jopan 1986

Sweden 1973

m ROI I ( local, estimated )

0 Bus

Sweden 1986

Figure 4. Passenger travel - per capita comparisons for all modes.

USA 1970

Source: Personal communication, Dr Lee USA 1985 Schipper, International Energy Studies, Lawrence Berkeley Laboratory, Berkeley, 0 5

CA. Passenger-km/coplta (x IO”)

15J.H. Gibbons, P.D. Blair, and H.L. Gwin, ‘Strategies for energy use’, Scienfific American, Vol261, No 3, September 1989, pp 13&143.

prices later fell. It will be difficult to gain further improvements in the 1990s since many of the easiest and cheapest cuts have already been made. Fuel efficiency for US automobiles improved from 11 to 27.5 miles per gallon in the 1970s and early 198Os, and the ratio of aggregate energy inputs to GNP outputs was cut almost in half. While real GNP climbed 52%) US oil consumption rose only 9% in the past two decades.

Efforts to improve automobile fleet standards to 40 miles per gallon have been stalled in Congress in recent years and threatened with a Presidential veto. Unfortunately, too many Americans are dependent on cheap petrol. Compared with other societies, they drive more cars over more miles a year (Figure 4), clogging cities and highways, and impairing clean air and fuel-efficiency programmes, alike. If car mileage could be improved to 40 miles per gallon, 3 millon barrels of oil imports each day could be saved, and CO2 emissions could be reduced by 500 million tonnes annually - or 10% of current US emissions. It is pessimistically assumed that these savings will never materialize until petrol taxes and prices are raised to the German level of $3 per gallon or the Italian level of $5 per gallon.

Electric power generation in the USA could become more efficient if radical innovations were applied to coal and natural gas technologies. Nearly one-half of the coal-fired power plants in the USA were built before 1975, and their useful life will end early in the 21st century. Carbon dioxide emissions could be lowered by 700 million tonnes (or 15% of 1988 emissions) if they were replaced with efficient plants.” Coal-fired generating capacity world-wide is expected to double over the next 30 years. It is vital that innovative clean coal technologies should be applied in both the industrial and the developing economies. No other fuel is as cheap or abundant as coal. More efficient burning processes could be introduced at remarkably little incremental cost, and the environment gain could be conspicuous.

Greater efficiency must also be realized in end-use technologies. The demand for electric energy in the USA is now 2500 billion kWh. Even if new appliance efficiency standards are phased in, demand could reach 3200 billion kWh in 10 years. Improved demand-side management could cut this increment by about 6.5%. If the most efficient technologies available in the industrial, commerical, and residential sectors were ever brought into service, consumption demand by the year 2000 could be cut


The conflict over glohul warming

appreciably, and possibly by as much as 24-44%. This would reduce CO2 emissions by 600 million tonnes - or 14% of the current total.lh

The success of energy efficiency and conservation campaigns in the

industrialized economies bodes well for the future. But they will be negated to the degree that consumption and COZ emissions multiply in the LDCs. ‘Primary energy intensity’ is calculated as a ratio of energy consumption to GNP output. It improved by 25% in the rich economies but fell 25% in the poor countries between 1973 and 1989. Energy demand is currently increasing at only l-2% a year in the rich countries, which consume 70% of the world’s oil and 50% of all energy supplies, but it is rising rapidly in the LDCs and in the centrally planned economies - including China, India, the USSR, and Eastern Europe. These countries depend to an alarming extent on the burning of coal. Their COZ emissions could dramatically multiply if they are not deterred by a sharp rise in energy prices, by the phasing-in of free market incentives, or by the constraints negotiated in the form of international treaties.

The first requirement, inescapably, is to raise energy prices or energy taxes to the point at which demand curves fall away smartly. The suppression of consumption will improve efficiency ratios but it will also lead to social hardship, unemployment, regressive taxation, and a fearsome mix of inflation and recession. It is obvious that rich countries and poor alike do not cherish the idea of rationing fuels or controlling energy wastage with higher prices. The price mechanism provides the most ruthless and also the least avoidable form of energy constraint.

A second requirement is to encourage fuel switching. If the 1991 crisis in the Arabian Gulf should push oil prices from $30 to $65 a barrel, industrial boilers and electric utilities will have to stop burning oil. Oil used to provide 54% of primary energy needs in the USA, but in the past 20 years it fell by more than 10% - clue largely to the price elasticity of demand. Oil use in Europe and the LDCs could fall much further if benchmark prices rise, or if emergency funds were allocated to promote nuclear, hydroelectric, solar, or other renewable energy technplogies. The drawback is that fuel switching is more likely to encourage the use of coal than natural gas or non-fossil fuels. This will certainly be seen in the many LDCs that are burdened with foreign debt and poorly endowed with energy technologies. China and the USSR command well over one-half of the proven reserves of coal and they are responsible for more than one-half of coal consumption. Like India and the larger LDCs, they rely on coal for their heavy industries. railroads, and the rapid expansion of electric utilities. If they remain committed to economic growth, they will cancel any gains that might be made in richer countries that are intent on reducing CO2 and other greenhouse gas production.

Industrialized countries have made some progress in establishing

alternative energy technologies. Photovoltaics (PV) directly convert sunlight into electricity, and they can be used both for large-scale utility networks or for small remote locations. If PV module costs could be cut from $4.50 to $2.00 per peak watt, PV might eventually dispiace millions of megawatts of diesel power. If a more economical design for

16’New push for energy efficiency’, EPRI Journal, Vol 15, No 3, April/May 1990, pp

PV collectors could be developed, PV could eventually supply 15% of

S-17. global electricity needs. In addition, large-scale wind farms could be

“‘Excellent forecast for wind’, EPRt Jour- built to compete economically with conventional power plants.” Instal- nal, Vol 15, June 1990, pp 14-25. led capacity for wind energy grew rapidly in the 1980s. Favourable tax


“Based on the following 1988 annual con- sumptions (in trillion Btu): utility Coal 15850 Natural gas 2 714 Petroleum 1 599 Transportation Gasoline 14 105 Jet 2 620 Industrial and commercial Coal 2 898 Natural gas 8810 Petroleum 3162 Residential Natural gas 4 784 Petroleum 1 084 (Source: New York State Annual Energy Review: Energy Consumption, Supply and Price Statistics 7970-1988, New York State Energy Office, Albany, NY, 1990, p 85.) 19For a sceptical criticism of emission controls by a noted economist, see William D. Nordhaus, ‘Count before you leap’, The Economist, 7 July 1990, pp 21-24. 20For a review of recent literature on tradeable permits and other forms of international cooperation, see Michael Grubb, ‘The greenhouse effect: negotiating targets’, international Affairs, Vol 66, No 1, January 1990, pp 67-89.


credits and 16 000 wind turbines added 1500 MW to California’s grid, and 200 MW of wind turbine capacity was installed in Western Europe. The potential for deploying this low-cost power in the LDCs is enormous. Unfortunately, the funds and the technology needed to assure deployment have yet to be guaranteed.

If the political will could be summoned, a carbon tax might be imposed on high CO2 emissions from fossil fuels, while leaving untaxed all forms of nuclear fuel or renewable energy sources. A carbon levy could be presented as an ‘atmospheric user’s charge’, say at $0.40 per million Btu. For a start, this could add $22 billion a year to the US tax base. ‘s A more radical proposal has been advanced in plans to auction or to trade off carbon emission permits between the poor and the rich economies. Trading in permits could be highly profitable for poor countries that record a low per capita ratio of GNP and CO2 emissions. If they sold their spare carbon emission permits to the heavily industrialized and richer economies they could earn a sizeable income in hard currency; and they could draw upon market incentives to retard their own emission totals.‘”

The two most compelling instances would appear in India and the PRC. They could sell valuable per capita entitlements to Europe or Japan; and with the proceeds they could finance economic development programmes that were both cost effective and energy efficient. This ‘tradeable entitlement’ strategy could be extended to the former com- munist regimes and many of the LDCs. It could be -further supplemented with an internationally agreed carbon tax. This resort to global cooperation would surely retard the doubling of greenhouse gases after 2000. A promising start in global policy making was seen in the Montreal Protocol of 1987. It required that the industrial nations eliminate their own production of the exceptionally harmful gases, CFC-11 and CFC-12, and subsidize or transfer elimination technologies

without charge to the LDCs.

Two intractable issues

It is likely that some of these measures will be implemented during the 1990s. A strong start was made in UNEP and in the Montreal Protocol on CFCs. UNEP has also won considerable support for the models and the tentative recommendations put forward in the reports of the IPCC. It might become politically feasible, too, to halt deforestation in the tropics or to fund marine algae. reforestation, and other ‘natural’ remedies during the 1990s. Moreover, it may be possible to put in place a novel set of financial incentives, or alternatively to rely on soaring energy prices, to prompt nations into a more determined course of action. The development of a profitable trade in CO2 emission entitlements, or a transfer of valuable technologies to the LDCs, could win considerable policy benefits.*”

Unfortunately, two outstanding problems are likely to go unresolved. The first concerns nuclear power and renewable energy sources. The second involves a great number of dangers, all of them associated with the thrust towards massive population growth.

On the first score, it is evident that the competition for industrial wealth has been fuelled over the past two hundred years by the availability of inexpensive and easily accessible fuel. Coal, oil and natural gas were relatively abundant, cheap to recover, and inexpensive


The conflict over global warmrng

to burn. Many of the LDCs, including the PRC and India, are endowed with these resources. It is not their fault, they argue, that the CO2 consequences of using fossil fuels became acute just as the leading LDCs reached the point of economic take-off. Naturally, they would benefit if atmospheric degradation could be avoided, retarded or bought off. But it is not fair or realistic to ask them to slow down their industrialization so that global climate stabilization can be achieved. Perhaps it will need a historic act of generosity, such as an outright gift of non-fossil-fuelled power installations to the LDCs, to satisfy their energy requirements in a manner that can safeguard the environment.2’

The most remarkable and possibly the most tainted of gifts to the LDCs could come in the transfer of nuclear technology and reactor fuels. Economic costs and CO2 consequences could be rigorously contained, and the transfer of nuclear capability could wean them away from burning oil or coal fuels in gigantic amounts. But there are two alarming factors that will have to be controlled at all times. The non-proliferation regime devised by the superpowers in the 1960s has prevented the spread of nuclear fuels and reactor capabilities for military purposes. It is vital that the regime be preserved into the next century. Similarly, the storage of nuclear waste leaves an unresolved issue. Until storage facilities are guaranteed against leakage for thousands of years, nuclear power will not be regarded as an acceptable substitute for fossil fuels. Indeed, nuclear energy generation may actually decline between 1995 and 2005, as a growing number of plants reach the end of their operational lives.

On the second score, it is doubtful that any strategy to contain greenhouse gases can succeed if global demographic curves continue to climb at projected rates. The basic needs of many of the world’s 6 billion people are not adequately provided for today, and malnutrition is all too widespread. If the planet has to sustain 10 billion within two genera- tions, and IO billion more after that, the survivability of the biosphere and of basic social coping mechanisms cannot be assured.

The critical difficulty is that one-quarter of the population lives in the rich countries. It commands three-quarters of the world’s total GNP, international trade, and energy production. Population growth in the poor countries threatens to multiply so rapidly that food and fuel resources will be overwhelmed. Starvation in Africa is becoming systemic and recurrent. If its population of 300 million people within 46 often-unstable countries keeps expanding at almost 3% a year, the continent will race not towards economic take-off but towards ecological disaster. But how can a people facing an explosion in numbers and expectations be urged not to burn wood, coal, or oil? The only answers given so far are problematic: the rich countries should open their markets wide to the LDCs, they should subsidize population control in the LDCs, and underwrite the costs of their environmental constraints too.

It is in this light that the opening argument of this article must be rephrased. It is accepted that the GCMs projecting global warming are far from flawless. It is also agreed that the magnitude and the timescale of the build-up of greenhouse gases remain fraught with supposition if

“For further discussion, see David not error. The cause-effect relationships that link rising global green-

Everest, The Greenhouse Effect: Issues house gases to climate changes in the atmosphere are still subject to

for Policy-Makers, Royal Institute of Inter- conjecture. The verification of scientific hypotheses with GCM techni- national Affairs, London, 1988. ques has only just begun, and the debate between the prophets of



ecological disaster and the status quo economists will surely continue. Arguments about what should be done will persist until the GCMs are improved and a better knowledge of market consequences has been

gained. All parties agree, however, that it would be prudent to move

cautiously towards a system for managing global warming and to buy ‘insurance’ against possible disasters. If the emissions of C02, methane, and nitrous oxide are stabilized at 1990 or 1995 levels, the gathering momentum could at least be held in check. A major achievement would be secured if the build-up of greenhouse gases were contained by international agreement. Victory would come not in one swoop but in small environmental steps and bureaucratic accords. The incremental value of progressing slowly and undramatically might be worth more than all the political rhetoric and the symbolic triumphs which are falsely celebrated today. It is sensible to buy a minimal coverage of insurance against future deterioration by holding atmospheric CO2 levels stable. An international consensus or a ‘no regrets’ policy is beginning to emerge in the scientific community. If the reports of the IPCC working groups generate wider support, the political determina- tion might be found to pay the first of the insurance premiums.


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￼The conflict over global warming

The conflict over global warming