Donald Trump’s departure will alter the face of geopolitics. The climate crisis and Covid response will affect all nations – while others face very particular challenges. Observer correspondents examine the 12 months ahead

A potent mix of hope and fear accompanies the start of 2021 in most of the world. Scientists have created several vaccines for a disease that didn’t even have a name this time last year. But many countries, including the UK and the US, are still stumbling through the deadliest period of the pandemic.

The shadow of Covid will not begin to lift, even in richer countries, for months. Britain was the first to approve a vaccine and has secured extensive supplies, yet Boris Johnson’s suggestion that life might be returning to normal by Easter is widely seen as optimistic. Other countries, particularly in the south, face a long wait to get vaccines, and help paying for them. The rebuilding of economies shattered by Covid everywhere will be slow; even countries that managed to contain it have taken a hit, from Vietnam to New Zealand.