Relations between the US and China are going through a rough patch. On trade, diplomacy and military matters the superpowers are at odds; they still have entirely different visions of the world and its future. Yet the world’s two biggest carbon emitters have pledged to cooperate more closely on cutting their emissions. Celia Hatton explores how the promises were hammered out and what it means for the rest of the planet.; Early in 2021 many hoped India might escape the worst of the pandemic, with a vaccine roll-out under way and infection rates dropping. But Covid cases and deaths have soared. The surge in patient numbers, and severe shortages of oxygen, have overwhelmed the health system in some places. In Delhi, Rajini Vaidyanathan sensed a marked shift in mood.; Brazil is also hard hit. Its President Jair Bolsonaro has scoffed at the virus, and clashed repeatedly with regional governors who wanted to impose stricter lockdowns and other measures. In the northeastern town of Lencois, Richard Lapper gauges the political fallout. Thousands of people gathered last week calling for the release of opposition politician Alexei Navalny. But Russia’s laws on public protest have tightened recently, and attending unauthorised rallies these days can mean a beating, a sacking or a prison sentence. Sarah Rainsford talked to some who still feel it’s worth speaking out. Idriss Deby, leader of Chad for more than 30 years, embodied the African "military strongman" until his death, apparently in the thick of fighting with rebels. The son of a herdsman, he faced down many uprisings and regional crises and was often considered an indispensable ally by the West in stopping jihadist groups in the Sahel. Andrew Harding considers the dilemmas he's left behind. Producer: Polly Hope