"I have never seen myself as an alarmist but rather as a scientist with a critical viewpoint, and in that sense I have always been a skeptic. I have devoted most of my career to developing models for predicting the weather, and in doing so I have learned the importance of validating forecasts against observed weather. As a result, that's an approach I strongly favor for "climate predictions." It's essential to validate model results, especially when dealing with complex systems such as the climate. It's essential do so properly if such predictions are to be considered credible."