BILL AND MELINDA GATES are increasingly worried about the future, according to a report published this week by their foundation. Usually heroically optimistic, the philanthropists fear that some aspects of global progress—of which the report demonstrates there has been lots—are under threat thanks to changes in demography and insufficient funding, as the priorities and moods of international donors have changed. Their report examines future scenarios, considering 18 global challenges from cutting child mortality to increasing financial inclusion, based on different degrees of optimism and pessimism. For instance, projections for HIV suggest that a 10% cut in global donor funding for treatment—a not unduly pessimistic assumption—could lead to 5.6m more deaths by 2030 than if spending remains on track. The couple argue that the decisions that the world makes over the next two years or so will have a huge impact on the futures of millions, if not billions, of people.