Imagine that you left earth before coronavirus and returned this week. That is pretty much what has happened to a team of 87 people on board the icebreaker Polarstern, who spent the past six months doing climate research in the Arctic and arrived back on land a few days ago.

The world greeting them is familiar, yet changed. Smiles have been replaced by masks; people avoid each other when walking down the street. And while the researchers were at sea, the topic they were studying – climate change and emissions – underwent the biggest shift in our lifetimes. With the world in lockdown, emissions will see their biggest drop this year since the second world war.

For the team who were on the icebreaker, it is a lot to take in. ‘On the Polarstern, we had only a very vague feeling about what actually the consequence of coronavirus on society is’, chief scientist Torsten Kanzow told me, recalling conversations with family over a patchy satellite connection. ‘There are lessons to be learnt, for sure; you can't count on many things that you used to count on.’

For his group, those things included the fact that they were supposed to leave the icebreaker by aircraft in April – a runway had been built on the floating ice – but instead arrived two months later, by boat. He finally returned home on Monday.

The €140m project, known as the Mosaic Expedition, is one of the most ambitious polar research programmes ever undertaken. Many of their observations show, depressingly, that warming in the Arctic is still very much under way.

Climate change has not taken a break, even while coronavirus has ravaged the global economy and, sadly, hundreds of thousands of lives. One item of particular concern is that the expedition observed very low ozone levels, raising the question of whether this is linked to the ozone hole over the Arctic. (More analysis has to be done before they can say for sure.)

Even though carbon dioxide emissions have fallen considerably during the pandemic, this is just a small blip when measured on a planetary scale. The drop in emissions in 2020 – about 8 per cent down on last year – will just about put us on track to where we should have been anyway, if we are to reach the Paris agreement goal of limiting warming to 1.5°C.