Executive leadership faces new vulnerabilities. Many leaders privately concede them, but few are willing to talk publicly about them. "Unthinkable" events since 2014 have revealed a new leadership fragility at the highest levels. And the pace of change in 2017 shows that the uncertainties are greater than ever. Is this the "new normal?"Thinking The Unthinkable is an investigation into why leaders have appeared more unable or unwilling than ever to anticipate the biggest issues of our time....

John Rafferty of Encyclopædia Britannica and Dr. Chris Langdon of the University of Miami examine the processes of ocean acidification and coral bleaching. This is the 11th part of the Postcards from the 6th Mass Extinction audio series.