Vol. 511996): 351-365. The application of agricultural land rating and crop models to C0 2 and climate change issues in Northern regions: the Mackenzie Basin case study Michael Brklacich, Patrick Curran and Douglas Brunt Department of Geography, Carleton University, 1125Colonel By Drive, Ottawa, Ontario KIS 586, Canada The Mackenzie Basin in northwestern Canada covers approximately 1.8 million km2 and extends from 52“ N to 70°N. Much of the Basin is currently too cool and remote from markets to support a viable agricultural sector, but the southern portion of the Basin has the physical potential to support commercial agriculture. This case study employed agricultural land rating and crop models to esti- mate the degree to which a C0 2 -induced global warming might alter the physical potential for com- mercial agriculture throughout the Basin. The two climate change scenarios considered in this anal- ysis would relax the current constraints imposed by a short and cool frost-free season, but without adaptive measures, drier conditions and accelerated crop development rates were estimated to offset potential gains stemming from elevated C02 levels and warmer temperatures. In addition to striving for a better understanding of the extent to which physical constraints on agriculture might be modi- fied by climate change, there is a need to expand the research context and to consider the capacity of agriculture to adapt to altered climates. Key words: agricultural land suitability, wheat yields, Northern Canada Introduction Research into the potential impacts of global cli- mate change on human activities has flourished over the last decade, and the relationships be- tween agriculture and climate change have re- ceived considerable attention. (For reviews of the effects ofglobal climate change on world ag- riculture see Reilly et al. 1996, and Parry 1990. Studies on the sensitivity of Canadian agricul- ture to climate change are presented in Arthur 1988, Bootsma et al. 1984,Brklacich and Stew- art 1995, Singh and Stewart 1991, Smit et al. 1989, Williams et al. 1988). In retrospect, agriculture was well-positioned to respond to the challenges that might accom- pany global climate change for at least three rea- sons. First, weather is an important input to ag- ricultural production on an annual basis and long-term climate trends exert considerable influence over the location of agriculture. These indisputable linkages underpin the sensi- tivity of food production systems to a global climate change and have become part of the rationale for investigating the potential bio- © Agricultural and Food Science in Finland Manuscript received February 1996 351 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Brklacich, M. et al: Applying land rating and crop models to climate change physical impacts of climate change on agricul- ture. Second, many of the climate change scenar- ios that were advanced throughout the 1980 s and early 1990 s suggested a less favourable climate for agricultural production (eg: drier conditions, greater variability) (IPCC 1990) and often con- tributed to a general conclusion that climate change would result in a less secure global food supply. This potential decline in food security in combination with other concerns regarding the long-term potential for meeting planetary food requirements led to a reframing ofglobal climate change concerns, and contributed to an explicit recognition of the economic, social and politi- cal dimensions of climate change impacts re- search (Brown et al. 1989, World Resources In- stitute 1990). Third, agricultural research has investigated the relationships among food production, weath- er and climate for many decades, and as a result addressing the agricultural impacts of climate change did not hinge upon the development of new scientific methods. Existing agricultural research frameworks and methods were able to incorporate climate change scenarios, and agri- culture became one of the first sectors to exam- ine impacts which might stem from global cli- mate change. Overall, agriculture and agricultural research were and continue to be well-positioned to in- vestigate the physical, biological, economic and social impacts stemming from global climate change. Much of this research into the agricul- tural impacts of climate change has, to a large extent, evolved from conventional agricultural research and it embraces the assumptions and context which underpin agricultural research in the major food producing regions. For example, agricultural research often draws upon reliable soils and weather data, well-documented crop trials, and high quality farm management data. However, reliable and complete biophysical and socio-economic databases do not exist for many regions which are near or beyond the current cli- mate margin for commercial agriculture. As a result conventional approaches for gauging the agricultural impacts of rising C02 levels and glo- bal climate change can be difficult to implement in northern regions. This paper focuses on assessing the impacts of a potential global climate change on agricul- tural opportunities in northern regions. It draws upon a case study in the Mackenzie Basin, Can- ada, and examines issues relating to: model applications near and beyond the cur- rent climate frontier for commercial agricul- ture, sparse data coverage, and linking biophysical and socio-economic as- sessments. The Mackenzie Basin context An overview of the Mackenzie Basin The Mackenzie Basin (Figure 1) is the world’s twelfth largest watershed with a drainage area of about 1.8 million km 2 . The main trunk of the Mackenzie River is the dominant feature, and theLiard, Athabasca and Peace River watersheds represent significant areas in the southern half of the Basin. The Basin extends from 52°N to 70°N, and includes portions of the Arctic, Bore- al and Grasslands ecoclimate regions (Statistics Canada 1986). Much of the Basin is currently too cool and remote from markets to support a viable agri- cultural sector, but the southern portion of the Basin has the physical potential to support com- mercial agriculture. Commercial agricultural production occurs primarily in the Peace River region. Wheat and barley are the key cash crops, but canola (rapeseed) has become increasingly important in the last 10 years. During the 1980s an average of 335 800 ha of barley and 383 100 ha of wheat were seeded in the Peace River re- gion. Forage production and pasture are the oth- er main agricultural land uses. About 1.2 mil- lion ha of land in the Peace River region is cur- rently used for commercial agricultural produc- tion (Agriculture Canada 1986, 1990). 352 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 5 (1996): 351-365. The Mackenzie Basin case study With the Mackenzie Basin covering a vast area, much of which is beyond the current climate boundary for agriculture, it should not be sur- prising that existing data bases impose con- straints on the opportunity to assess the agricul- tural impacts of climate change. For example, detailed, high resolution soils maps have been compiled for only a limited number of sites within the Basin, and do not pro- vide a foundation for exploring the Basin’s ag- ricultural prospects. Basin-wide coverage of ba- sic soils data is not available below the scale of 1:1 million. At this scale, the smallest recogniz- able land parcel is about 4000 ha and provides a foundation for reconnaissance level assessments. There were 567 weather stations operating in the Mackenzie Basin between 1951 and 1980. Since the study presented in this paper repre- sents one component of a multi-sector assess- ment ofclimate change impacts on the Macken- zie Basin (Cohen 1992), for consistency, all sec- toral studies contributing to the Mackenzie Ba- sin project utilize the 1951-80 climate base line. For many of the weather stations, the record has Fig. 1. The Mackenzie Basin. 353 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Brklacich, M. et al.: Applying land rating and crop models to climate change been compiled for a relatively short period (i.e. less than a decade), and lengthy gaps in the record and/or observation of a limited number of weather properties limit their utility. A com- parison of the data requirements of the current generation of crop models to the observed weath- er records revealed that the datarequired to im- plement these models could be satisfied at less than 20 sites throughout the Basin. Given this level of coverage, it is feasible to conduct as- sessments of crop yield sensitivities to climate change for selected indicator sites, but clearly it is not possible to extrapolate from these select- ed assessments and draw conclusions about the Basin in general. Crop trials supported by detailed weather, soils and management data are required to cali- brate crop models to local conditions. Data from crop trials are available for limited areas, and all are within the southern reaches of the Basin. Under these restrictions, full calibration of crop models is simply not feasible. The research framework developed for the Mackenzie Basin study recognized the limita- tions imposed by the available information base, and was designed to make the best use of the available information. The assessment began with a Basin-wide assessment of the extent to which possible changes in long-term climate averages mightalter agroclimate constraints and land suitability for commercial production of spring-seeded cereal grains. Regions identified as having a physical potential to support com- mercial agriculture under this initial assessment were targeted for more intensive investigations into the effects ofa C02-induced climate change on annual spring wheat yields. An agricultural resource potential perspective Resource rating scheme overview The primary analytical tool used to estimate the climate change impacts on agricultural land potential was the Land Suitability Rating Sys- tem for Spring-Seeded Small Grains (LSRS) (Agronomic Interpretations Working Group 1992). This rating scheme was selected for two reasons. Firstly, climate properties are consid- ered explicitly by the rating scheme and there- fore it could be applied to climate change issues. Secondly, implementation of the LSRS requires routinely collected soils, climate and landscape data and therefore it can be applied to broad re- gions. The LSRS is based on rating the extent to which soil, climate and landscape represent lim- itations for the production of common spring- seeded grains (e.g. wheat, oats, barley). Each of the components is rated separately and assigned an initial value of 100. Then the extent to which a range of factors (e.g. effective growing degree days, drainage class, topography) impair crop production is determined and points are deducted to reflect the severity of the limitation.The overall land suitability rating ranges from 0 to 100, and is based on the most limiting component. An over- view of the analytical units upon which the land suitability assessments are founded and a brief de- scription of each component and the data used to implement each component follows. Units of analysis The polygons defined for the Soil Carbon Data Base (Soil Carbon Base Working Group 1992) are compiled at a 1:1 million scale and repre- sent the analytical units used in this assessment. These polygons are not necessarily homogene- ous and can include a Dominant Soil which ex- ceeds 40% of the polygon’s surface area, and a Subdominant Soil accounting for between 10% and 40% of the polygon area. About 1800 poly- gons containing mineral soils were extracted for further analysis and account for about 57% of the Basin’s land area. Climate component The climate component considered the extent to which accumulated heat and moisture limit 354 AGRICULTURAL AND FOOD SCIENCE IN FINLAND spring-seeded cereal growth and development. Growing degree days above 5°C was the prime indicator of heat accumulation during the frost- free season. The May through September mois- ture supply, estimated as the difference between accumulated precipitation and potential eva- potranspiration, was used to calculate the sea- sonal moisture supply. The LSRS can consider the impacts of earlier than average fall frosts on land suitability for commercial crop production, but insufficient data prohibited the use of this component of the rating scheme. Details on point deductions associated with each of the climate parameters are described in Agronomic Interpre- tations Working Group (1992). The 10 km by 10 km baseline (1951-1980) of monthly mean temperatures and total precip- itation compiled by Environment Canada (Smith and Cohen 1993) was augmented with monthly normals for minimum and maximum tempera- tures. Many of the land units (i.e. Soil Carbon Data Base polygons) used in this analysis fol- low natural drainage systems and therefore are delineated as relatively long narrow polygons. Several 10 km x 10 km climate grid cells inter- sect partially with these land units. The devel- opment of climate profiles for these land units based on an averaging ofclimate grid cells would have regularly included substantial areas of land outside the soil polygon and thereby contribut- ed to unreliable estimates. To minimize the oc- currence of this error source, baseline tempera- ture and precipitation data for the land units of analysis used in this assessment were estimated as the climate associated with the 10 km by 10 km grid cell closest to the centroid of each soil polygon. The moisture supply was calculat- ed using monthly data for the following climate properties: precipitation, maximum and mini- mum temperature, solar radiation at the top of the atmosphere. Solar radiation estimates at the top of the atmosphere were obtained from Rus- selo et. al. (1974). The Brooks (1943) method was employed to estimate daily mean tempera- tures from monthly climate normals, and these daily estimates were used to calculate the accu- mulation of growing degree days. Scenarios for long-term climate change were derived from the application of the Canadian Climate Centre (CCC) and Geophysical Fluid Dynamics Laboratory (GFDL) GCMs to 2 x CO, atmosphere experiments (Boer et al. 1984 and Manabe and Wetherald 1987,respectively, as re- ported in Smith and Cohen 1993). Scenarios were generated by applying differencesbetween 2 x C02 and I x CO, GCM model runs to the 1951-80 monthly temperature and precipitation means. Warmer temperatures were estimated for the entire Mackenzie Basin and for all seasons un- der the CCC scenario, but the greatest tempera- ture deviations were estimated for the winter months and in the northerly portions of the Basin (Fig. 2). The regional climate change sce- nario derived from the GFDL GCM was con- siderably different from the CCC scenario. Esti- mates under the GFDL scenario of summer tem- perature increases for the southern half of the Mackenzie Basin were in the 4°C to 6°C range whereas the CCC scenario estimates ranged from I°C to 3°C. Estimated summer temperature in- creases for the northern half of the Mackenzie Basin were similar under the two scenarios. The estimated changes in winter temperature also varied. The CCC-derived winter tempera- ture increases tended to be in excess of 4°C for most of theBasin. Estimated increases under the GFDL scenario were considerably less, and in general did not exceed 3°C. Changes in precipitation patterns were also considerably different between the two scenari- os (Fig. 3). Precipitation estimates under the CCC scenario for all seasons were in the +25% range over most of the Basin. Estimated devia- tions from the current under the GFDL scenario were more severe, especially during the summer for which estimatedprecipitation changes ranged from decreases of up 25% to increases in excess of 100%. Soils component The rating of mineral soils was based on the ex- tent to which moisture supply capacity, surface 355 Vol. 5 (1996): 351-365. AGRICULTURAL AND FOOD SCIENCE IN FINLAND 5 Brklacich, M. et al: Applying landrating and crop models to climate change factors, subsurface factors and drainage impose limitations on crop production. Limitations were estimated as a function of depth of top soil, tex- ture, drainage, soil structure and consistency, organic carbon content, pH, depth to an imped- ing layer, and bulk density. The required data were either extracted directly from the Soil Carbon Data Base or information from the Data Fig. 2. Temperature changes estimated under the Canadian Climate Centre (CCC) and Geophysical Fluid Dynamics Labo- ratory (GFDL) model-based 2 x CO, scenarios. 356 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 5 (1996): 351-365. GFDL Scenario Base was used to infer the required data. Point deductions for soil factors are presented in Agronomic Interpretations Working Group (1992). Landscape component The landscape component considered slope and slope length, stone removal requirement and Figure 3. Precipitation changes estimated under the Canadian Climate Centre (CCC) and Geophysical Fluid Dynamics Laboratory (GFDL) model-based 2 x C0 2 scenarios. 357 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Brklacich, M. etal: Applying land rating and crop models to climate change coarse fragment content. Lack of reliable infor- mation prohibited the use of the flooding factor in this analysis. The data required to rate the landscape component were taken from the Soil Carbon Data Base, and were either used directly or used as proxy data. Details on the implemen- tation of this component are found in Agronom- ic Interpretations Working Group (1992). Interpreting the overall rating The lowest or most limiting score of the three components becomes the basis of determining the overall land suitability ranking for spring- seeded cereal crops, while the other two compo- nents are included as subfactors influencing ag- ricultural potential. This approach provides a preliminary estimate of the combined effects of soil, climate and landscape factors on agricul- tural land potential. To assist with interpretation the overall score can be grouped into three broad categories (Ag- ronomic Interpretations Working Group, 1992). Lands with a rating ranging from 60 to 100points are considered highly suitable for sustained crop production. Ratings from 30 to 60 points repre- sent lands which are moderately suitable for ag- riculture, and scores less than 30 points desig- nate lands which are unsuitable for commercial agriculture. Climate change impacts on agro-climate potential The current average frost-free period for the Basin of 132 days (Figure 4) represents a sub- stantial constraint to the commercial production of crops. Each of the climate change scenarios implies a considerable extension of the frost-free period, with the greatest estimated increase of 29 days occurring under the GFDL scenario. With the longer frost-free period and higher temperatures associated with the climate change scenarios, it was estimated that there would be substantial increases in effective growing degree Fig. 4. Impacts of climate change on selected agroclimate properties in the Mackenzie Basin. 358 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 5 (1996): 351-365. days (GDD) over the duration of the frost-free period. The current Basin-wide average falls short of 1000 GDD, and represents a moderate to severe constraint to the production of spring- seeded cereals. Spring-seeded cereals typically require about 1600 GDD. and this threshold is reached on average under both ofclimate change scenarios considered in this study. The estimated seasonal moisture supply, de- fined as the differencebetween precipitation and potential evaporation, was also sensitive to the climate change scenarios. Substantial precipita- tion increases estimated under the GFDL sce- nario are offset by anticipated potential evapo- ration increases, resulting in only minor adjust- ments to the estimated seasonal moisture sup- ply. However, the CCC scenario assumes only a modest precipitation increase, and this was more than offset by the estimated potential evapora- tion increase. As a result, the estimated seasonal moisture supply decreased under the CCC cli- mate change scenario. Climate change impacts on agricultural land suitability Figure 5 illustrates the estimated impacts of the CCC and GFDLclimate change scenarios on the agricultural land suitability throughout the Mac- kenzie Basin. Under current conditions, it is es- timated that nearly 6 million ha of mineral soils throughout the Mackenzie Basin are physically suitable for the production of spring-seeded small cereals. Moderately suitability agricultur- al lands account for nearly 36 million ha, while the remaining 62 million ha of mineral soils are estimated to be unsuitable for spring-seeded ce- reals. The largest adjustments in land suitability for agriculture stemming from global climate change are estimated under the GFDL scenario. A 41% increase in the total area of land which is either highly or moderately suitable for cereals is esti- mated under this scenario, and this includes an estimated 64% increase in highly suitable land. Fig. 5. Climate change impacts on agricultural land suita- bility. 359 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Brklacich, M. et al: Applying land rating and crop models to climate change Under the CCC scenario, the total area of lands highly and moderately suitable for spring- seeded cereals is estimated to increase by 31%. This aggregation of highly and moderately suit- able lands however masks an estimated 29% decline in land which is highly suitable for agri- culture. Under the CCC scenario, the estimated temperature increases relax constraints associ- ated with the current short, cool frost-free sea- son, but this potential benefit is offset by esti- mated increases in moisture deficits. As a result there was an estimated decrease in the land area with the highest potential for crop production. A crop yield perspective CERES-WHEAT overview The primary analytical tool used in this compo- nent of the study was the CERES-WHEAT crop growth and productivity model. This crop mod- el was selected as it is one of only a few models which can consider the combined effects of CO, and climate changes on crop yields, and the model has been applied elsewhere at higher lat- itudes (Brklacich and Stewart 1995). The version of the model used in this research is described in Ritchie and Otter (1985) and Godwin et al. (1989). CERES-WHEAT predicts crop growth and yields for individual wheat va- rieties, and the model employs simplified functions which advance on a daily time step to estimate crop growth and yield as a function of plant genetics, daily weather (solar radiation, maximum and minimum temperature, precipita- tion), soil conditions, and management factors. Modelledprocesses include phenological devel- opment, growth of vegetative and reproductive parts, biomass production and partitioning among plant parts, and root system dynamics. The model also tracks moisture inputs and with- drawals, and estimates the impacts of soil-water deficits on photosynthesis and partitioning. For this analysis, seeding date (SD) was estimated as the first day of the frost-free season and soil moisture conditions at seeding reflected the ex- tent to which soil moisture reserves were re- charged over the winter period. The intensive data requirements of the CERES-WHEAT crop model limited the appli- cation of the model to 16 sites scattered through- out the Mackenzie Basin. The remainder of this section summarizes the input data used in the crop yield assessment and presents selected find- ings for two sites. Beaverlodge at 55°N is in the Peace River region and within the area of the Basin which presently supports commercial ag- riculture. Hay River at 61°N is beyond the cur- rent climate frontier for agriculture (Fig. I). This analysis focuses on isolating the sensitivity of spring wheat yields to climate change, and changes in production practices. The use of alternative crop varieties and other adaptive measures are beyond the study’s scope. Model performance Crop development aspects of the model track well with observed conditions, and differences between the estimated and observed times from sowing to maturity are minimal (Brklacich and Stewart 1995).This indicates that the model rep- licates crop development processes reasonably well and therefore can be applied in climate change studies. Model estimates of crop yields however often exceed observed yields, and the models provide little insight into the effects of poor weather on crop quality. Overall, this sug- gests the model can be used to provide insight into the relative rather than absolute impacts of climate change on wheat yields. Atmospheric C0 2 data The current level of carbon dioxide in the at- mosphere is assumed to be 360 ppm. Future lev- els are set at 555 ppm and are based upon an “equivalent of a 2 x CO,” atmosphere. This ap- proach has been used elsewhere in climate im- 360 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 5 (1996): 351-365. pact assessments (Rosenzweig and Parry 1994) and recognizes that increases in the atmospher- ic concentrations of other trace gases will result in a radiative forcing of the atmosphere equiva- lent to that due to a doubling of C02 but occur- ring prior to actual C02 doubling. Climate data Baseline climate data for the period 1951 to 1980 were derived from the observed weather record at each site. Recorded daily values for maximum and minimum temperature and precipitation were employed. Solar radiation data are not collected on a routine basis and therefore the deJong and Stewart (1993) method was used to estimate dai- ly solar radiation values from temperature and precipitation data. Scenarios for long-term climate change (Figs 2 and 3) were derived from the application of the CCC and GFDL GCMs to 2 x CO, atmos- phere experiments (Smith and Cohen 1993). These climate change estimates were then su- perimposed onto the daily baseline climate data. Soils data Soil data were obtained from the Canada Soil Information System (CanSIS). The latitude-lon- gitude position of each weather station was used to locate the corresponding CanSIS soil poly- gon, and the following soils data for the domi- nant soil in the polygon were utilized in the anal- ysis: texture, bulk density, organic carbon, pH, coarse fractions, layer thickness, and soil clas- sification. Management data Though many wheat varieties are grown in the Peace River region, this study is based upon cv. Manitou. Many oftoday’s wheat varieties have been derived from cv. Manitou and it has been used as a representative variety in previous stud- ies (Brklacich and Stewart 1995). The application of fertilizer, particularly ni- trogen, on commercial crops is considered very important for most agricultural regions in the Basin. The findings presented in this paper are based on 36 kg/ha N, which is consistent with recommended fertilizer application levels for wheat. Climate change impacts on seeding date for wheat The frost-free season in the Mackenzie Basin is relatively short and cool, and therefore the esti- mated seeding date (SD) for spring-seeded crops was assumed to be the first day of the frost-free period. At Beaverlodge, which is situated in the Peace River region, the estimated mean SD oc- curs in the last week of April (Figure 6), but can vary from mid-April to mid-May. The estimated mean spring wheat SD for Hay River, which is located beyond the current climate frontier for agriculture, was about one week later than the mean SD at Beaverlodge but the range in SDs is similar at both sites. An earliest possible SD of mid-May repre- sents a relatively late start to the crop season. It is rare under current climate conditions that the estimated SD at Beaverlodge occurs after this threshold, thereby reducing the risk associated with farming in a climateally marginal region. Spring conditions at Hay River are considerably more risky,.and the estimated SD occurs after mid-May about 25% of the time. Both climate change scenarios imply an ear- lier SD, however the magnitude of the estimated impacts are not uniform. Mean SD is advanced to a greater extent under the CCC scenario than under the GFDL scenario. A comparison of the two climate change scenarios suggests that larg- er precipitation increases and less pronounced temperature increases for the winter and spring seasons under the GFDL scenario would result in wetter and cooler soil conditions in the early spring, thereby limiting the impacts on seeding dates. It shouldbe noted, however, that both sce- narios lead to a decline in production risk at Hay 361 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Brklacich, M. et al: Applying land rating and crop models to climate change River. The estimated SD occurs after mid-May about 25% of the time under current climate con- ditions, however therisk associated with this rel- atively late SD is removed under the CCC sce- nario and reduced to about 10% of the years un- der the GFDL scenario. Climate change impacts on wheat yields The short, cool frost-free seasons and the potential for crop failures at Hay River tend to suppress crop development and yields. Estimat- ed current mean wheat yields at Hay River are about 50% of the mean yield estimated for Bea- verlodge (Figure 7). The estimated impact of the equivalent of a 2 x C02 atmosphere in isolation (i.e. C0 2 in- creases without climate change) was an increase in wheat yields of about 30%. The potential ben- efits of increases in atmospheric C02 tended to be offset by the climate changes specified under the CCC and GFDL scenarios. The warmer tem- peratures, especially during the later phases of crop development, shortened the time available for grain filling and therefore the climate change scenarios do not necessarily imply more favour- able conditions for cereal crops. At Hay River, it is estimated under both scenarios that the com- bined effects of C0 2 increases and climate change would result in mean wheat yields that are similar to yields estimated under the current Fig. 6. Climate change impacts on estimated spring wheat seeding dates. Fig. 7. Climate change impacts on estimated spring wheat yields. 362 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 5 (1996): 351-365. climate. For Beaverlodge, this estimated trend also applies for the GFDL scenario, but it is es- timated that the expected increases in crop mois- ture stress associated with the CCC scenario would further reduce mean wheat yields to about 75% of the current estimated mean. Expanding the research context The research framework used in this study was initiated by specifying scenarios for climate change, and then the implications of these pos- sible changes were estimatedfor agricultural re- source potential and wheat yields in the Mac- kenzie Basin. This approach has been instrumen- tal in isolating the sensitivity of particular at- tributes of agricultural systems to a pre-speci- fied climate perturbation. While the spatial displacement of conditions which are physically suitable for the production ofa particular agricultural activity will undoubt- edly have considerable impact on the future of agriculture, this sort of information does not di- rectly address the vulnerability of agricultural systems to changing conditionsand the capacity of agriculture to adapt to change (Carter et al. 1994; HDP 1994; Smit 1993). In order to inves- tigate the adaptive capacity of agricultural sys- tems to potential changes in climate and other conditions which influence agriculture, there is a need to expand the conventional research framework employed in this analysis and also consider: Do farmers perceive a change (in climate and/ or other conditions)? What role does climate play in agricultural de- cision-making relative to other influences in- cluding other environmental, economic, polit- ical and socio-cultural factors? • Is the farm vulnerable to the changing conditions? • If the farm is vulnerable, what is the perceived range of adaptive responses? Which of these adaptive responses could be implemented? Which of the feasible adaptive responses comes closest to meeting the goals for farm- ing? Conclusions This study provided preliminary insights into the potential effects of global climate change on ag- ricultural prospects in the Mackenzie Basin. The relatively short and cool frost-free periods char- acterizing the current climate impose consider- able constraints on spring-seeded cereal produc- tion in this region. The two climate change sce- narios considered in this analysis would relax these constraints, but it is important to note that, the magnitude and the geographical distribution of the estimated impacts are not uniform across the region. Furthermore, it was estimated that without adaptive measures, accelerated crop growth rates and drier conditions associated with the climate change scenarios could offset poten- tial gains associated with elevated C02 levels and expanded frost-free seasons. Improving upon these preliminary assess- ments hinges upon advances in at least two are- as. Incomplete data is clearly a substantial limi- tation.The available data on weather, soils, crop trials and farm management are sufficient to sup- port reconnaissance level assessments. Creative methods for supplementing the existing data bases are required. This assessment considered the physical po- tential for commercial production of cereals. Logical extensions of this research would in- volve considering the role of climate relative to other biophyscial and socio-economic factors which influence agricultural systems, and ad- dressing the capacity of agricultural systems to adapt to climate change. Acknowledgements. The authors gratefully acknowledge the support provided by the Atmospheric Environment Serv- ice, Environment Canada, and the Centre for Land and Bi- ological Resources Research, Agriculture Canada. The pa- per has benefitted from the constructive reviews by two anonymous reviewers. 363 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Brklacich, M. et al.: Applying land rating and crop models to climate change References Agriculture Canada 1986. Tests on cereal and oilseed crops in the Peace River region: 1985. Research Branch, Beaverlodge. 48 p. - 1990. Tests on cereal and oilseed crops in the Peace River region: 1989. Research Branch, Beaverlodge. 50 p. Agronomic InterpretationsWorking Group 1992. 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In: Parry, M. et al. (eds.). The impact of climatic variations on agricul- ture. Volume 1. Assessments in cool temperate and cold regions. Kluwer, Dordrecht, p. 221-379. World Resources Institute 1990. World resources 1990-91. Oxford University Press, Oxford, p. 11-31. 364 AGRICULTURAL AND FOOD SCIENCE IN FINLAND SELOSTUS Viljelyvyöhykkeiden ja kasvumallien soveltaminen ilmastonmuutoksen tutkimisessa: Mackenzien jokialue, Kanada Michael Brklacich, Patrick Curran ja Douglas Brunt Carleton University, Kanada Mackenzien jokialue sijaitsee Kanadan luoteisosas- sa ja on laajuudeltaan noin 1,8 miljoonaa km2. Tällä hetkellä alue on liian viileä ja etäisyydet ovat liian pitkiä, jotta maataloutta kannattaisi harjoittaa merkit- tävässä määrin. Jokialueen eteläosien luonnonolot ovat kuitenkin sellaiset, että taloudellisesti kannatta- valle maataloudelle on edellytyksiä. Tutkimuksessa selvitettin, miten ilmastonmuutoksesta aiheutuva maailmanlaajuisen lämpötilan nousu vaikuttaa Mackenzien jokialueen luonnonoloihin. Tutkimukses- sa sovellettiin maatalousmaan luokitusta ja kasvumal- leja, joiden avulla arvioitiin alueen potentiaalista maataloustuotantoa muuttuneissa olosuhteissa. Ana- lyysissä käytetyt kaksi ilmastonmuutosta kuvaavaa skenaariota viittaavat siihen, että lämpötilan nousu lyhentää nykyisin hyvin pitkää routajaksoa. Saman- aikaisesti kuitenkin kuivuus ja viljan nopeutunut kas- vu vähentävät hyötyä, joka maataloustuotannolle koi- tuu lisääntyneestä hiilidioksidista ja kohonneesta lämpötilasta. 365 Vol. 5 (1996): 351-365. AGRICULTURAL AND FOOD SCIENCE IN FINLAND