In Reply to: Re: Coldest day in recorded history posted by Jaco D on November 23, 2005 at 15:56:03:

rivers rarely freeze over nowadays because of "thermal pollution"

Thermal pollution is caused by industries taking water from the rivers for cooling and then returning the water to the river at a higher temperature than when it went in. Even when you have a shower or take a bath youre generating thermal pollution because the water going down the drain is warmer than the water coming into your house (unless youre into cold showers) up to a certain point thermal polution isint much of a problem but if its severe enough to raise the temperaure of the river by more than a few degrees some fish species start dying off