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1072-9240/00$2000 + .00 Technology,Vol. 7S,pp. 189-213,2000 Printed in the USA. All rights reserved Copyright IQ 2000 Cognizant Communication Corporation POTENTIAL CONSEQUENCES OF INCREASING ATMOSPHERIC CO2 CONCENTRATION COMPARED TO OTHER ENVIRONMENTAL PROBLEMS Indur M. Goklany Vienna, VA TS 9907-532M (Received16 June 1999;accepted14 April 2000) This paper examinesthe validity of the assertionthat anthropogenicclimate changeis the overriding environmentalconcernfacing the globe today. Examinationof recenttrends for someclimate-sensitive indicators (e.g., global food security; U.S. deathsdue to storms and floods; global deathrates due to infectiousand parasitic diseases;andbiomassin the northernforests)shows thatmattershaveimproved notwithstandingany climate changeto date. For others (suchas global deforestationand sealevel rise). recenttrends havecontinuedto worsen; but so far the contribution of any anthropogenicclimate change to theseimpactsseemsto have beenrelatively minor. Next, basedlargely uponthe Intergovernmental Panelon Climate Change's 1995ImpactAssessment.the paperdeterminesthat over the next several decadesthe projected global impactsof climate changeuponfood security, deforestation,biodiversity, and human health could be an order of magnitude smaller than those due to other stressorssuch as population growth, poverty, land conversion, or baseline (i.e., non-climate change related)rates of infectiousand parasiticdiseases. Therefore,eliminatinganthropogenicclimate change,evenif feasible, would-for the next several decades-do little to reduce the much larger baseline rates of global deforestation,biodiversity loss, and infectiousand parasitic diseases. Hence,climate change,while a potentiallyserious long-termproblem. is nottoday-nor likely to be in the foreseeablefuture-as urgent as other current environmentaland public healthproblems. The paper then proposesan integrated approachto deal with today's urgentenvironmentalproblemswhile enhancingthe ability to addressthe long term-problem of climate change. INTRODUCTION Many scientists and, perhaps more importantly, policy makers claim that climate change is the overriding environmental challenge facing the globe today (1-4). This assertion is in no small way responsible for the emphasis placed upon the Kyoto protocol on emission reductions (5). This paper examines whether this claim is supported by the available information on the impacts of climate change that may be occurring now and in the "foreseeable" future by comparing those impacts with the impacts of other environmental problems. Such a comparison would help in the development of a rational approach to dealing with not only climate change but other critical environmental and public health problems facing the globe over the next few generations. 189 I. M. Goklany 190 The paper will focus on the economic sectors and environmentalconsequencesand indicators forwhich long-termretrospective dataand future projections are available. These sectors and indicators-agriculture and food security; forests and biodiversity; human health; hurricanes and other extreme weatherevents; and sea level rise-are also thought to be the most sensitive to climate change. For brevity, the paper will refer to these as the climate-sensitive sectors or indicators. The paper's time horizon is the foreseeablefuture, which it assumes is the middle of the twenty-first century. Postmortems of several studies (e.g., 6, 7) projecting future use of natural resources and the resulting impacts have shown the difficulty of accurately projecting use and associatedimpacts evenone or two decades-let alone a few generations-ahead; mainly because the projections did not adequately account for technological progress and adaptation to any adverse social and economic circumstances arising from the use or impact of the resources (8-11). Also, because the paper limits itself to the foreseeable future, it will not examine potentially catastrophic consequencesof climate change which are unlikely to occur, if at all, until a few centuries have passed. These catastrophic consequencesinclude the rapid collapse of the West Antarctica Ice Sheet, which could occur after about five to seven centuries (12, 13), and the shutting down of the "ocean conveyor belt" which warms Northern Europe and contiguous Asia due to a termination in the thermohaline circulation (14, 15). CURRENT TRENDS IN THE CLIMATE SENSITIVE SECTORS Analysis of past trends in the impacts of various climate-sensitive phenomena and in the ability of the climate-sensitive sectorsto meethuman demandscan help determine whether it is becoming harder to meet those demands because of, or despite, any warming that may have taken place so far. An understanding of thesetrends can also instruct us as to the factors which determine adaptation and vulnerability to various climate-related challenges. Agriculture and food security Between 1900 and 1997, global population in- creased 260% from 1.62 billion to 5.85 billion, but cropland increased only 95% from 7.7 Tm2 to 15.1Tm2asindicatedinFig.1 (16, 17). The 165%gap between the increases in population and in cropland (equivalent to 12.8 Tm1 is the minimum amount of habitat savedfrom conversion to cropland becauseof increased productivity in the food and agricultural sector. The 12.8 Tm2 estimate assumesthat despite freezing technology at the 1900 level (16, 18, 19): 1. All new cropland would, on average, be as productive as existing cropland was in 1900. This may be an optimistic assumption because, arguably, the most productive croplands were probably already under cultivation in 1900. 2. All cropland that was in existence in 1900 would maintain its level of productivity at the 1900 level. 3. The penetration of any existing technology would expand only to the extent necessary to ensure that assumptions 1) and 2) are realized. This implies that, at a minimum, inputs would probably increase in proportion to the amount of total cropland. 4. Average global food supplies per capita would be frozen at the marginal levels of 1900. Absent the large (12.8 Tm1 reduction in land conversion, deforestation and loss of habitat-the major global causesof the loss of biodiversity-would have been worse than they already are (18, 19). Figure 1 shows that although the amount of cropland needed to feed the average person has been reduced almost by one half during this century (4,770 m2 per capita in 1900 versus 2,580 in 1995), food is cheaper and, consequently, the average person is better fed. Between 1961-63and 1994-96, global per capita food supplies increased19%(from2,280t02, 720 kcald-I), and global protein supplies per capita increased 16% (from 62.8 to 72.6 g d-1). Between 1960 and 1996, world food prices (in constant dollars) declined 41 % (20, 21). Consequently, although global population increased 45% between 1969-71 and 1990-92, the absolute number of people suffering from chronic undernourishment in developing nations decreased from 917 million (or 35% of their population) to 839 million (or 21%) (22). These data indicate that despite the increase in population, global vulnerability to famine and malnourishment has declined. In turn, that helped improve the world's health status by contributing to reduced infant and maternal mortality rates, and higher expected life spans (23). Poten1ialco~eoces of iocreasinga~ric 191 CO} coocentration 6 0.6 0.5 0 ... u 0.5 84 0.4 'C C ~ --0 ! ~ 'a U G 0.3 ~3 g ~ ;; DJ 'a == :c 02 DJ 0.2 -s: .!!. G 0. 0 G 0.1 0,1 c ~ :c a 0 1700 1750 1800 1850 '1900 1950 2000 Sources:Goklany(16,19); FAD (17). Fig. 1. Cropland and croplandproductivity, 1700-1997. Although the amount of cropland per capita has never been lower, the fact that the average person is better fed today is only possible because global productivity in the food and agricultural sector is at an all time high. This is in contrast to the contention that warming may reduce global agricultural productivity through a combination of factors including more frequent floods, droughts and loss of soil moisture, and pest and disease outbreaks (24) --especially given Mann et al.'s (25) centuries long reconstruction of temperature trends which suggests that the earth today is the warmest it has been in the last six centuries (26), and Dai et al.'s (27) analysis indicating an increasing trend in the global combined areas of severe drought and severe moisture surplus since the 1970s. So how can one explain the historical increases in agricultural productivity and improved food security at a time when the climate is getting worse? The three possible explanations for this divergence are as follows: I. Perhaps the net effects of global warming at current CO2 and temperature levels are not particularly detrimental to global agricultural productivity or, more importantly, global food security. In fact, there is some evidence that so far CO2-enhanced warming may be contributing to increased agricul- tural productivity. Nicholls (28) estimatedthat 3050% of the post-1950increasesin com yields in Australia maybe due to higher minimum temperatures. In the far northernlatitudes,the active growing seasonseemsto havelengthenedby 12:i: 4 days in the 1980sand plant growth has apparentlyaccelerated(29). In addition, numerouscontrolled field experimentsshowthat increasingatmosphericCO2 concentrationsincreasescrop yields. The IntergovernmentalPanelon Climate Change (IPCC) 1995 ImpactAssessment suggeststhat yields of C3crops (i.e., the majority of crops) mayincreasean average of 30% due to a doubling of CO2 (30). Wittwer estimatesthat the increase in CO2concentrations over the last two centuries may have increased productionby as muchas 14%(31). Between1961 and 1996,globalcerealyields increased115%(20), while CO2concentrationsincreasedonly 14%(32), and annualglobal temperatureincreasedless than 0.3°C. (26). Thus, CO2-enhancedwarming is unlikely to explain more than a small portion of the increasein global agricultural productivity. 2. The increasedglobal agricultural productivity and global food security is due to technological progress driven by the mutually-reinforcing, coevolving forces of economicgrowth, technological change,andtrade(9, 16, 18, 19,33). 192 M. Goklany 3. Perhaps the most plausible explanation of all is that both CO2-enhancedglobal warming and technological progress have contributed to reduced human vulnerability to hunger and malnourishment, with the latter being the major contributor. much of it at the expenseof forests and woodlands(20). Forest cover and biodiversity Deaths and death rates: Long-term data on V.S. fatalitiesdueto tornados,floods, lightning, and North Atlantic hurricanesand cyclones hitting the V.S. mainland from 1916-97, 1903-97, 1959-96, and 1900-97,respectively,were obtainedfrom various groupswithin the National Oceanicand AtmosphericAdministration (NOAA) (39-43). However,thereareseveraldiscrepanciesbetween the flood fatalities datafrom NOAA's Hydrological InformationCenter(HIC) and its National Climatic Data Center(39), and both differ from data in the Bureauof the Census' StatisticalAbstractsand the Historical Statistics(44). Since HIC was supposedly the original source for the flood data for the other groupsas well, it was decidedto use its data set (40). However, in the earlier years, even the HIC data set may be prone to error, possibly undercountingfatalities (45). For instance,in 1911, that data set shows0 fatalities; however,the New York Timesindicates that there were at least 55 fatalities that flood year. Similarly, the Timesindicates at least 244 in 1928 and 42 in 1931 compared to 15 and 0, respectively, in the HIC data set (45, 46). However, the corrected values may themselvesbe lower bounds. Notably, the keeper of the HIC's data setexpressesgreaterconfidence in the data after the mid-1960s on fatalities and mid-1950son property losses. For the most recentnine-yearperiod for the various data series(1989-97 for tornados,floods, and hurricanes;1988-96for lightning), averageannual deaths for these extreme weatherevents declined 86.5,53.5,97.3and 46.5%,respectively,since their Through the ages, human demand for land for agriculture and-toamuch lesserextent-settlements and infrastructure, has been the major reason for the loss of forest cover and diversion of habitat away from the rest of nature (9, 16, 19,33). Such deforestation and habitat conversion, in turn, is responsible for much of the presumed threat to global biodiversity. Between 1980 and 1995, global population increased 28% (33). To meet the additional food demand, net agricultural land increased by about 4% or 2.0 Tm2 (including 0.8 Tm2 of cropland), and net forest cover decreased by about 1.7 Tm2 (34). In the developing countries, net forest cover declined about 1.9 Tm2. By contrast, forest cover increased by about 0.2 Tm2 in the developed countries. There is no evidence that anthropogenic global warming has contributed to the loss of forest cover, significantly or otherwise. In fact, for forests as for agriculture, CO2-enhanced warming may have increased productivity, thereby stimulating timber growth and forest mass (29, 35-37). The trends in developing and developed countries (taken as groups) confirm the importance of economic growth and technological progress in limiting deforestation (34, 38). Forest cover is declining in developing countries largely because their increases in agricultural and forest productivity lag behind the demands of their growing populations for food and other products. Meanwhile, developed countries are being reforested because-despite diversion of land for urbanization and infrastructure projects -productivity in the agricultural and forestry sectors is growing faster than the increase in demands for food and timber. Without science-based and market-driven increases in food and agricultural productivity, global deforestation would have been greater. Thus, between 1980 and 1995, at least an additional 12.3 Tm2 of agricultural land (including 4.0 Tm2 of cropland) would have been needed, Mortality and property loss due tc~storms, floods and other extreme weather events nine-year averages peaked in 1917-25, 1969-77, 1900-08,and 1959-67,respectively(45, 46). The declines in death rates (measured as deaths per million population) are even more dramatic (45). For the latest nine-year periods, death rates are 94.3, 70.9, 99.2 and 60.7% below the 1917-25, 1913-21,1900-08, and 1959-67peaksfor tornados, floods, hurricanes, and lightning as indicated in Fig. 2 (45,46). 193 Potential consequencesof increasing atmospheric CO2 concentration (deatb,permiUioopopolotioo, 9-y..r mo.iqa.erac... 1900-1997) 3.5 14 3 12 ~ + + 10 ~2.5 . ~ . i ..i 2 8 ~ ~ . Co c '0 6 S 1.5 ~ c ~ Ii = ~ ... = ;: ~ ~ ! . c ~ n 4 1 ... .a i i ~O.5 ! ~ ' t i !I'\~'-\i 0 I ~,I 2 II i\!"-..,,t "" ,i , ,.-.', ."r' ~ I , I',_.~.-,.,.,-,_,:,_-,-,-,- - 0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Source: GokIany (45). Fig. 2. Deathratesdueto tornados,floods, lightning, andhurricanes. While a portion of the declines in deathsand deathrates for hurricanes may be due to a reduction in the number and wind speedsof violent Atlantic hurricanessince the 1940s(47), a portion of the credit is perhaps also due to technologyTable Type of Event Tornados Resultsof curve fitting analysesfor deathsand deathratesdue to extremeweatherevents. Years,no. of observations (obs), period Equationsfitting the data r 1916-97 DR = 2.484 -0.0341 1 Log DR = 0.395 -0.01541 0.563 82 annualobs. t=lt082 Floods 1903-97 19 non-overlapping 5-yr periods, T = I to 19 Hurricanes Lightning basedadaptation(46). The declinesin deaths(D) [and deathrates (DR) per million populationper year] canbe fitted using curve-fitting modelsthat vary linearly with time (t) for D or log D [or DR or log DR]. (Table 1) 1900-97 14 non-overlapping 7-yr periods, T = I to 14 1959-96 38 annualobs 0.367 D = 289.3 -3.401t Log D = 2.395 -O.OI00t 0.269 DR = 0.859 -0.0219 T Log DR = -0.176. 0.0089T 0.094 0.354 0.037 0.630 p for the slope <0.001 <0.001 <0.001 <0.001 >0.1 >0.1 D=148.7-3.541T Log D = 2.180 -0.0136T 0.613 <0.001 <0.001 DR = 5.514 -0.5141T Log DR = 0.640 -0.1357 T 0.281 0.702 <0.05 <0.001 D = 456.2 -40.07T Log D = 2.519 -O.0960T 0.299 0.549 <0.05 <0.005 DR = 0.686 -0.0137t Log DR = -0.143 -0.0140l 0.639 0.749 <0.001 <0.001 0=127.6-1.981t LogO=2.IIO-O.OO94t 0.507 0.576 <0.001 <0.001 t = 1 to 38 -10 194 I. M. Goklany With respectto floods, according to Karl and Knight (48) the intensity of heavy and extreme precipitation events(defined as daily precipitation eventsexceeding2 inches or 50.8 mm) apparently hasincreasedfor the U.S. since1910which, all else being equal, ought to increasethe frequencyand intensity of floods and the risk of fatalities due to floods. On the otherhand,the Lins and Slack(49) analysisof streamflowdatafrom 1914onward for relatively undisturbedwatershedsshowsthatwhile there may be an increasein the dischargesdue to lower and middle streamflowregimes,there seems to be no generalupwardtrend in the highestflows due to hydrological eventsalone-suggesting that the likelihood of floods due to weatheror climate mayhave actuallydeclined. Regardlessof whether frequencyand intensity of flooding may have increasedor decreased,what is more important is that fatalities as well as deathrateshave declined. (Fig. 2) It is likely that the bulk of thesedecreases, as well as for other extremeevents, is due to increasedwealth and new technologieswhich have ~ enabled people to benefit from adaptation measuressuchasmorereliable forecasts;early warning systems;elaborate evacuationplans; more robust constructionof housesand infrastructure;an extensive transportationnetwork; andthe constantdrumbeat of television and radio weathermenonce a stormregisterson their radar screens. Property losses: One might expectthat while a wealthier societymaytake extra effort to limit loss of life, it may be less concerned about property losses. A wealthier society is also likely to have more property at risk. Moreover, if the interpretation by Karl and Knight of trends relatedto floods in the U.S. are more accuratethan that of Lins and Slack, the frequencyand intensity of floods in the U.S. may have increased. Figure 3 shows that at first blush, despitewide year-to-yearfluctuations, the overall trend between1903and 1997 for property losses due to U.S. floods (adjusted to real dollars using the construction cost index) seems upward(45). 20 0.28 15 0.24 10 0.2 a .. .. --c ~ = ~ ~ ~ .~ 5 0.16 : 0 0.12 to~ ~ ... 0 ~ .E . ~ ~ : ... ;. 0.08 -5 0.04 0 -15 1900 1920 .Wealth 1940 1960 1980 2000 measured as fixed reproducible tangible assets. SaIIt:r::~y (45). Fig. 3. Propertylossesdueto floods, 1903-1997. However, if property lossesdue to floods are estimatedas a percentof the nation's wealth measuredas fixed tangible reproducibleassets(exclud- ing land values) using data from the Bureau of Economic Affairs (50) for 1925-1996-a better indicator of the amount of property at risk-then the Potentialco~elx:eS of iocreasinga~ric Caz coocenn-ation 195 overall direction of the trend between 1925 (the first year for which suchwealth dataare available) and 1997 (51) is unclear. (Fig. 3) Curve-fitting modelsutilizing property loss rate (LR) specified in tenDsof percentof wealth, give poorerfits than thoseutilizing real dollars. (Table 2) In this analysis, wealth for 1997was basedupon an extrapolation for the previousthreeyears(45). Table2. Resultsof curve fitting analysesfor propertylossesdueto floods. r Curve fitting equations Period, Property Loss, in terms of: p fi)f the slope no. of observations LR= 1.183+0.1732T Log LR = 0.1207+ 0.0257 T 0.283 nineteen5-yr periods 1903-97 0.240 <0.02 <0.05 Billions of Real (1997) $ 1926-97 eight9-yr periods LR=17.11+2.900T Log LR = 0.3055+ 0.0423T 0.373 0.358 >0.1 >0.1 % of wealth 1926-97 eight 9-yr periods LR = 0.2829 -0.0135 T Log LR = -1.525 -0.0242 T 0.136 0.140 >0.3 >0.3 Billions of Real (1997) S warmerworld has beenraised as one of the major concernsregardinganthropogenicclimate change. Some fear that vectors such as the anopheles mosquito--the carrier of malaria--could become more widespreadwith warming since a changein climate could alter the range and abundanceof species(52, 53). However, this has beendisputed on the basisthat global warming would not necessarily expand-nor is it the major determinant of-the range of all vectors (54-57). Today the Similarly, any upward trend in property losses due to hurricanes in terms of real dollars between 1900-97 is obscured if losses are measured in terms of percent of wealth as reflected in Fig. 4 and Table 3. (45; seealso, 51) Infectious and parasitic diseases, health impacts and other The potentialspreadof vectorbornediseasesin a 40 0.35 30 0.3 0.25 ~ .. 20 : : - 10 .. .. 0.2 : 0 ; a :E !"' ~ -. 0 0.15 0 oS ~ ; -10 ' ~ 'f :I ,, ,!of , !: -20 ::! :: I I 1900 1920 . .0 1940 1960 1980 .Wealth measuredas fIXed reproducible tangible assets S~e 0.05 I:: " ...' -30 0.1 " " ., Goklany(45) Fig. 4. Hurricane property losses, 1900-1997. . ~ ... i ' i .:...i i '.' ~ .. ~ [ 2000 M. Goklany 196 Table 3 Resultsof curve fining analysesfor property lossesdue to hurricanes. Property Loss, in terms of: r p for the slope LR = -825.0 + 283.37T LogLR= 1.916+0.1223T 0.604 0.826 <0.001 <0.001 LR = -623.9 + 518.39T Log LR = 2.428+ 0.1415T 0.553 <0.05 0.716 <0.01 LR = 0.0087 -0.0011 T Log LR = -2.0389 + 0.0277 T 0.152 0.082 >0.3 >0.3 Period, no. of observations Curve fitting equations 1903-97 Billions of Real (1997) $ fourteen7-yr periods 1926-97 Billions of Real (1997) $ eight 9-yr periods % of wealth 1926-97 eight 9-yr periods prevalence of these diseaseshas less to do with their potential rangesthan with the public health measures taken to deal with the vectors and the diseasesthey spread. For instance, in the last century, malaria, cholera, and other diarrheal and parasitic diseases were prevalent around the world-including the United States and Western Europe-but today they are problems only in countries where the necessary public health measuresare unaffordable or have been compromised (58,59). For instance, mainly because of cholera, yellow fever, typhoid, and various diarrhoeal and gastrointestinal diseases,the mean crude death rate (CDR) in New Orleans for a 30-year period between 1830 and 1859 was 60,000 per million (60). By comparison, in 1990-1995, it was 44,600 per million for Rwanda-the nation with the highest CDR-and 8,800 for the U.S. (21). In 1900, the cumulative death rate in the U.S. for typhoid, paratyphoid, various gastrointestinal diseases, and all forms of dysentery was 1,860 per million population (9). Today, due to a host of public health measures,these diseases barely show up in current statistics-accounting for a death rate of less than 5 per million (61). Better nutrition, advancesin-and increasedavailability of-medical and public health technology, and greater investments in public health programs and infrastructure helped reduce infectious and parasitic diseases worldwide-particularly among the young in developing countries. As a result, crude global deathrates dropped from 19.8 per 1000 population in 1950-55 to 9.3 in 1990-95, helping push global life expectancy at birth from 46.4 to 64.7 years (62). These improvements would have been unlikely, if not impossible, without: I) the transfer of scientific information and technologies generated in the richer nations; and 2) the wealth generated by economic growth which made those technologies affordable (9, 33). Table 4 shows, for a sampling of countries, how various public and environmental health indicators improve with wealth (46). Table 4. Improvement in public and environmental health status with wealth for selected countries Child mortality Country rate, 1995 (per 1000) Accessto safe water, 1994 (% of population) Accessto adequate sanitation,1994 (% of population) Foodsuppliesper Life expectancyat GNP per capita, 1994 birth, 1990-95 capita 1993 (Kcal/day) (years) (US $) Sweden 6 100 100 3,239 78.2 24,740 Chile 17 96 71 2,755 73.8 3,170 66.3 850 Philippines 48 84 75 2,393 Ghana 113 56 42 2,585 56.5 430 240 <200 Guinea-Bissau 207 57 20 2,443 435 Afghanistan 251 10 8 1,670t 43.5 t 1990-92average. Source: Goklany (46) 197 Potentialconsequences of increasingatmosphericCO2concentration Despitetheseimprovements,poorsanitation,unavailability of safe water, and indoor air pollution are still among the major causesof higher mortalities and lower life expectanciesin developing countries. An estimated2.9 billion people lack adequatesanitationand1.1 billion haveno accessto safewater in developingcountries.Thesedeficiencies are largely responsiblefor about 2.5 million deathsdue to diarrhoealdiseases(in 1996). According to the World HealthOrganization,another 3 million prematuredeaths-mainly in developing countries-were causedby air pollution globally, of which 2.8 million deathswere due to indoor air pollution (63). In addition, malaria caused an estimated 1.5-2.7 million deaths in 1996, almost exclusively in the developingcountries. It hasbeen suggestedthat climatechangemaybe a factor in the recentresurgencesin vector-bornediseases(52,53). Resurgencesinclude malaria in Henan Province (China); malaria and denguein the Americas; and cholerain PeruandRwanda.However,increasesin drug resistance;increasedurbanizationwhich can lead to unsanitary conditions and facilitates the spread of infectious diseases;premature discontinuation of control measuressuchas indoor spraying and use of impregnatedmosquito nets; and faltering mosquito control and public health measures(e.g., reduction in DDT usageand chlorination) aggravatedby poor nutrition seemto be more likely causes(57, 64-68). Finally, althoughextremetemperaturesposelesser public healthproblemsthan infectious and parasitic diseases,they are knownto causedeaths(52, 53,69,70). GaffenandRoss(71) havereportedthat between1949and 1995the frequencyof "extreme heatstressevents" hasincreasedfor the U.S. They suggestthat continuationof this trend could pose public health problems in the future. However, analysisby Goklanyand Straja(72) of deathcertificatedata from the Centersfor DiseaseControl and Prevention(73), shows no upward trends in U.S. CDRs due to excessive heat and excessivecold between1979 and 1997, despitethe aging of the populationwhich, if all else is equal, oughtto have increasedrisks of deathdue to either. Notably, deathsand deathratesin the U.S. during the 1979-1997period due to extremecold exceed thosedue to extremeheat. During that period there were cumulatively 13,319and 6,693 deathsattrib-~ uted in deathcertificates to extreme cold and extremeheat,respectively(73). However, it doesnot necessarilyfollow that warming would reduce net mortality. This is becauseof two competingphenomenanot captured in the death certificate data (53,69, 70). First, excessdeaths(i.e., deathsabove a background level in the absenceof an extreme event,adjustedfor the period of the year) due to all causes(e.g.,strokesor heartdisease)on averagego up more due to extreme heat than due to extreme cold events. This is true even if one considersthat the deathrate drops below the background level after the extreme event has ended, and that such drops (like the increases)are more pronouncedfor extremeheatevents. Overall, there are manymore deathsduringthe winter monthsthan in the summer months. A proper evaluation of the net effect of any warming on mortality ought to considerthese factors-as well as possiblechangesin background death rates-within a framework which considers adaptationand uses "years of life lost" and "disability-adjustedlife yearslost" becausemortality ratesdueto both extremecold and extremeheat eventsarehigher amongthe agedandthose already susceptible(74). While this is outsidethe scopeof this paper,one oughtto expectsomecancellationof mortality effectsdue to more heatwavesand fewer cold onesbecauseof climate change(53, 69, 70). Accelerated sea level rise A major concern related to global warming is that it could accelerate the rate at which sea level has been rising for millennia. Preliminary results from the TOPEX/POSEIDON satellite observations from 1993-1996 are consistent with the historical tide gauge record, which shows mean sea level rising at a rate of about 18 :!: 1 cm (about 8 inches) over the last 100 years (75, 76). While it is not known what fraction, if any, of that might be due to any anthropogenic warming, it is worth noting that the IPCC's Science Assessment notes that there is no detectable acceleration of sea level rise over the last century (76). Suffice it to say, so far any accelerated sea level rise due to man-made warming is unlikely to have caused anything other than a minor impact on human or natural systems compared to other environmental stressors such as development of coastlines, conversion of lands for 198 aquaculture,drainage for other humanland uses, sedimentdiversion due to dam constructionupriver, construction of seawalls, and subsidence owing to water, oil and gas extraction(77). FUTURE IMPACTS OF WARMING RELATIVE TO THE BASELINE There are numerous reasons to be skeptical of the studies reported in the IPCC's 1995 assessmentof the impacts of climate change (78). This is because projections of future impacts are basedon a series of model calculations with each succeeding model using, as its inputs, increasingly uncertain outputs of the previous model (8, 78, 79). First, future emissions of greenhouse gases (GHGs) have to be modeled using uncertain projections of future population, economic conditions, energyusage,land use, and land cover. These emissions are themselves sensitive to climatic conditions and atmospheric concentrations. Next, these emissions have to be converted into each GHG's atmospheric concentration. These concentrations then have to be used to determine future radiation forcing which is used (ideally) by coupled atmospheric-ocean models to project climatic changes (such as changes in seasonaltemperatures and precipitation; seasonal highs and lows; and changes in diurnal variability). Moreover, these climatic changes should be estimated at relatively fine geographical scales because the impacts of climate change are locationspecific (8), but the finer the geographic scale, the more uncertain the results. These uncertain climatic changes then serve as inputs to simplified and often inadequate models which project location-specific biophysical changes (e.g., crop or timber yields). Next, depending on the human or natural system under consideration, the outputs of these biophysical models may have to be fed into additional models to calculate impacts on those systems. For example, estimates of crop yields at various locations should serve as inputs for national and global models of the agricultural system in order to estimate overall impact on food security. Thus, estimates of the impacts of global warming in any specific location at any particular time are probably even more uncertain than estimates of the globally-averaged temperature and/or precipitation. M. Goklany Moreover, net global impacts are also uncertain because they are an aggregation of the various location-specific impacts, although there may be some cancellation of errors. Nonetheless, the uncertainties are large enough that one cannot be confident either of the magnitude or, in many cases, even the direction of impacts, i.e., whether the net impacts are positive or negative. This is true not only at any specific geographic location, but also at the global scale. Beyond these uncertainties, there are major sources of systematic upward biases. These studies do not fully or adequately account for technological progress and adaptation (8-11, 79-81) which not only overestimates the potential negative impacts but also underestimates the potential gains from harnessing positive aspects of global warming. Figures 1 and 2, as well as the virtual elimination of malaria, cholera, and other infectious and parasitic diseases in the richer countries, for instance, show that while adaptations may be difficult-if not impossible--to model in advance of their occurrence, they are, nonetheless, real and quite substantial. The above-noted trends also show that for these climate-sensitive sectors and indicators over the last century (or so), adaptations have so far more than offset any increases in negative impacts due to any climate change. While failure to fully account for adaptations significantly simplifies the mechanics of estimating "impacts," it also inflates purported impacts. At best, that could provide misleading information to policymakers; or, at worst, that could skew societal priorities, unless users of such impacts analyses are fully aware not only of their shortcomings, but also their implications. Yet another reason for a bias toward overestimation of climate change impacts is that the climate change scenarios used in the studies relied upon by the IPCC 1995 Assessment, are sometimes more extreme than the IPCC's "best estimate" scenarios. Despite all these shortcomings, it is assumed in the following that the IPCC's 1995 assessment provides robust impact estimates. Agriculture Rosenzweigand Parry(82), an importantsource of the IPCC's 1995ImpactsAssessmentchapteron agriculture (30), estimatedthat the baselineglobal 199 Potentialconsequences of increasingannOSpheric CO2concentration cereal production, i.e., production in the absence of climate change, would rise 83% between 1990 and 2060. The baseline assumed a 2060 population of 10.3 billion and a 330% economic growth between 1980 and 2060. With climate change (but no mitigation policies, i.e., "business-as-usual" or BAU), some production would shift from developing to developed nations, thus increasingthe former's food imports and vulnerability to chronic malnutrition and hunger. However, assuming some adaptations, the net change in global production would be relatively modest: the baseline production level would be perturbed by -2.4% to + 1.1% in 2060 due to an "equivalent doubling of CO2 concentrations." The climate change scenarios utilized by Rosenzweig and Parry effectively assumeda global warming of 4.0°-5.2 °C, and a CO2concentration of 555 ppm (/lL/L) in 2060. By comparison, the IPCC estimated a temperature range ofO. 7-1.7°C (with a best estimate of 1.1-1.2°C) in 2060, and 0.8-4.5°C in 2100 (with a best estimate of2.0°C) (82:40). It would be a mistake to assume that although this may overestimate the impacts in 2060, Rosenzweig and Parry's estimates would nonetheless be a reasonable upper bound of negative impacts for 2100 (or shortly thereafter) under BAU. First, by the year 2100, the BAU CO2 concentrations would be closer to 700 ppm (/lL/L), not 555 ppm (/lL/L) (84). Thus, the beneficial direct CO2 effects would be underestimated for 21 00, while the more negative temperature- and evaporation-related effects would not. This is a major problem with estimating impacts using the equilibrium climate based upon equivalent CO2 doubling (8). Another reason why the estimates of Rosenzweig and Parry would not be valid for 2100 is that the capacity to adapt will be greater in 2100 than in 2060 because of the secular upward trend in technological change and adaptability which, moreover, could be further boosted by economic growth (8, 18, 19,33). Nevertheless, despite the tendency for the Rosenzweig and Parry approach to overestimate negative impacts, the agricultural impacts due to climate change (-2.4% to +1.l%)-and their food security consequences-will be lost in the "noise" due to uncertainties in future levels of population and economic output, either of which could be off by :1::20%(or so) by 2060. For instance, the U.N.'s 1998 population projection for 2050 ranges from~ 7.3 billion to 10.7billion with 8.9 billion beingthe "most likely" estimate(85). Clearly, at leasttill the middle of the nextcentury, theeffectsof climatechangeuponfood securitywill be relatively minor comparedto population and economicgrowth. If the world's populationin 2060 cannotbe adequatelyfed, it will not be becauseof climate change,but becauseof a largerpopulation, insufficienteconomicgrowth,technologicalchange, and trade. Moreover, if the questfor food security leadsto massiveland conversionand consequent habitat and biodiversity losses, that too will be due to insufficient technologicalprogressduring a period of high populationgrowth, ratherthan CO2enhancedwarming (8, 33). Forests and biodiversity The IPCC's Impact Assessment notes that one computer model (BlOME) estimates that in the absence of any additional human demand for land, climate change alone (but excluding the largely beneficial direct effects of CO2 on plant growth) could, by 2050, actually increase global forest area by + 1 to +9% over 1990 levels (86). Another model (IMAGE) which essentially combines BlOME with models that can account for human land use changes and direct CO2 effects estimates that global forest cover would decline by 25%, including a 47% decline in tropical forests and a 10% increase in boreal forests (86). Thus, even if global warming were to be completely halted-and the notion that warming could increase net global forest area was totally discounted-then according to the models used in the studies relied upon by the IPCC, massive loss of forests should still be expected. Not surprisingly, the IPCC assessmentstates that land use change is obviously the greatest threat to species diversity of tropical forests (87). Once again, over the next few decades,the impacts of climate change are likely to be small compared to other non-climatic factors-namely, conversion of forests to relatively low yield agricultural uses in developing nations due to increasing food demand, and reversion of agricultural lands to forests in the richer nations due to increasing agricultural productivity (33,34). Climate change will also affect the rate of forest growth. CO2-enhanced warming may in fact M. Goklany 200 accelerate wood production (e.g., 29, 35, 88, 89), though some have suggested that much of the increased growth could fall prey to pests, diseases, and fires (86). Nevertheless, in more carefullymanaged forests, it ought to be possible to harness technology to take advantage of the positive features of CO2-enhanced wanning, while minimizing any negative effects (33). For instance, King et al. (88) estimate that due to equivalent CO2 doubling, vegetative carbon could increase 12-16% owing to climate change alone, and 31-37% if CO2fertilization is also considered. Recent evidence indicates that the Northern latitudes may already have become more productive (29). Goklany, based upon a population estimate of 9.6 billion in 2050, has estimated that 8.15 Tm2 of plantations and agroforestry enterprises could meet the global demand for wood in 2050 (33). Thus, even a 12% increase in sustainable yield could reduce the amount of forest land needed to meet human needs for forest products in 2050 by 1.0 Tm2 Extreme weather events The IPCC's 1995 Science Assessmentnoted that it was unable to state whether the frequencies or intensities of extreme events such as hurricanes and cyclones would change due to any anthropogenic warming (83). As noted, empirical data suggests that the number and intensity of hurricanes touching the United States may have declined since the 1940s. Gray (90) has suggested that we may be entering a period of heightened hurricane activity, but bases his claim not upon any global warming but on the Atlantic Ocean thermohaline circulation. A recent post-IPCC assessmentconcluded that while thermodynamic calculations predict a 10-20% increase in the maximum potential intensity due to a doubled CO2 climate, the known omissions in these calculations all act to reduce these increases (91, 92). Infectious and parasitic health impacts diseases, and other The IPCC suggests that malaria cases may increase 10-16% by 2100, based upon studies which have focused upon changes in the potential ranges of anopheles mosquitos (52,53). Skeptical public health specialists point out that such prognostications disregard historical fact that disease incidence depends more upon public health measures (or lack thereot) which is determined by a nation's economic status and state-of-the-knowledge regarding the disease, rather than the potential range or by climatic factors (55-57). This is exactly why the current geographical distribution of incidences of a number of infectious and parasitic diseases no longer correspondsto their historic potential ranges. The studies underlying the IPCC report also assume essentially no medical progress against these diseases over the next 100 years, which seems quite unlikely, given the experience of the past 100 years and the accelerating rate of the creation and spread of new knowledge and technology in the fields of medicine and its supporting disciplines. Nevertheless, this study relies on the 10-16% estimate, which translates into about 50-80 million potential additional cases in 2100, compared to a baseline of 500 million in the absence of climate change. Assuming that the additional casesdue to climate change (expressed as fractions of baseline cases) increase exponentially with time, that implies a 5-8% increase by 2060. Further, assuminga similar increase in all infectious and parasitic diseases,the public health impact no doubt would be significant since currently, globally 17 million people-including 1.5-2.7 million due to malaria-die prematurely from such diseases each year, with over 99% occurring in the developing world (63). Nevertheless, until at least the middle of the 2151century, such an increase would be less than one-tenth of the global base rate in the absence of climate change. The potential impacts of extreme heat and cold because of anthropogenic climate change are relatively modest by comparison with the potential impacts of infectious and parasitic diseases. Moreover, globally there may be at least a partial cancellation of adverse effects due to increased incidences of heat stress in some locations, e.g., North America, and reduced incidences of cold stress in others, e.g., Europe (52, 53, 93-96). Finally, the recent IPCC assessment of the regional vulnerabilities to the impacts of climate change, which essentially employed similar methodologies and GCM inputs as those used by the 1995 Impacts Assessment, observes that in 2100 --compared with the total burden of ill health-the Potentialcomequencesof increasingaunosphericCO2concentration public health problems due to climate change through increasesin heat-stressmortality, tropical vector-borne diseases,urban air pollution problems, and decreasesin cold-related illnesses are unlikely to be large(97). Accelerated sea level rise According to the IPCC, between1990and 2100, sea level may rise between 13 and 94 cm (5 to 37 inches) due to anthropogenicclimate change, with a best estimate of 49 cm (19 inches) by 2100, with only abouthalf that occurring by 2060 (76). Notably, the IPCC furnishes a global estimate of about$1 billion peryear to protect against a sea level rise of 50 cm by 2100 (98) which translates into less than 0.005% of the world's economic product (45). DISCUSSION Over the last century or more, according to the IPCC, the globe has warmed 0.3-0.6 °C, perhaps due to man's influence (e.g., 83). The foregoing analysis of historical trends indicates that during that period, certain climate-sensitive biophysical indicators-forest cover, biodiversity and sea level -have continued to deteriorate. But anthropogenic warming has had very little to do with that. Current threats to forest cover and biodiversity are the result of increased human demands for food, clothing, and shelter from a larger and richer population, while sea level has risen mainly due to natural warming. On the other hand, for other climate-sensitive indicators, matters have improved substantially. Land is more productive (Fig. 1); the average person is better fed; infectious and parasitic diseases have been reduced if not eliminated in many areas; infant and child mortality are down; life expectancies are up (21); and while property losses (relative to wealth) due to various extreme weather-related conditions mayor may not be increasing (Fig. 3 and 4), more significantly, deaths and death rates due to such phenomena have declined (Fig. 2). Hence, although the world may have warmed, by virtually any measure of human well-being, the average person's welfare has improved markedly (99). Although some credit for increasing agricultural 201 productivity is probably due to CO2-induced climate change, most of these improvements in climatesensitive indicators of human well-being are due to technological progress driven by market- and science-based economic growth, technology, and trade. Such progress has also reduced the vulnerability of the human enterprise to climate change (8, 16, 19). As a result, technological progress has had a greater impact upon the climate-sensitive sectors than has climate change itself. With respect to the future, the foregoing analysis of the IPCC's 1995 Impacts Assessment (summarized in Table 5) shows that at least until the mid-21 51 century, the effect of climate change upon the most critical climate-sensitive indicators will probably be small compared to those due to other stressors such as population growth, poverty, land conversion, habitat losses, and infectious and parasitic diseases (82, 30, 87, 86, 52, 76). By 2100, only the impact of sea level rise (as estimated by the IPCC's 1995 Assessment) may verge on becoming significant. Thus, over the next several decades, other environmental and public health problems plaguing the world will probably be substantially larger-and more critical-than climate change. This conclusion is relatively robust unless the estimates of the impacts reported in the IPCC are substantially underestimated. But that seems unlikely for several reasons: 1. The studies underlying the IPCC's Impact Assessmentgenerally do not adequately account for technological change and human adaptability. 2. Recent analyses of agricultural and sea level impacts of climate change indicate that they could be less adverse than reported by the IPCC (80, 81, 100, 101). Recent studies of mortality due to or associated with extreme heat and cold continue to suggest at least partial cancellation of effects globally (93-96). 3. For some sectors, the IPCC's underlying impact studies assumed,as noted, a greater climatic change than that estimated by the IPCC's Science Assessment, e.g., agriculture (45, 102). 4. Empirical data on CO2 concentrations suggest that carbon fertilization is real and probably already taking place which, by itself, ought to moderate CO2 growth rates, at least for a while (e.g., 29, 35); increase timber production, at least in managed forests; and help reduce loss of forest cover (16). 202 M. Goklany Table 5. Projected climate change impact V5. impacts of baseline (ie., other environmental) problem~ Impact/Effect Climate-Sensitive Sector/Indicator Projectionfor Year Baseline, includes impacts of environmental problems other than climate change Impactsof climate change,on top of the baseline Agricultural Production 2060 for baseline; >2100 for climate change(see text) must increase83% over 1990levels net global production would change -24% to + 1.1%; but could substantially redistribute production from developing to developedcountries Global Forest Area 2050 decrease25 to 30 (+) % relativeto 1990 reducedloss of global forest area 2060 500 million 25 to 40 million additionalcases 2100 500 million 50 to 80 million additionalcases 2060 variesby location less than 25 cm (or 10 inches) 2100 variesby location less than 50 cm (or 20 inches) Malaria Incidence SeaLevel Rise Sources: Rosenzweig and Parry (82); Reilly et aI. (30); Kirschbaum et aI (87); Solomon et al. (86); McMichael et al. (52); Warrick et al. (76) 5. Empirical data indicate that the atmospheric methane growth rate, which had been increasing since 1945, seems to have peaked in the early 1980s and may stabilize in the next decade (103). Dlugokencky et al. (104) estimate that between 1984 and 1996, the growth in atmospheric concentrations of methane had slowed down by about 75%. 6. Recent calculations of radiative forcing due to greenhouse gases suggest that the forcing used by the IPCC's climate change projections may have beenoverestimated by a net 10% becausean underestimate of the forcing due to chlorofluorocarbons was more than compensated by an overestimate of the CO2 forcing (105). 7. Recent data indicates that the world's population is growing less rapidly, which ought to somewhat reduce estimates of future impacts of cl imate change and deforsetation. For instance, the International Institute for Applied SystemsAnalysis' 1996 central estimate for the population in 2100 was 10.4 billion (106), against the 11.3 billion central estimate assumed in many of the IPCC's projections (78). Thus, based on both historical trends and future projections of impacts, it seemsthat anthropogenic climate change is not now or in the foreseeable future as urgent as other global environmental or public health problems. However, it may be argued that climate change on top of all the other environmental problems may be the straw which breaks the camel's back-particularly with respect to forests, ecosystems, and biodiversity. Thus, goes this argument: immediate action must be taken to curtail GHG emissions. There are two approaches to dealing with the problem of the last straw, and neither has to be mutually-exclusive (46, 99). The first, more common approach is to concentrate only on reducing or eliminating the size of the last straw. Another approach would be to lighten the entire burden before the last straw descends (46, 99). With respect to malaria, for instance, under the first approach-focusing on the last straw--one would attempt to eliminate the 50-80 million new cases in 2100 by totally eliminating climate change; under the second approach, one could try to reduce the total number of cases-whether it is 500 million this year or 550-580 million in 2100. This second approach is more comprehensive since it would reduce cumulative adverse impacts rather than merely a portion, and that, too, merely a small portion (Table 5). It would effectively strengthen the ability of human and natural systems to adapt and cope with climate change as well as other currently, more urgent environmental stressors. There are numerous advantages to the second approach, i.e., enhancing adaptability by reducing vulnerability: 1. Even a small reduction in the baseline (i.e., nonclimate change-related) rate could provide greater aggregate public health benefits than a large Potential consequences of increasing aunospheric CO2 concentration reduction in the additional number of cases due to climate change. Assuming exponential growth in the relative number of additional malaria casesdue to climate change, reducing the number of baseline malaria cases an additional 0.2% per year between now and 2100 would more than compensate for any increases due to climate change. 2. Resourcesemployed to reduce the base rate 203 these sectors include agricultural production, food security, forest cover, ecosystems,and biodiversity. Reconciling winners regional losers with regional Another criticism of the conclusion that climate change is not the globe's most urgent environmental problem is that its underlying rationale overemphasizes net global impacts while ignoring the possibility of severe dislocations that may occur in specific areas because of climate change. For instance, currently most developing nations have food deficits. These deficits may worsen in the future and deteriorate even further if climate changes. Today, developing countries import food from developed countries to make up their deficits. Expansion of this trade would help developing countries cope with any additional shortfalls (whether due to climate change or not). In fact, international trade can help alleviate any geographically non-uniform effect, regardless of its cause. But such trade is only possible if developing countries' economies produce and sell other goods which then can generate the revenues to purchase food grown elsewhere (16). Moreover, as noted below, bolstering economic growth will have many other benefits. would provide substantial benefits to humanity decades before any significant benefits are realized from limiting climate change. 3. Given the uncertainties noted previously regarding impacts assessments,the benefits of reducing the base rate are much more certain than those related to limiting climate change. 4. The lessonslearned, technologies developed, and public health measures implemented to reduce the base rate would themselves serve to limit additional casesdue to climate change when, and if, they occur. 5. Reducing the base rate would serve as an insurance policy against adverse impacts of climate change whether that change is due to anthropogenic or natural causes, or if it comes more rapidly than the IPCC's "best estimates." In effect, by reducing the base rate today, one would also be helping to solve the cumulative malaria problem of tomorrow, whatever its cause. 6. Because of the inertia of the climate system, it is unrealistic to think that future climate change could Increasing the resiliency of developing be completely eliminated evenifGHG emisions were countries to be frozen immediately at today's level. Given the progress in reducing GHG emissions in responseto It is generally recognized that developing counthe Kyoto protocol, such a freeze is most unlikely. tries are most vulnerable to climate change (8, 78, 110). The fundamental reason for this is not that Moreover, full adherence to the protocol would reduce projected temperature increase for 2100 by climate change will be greater in developing counless than 10% (107-109). Thus, the first approach tries, but poverty. Being poorer, developing countries are less able to develop, acquire, and implecan, at best, only be partially successful, and that too, for only a small portion of the malaria problem. ment technologies to adapt to or cope with any hardship or misfortune (8, 16, 19). 7. The stated objective of the Framework Convention on Climate Change is to prevent anthropogenic Thus, poorer countries have lower crop yields (Fig. 5) and lower available food per capita (Fig. 6), climate change from becoming dangerous. But, however "dangerous" may be defined, it depends which leads to higher rates of malnutrition and greater susceptibility to infectious and parasitic upon societal and environmental adaptability. Endiseases(98). Hence, poorer countries have higher hancing adaptation would, therefore, increase the infant mortality rates and lower life expectancies level at which GHG concentrations become dangerous," potentially resulting in substantial savings in (Figs. 7 and 8). Moreover, because their land use is the cost of controls (8). less efficient (Fig. 5), their forest cover continues to Similar logic applies to the other climate-sensitive decline; whereas, by contrast, developed countries sectors where the problems are dominated by nonare being reforested (34, 45). Lack of economclimate change-related factors. As Table 5 indicates,~ ic growth also maintains conditions that are not I. M. Goklany 204 conducive to reducing population growth rates voluntarily (Fig. 9) (16,19,46). Furthennore, poverty reducesthe ability of nations to afford technologies to limit climate change, such as more efficient power plants-particularly those which entail a higher initial cost (8, 19). Finally, poorer countries are more dependent on their climate-sensitive natural resourcesectors(i.e., agriculture and forestry). In 1996, for instance,55% of the developingworld's populationwas engagedin agriculture,comparedto 22% in the transitioncountries,and 5% in the restof the developedworld (20). Thus, economicgrowth oughtto reduceacountry'seconomicvulnerabilityto climatechange(8, 19). 8,000 - ca :E 6.000 C) .¥. "C 'i) ~4.000 ~ 2,000 < 0 a 21,000 14,000 7,000 28,000 GDP/capita Sources: Goklany (99) basedon WRI(21). Fig. 5. Cerealyields (CY), 1995. 2.7 3 Sources: Goklany (99) basedon WRI(21). 3.3 3.6 3.9 Log (GDP/capita) Fig. 6. Daily food supplies(FS) per capita,1995 4.2 4.5 Potential comequences of ilx:reasing aanospheric C~ coocenttation 205 2.5 2 0.5 0 2.6 3 3.4 Sources: Goklany (99) basedon WRI (21). Fig. 7 - 3.8 4.2 4.6 Log (GDP/capita) Infantmortality(IM),1990-1995. 90 U) 80 ... IV Q) 70 :?;:; .c 't: 60 - :c IV 50 >t) C IV 40 t) Q) 30 )( Q) 20 Co - Q) :J 10 0 2.6 3 3.4 Sources: Goklany (99) basedon WRI (21). 3.8 Log (GDP/capita) Fig. 8. Life expectancy,1990-1995. 4.2 4.6 I. M. Goklany 206 8 I 2.6 I i 3.1 Sources: Goklany(99) basedon WRI (21). 3.6 4.1 4.6 LogW Fig. 9. Total fertility rate (TFR) 1990-1995 Therefore,developingbetterinstitutionsto foster economicgrowth, particularlyin the poorernations, will increasetheir resiliencyand boosttheir ability to cope with adversity in general, including those due to climate change. Theseinstitutions, which alsoundergird civil societies,include free markets, freer trade, secureproperty rights, and honestand predictablebureaucraciesand governments.These are,by and large,the very sameinstitutionsthat also stimulatetechnologicalchange(8, 19). Longer term perspective It might also be argued that although climate changemay not be an urgentproblem in the shortto medium-term,becauseof the inertia of the climateand energysystemsit maybe too late to affect it by the time it becomesurgent. Therefore-runs this argument-from a longer term perspective, climate change is a critical problem even today; thus, we must act now (111-114). However, in light of the informationpresentedin Table 5, various analyseson the timing of GHG controls (114-116)suggestthat evenwith a 50-year lag between initiation of climate changecontrols pursuant to specified targets and final compliance, humanity can wait a couple of decades until initiation of control efforts without the impacts of climate change becoming excessive in comparison with those of other existing environmental and public health stressors. In the meantime, one may argue, the cumulative benefit obtained from reducing overall vulnerability (i.e., vulnerability not only to climate change but also to other environmental stressors) through bolstering economic growth, technological change, and trade ought to be greater (Figs. 5-8; and Table 4) than any controls designed to address only climate change. Moreover, one cannot get to the long-term without getting through the short- and medium-terms successfully. Consider the interrelated problems of agriculture, food security, forest cover, and biodiversity. Even if climate change were halted completely, by 2050 more than 25% of the World's forest areawould be lost (Table 5). Not only would this affect biodiversity, it would add to CO2 emissions by reducing carbon stores and removing sinks. In fact, the world would be undergoing the very samecatastrophe that the control of climate change hopes to avoid. The issue, therefore, is how to deal 1.. Potential consequences of increasing atmospheric CO2 concentration 207 with the critical problems of today and tomorrow without compromising-and, if possible, magnifying-our ability to deal with the important problems of the day after. With respect to deforestation and loss of biodiversity, this issue can be addressed by attacking their major causes, namely, the conversion of land and water to satisfy the demands of a larger and wealthier population for food, fibre, and timber (8, 16, 18, 19,33). Some analysts contend that it is, therefore, necessaryto decreasedemand by reducing populations and/or modifying dietary and consumption habits (117). However, this is much easier said than done. In a democratic society where families are free to choose their own sizes and individuals their diets and consumption patterns (as constrained by the market), it is doubtful whether such recommendations can have a significant impact because they ignore human nature (16,33). An alternative approach-one, arguably, more likely to succeed because it accepts human nature for what it is-would be to increase in an environmentallysound manner the productivity of land and water to produce more food, timber, and other products per acre of land or gallon of water diverted to human use. This would limit conversion of these natural resources to human use while meeting human demands adequately. Figure 10 indicates for a hypothetical food demand case in 2050, how much additional land would have to be converted to cropland between 1993 and 2050 as a function of increases in the productivity of the food and agricultural sector (46). It assumes: that the global population will be 9.6 billion, consistent with the World Bank's 1994 "medium" projection; that food supplies per capita would increase at the historical 1969-71 to 1989-91 rate; and that new cropland will, on average, be just as productive as cropland in 1993 (an optimistic assumption). Figure 10 also shows that if productivity does not increase, cropland would have to increase by 17.5 Tm2. Much of this would necessarily have to come from forested areas (46). On the other hand, a 1 % per year increase in productivity would reduce additional (net) cropland requirements to 3.7 Tm2, while a productivity increase of 1.5% per year would result in a net conversion of 0.8 Tm2 of cropland to forests or other uses. -aGO 0 0 0.2 0.4 0.8 0.1 1 Annual Productivity 1.2 1.4 1.8 z Incr9aSe (0/0) Sourcc: Gokllny (16). Fig. 10. Trade-off between productivity growth and habitat loss net conversion of land to cropland from 1993 to 2050. Such increases in productivity are plausible given the numerous existing-but-unused opportunities to enhance productivity in an environmentally sound manner, and that technological change has yet to run its course (33, 46). However, to capitalize on these opportunities and to increase productivity, it is 208 essential to have economic growth in order to generate the investments needed for: 1) researching, developing, acquiring, and operating more productive technologies; and 2) any additional infrastructure necessaryfor the efficient functioning of the food and agricultural sector. By 2050, an estimated $250 billion may have to be invested annually in developing countries' food and agricultural sectors (33). One approach toward increasing productivity is to enhance efforts to develop crops and agricultural practices for adverse conditions that exist today but M. GokIany modified to grow faster in poor soils or adverse climatic conditions; developing technologies to more fully utilize felled treesand extendthe useful life of timber and wood products; improvingextensionservicesto transfertechnology;andresearching methodsto increasegrowth rates,and combatpests and diseaseswithout undue environmentaleffects throughbroader,but more careful andtargeted,use of various inputs (8, 33, 68, 99). CONCLUSION: DEALING WITH THE URGENT WITHOUT IGNORING THE SERIOUS would either persist or become more prevalent because of climate change. Thus, research and development (R&D) could emphasize developing and improving seeds and crops for dry and saline conditions; methods to mitigate soil erosion; and technologies to reduce pre- and post-harvestand end use wastage and spoilage. Obviously, bioengineered crops can play an important, beneficial role in meeting global food demands whether or not climate changes (68). Similarly, developing institutions and economic instruments to use or reuse water more efficiently would help deal with current and future water supply problems (16). The resulting decrease in forest conversion due to enhanced food productivity would also reduce CO2 emissions, and limit habitat loss and fragmentation which would otherwise add to the substantial existing barriers to "natural" adaptation (via migration and dispersion) of species if climate changes. Notably, Article II of the Framework Convention on Climate Change refers to allowing ecosystems to adapt naturally to climate change. Finally, increased agricultural productivity would lower the demand for cropland which would reduce land prices, thereby decreasingthe costs of purchasing or reserving land for conservation, carbon sequestration, or both (33, 46). Similar logic also applies to other spheres of human activity that rely on land and water, such as forestry, habitation, and irrigation. For example, sustainably increasing the usable amount of forest products produced per acre of intensively-managed plantation forests would likewise reduce the amount of forestlands diverted to human use, and reduce pressureson habitat, biodiversity, and carbon stocks and reservoirs. Measures which would increase forest productivity regardlessof any climate change include boosting R & D on tree species genetically- Global warming may be a serious problem in the long run, but if the IPCC's impact assessment is even qualitatively credible, it is not now-nor is it likely to be in the next several decades-among the world's list of critical environmental or health problems. In the unlikely event that further climate change can be halted, that would do little or nothing in the foreseeable future to alleviate the very problems which are proffered as reasons for controlling GHGs. Specifically, mortality and morbidity due to infectious and parasitic diseaseswould be virtually unchanged; conversion of land and water to human uses-the major, imminent threat to global forests, ecosystems, biodiversity, and loss of carbon sinks and stores-would continue almost unabated; and food security will not be markedly advanced, if at all. Yet, it is possible to deal with urgent short- and medium-term public health and environmental problems, while also addressing the potentially serious longer-term problem of climate change. This can be done, for instance, by bolstering the institutions underpinning the mutually-reinforcing forces of economic growth, technological change, and trade. Strengthening them would: I. Address the root cause of the vulnerability of the poorer nations to climate change as well as to other -and, at present, more critical-sources of adversity such as hunger, malnutrition, and infectious and parasitic diseases. 2. Increase the productivity of land and water diverted to meet human needs for food, clothing, shelter, paper, and other material goods, which would reduce the loss of forests, habitat, biodiversity, and carbon sinks and stores, whether or not there is any climate change. 3. Increase the voluntary movement of food and other goods to move from surplus to deficit areas, in 8. Potentialconsequeoces of increasingatmosphericCO2concentration 209 order to alleviate shifts in competitive advantage whetherdue to warming, or anotherfactor. 4. Increasethe ability of developing nations to afford mitigation and adaptationtechnologies. Adaptation can also be enhancedby developing and implementing technologies to addressthose 9. environmentaland societalproblemswhich would be further aggravated by climate change. This would require, for instance,putting resourcesnow into reducing malaria and increasingagricultural 10. and forest productivity in hot and dry conditions. 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