Mark Wood - polar explorer
Explorer Mark Wood is bidding to become the first person to ski both the South and North Poles back-to-back and alone.
He will receive no help and admits there's a 25% chance he might not come back alive.
And he's taking this risk to raise awareness about what he sees as a much bigger threat to survival - climate change.
We spoke to the ex-firefighter before he set off on his historic bid from one pole to another.
What's your aim, apart from staying alive and being the first person ever to do this?
To raise awareness of climate change - not just within the UK, but around the globe. I feel like this can inspire people to look at themselves and their planet, and how they move forward.
Any risk of a suntan?
The South Pole's supposed to be the coldest place on the planet.
In November, when I go, the temperatures can range from about -35 downwards. When I head to the Arctic Circle, at the end of February, temperatures can plummet to about -50. But your body adjusts and your sledge gets lighter. Without knowing it, you actually warm up.
You're giving schoolchildren the opportunity to communicate in real-time with a real-life explorer.
Children will be able to Skype me while I'm actually on the ice. Hopefully I'll open up debates in classrooms.
It was really important to bring in students and help them understand their own planet.
The educational project is called My life in a freezer. We took it to the teachers and asked, "How can we fit this into the curriculum?"
After the expedition myself and others will head into the schools. We'll be talking about healthy lifestyle, the environment and team work - which are really important.
What's the food like out there?
I'll be taking packet food: chillies, pastas and curries. You rehydrate it with ice and snow. I actually eat it at home and some people think I'm a bit mad. I'll need between 6,000 and 8,000 calories per day. At home I'm on about 2,500 calories a day.
How do you get rid of those calories? How do you erm... go to the toilet?
You burn the calories first - pulling the sledge for about 10 hours a day at a very slow pace. But to actually go to the toilet - I won't demonstrate.
I remember Sir Ranulph Fiennes saying that the only way to go to the toilet at -35 degrees, is quickly.
Sir Ranulph Fiennes also says your solo mission is "the toughest journey on the planet". Who does this to themself? Describe yourself in 3 words?
Blimey. Well, I've got multiple personalities - that's why I can do solo expeditions. No, to be mad, really wouldn't work. You need to keep your wits about you. Oh, I've got it now. Handsome, suave, sophisticated. And Modest. Put that one in.
What will be the toughest part of the trip?
In the Arctic Ocean because it's so unpredictable. Everyone thinks the world's been mapped now, but because of global warming, that particular area's changed. Explorers today are actually walking into the unknown. That's why I think we can call ourselves explorers.
When you see the impacts of climate change first-hand, do you wonder why the world is still talking and not acting?
If you stop talking, that's it, finished. But there seems to be a lot of debate and not enough hard-line action. The people who can make these decisions are governments.
What did you make of the recent polar bear attack in Svalbard?
I was shocked. I know the schools that operate out there and how professional they are. It proved that you're dealing with a wilderness in extreme areas of the planet. And although it's really tragic, lessons will be learned.
Do polar bears hunt humans?
The Inuit people that live out there are being affected by the seasonal change - just like farmers in the UK.
The ice is melting and the bears are coming back onto land. There's going to be a lot more contact with humans.
Will they hunt humans? They're the biggest predator on the planet, so the potential is there.
How do you guard against hungry visitors?
In the Arctic Circle I've seen 18 polar bears close up [including the one in Mark's photo, above]. When I say close up - a bear actually put his face into the tent. Each time we've managed to scare the bear away.
The way to deal with this is to look for prints and observe as you're going along. I carry things like flares and bangers to scare the animal away. Of course, you do carry a gun. But I haven't had to harm a bear yet, which is good.
The expedition's about climate change. Understandably some people will be asking about the impact of the mission itself.
I will be taking flights, but the cause is greater. The message is greater. We need to get people together, and I think one person doing an extraordinary journey is well worth it.
Also people can get involved and reduce their carbon footprint. On my website you can pledge to cycle three days of the week into work. It may seem a very small thing to do, but it does have an impact.
What can our supporters do?
Go to markwoodexplorer.com, you'll see a section called 'donation'. This is not donating money, but donating action. You can work with me to help the environment.
Follow the journey. Send messages of support. Send anything - any burning issues. I'll try and answer them while I'm on ice, so we can get a real connection going on.
Like Mark, you can get active on climate change too: