2 Volumes Final Proceedings - Washington 1984.pdf - IARC Research

154sphere as a whole. In coastal regions of the Arctic,climate changes are complicated by simultaneouschanges in the ice regime, but the general implicationsof C02-induced climate change would bea warming in the Arctic with a likely increase inprecipitation (Harvey, 1982). If we accept thisas a hypothesis valid for the next 100 years, thenthe following questions might be posed.First, how can we assess the effects of climatechange on permafrost conditions, given thatlocal conditions exert such strong influences onground thermal regime, as discussed by Smith andRiseborough (1983). Unfortunately there is adearth of published information on ground temperatureregimes at neighboring sites over long periodsof time. There appears to be no report in theliterature of any monitoring network of shallowpermafrost temperatures that has been continued ona regular basis €or any length of time. Figure 3is based on a few years' data from Brown (1978);it illustrates that, within a small area, there isconsiderable variation in the thermal regime fromsite to site and from year to year, For example,the warmest year was 1976 at some sites, but 1975at others. Thus we cannot expect individual locations,where permafrost is present, to respond inthe same way to the same climate-forcing function;there are intervening processes that have to beunderstood before we can predict the influence ofclimate and climate variation on permafrost conditions,How can we best address this particularproblem of the complexity introduced by the variationin local conditions? Goodwin et aL. (1984)have addressed this issue, using a numerical energybalance model.Secondly, is the likely rate and magnitude ofpermafrost change due to climate likely to beless, equally, or more Important than changes dueto other natural processes, such as the spontaneousthawing of ice-rich sedient exposed by riverbankerosion or fire? A corollary to this is, howwill climate change affect the rate of such naturalprocesses? We have initiated some work in thecentral Yukon to monitor the year-by-year retreatof retrogressive thaw flow slides to see if thereis any relationship between the rate of retreatand climatic conditions. Such studies could berepeated in various places. Lastly, are changesin the permafrost regime resulting from possibleclimate change likely to be important considerationsin northern geotechnical engineering? GivenYEARS0 5 10 15 20 25double snowfall1 Rock2 Tlll3 Palsa4 DepressionV-20c- 1973 1974 ' 1975 ' 1976DATEI1FIGllRE 3 Ground temperatures at 1.06-m depth for FIGURE 4 Predicted annual maximum active layerfour sites at Churchill, Manitoba (from Smith and development for different sites under a uniformRiseborough, 1983).climatic warming trend (from Smith and Iilseborough,1983).