This afternoon I was on watch. Bear watch.

Whenever there are people out on the ice, it’s necessary for a couple of people at least, and more if there’s fog, to be keeping a look out. On these occasions there’s usually one person up on the wings of the bridge, another person up in the crow’s nest, and somebody else out on the helipad. There’s a rota so nobody has to stand for hours on end and get too cold, but today I did an hour in the heli slot.

Standing with a radio, eyes scanning the horizon, you feel quite a sense of responsibility. This is especially so when, like today, the fog is down and you can’t see more than a few hundred metres. As I learned last week, polar bears can appear from nowhere, because they camouflage so well and they seem to have no fear whatsoever. In the distance, the only way of spotting them is their movement, and the slightly yellow colour of their coats. I’m told that if a bear is hungry or worried for it’s cub, and therefore quick to attack, it can run at around 30km/hour, about double the speed that somebody can run. So when, as today, the scientists are out busying themselves with their data collecting and readings, they’re pretty vulnerable and you can’t afford not to be paying attention.

But visits from polar bears are just one of the challenges for the scientists as they seek to measure the thickness of the ice floe that we’ve moored alongside. Freezing fog also means that not only is the visibility very poor, but it also quickly starts freezing up their equipment. It also means that it isn’t safe for large numbers to be out on the ice so there are fewer hands to help out with drilling and core-ing.

In particular when the temperature is above zero and everything is melting, there’s also the risk that the ice floe will just break up into pieces beneath our feet. I didn’t properly understand until I got here that the sea ice, which comes in all different shapes and sizes, is constantly moving around, rubbing against other pieces of ice, swirled by the swell of the sea underneath and alongside. This means that even though our ship is tethered to the fairly large ice floe that the guys are working on, that chunk of ice can quickly break off and if that happens they’re essentially stranded if they’re not very quick to get back across and on to the ship. Cracks can appear and open up leaving windows of open water in between in less than five minutes.

This is pretty problematic, especially given bears can swim, and that it can take time to navigate the ship back and close enough to wherever you’ve been left behind. Fortunately on the two occasions when the floe they’ve been working on has broken up, everyone was quick to move themselves and their various bits of kit back onto the ship – even though it did require some good leaping.

One problem we don’t encounter up here is darkness. In the land of the midnight sun, given the other constraints if the conditions are sufficiently good to be working, that’s what all we need to do – even if that means getting up at the crack of dawn or working fairly late into the evening.

Next time I’m back in London, and reading a dry sentence in a report about the state of the sea ice, I’ll have a much greater appreciation of exactly what went into getting that information through challenging field research expeditions like this one.

Joss Garman is the communications officer aboard the Arctic Sunrise, now positioned at 81 degrees north in the Arctic’s Fram Strait.