Given $50 billion to spend, which would you solve first, AIDS or global warming? Danish political scientist Bjorn Lomborg comes up with surprising answers. Bjorn Lomborg isn't afraid to voice an unpopular opinion. In 2007, he was named one of the 100 Most Influential People by Time magazine after the publication of his controversial book The Skeptical Environmentalist, which challenged widely held beliefs that the environment is getting worse. This year, he was named on of the "50 people who cold save the planet" by the Guardian newspaper. His newest book, Cool It: The Skeptical Environmentalist's Guide to Global Warming, further analyzes what today's science tells us about global warming and its risks. In 2004, he convened the Copenhagen Consensus, which tries to prioritize the world's greatest challenges based on the impact we can make, a sort of bang-for-the-buck breakdown for attacking problems such as global warming, world poverty and disease. It begins from the premise that we can't solve every problem in the world, and asks: Which ones should we fix first? The Copenhagen Consensus 2004 tapped the expertise of world-leading economists, as well as a diverse forum of young participants; collectively, they determined that control of HIV/AIDS was the best investment -- and mitigating global warming was the worst. Lomborg summarized these findings in How to Spend $50 Billion to Make the World a Better Place. In spring of 2008, Copenhagen Consensus will convene, assembling over 55 international economists, including 4 Nobel laureates, to assess, prioritize and brainstorm solutions for the major global challenges of today.