The Great Lakes of North America, that is. Could the millions who live in the 'interlake' region live without them, especially those of us who inhabit the Hurontario highlands? Few others are so closely linked to the varying moods of the fresh water seas. What a wonder they must have been to the French explorers who first looked westward across Georgian Bay and Lake Huron and thought that the evening sun went down in China. Some speculated that it was the spices of the Indies that turned those waters from salt to fresh.

Four hundred million years ago (with apologies to those who think the world to be much younger) central Canada was below the surface of a tropical sea. To the west were the foothills of the Rocky Mountains and to the east the Laurentians with peaks higher than the present Mount Everest. In an evolving world the latitude was that of present day Peru. The equator ran through where Winnipeg now stands.

Continental drift and tilt drained water eastward. What is now southern Ontario was layered with sediment in which entrapped plant and animal life created under great heat and the pressure of the following Ice Age the first-discovered petroleum. That was to the north and south of Lake Erie. The ice had buried everything up to three kilometres deep.

Ten thousand years ago the warming climate, glacial movement and melt water cut river courses and formed the lakes that we know.

An acquaintance of mine who now lives in Australia visits her native Province of Ontario infrequently. Time may solve the problem of distance for those who live so far away. In any event, she tells me that among the things she misses most on her island continent are the fresh water swimming and the sunsets of the Great Lakes. There is no scarcity of sea coasts 'Down Under'. And there are the beach parties that can be planned for Christmas Day. Even in North America, of course, there are those who insist on decamping to sand and surf for 25 December but I am not one of them. My racial conditioning requires a cold, preferably a snowy, winter holiday season with evergreens, firesides, short days and long nights.

My concern is, however, that Lakes Superior, Michigan, Huron, Erie and Ontario could disappear as the glaciers once did. I am so much a son of the lands between them that from childhood I have been able to draw from memory a crude but recognisable map of their relative positions and contours. Just as I know without 'referencing' it that there are 5,280 feet and 1,760 yards in a mile, I am aware that Superior is the deepest and largest body, Erie the shallowest and Ontario the smallest in area. Lake Michigan may lie entirely in another country but the vastness of Georgian Bay is all ours.

Perhaps that is why the past summer's low water levels there are a special concern. The first European to see its shining water was Etienne Brûlé in 1610. Captain William Owen who charted much of its shoreline in 1815 wished to call it Lake Manitoulin but it was eventually named for King George IV, not George II. Its connection to Lake Ontario by Lake Simcoe and the adjacent rivers of the "Toronto Passage" was of military and economic significance to Canada's history.

An owner of lakefront property on the bay said in August that he had a putting green where he used to tie up his boat. He knew that the water levels vary both seasonally and cyclically. Whether or not the 'greenhouse effect' is part of the problem is uncertain but the fact is that the current low-water cycle has lasted almost a decade longer than was expected.

Maude Barlow's new book Blue Water Covenant: the Global Water Crisis foresees pressure on Canada to export potable water. It is in short supply all around the world. The recently formed Gordon Water Group of scientists and policy experts warns that although Canada has a high percentage of the world's fresh water it has only 6% of the world's renewable supply. Meanwhile industry and vessels using fossil fuels are polluting our lakes that are, on average, less than 100 metres deep as compared to the oceans' average of 3,000 metres.

What is more, dredging in the St. Clair River between Lakes Huron and Erie is said to have caused river bed erosion that has become a major leak of water from further north. Like global warming, that is a problem that the next generation will understand better.

Meanwhile, Lake Superior has dropped 29 centimetres in the past year and is 54 cm below the average 30 year level for this season. Lake Huron is 58 cm below that average and has dropped 13 cm in the past 12 months.

Lake Ontario's average is down 16 cm. The figures come from the U.S. Army Corps of Engineers.

Environment Canada predicts that, other things being equal, global warming alone will result in the levels of the lakes dropping 1.56 metres by 2050. The International Joint Commission (IJC) keeps an eye on the lakes for the two national governments involved. It is looking at the St. Clair River problem but is not expected to report before 2010.

Lower water levels will result in higher on-shore temperatures and hasten the prediction that Southern Ontario' climate will in the foreseeable future be like that of Virginia in the past two centuries.

To top it all comes news that Robin Hood's Sherwood Forest is being "stolen by time". For the past thousand years, while England was deforested for building material and fuel, 'the greenwood' had a net loss of only one tree a year. Now it is five a year.

As Charlie Brown used to say "Good grief!".

Lakes and forests are disappearing. Does nothing matter but oil? Will it be water and wood that the world fights over next? If so, Canadians will be most vulnerable. Clearly, we need a federal/provincial freshwater conservation strategy, restraint on all who exploit our water resources and a ban on bulk water exports. Above all we need heightened public awareness of the problem.