Fredrick Ericsson and Trey Cook have headed back down from C1 after poor weather on K2.
When they awoke in the morning at C1 on the Cesen route, they were awoken to a storm. This caused them to second guess whether they would make it to C2. Ericsson considers the Cesen route more difficult than the Abruzzi Ridge. And that is why 80% of climbers on K2 go on that route instead.
They also wanted to ski from C1 back to base camp. But with the worsening weather they decided to trek it instead and this took much more time.