They foresee further changes ahead - increased global average rainfall, for instance, more frequent floods and droughts in certain areas of the US as temperatures increase by a projected three to six degrees C by 2100 and salt water penetrating further inland as glaciers melt and sea levels rise. And they believe that it is not only species distributions that will shift northwards in response to rising temperatures. The authors are concerned about the possibility that rising sea levels will let sea water into groundwater aquifers and freshwater coastal systems. Areas at greatest risk, they say, include Hawaii, Nantucket, Martha's Vineyard, Long Island, New York, and central coastal California. They call for research on the implications of climate change for international water law, US treaties and agreements with Mexico and Canada, and international trade in water.
Some scientists still dispute that human-induced global warming is happening.
They argue that the computer models on which future scenarios of climate change are based, and which are driving the greenhouse debate, are deeply flawed. They also dispute the view that the Earth is currently experiencing a rapid warming. They say that satellite data and balloon studies suggest no such warming is taking place.