James Ball: 2015 – What’s the big idea?: Against a backdrop of hacks and terror attacks, it’s possible that surveillance powers will be strengthened

Julian Borger: 2015 – What’s the big idea?: Never mind Cuba, this is the big one for the west. Failure to reach an agreement could trigger a wave of nuclear proliferation

Rafael Behr: 2015 – What’s the big idea?: With no clear-cut winner likely in May’s general election, 2015 will be a year in which British politics takes an arithmetical turn

Sarah Boseley: 2015 – What’s the big idea?: The epidemic has been a shocking wake-up call to the world. Minds and money are now concentrated on clearing Ebola from west Africa