Renjo Pass — the body fights back

Brutal day. We climbed the Renjo Pass — well, for Niall and me, for the second time. It was so much harder this time. Total lack of energy, severe headache, nausea, nose bleeds, pretty much every box on the AMS checklist. I wasn't the only one. Jackson was hit hard, and Julie, who has been sick since the start, is no better. Bic and Dora seem fine, which is fortunate — some of us needed to be healthy.

I asked Balram about it; I'd climbed strongly only yesterday on the acclimation walk. He suggested I'm pushing too hard and using too much of the tank each day, which is why I'm being hit hardest. A frustrating answer — there's so much to explore once we reach camp in this stunning environment — but from here forward I'll have to stick to the bare minimum.

Even minor things bring on symptoms. We all wake with tent headaches in the morning, the reduced air flow and the build-up of CO2 from our breath. It's all a reminder that we are operating on the very fringes of habitable environment. Even some of the Sherpas are getting sick.

The good news from today: we had our first view of Abi Himal, and I have a tent-window view of Everest, Lhotse and Nuptse.