If automobile emissions continue to rise at their present rate global warming will start to have a major impact on the natural environment according to the findings of a new study by scientists at the University of Michigan.

George Kling, a biology professor at the University of Michigan and the lead author of a report into the phenomenon, says the temperature of America's famous Great Lakes is set to rise by up to 16 degrees Fahrenheit in the summer and 14 degrees in the winter by the end of the century.

'In the next 100 years, we will have the same amount of warming as seen since the last Ice Age - 100,000 years ago,' he declared.

The news has prompted the Union of Concerned Scientists, in conjunction with the Ecological Society of America, to call for more urgent action to reduce emissions.

According to David Friedman, a senior engineer at the Union of Concerned Scientists Clean Vehicles program 'Alone', the US is now producing more emissions from its automobiles than the total emissions from any single country, save for China, Japan and Russia.