According to this story at ExWeb the team ran into problems after they crossed 82ºN. From there they started to see increased ice build up on the surface of the Arctic Ocean which was making it increasingly more difficult to make any kind of progress. On Saturday, August 31 they had only managed to cross .8 miles (1.3 km) by noon. Temperatures had fallen rapidly and the conditions were right for more ice to build up. Worse yet, the forecast said that those conditions would remain the same for the next eight days, which meant little or no progress in the future. It was than that Sébastien and Vincent made the tough choice to pull the plug on their adventure and head home.
Of course, even that won't exactly be easy to do. They are fairly far north and the bad weather conditions continue to hamper them. They also happen to be a long way from land. In fact, as of Saturday, they were just 100 miles from the Pole of Inaccessibility, which is the furthest point from land anywhere in the Arctic Ocean. That means they still have quite a journey ahead even if they aren't going to be able to complete their intended adventure.
I'm a bit sad to see these expedition come to an end. I was hoping to follow them all the way to Svalbard as I really liked the concept of their travels. It's too bad that they won't be able to continue, but it sounds like the conditions in the Arctic have been especially difficult this season, not just for this team but others who have been in the Northwest Passage. Lets hope these two men make back to land safely.