Global warming -- you may accept or reject those who say it is a dangerous phenomenon.

Possible solutions to global warming range from the simple to the complex -- from changing a light bulb to engineering giant reflectors in space. The most talked about solutions involve expanded use of alternative energy technologies, and less reliance on fossil fuels.

Michael MacCracken

Climate scientist Michael MacCracken says society has to make the commitment to change. "You have to commit to taking actions that will require society to do certain things, but many of those can be beneficial and helpful, but we're going to have to change the path that we are on and how we get energy."

Some scientists believe global warming is part of a natural cycle and will take care of itself.