A first approximation of ground ice volume for the area surrounding Eureka, Nunavut, indicates that it comprises 30.8% of the upper 5.9 m of permafrost. Volume depends on the type of ice examined, ranging from 1.8 to 69.0% in different regions of the study area. Excess ice makes up 17.7% of the total volume of frozen materials in the study area. Melt of ground ice in the past has produced thermokarst features which include ground subsidence of up to 3.2 m, formation of tundra ponds, degradation of ice wedges, thaw slumps greater than 50 m across, gullying, and numerous active layer detachment slides. With a doubling of atmospheric carbon dioxide, the rise in mean annual temperatures for the area is projected to be 4.9 to 6.6°C, which would lengthen the thaw season and increase thaw depths by up to 70 cm. The expected geomorphic changes to the landscape are discussed.

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We examined how fast- and slow-growing families (based on height at 10 years) of Pinus banksiana Lamb. are affected by a climate altered by CO$ sb2$ during their first growing season. Our primary objective was to evaluate the possibility that genotypes performing best under present conditions may not necessarily do best under projected warmer climate. Seedlings were grown for six months in two climatic environments (350 $ mu$L/L CO$ sb2$ x present temperatures and 700 $ mu$L/L CO$ sb2$ x 4$ sp circ$C warmer temperatures) and with 100 ppm and 5 ppm nitrogen. / The CO$ sb2$T$ sp circ$ environment had a significant effect on most biomass components of seedlings and water-use efficiency but not on height and other growth variables. The nitrogen fertilization was generally the most significant effect of the treatments for most growth variables. / All the families responded in a similar way to variations in the growing environments except for WUE. Family differences were more important for measurements of height and growth variables than for biomass components. The architecture of seedlings was also highly variable between families. Norm of reaction graphs were built for several growth variables to outline which families were overall most successful in an enriched CO$ sb2$T$ sp circ$ environment. Of the 15 families studied, four of them were classified as most successful in a projected high CO$ sb2$T$ sp circ$ climate.

No description available.