She, herself, refuses to buy tobacco stocks. Tobacco use is linked to a number of potentially fatal diseases.

Her sentiments were echoed by another speaker, Michael North, president of Greenstar Corporation, a technology company that focuses on solar power, wireless communications and media development. He says the planet can expect to suffer a number of environmental crises over the next 10 years as the climate warms.

"The pattern is going to be sustained for some time, and those events when they take place, as tragic as they are, they are needed wake-up calls for the investor and for the entrepreneur, for the people building businesses," North said. "They will see opportunities in those crises – the little Warren Buffetts will be going green."

Both Buffett and North say they think the worst of the global financial crisis is over, although the next two years will remain tough, and will be followed by a period of low but steady growth.

The investment conference ends Tuesday.