t was a grim irony that the best transport news in ages was buried in the first few days of the coronavirus lockdown. On 26 March, the government published a document, Decarbonising Transport, which went further in facing up to the problem of emissions from air and vehicle traffic than most campaigners had dared to hope for. The challenge is enormous. In 2016, transport overtook energy to become the single biggest source of domestic emissions. Motor vehicles on their own are responsible for around a fifth of the total. On aviation, the UK is the world’s third-worst polluter, behind China and the US. But here was the transport secretary, Grant Shapps, declaring that “public transport and active travel will be the natural first choice”, adding “we will use our cars less” for anyone who missed the point. Transport was to be a centrepiece of the UK’s preparations for the postponed Cop26 climate talks. Finally, it appeared we were on the way to grasping the nettle of our polluting driving and flying habits. Six weeks on, we are in a different world. Travel of all sorts has collapsed: there were 90% fewer flights from European airports in April compared with a year ago. In the UK there are just 5% of the normal number of rail journeys, while road traffic has fallen to levels last seen in 1955. In the short-term, this means steep drops in emissions: one estimate says the UK’s have fallen by 36%. But already experts are warning that unless strong action is taken, any temporary benefits could be quickly erased. Probably the biggest risk is that governments will take their eye off the climate emergency, bailing out airlines and car manufacturers as they have already bailed out oil companies. But while some observers have pointed to the collapse in vehicle sales as the beginning of the end for petrol and diesel, other voices warn of the even greater risk to public transport due to worries over being able to maintain social distancing. Last month Milan’s leaders declared their determination to avoid a surge in car use, even if residents were reluctant to return to trains, trams and buses. “If everybody drives, there is no space for people, there is no space to move,” said the city’s deputy mayor Marco Granelli. Milan’s authorities are among the leaders of a group of mayors working together worldwide on plans for a green recovery. At the heart of schemes announced so far is a radical reorientation of street space in favour of walking and cycling – a goal that is made all the more urgent given the tentative links being made by researchers between air pollution and coronavirus. Milan has announced that 35km (22 miles) of road will be transformed over the summer. In Paris, the mayor is spending €300m (£262m) on a new cycle network. New York, Mexico City, Bogotá and Barcelona are among other cities with schemes ranging from new car-free days to the temporary reclassification of streets as recreation areas. So what of the UK? While it is only fair to point out that the country has been a leader on decarbonisation (after doing so much to carbonise the planet in the first place), when it comes to transport we are a laggard. For a mixture of reasons (powerful oil companies; successful car manufacturers; an unhealthy identification, nourished by popular culture, with the car-mad US), we have been painfully slow to take even obvious steps. Hence our illegally dirty air, astronomical rail fares and irrational hostility to cyclists – who are routinely pilloried for the kinds of selfish, careless behaviour that goes unremarked when the culprits are drivers. All is not lost, as March’s draft decarbonisation document showed. This week Boris Johnson – who, when he was London mayor, shrank the capital’s congestion zone – suggested that a “golden age of cycling” could be about to dawn. Having started slowly, British cities are putting in place pandemic measures such as temporary cycle lanes in London, and a Safe Streets Save Lives scheme in Greater Manchester. The Committee on Climate Change, which advises the government, has told ministers that green policies such as an accelerated transition to electric vehicles would be the strongest basis for an economic recovery. The UK’s chronic overcentralisation remains a brake on progress. Properly accountable and resourced regional government is needed to engineer, both politically and practically, the modal shifts that are needed. But politics is not all top down, and the shift in behaviour during the lockdown, as millions of people have spent far more time on two wheels or feet, is also important. On a recent walk through my London neighbourhood I saw rollerbladers, sunbathers, neighbours playing darts against a gate and a game of badminton between parked cars. It’s almost 40 years since Donald Appleyard showed in his book Livable Streets that less busy roads lead to stronger communities. Could the pandemic see the start of a broader movement to reclaim our town and cities from cars? • Susanna Rustin is a Guardian leader writer