Norm Catto

Climate and glacier change in southwestern China during the past several decades

Glaciers are distributed in the Nyainqntanglha Mountains, Himalayas, Tanggula Mountains, Gangdise Mountains and Hengduan Mountains in Southwestern China. Daily temperature and precipitation data from 111 stations, together with the records of glacier changes, indicate that temperature patterns during 1961?2008 were consistent with warming at a statistically significant level. Seasonal warming was greatest in autumn and winter. Temperature rise showed a significant relationship with sea surface temperature in the Western Pacific, net longwave radiation flux, altitude, sunshine hours, strengthening anticyclonic circulations in summer and anomalous cyclonic circulation in winter. The increase was more apparent in higher altitude areas than in lower ones. Precipitation variations were less marked than those of temperature, generally showing weak decreasing trends during 1961?2008. Increasing trends were apparent only in spring and winter, when regional trends of precipitation increases with altitude also were evident. The strengthening Western Pacific Subtropical Highs were related to precipitation variation. Against the background of increasing temperature, especially the increasing warming with altitude, the fronts of 32 glaciers and areas of 13 glacial basins have retreated, mass losses of 10 glaciers have been considerable, glacial lakes in six regions have expanded and melt water discharge of four basins has also increased, but these glaciers and basins in our study are only a fraction of the retreating glaciers over southwestern China.

Magnetoclimatology: Teleconnection between the Siberian loess record and North Atlantic Heinrich events

New environmental magnetic data from loess and paleosol successions in outcrops in the upper reaches of the Ob River drainage, southern Siberia, track the major climatic variations over the last glacial-interglacial cycle. Profiles of magnetic susceptibility and alternating deposition of loess and soil-formation events correspond to oxygen isotope stages 1–5. The magnetic-susceptibility data, in association with the stratigraphic succession, confirm that the wind-vigor magnetoclimatological model is a viable alternative to the classic pedogenic model. Interpretation of magnetic-susceptibility data from loess- paleosol successions must therefore consider eolian dynamics, available source materials, and transport directions, in addition to pedogenic processes. Rapid magnetic fluctuations are also observed. These are identified—for the first time in Siberian records—as the signature of the abrupt cold pulses responsible for the Heinrich layers in North Atlantic marine sediments. The data thus form a component of climatic teleconnections across the Northern Hemisphere, allowing correlations to be made among (1) Siberian magnetic susceptibility stratigraphy, (2) data recorded from other loess-paleosol successions in China, European Russia, Europe, and North America, (3) North Atlantic ice-rafted detritus, and (4) sea-surface temperatures derived from molecular stratigraphy of marine sediments off the northwest coast of Africa.

Richardson Mountains, Yukon-Northwest territories: The northern portal of the postulated ‘Ice-Free Corridor’

Abstract The Richardson Mountains, located to the east of the Porcupine Plateau and Old Crow Basin, constitute the first barrier that migrating organisms would have to traverse in order to follow any potential ‘Ice-Free Corridor’ in western Canada. Two gaps exist in the mountain range: McDougall Pass in the north, and Peel River Canyon in the south. The existence of the ‘Ice-Free Corridor’ in this region thus hinges upon the chronology and extent of Laurentide glacial advances in these areas. Three glacial events have been recognized in the Richardson Mountains-Peel Plateau region. An initial event occurred during the middle Quaternary, depositing sediments subsequently reworked into the ‘Brown Bear’ gravels of the central Peel Plateau. A second glacial event occurred at some later time prior to the Late Wisconsinan. This glaciation, correlative to the Buckland event of the Yukon coastal plain, reached McDougall Pass, blocking the northern access through the Richardson Mountains. The glaciation did not extend into the Bonnet Plume Basin, but the presence of glacial ice in the southern Peel Plateau impounded a large lake in the basin, depositing lacustrine sediments and preventing use of the flooded Peel River Canyon route. The most recent major glaciation, of Late Wisconsinan age, was less extensive than the second event in the central and northern Peel Plateau. Although glacial ice did not penetrate McDougall Pass at this time, lacustrine impoundment in the pass and the Bell Basin precluded use of this route by any potential migrants during the Late Wisconsinan. In the Bonnet Plume Basin, Late Wisconsinan ice advanced over the deformable, previously deposited lacustrine sediment, reaching its maximum position at Hungry Creek. The southern passage through the Richardson Mountains was blocked by glacial ice during the Late Wisconsinan, and thus no suitable gateways to the ‘corridor’ route existed prior to the ultimate deglaciation of the region.

Geomorphological Landscapes and Geoconservation

The intrinsic value of geomorphological landscapes is considered in the context of aesthetics, culture, socio-economics, and ecology as well as geoscience. Geoconservation has become more urgent as geodiversity, biodiversity, and cultural diversity have declined. The evolution of western Canada’s parks and natural heritage sites is a story of alternating successes and failures to achieve geoconservation in the face of hostile economic and political visions. The recent emergence of tribal parks and geoparks is yet further evidence of the lively debate that continues. The common element in these debates is the increasing awareness of the intrinsic value of the geoheritage of which geomorphological landscapes are a central part.