The water desalinization effect you mention has been speculated as the cause of the Little Ice Age, that occurred between 1550-1850. In the previous, warmer era, water from Greenland and the northern ice cap supposedly stopped the flow of the North Atlantic Current, which makes Europe nice and warm. There is a lot of good literature on the effect on mankind of the Little Ice Age. Not all scientific investigators of this period believe this was the cause, or the main cause. Some point to increased volcanic activity, while others suspect decreased solar output. Those who disagree with the concept of Global Warming point to this last effect, saying that we are not affecting our environment as much as we think we are, we are just in a cyclical phase starting from the end of the Little Ice Age.
What I find interesting is that, if Global Warming triggers the stoppage of the NAC, thus cooling the Earth, then the Earth sounds like its pretty good at regulating itself. While little creatures such as we may be pretty frightened with all this, it does show that the Earth can put up with quite a bit.