Bush: Climate change is 'serious problem' US President George W. Bush said it was time to move past a debate over whether human activity is a significant factor behind global warming and into a discussion of possible remedies. "I have said consistently that global warming is a serious problem. There's a debate over whether it's manmade or naturally caused," Bush told reporters. "We ought to get beyond that debate and start implementing the technologies necessary to enable us to achieve a couple of big objectives: One, be good stewards of the environment; two, become less dependent on foreign sources...