Life in the UK and around much of the world has changed immeasurably in just weeks.
In response to the Covid-19 pandemic, millions of people are working from home, avoiding travel and dramatically altering the way they live.
These changes are intended to save the lives of thousands of people who would be most at risk from the fast-spreading respiratory disease. But they're having another side effect.
In New York, pollution levels have fallen 50% compared to before anti-coronavrius measures were put in place. In China, coal use has fallen by 40% and the number of days with “good quality air” have gone up.
These are the sorts of changes which could address another crisis which could prove life-threatening: the planet's rapidly rising temperature.
So could the response to Covid-19 help us tackle climate change?
Newcastle University hydroclimatoligist Professor Hayley Fowler says there are important differences in the two emergencies - but the lessons learned now could help with the rapid response needed to prevent the global temperature rising to above 2C beyond pre-industrial revolution levels.
She said: "We just don't know yet, in the sense that it depends what happens after this is over.
"It seems positive in the sense that the ability to act like you're fighting a on a war front, to mobilise resources when needed is great - it just shows that we can do it when we want to, how much money can be mobilised in a crisis when it's needed.
"We've also showed how quickly you can change people's habits. This is what's needed to address global heating.
"But what we're doing now isn't sustainable in the long term. It's an immediate reaction, a massive change in behaviour in the short term - afterwards, I would imagine things will go back to the way they were.
"We are responding to an acute situation, whereas with climate change it's a chronic situation: we will see the effects of what we do now in 20 or 30 years time."
But, she said, there is some reason to hope. Some of the changes in behaviour that have been forced by the coronavirus crisis could be sustained in the long term - and could do wonders for the climate.
She said: "I would hope that people will realise what they can change. People have had to develop much better ways of contacting each other, I would hope that we would be able to to reduce the amount of business and academic travel - people will have realised what they can do without flying. I don't think people realised before quite how unnecessary a lot of it is.
"Some airlines may go bust, and I imagine there won't be quite so many low-cost flights for some time after this. And, after a lockdown of perhaps six months, will we still feel the need to travel the way we do at the moment?"
The response to coronavirus does not address many of the issues which urgently need to be solved to save the planet. But it could be a first step.
She said: "It's not the solution to climate change. I would hope that it will mean we won't continue to increase Co2 emissions this year, because we are still increasing every year, so we could see a stagnation and it would be amazing if we saw a reduction. But we still need to make huge changes, including to the way we make energy."
And the changes in society could prove key, to showing the changes needed to save the planet can be made.
Prof Fowler said: "It's interesting, because this does seem to be bringing communities together, and it will be interesting to see if that community effect continues after this.
"I think we are appreciating each other more, and I would like to hope this will continue after this.
"There has been a huge social and cultural change - people have proved they can change their behaviour. It shows society doesn't have to function the exact way it currently does, because it isn't functioning like that any more."