The naming of this unit was far from original because SI advocates derived the name of their unit from the already well established ton and added an '-ne' suffix to differentiate between the SI tonne and non-metric ton. The tonne is also less formally called metric ton but this name is deprecated since it mixes metric and non-metric terms.

This wasn't done by "SI advocates"; the names ton and tonne existed long before there was an SI, which was only introduced in 1960.

It wasn't the adding of an -ne to the English word for this distinguishing purpose. Rather, it was a direct borrowing of the French word. A French word which dates back to even before there was any metric system, let alone the modern version called the International System of Units.

In French, of course, "tonne" is just as ambiguous as "ton" is in English. What do you suppose an unidentified "tonne" would have been in Quebec 50 years ago, for example? Most likely a tonne courte, or 2000 English pounds, unless it was in shipping where it would likely be the tonne forte of 2240 lb.

I'm no expert in French, but I think it would be a pretty safe assumption that today (though not necessarily in the past), wherever French is spoken or written, if tonne is used without any other identifying adjective, it is the tonne mètrique.

In English, "tonne" is somewhat less ambiguous than in French. Nonetheless, the terms "short tonne" and "long tonne" are used, rarely. Furthermore, many are careful to specifically identify the units as "metric tonnes"; Google
"metric tonne" 37,200 hits
"metric tonnes" 149,000 hits

Gene Nygaard 14:09, 16 Dec 2004 (UTC)