I'm just back from running a marathon at the North Pole. It's only by continuously repeating this sentence out loud that the experience has started to become more real. Certainly, when you are at the Pole -- a place of absolute wondrous beauty, isolation, and harshness -- it feels very surreal. The 24-hour light with the sun always at the horizon, the mind-numbing cold, the lack of sleep -- it all gets to you. Wow, don't I make it sound like fun?

So why, you might ask, did I put myself through this?

Well, a friend and I also ran the Sahara marathon at the end of February as a kick start to launch EarthFireIce, a campaign to raise awareness for the importance of individual action to reduce carbon emissions. By racing in such extreme conditions, the hottest and coldest marathons in the world, we also hoped to highlight two regions that stand to be seriously affected by climate change. People can make simple pledges of action on an interactive Google Maps mashup at our campaign site.

We've frequently been asked how we prepare for such extremes. The answer is that it's very hard. We tried to wrap ourselves in plastic wrap to replicate the Sahara heat, and we sat in a Kriotherapy chamber at -130 C (-202 F) to get used to the extreme cold. Neither experience, I must confess, was that useful. The Sahara, at 42 C (approx. 108 F), simply sapped all my energy. And the second half of that run was one of the slowest and most painful in my life. Watch the video of the Sahara run, and me struggling through it:

The North Pole, on the other hand, was tough because you have to wear those ridiculous snowshoes, and because the terrain varies from hard ice to 2 foot deep powder snow. So it's much more of a slow jog, and thus less exhausting. However, the battle there is with the cold: at -30 C (-22 F), you really feel it despite the act of running.

What's next, you may ask? Well, a lot of rest and relaxation, and back to my day job -- and then, some more events under the EarthFireIce banner, hopefully with lots of others joining us!