At 13.56 GMT on 10 April, I reached the Geographic North Pole.
This was my third expedition to the North Pole and yet, despite my previous experience of the region, I was once again struck by both the beauty and the hostility of the place.
The challenging and ever-changing landscape is a constant reminder that the world has got to stand up and take notice of climate change. If there is one small contribution I can make, it is using my expeditions to generate greater understanding of this phenomenon, so that future generations can work to address it.
It's almost impossible for me to express the mix of emotions I felt throughout the expedition: gratitude; relief; excitement and anticipation for the road ahead.
Looking back, I remember times when my fingers were frozen numb and my hands were dug deep into the snow in -25C, collecting isotope data for the International Atomic Energy Agency.
However, I tried to find moments to break from pushing north to simply appreciate the beauty and the power of the region I was standing in.
I feel sad that the expedition is over and I've had to leave such an amazing place, even though I can still remember the raw feeling of being soaking in sweat and completely freezing at the same time.
During the expedition, there was for me a very clear low point. On day three, we stopped for a break mid-morning. It was a peaceful day and I knelt down to get out the science kit for the research sampling. When I looked up a few moments later, complete whiteout had descended on us. We could barely see more than 40 feet in front of us and when we got going again, a feeling of hopelessness set in. We were driven into some very difficult terrain and I imagined that the terrible conditions would never end. That was mentally very challenging.
However, later that evening the whiteout lifted, and in front of us lay a vast open plain of ice. I thought to myself that this was the purest form of peace. My mind relaxed and retained its focus on the road ahead. It was then that I realised that everything eventually averages out - that nothing difficult will ever last forever.
However, in order for me to succeed mentally, I needed to actually visualise success. I pictured myself arriving at the pole, driving a flagpole into the Arctic ice.
When we did finally reach the North Pole, there was of course a moment of celebration, followed closely by a realisation that we were all alone. I sat frozen on my sled and waited for three hours for a pick-up. I had overexerted myself to get to the Pole, however it was an incredible feeling to know that I had made it.
There are so many people who have helped me on this journey and stood by me along the way. These people I thought about constantly during the long hours I spent on the Arctic Ocean.
As an ambassador for the international youth forum One Young World, I am so lucky to be able to count on the support of many young global leaders whom I have met and worked with over the last few years. I also feel privileged to have seen and listened to so many inspiring figures at last year's summit in Zurich, including Archbishop Desmond Tutu, Jamie Oliver, Sir Bob Geldof and Professor Muhammad Yunus. Their support and encouragement of today's young people is immeasurable and their inspiring words spurred my desire to carve my way as an explorer and an environmental campaigner. I can't wait for this year's summit, which is taking place in Pittsburgh in October.
And the most eternal and sincere thanks goes to my teammate and true friend Doug Stoup, who has led me through so many challenges and helped me to this point, from the start of the project almost three years ago.
There is a long but exciting road ahead. In July, I will embark on another expedition, where I will attempt to become the first person to circumnavigate Svalbard, a large polar Archipelago about 600 miles from the North Pole. This is without doubt the most ambitious project I have undertaken - at over 1,000 miles in distance, this expedition will likely take our team over six weeks to complete, and the danger will be greater than ever, with over 3,000 polar bears living on the coasts of Svalbard. The purpose of this expedition will also be scientific, building on and extending current research partnerships.
Then, in March 2013, I will endeavour to become the youngest person ever to reach the North Magnetic Pole, in a 250-mile unsupported expedition starting at the Geographic North Pole.
There is a long road ahead, but I'm looking forward to it.