Canada's twin---the two were parted at birth---is Australia. Like all permanently separated twins, living very far apart, the differences between them are enormous. In Australia's night sky, you see the Southern Cross, which Canadians never see, while Canadians look up at the Great Dipper and the North Star, which is never visible to Australians. In Australia, the sun always moves to the left in the sky and in Canada it always moves to the right. That said, the twins share striking similarities.

Canada and Australia were established as settler colonies whose founding populations occupied territories that had been the homelands of aboriginal peoples for thousands of years, in the case of Australia for about forty thousand years, in the case of Canada for ten or twelve thousand years. French settlement in what is now Canada began in the early 17th century. Permanent British settlement in Australia commenced in the late 18th century. And while the conflict between France and Britain for control of Canada and the permanent fact of English and French populations were a defining feature of Canadian existence, both countries came of age as continent-spanning enterprises during the Victorian age at the height of British imperial power. In downtown Toronto, Sydney and Melbourne, Victorian British street names---King, Queen, Albert, Wellington, York etc.---enjoy pride of place.

Sparsely populated countries with large diverse sophisticated cities, Australia and Canada are advanced nations that rely enormously on their role as commodity producers that export their products to other countries. For over a century, the two countries have been rivals in the production of wheat and other grains to meet the demands of global markets for these commodities. Times of high prices have been a boon to farmers in Manitoba, Saskatchewan and Alberta, as well as in South Australia, Victoria and New South Wales. Similarly when prices fall, farmers in these regions, though they are separated by thousands of kilometers, have suffered simultaneously.

Australia and Canada share a history of making enormous public investments to construct roads, railways, other infrastructure, and educational facilities in regions whose economies are devoted to farming, as well as to the extraction of coal, iron ore, uranium and other resources for export markets. The public in both countries has been saddled with the high fixed costs that go with expenditures to support primary products industries. When commodity markets boom, Australia and Canada prosper. When commodity markets go bust as they have during the present economic crisis, their economies suffer. The rise and fall of external demand for products from minerals to wheat and the changing technology that affects the value of specific commodities is a major source of economic vulnerability in Australia and Canada.

In the early years of the 21st century, Australia and Canada are respectively the hot and cold twins and the dry and wet twins. Both countries are highly vulnerable to the threat of climate change although in quite different ways.

Much of Australia, especially the south and southeastern states of South Australia and Victoria and much of Western Australia have experienced a severe drought for many years. Adelaide, the fine English style city that is the capital of South Australia, was parched when I visited in February 2009. The Barossa Valley, just north of the city, is one of Australia's most prestigious wine producing regions. When I toured it by bus, the vineyards were sparkling green thanks to massive irrigation efforts. But the surrounding countryside was brown and dry, with the beds of streams completely dry and rivers reduced to a trickle. Our guide spoke continually about the rising threat to wildlife and human activities as a consequence of the drought. Later on a tour through the Grampian Mountains and along the Great Ocean Road in the State of Victoria, the consequences of drought and of fire, its dark companion, were even more starkly apparent. A couple of weeks earlier over two hundred people had died in the terrible fires in Victoria in the worst natural disaster in the history of Australia. Without being too apocalyptic about it, the viability of heavily populated regions of Australia is at stake as a consequence of potential long-term shortages of water and the threat of climate change.

While Canada's supply of fresh water is much more ample than Australia's, there are important regional exceptions. The western prairies have been afflicted with major droughts. The massive use of fresh water in the process of producing synthetic crude oil in the Alberta oil sands poses a threat to the supply of water available to meet the needs of agriculture, industries and cities.

The oil sands, it should be noted, are the largest source of green house gas emissions in Canada. In that sense, Canada's oil sands emissions add to the greenhouse effect that is generating climate change, not least in Australia as well as in Canada's north, where temperatures have been rising with dire consequences for the wildlife of the region.

The global markets for Australian and Canadian commodities plunged in 2008 and the currencies of both countries dropped appreciably against the U.S. dollar. Australia and Canada rode high during the commodity boom, especially Canada, whose oil industry roared ahead as the price of oil peaked in July 2008. Given the structures of their economies, with their dependence on commodity exports, both countries waited anxiously for the return to economic health of the countries that were home to their export markets.

The conundrum of Canadians and Australians is that of prosperous peoples with plenty of capital of their own in a world that is entering a new age. Do these countries that have served as suppliers of primary products for others have to remain in that role in the future? In a time when the key to the future is development that is sustainable, can other options open for these peoples?

It would make a good deal of sense for Canadians and Australians who are thinking about the crash and its aftermath to consider these questions together. The similarities and differences between Australia and Canada should provoke sparks of insight helpful to these long separated twins.