Just read a pretty good analysis of "Global Risks" (where Global Risk is defined as an occurrence that causes significant negative impact for several countries and industries over a time frame of up to 10 years).
A key characteristic of global risks is their potential systemic nature – meaning that they have the potential to affect an entire system, as opposed to individual parts and components.
Here are the Top 5 Global Risks, based on likelihood and severity of impact.
via World Economic Forum.
So, the big issues are: Financial Crisis caused by or in conjunction with … Social Problems (employment levels and income disparity), Environmental Issues (e.g., climate and weather), and/or Cyber Threats. Surprise, Surprise, Surprise …
The WEF article is much more nuanced and worth reading if you are interested.
On a related note, here is a video clip where Jon Stewart discusses the World Economic Forum:
It is a little funny to think about a group of the world's wealthiest people gathering in an secluded mountain enclave to discuss concerns over income inequality.