Arctic scientists from across Canada will discuss how global warming and other factors are altering northern ecosystems as the theme of this year's Northern Lectures.

        Beginning Jan. 15, the Thursday-evening series entitled The Arctic Environment, Landscape Under Pressure, features five talks on current and future conditions of Arctic wildlife, land, air and water. Lectures take place in Lady Eaton College lecture hall at 8 p.m. and are followed by receptions.

        The dates and topics of the lectures are:

• Jan. 15 The Arctic Ocean: Global Contaminant Dump, Robie Macdonald of the Institute of Ocean Science in Sidney, B.C.

• Jan. 22 How to Make a Polar Bear: Comments on the Arctic Food Web, Robert Conover, formerly of the Bedford Institute of Oceanography

• Jan. 29 Permafrost in Retreat? Permafrost and Climate Change in the Northwest, Chris Burn, Carleton University geography department

• Feb. 5 Is Arctic Air Pollution Changing the Northern Environment?, Leonard Barrie, Atmospheric Environment Service, Toronto

• Feb. 12 Ecology of Polar Bears, Ian Stirling, Canadian Wildlife Service, Edmonton