0:00:06 > 0:00:10This is Badwater Basin in Death Valley.
0:00:10 > 0:00:13It's the lowest point in the USA,
0:00:13 > 0:00:16which makes it one of the hottest places on the planet.
0:00:16 > 0:00:20It's 41 degrees today. That is really hot.
0:00:20 > 0:00:23Not a record-breaker for here, but feels it to me.
0:00:23 > 0:00:27We're finding out what makes this unique place so scorching hot.
0:00:29 > 0:00:33This is a Fierce Earth Special and it's going to be epic.
0:00:33 > 0:00:36It is H-O-T - hot!
0:00:36 > 0:00:40We'll meet the tough kids who get up early to go to school here...
0:00:42 > 0:00:46..learn how to harness the power of the sun to cook our dinner...
0:00:46 > 0:00:49Tastes a bit desert-y. But we did cook it in the desert.
0:00:49 > 0:00:53..and we'll discover the secrets of staying cool in scorching heat.
0:00:53 > 0:00:55The things we do for science!
0:00:58 > 0:01:02What happens when the ground shakes, the seas rise up
0:01:02 > 0:01:05and the air tears itself apart?
0:01:05 > 0:01:07The Fierce Earth team move in,
0:01:07 > 0:01:11taking on the most powerful forces on the planet.
0:01:26 > 0:01:29Get ready for Fierce Earth -
0:01:29 > 0:01:31the Earth and how to survive it.
0:01:35 > 0:01:39In 2012, this fierce desert was officially declared
0:01:39 > 0:01:42the hottest place in the world with a record-breaking temperature
0:01:42 > 0:01:44of 57 degrees Celsius.
0:01:47 > 0:01:51This is warmer than the water that comes out of your hot tap at home
0:01:51 > 0:01:56and it feels like standing in front of a hairdryer on maximum heat.
0:01:58 > 0:02:01It's in the United States of America and this is where...
0:02:02 > 0:02:06The Statue of Liberty is here,
0:02:06 > 0:02:09Hollywood is here,
0:02:09 > 0:02:12and the hottest place on the planet is right here.
0:02:14 > 0:02:17It's called Death Valley, and for good reason,
0:02:17 > 0:02:20because not much can stay alive here.
0:02:20 > 0:02:25This desert is the same size as the whole county of Yorkshire in the UK.
0:02:25 > 0:02:27But 5.3 million people live there,
0:02:27 > 0:02:31whereas in Death Valley, there are just 620.
0:02:31 > 0:02:33That's now 622, because in the month
0:02:33 > 0:02:37that Death Valley was named the hottest place on the planet,
0:02:37 > 0:02:42Leo and I have travelled here to find out what creates the deadly heat
0:02:42 > 0:02:43and how to survive it.
0:02:48 > 0:02:52What is it about this place that makes it so very hot?
0:02:53 > 0:02:58I've come to meet Ron Peck, who will be our very own bird-man.
0:02:59 > 0:03:04To understand what makes it so hot here, we need to take to the sky.
0:03:04 > 0:03:08- How are you?- Good.- What are you going to do today?- Paragliding.
0:03:08 > 0:03:11What happens is that the ground heats up,
0:03:11 > 0:03:14and that hot air rises and carries mass of air up,
0:03:14 > 0:03:18- and we're going to rise with it. - Good luck.- Thanks.
0:03:20 > 0:03:23One reason Death Valley is so hot
0:03:23 > 0:03:26is that some parts are 80 metres BELOW sea-level.
0:03:26 > 0:03:28And there is a general rule -
0:03:28 > 0:03:31the lower somewhere is, the hotter it tends to be.
0:03:31 > 0:03:34But there are more reasons. To reveal them,
0:03:34 > 0:03:37Ron is going to get some real height.
0:03:37 > 0:03:39- Can we let go?- Let go, let go.
0:03:42 > 0:03:46Ron's paraglider is lifted by currents of hot air
0:03:46 > 0:03:47rising from the ground.
0:03:47 > 0:03:50These currents of hot air are called thermals.
0:03:54 > 0:03:56In two minutes,
0:03:56 > 0:04:00Ron shot up 1,000 metres on one of those hot currents of air.
0:04:00 > 0:04:04These thermals explain the super-high temperatures
0:04:04 > 0:04:06that exist in Death Valley.
0:04:07 > 0:04:09The scorching sun bakes
0:04:09 > 0:04:12the low-lying, rocky and sandy ground of the desert.
0:04:12 > 0:04:14The hot air rises.
0:04:16 > 0:04:19It's trapped by the mountains surrounding the valley.
0:04:19 > 0:04:23It cools slightly before sinking towards the valley floor again.
0:04:23 > 0:04:28After that, it is heated by the sun, rises back up again
0:04:28 > 0:04:31and is trapped by the mountains again.
0:04:31 > 0:04:35That super-heated air in the valley moves up and down
0:04:35 > 0:04:37like in a fan-oven at home,
0:04:37 > 0:04:40and it increases the temperature on the ground hugely.
0:04:41 > 0:04:45It's the mountains that trap this really hot air
0:04:45 > 0:04:47and that's the reason why this place
0:04:47 > 0:04:50is one of the hottest places on Earth.
0:04:50 > 0:04:53There's no escape for this hot air, it stays in this region.
0:04:56 > 0:05:01Clare calling Ron. You're up in the sky. What can you see?
0:05:01 > 0:05:03Clare, it's beautiful!
0:05:03 > 0:05:06I can see across the valley!
0:05:06 > 0:05:09I can see all the mountains as far as your eye can see.
0:05:11 > 0:05:12With the secrets revealed,
0:05:12 > 0:05:16it's time for Ron to come back to earth...with a bump.
0:05:17 > 0:05:21Ron, thank you so much for that. It was incredible.
0:05:21 > 0:05:23- Cheers.- Cheers.
0:05:29 > 0:05:32The huge thermals and scorching winds of Death Valley
0:05:32 > 0:05:35show the fearsome power of the sun rays.
0:05:36 > 0:05:41It's hard for us human types to settle in areas as hot as this.
0:05:41 > 0:05:44We're ideally suited to cooler and wetter places.
0:05:44 > 0:05:48But our ancestors seemed to find one way of coping,
0:05:48 > 0:05:50by sheltering in white houses.
0:05:50 > 0:05:53People today continue to live like this.
0:05:54 > 0:05:57How could that help us in Death Valley?
0:05:57 > 0:06:01We're back in the hottest place on the planet,
0:06:01 > 0:06:04and these two mysterious figures are going to find out.
0:06:04 > 0:06:07SCARY MUSIC
0:06:07 > 0:06:11This afternoon, we are going to be a walking, talking, breathing,
0:06:11 > 0:06:14SWEATING science experiment.
0:06:14 > 0:06:18Leo is wearing a white bodysuit. I'm wearing the black one.
0:06:18 > 0:06:22We're going to stand here for 15 minutes in the direct sun,
0:06:22 > 0:06:25to see who reaches the highest temperature.
0:06:25 > 0:06:28It's 3pm, the hottest part of the day
0:06:28 > 0:06:31and the temperature is a scorching 44 degrees Celsius,
0:06:31 > 0:06:34the temperature of a hot bath.
0:06:34 > 0:06:37When we measure the temperatures of the suits,
0:06:37 > 0:06:40Leo should be much cooler than me.
0:06:40 > 0:06:43When the sun's rays hit Leo's white suit,
0:06:43 > 0:06:46many of them will be reflected and bounce off.
0:06:46 > 0:06:50But my black suit will absorb the sun's light
0:06:50 > 0:06:55and will be converted to heat energy, making ME super hot...
0:06:55 > 0:06:56and keeping ME super cool.
0:07:05 > 0:07:09As extreme heat can be dangerous, we've called in a medical expert
0:07:09 > 0:07:12to keep an eye on us and measure our temperatures.
0:07:15 > 0:07:18This is Dr Vicky Mazzeroni, or to her friends, Dr Maz.
0:07:19 > 0:07:22Leo, you are blue-purple
0:07:22 > 0:07:24and Clare, you are red hot.
0:07:24 > 0:07:27I feel red hot, like I'm a coal burning on a fire.
0:07:27 > 0:07:32The lighter the colour on the camera, the hotter something is.
0:07:32 > 0:07:36As you can see, there's only one winner in our tournament.
0:07:36 > 0:07:38We'll let the doctor make it official
0:07:38 > 0:07:41with a surface thermometer reading.
0:07:41 > 0:07:44Let's check your temperatures.
0:07:47 > 0:07:50- 42 degrees. That is hot.- Hot.
0:07:50 > 0:07:53- Let's check you out. - I think I'm going to win.
0:07:55 > 0:07:59- 39...38.- The white knight shines through once more.
0:07:59 > 0:08:03- The things we do for science. - Same time tomorrow?
0:08:03 > 0:08:04Why not? Come on, Dr Maz.
0:08:06 > 0:08:10We have learnt how to keep cool in the world's hottest place.
0:08:12 > 0:08:16What happens when summer heat waves hit whole continents
0:08:16 > 0:08:19and millions find themselves in the hot zone?
0:08:19 > 0:08:23Those heat waves can be more dangerous than floods
0:08:23 > 0:08:25and hurricanes combined.
0:08:25 > 0:08:28These are the deadliest in modern history.
0:08:29 > 0:08:36A heat wave hit America in 1980 and caused at least 1,250 deaths.
0:08:36 > 0:08:38Memphis, Tennessee, sweltered
0:08:38 > 0:08:43through a record-breaking temperature of 42 degrees Celsius.
0:08:43 > 0:08:46Wildfires broke out everywhere and crops died,
0:08:46 > 0:08:50costing the nation 20 billion.
0:08:50 > 0:08:53People sprayed the roads to stop them from melting.
0:08:54 > 0:09:00You may remember the next heat wave, the European heat wave of 2003.
0:09:01 > 0:09:04Temperatures hit 48 degrees Celsius -
0:09:04 > 0:09:08the hottest the continent had been for more than 500 years
0:09:08 > 0:09:12and claimed the lives of more than 70,000 people.
0:09:12 > 0:09:16Electrical cables melted and nuclear reactors couldn't be cooled.
0:09:16 > 0:09:18Even Britain got hot,
0:09:18 > 0:09:21with a new temperature record of 38.5 degrees Celsius.
0:09:21 > 0:09:25You'd expect that in Greece, but not Bournemouth!
0:09:25 > 0:09:29These heat waves lasted for a matter of weeks, but in Death Valley,
0:09:29 > 0:09:33the temperature can be above 32 degrees C for five months.
0:09:40 > 0:09:44For thousands of years, hardly anyone lived in this desert.
0:09:44 > 0:09:47It's so hot, you can see why!
0:09:47 > 0:09:49But now, it's a National Park,
0:09:49 > 0:09:53so tourists want to visit so they too can feel the heat.
0:09:53 > 0:09:55Families do have to live and work here,
0:09:55 > 0:10:00so even in the world's hottest place, you need a school.
0:10:02 > 0:10:05It's 5.30 in the morning, the coolest part of the day.
0:10:05 > 0:10:09I'm here cos it's my first day at school in the desert.
0:10:09 > 0:10:12Kids get up super-early to beat the heat.
0:10:12 > 0:10:16This is one of the earliest school runs in the whole of America.
0:10:16 > 0:10:19First to be picked up is five-year-old Autumn.
0:10:19 > 0:10:24What's it like living in the desert? It's so hot, isn't it?
0:10:24 > 0:10:27Well, I like it because it's pretty in the morning.
0:10:29 > 0:10:30What time do you get up?
0:10:30 > 0:10:34- 5.30.- 5:30! It's still dark outside?- Yeah.
0:10:36 > 0:10:405.30am sounds like an early start, but in a place as hot as this,
0:10:40 > 0:10:44you have to get up in the dark to avoid the fierce sun.
0:10:44 > 0:10:47It's 7am. Classes are about to start.
0:10:47 > 0:10:50It's early, but it feels so hot here already.
0:10:50 > 0:10:53I'm going to see what they're doing.
0:10:53 > 0:10:57One school in the whole of Death Valley. One class. One teacher.
0:10:57 > 0:11:00And get this, just five kids.
0:11:01 > 0:11:03Hello, this is Magnolia.
0:11:03 > 0:11:06- I'm Kimmy.- I'm Autumn.
0:11:06 > 0:11:09- My name's Eden.- Hi, I'm Michael.
0:11:09 > 0:11:14ALL: I pledge allegiance to the flag of the United States of America...
0:11:14 > 0:11:18'They might have one of the earliest starts in the country,
0:11:18 > 0:11:20'but like everywhere in the USA,
0:11:20 > 0:11:23'the day begins with a Pledge of Allegiance.'
0:11:23 > 0:11:25What is the weather like?
0:11:25 > 0:11:28ALL: Sunny and hot.
0:11:28 > 0:11:32At 9am, it's already 40 degrees Celsius -
0:11:32 > 0:11:35hotter than any temperature recorded in the UK.
0:11:35 > 0:11:38There's no football at lunchtime or outdoor play.
0:11:38 > 0:11:42The Death Valley kids have to stay inside to avoid the intense heat.
0:11:42 > 0:11:45The only play-time is early in the morning
0:11:45 > 0:11:48when the temperature is slowly rising.
0:11:48 > 0:11:51They've had 20 minutes outside, before 9am.
0:11:51 > 0:11:56This is Magnolia. Hello, Magnolia. What's it like to live in the desert?
0:11:58 > 0:12:02- Quite dull, actually.- How do you entertain yourself?- Video games.
0:12:02 > 0:12:06If you could go on holiday, where would you go?
0:12:06 > 0:12:09- To England. - Would you go to England?- Yeah.
0:12:09 > 0:12:12- Why would you like to go to England? - I love the rain.
0:12:12 > 0:12:15For Death Valley to be a better place to live,
0:12:15 > 0:12:17what do you think it needs?
0:12:17 > 0:12:20I think it needs to be cooler.
0:12:20 > 0:12:26I make my exit whilst the kids play one of the few games they're allowed.
0:12:26 > 0:12:30A cold water balloon fight - in the shade, of course!
0:12:30 > 0:12:36What a morning! It's now midday, It's scorching hot outside.
0:12:36 > 0:12:40It's been fascinating meeting tough kids in such a tough environment.
0:12:42 > 0:12:45Coming up, Leo takes on the world's toughest run.
0:12:45 > 0:12:48Can he beat the ferocious heat of Death Valley?
0:12:58 > 0:13:02Back at the hottest place in the world, the sky is looking stormy.
0:13:03 > 0:13:06As it's so hot here, you don't get much rain.
0:13:06 > 0:13:09But when it does rain, it pours.
0:13:11 > 0:13:15That water has made Death Valley look very different to other places.
0:13:17 > 0:13:21What seem like hills are actually huge piles of dirt and loose rock,
0:13:21 > 0:13:23that water has carved canyons out of.
0:13:25 > 0:13:29These canyons may look amazing, but they can also be lethal.
0:13:29 > 0:13:33I'm about to find out why with Jay Snow.
0:13:34 > 0:13:37Jay calls this scary-looking place home.
0:13:37 > 0:13:40He's been a Park Ranger here for 15 years.
0:13:40 > 0:13:43He is one of the few people brave or qualified enough,
0:13:43 > 0:13:45to explore and patrol these canyons.
0:13:47 > 0:13:50And he's climbed nearly every single one...
0:13:50 > 0:13:52apart from this one.
0:13:52 > 0:13:56- Anyone been up here before, Jay? - Nobody's been up there.
0:13:56 > 0:13:59We're the first, and that's pretty exciting in my opinion.
0:13:59 > 0:14:02Does this canyon have a name?
0:14:02 > 0:14:05This canyon does not have a name.
0:14:05 > 0:14:09We can name this canyon. In fact, YOU can name this canyon.
0:14:09 > 0:14:11We'll have to think of a name.
0:14:15 > 0:14:20- Good luck, Jay.- All right. I'll meet you up there.- Be safe.- Here we go.
0:14:20 > 0:14:23Definitely don't try this at home.
0:14:23 > 0:14:26Jay is climbing these hot rocks with no rope or harness.
0:14:26 > 0:14:28A job for experts only.
0:14:31 > 0:14:34That rock is hot! It's extreme! It's unbelievable!
0:14:34 > 0:14:38You're going to LOVE this! But first, I've got to get over this.
0:14:38 > 0:14:41Be careful up there, Jay!
0:14:44 > 0:14:47With Jay safely up, it's my turn.
0:14:47 > 0:14:51I've climbed all over the world, but never faced anything like this.
0:14:51 > 0:14:56Loose rock is a climber's enemy - the worst thing you come across.
0:14:56 > 0:14:59This is as about as loose as you can climb on.
0:14:59 > 0:15:01The rocks have been heated by the sun
0:15:01 > 0:15:04to temperatures over 60 degrees Celsius,
0:15:04 > 0:15:07and they are so crumbly, every handhold could disintegrate.
0:15:09 > 0:15:11OK.
0:15:19 > 0:15:20LEO GROANS
0:15:22 > 0:15:25- You made it up! - That was great fun!- Cool!
0:15:25 > 0:15:28We've made it, but the danger isn't over.
0:15:30 > 0:15:33The power of water is so incredible here.
0:15:33 > 0:15:36If it rains, this is the worst place to be?
0:15:36 > 0:15:40You do not want to be up here. We need to get down as fast as we can.
0:15:40 > 0:15:43If it even starts to become a sprinkle.
0:15:43 > 0:15:45If it started raining now,
0:15:45 > 0:15:48and a waterfall came down, it would be terrifying.
0:15:48 > 0:15:52Jay showed me this video of exactly that happening. Check it out.
0:15:53 > 0:15:57The shallow, sandy soil of Death Valley is bad at soaking up water.
0:15:59 > 0:16:03It doesn't happen often, but when you do get rain here, it's trouble.
0:16:06 > 0:16:10There's clouds building. Jay's setting up the abseil to get down.
0:16:10 > 0:16:14I can't resist going round the corner to see what's there.
0:16:16 > 0:16:18It's such an amazing place to explore.
0:16:18 > 0:16:21There is no record of anyone else ever climbing here.
0:16:23 > 0:16:27At the top of the canyon, the rocks have been baking in the sun.
0:16:29 > 0:16:32I've brought a thermal-imaging camera,
0:16:32 > 0:16:35so I can see what temperatures they've reached.
0:16:38 > 0:16:40Wow.
0:16:40 > 0:16:45These white rocks that I'm looking at here, are nearly 70 degrees.
0:16:45 > 0:16:4669 degrees Celsius.
0:16:46 > 0:16:50Hotter than the water from your hot-water tap!
0:16:52 > 0:16:57And three times hotter than the temperature of a UK summer's day.
0:16:58 > 0:17:00It's really... Oh, it's like a...
0:17:02 > 0:17:04It's like a kettle. Ahh!
0:17:04 > 0:17:09OK, get some evidence of our first descent here in Death Valley.
0:17:09 > 0:17:12Nobody's been up here before so we get to name it.
0:17:12 > 0:17:15It's not every day you get to name your own canyon.
0:17:15 > 0:17:18Only one name fits.
0:17:18 > 0:17:22I hereby name this terrifying place, Fierce Earth Canyon.
0:17:22 > 0:17:25The tablet's overheating. The camera's overheating.
0:17:25 > 0:17:29We're going to have to go before everything melts, including me.
0:17:29 > 0:17:31Let's go.
0:17:32 > 0:17:35No rain, which is good news,
0:17:35 > 0:17:38but the intense heat is the real winner today.
0:17:40 > 0:17:43That was amazing. It is H-O-T - hot.
0:17:49 > 0:17:53We've come back to one of the hottest parts of Death Valley
0:17:53 > 0:17:55where it's a baking 43 degrees Celsius.
0:17:57 > 0:18:00That's hotter than the water in a Jacuzzi!
0:18:00 > 0:18:02We've been challenged to see
0:18:02 > 0:18:07whether we can use the power of the sun to cook some food.
0:18:07 > 0:18:09This is the Death Valley dinner party.
0:18:11 > 0:18:15They have a saying here, "hot enough to cook an egg on the sidewalk".
0:18:15 > 0:18:17I'm going to put that to the test.
0:18:17 > 0:18:23Can I cook an egg with just the power of the sun?
0:18:23 > 0:18:25Brilliant. It's going white.
0:18:25 > 0:18:29I don't want to poison Clare, so we'll come back in a few minutes.
0:18:29 > 0:18:31For an egg to start cooking,
0:18:31 > 0:18:35the temperature of the pan has to be above 62 degrees Celsius.
0:18:35 > 0:18:39Hotter than your radiators at home on full blast!
0:18:39 > 0:18:42This speeded-up shot shows that
0:18:42 > 0:18:46the sun has already heated the pan well above that.
0:18:46 > 0:18:50But I've got a way of cooking that's a lot more scientific.
0:18:50 > 0:18:55Take a look at this nifty bit of kit. It's fantastic.
0:18:55 > 0:18:59It's called a parabolic solar cooker. The rays hit the surface,
0:18:59 > 0:19:01and are converted into heat energy.
0:19:01 > 0:19:04That heat heats up the pot and the food.
0:19:04 > 0:19:06And in here, I have some popcorn.
0:19:06 > 0:19:10POPPING Oh, the popcorn is popping.
0:19:10 > 0:19:13And so, I'm pleased to announce, dinner is served.
0:19:13 > 0:19:16Looks absolutely minging...
0:19:18 > 0:19:20Oh, wow.
0:19:20 > 0:19:23And this is something I did prepare earlier.
0:19:23 > 0:19:25Ah, it's hot!
0:19:25 > 0:19:27And it's spicy.
0:19:27 > 0:19:32We've got the world's hottest dish, chilli con carne.
0:19:32 > 0:19:36- Would you like some of my car-bonnet egg?- I might skip it.
0:19:36 > 0:19:38Let's go straight to the popcorn.
0:19:40 > 0:19:43- Tastes like popcorn. - Tastes desert-y,
0:19:43 > 0:19:46but we did cook it without electricity.
0:19:46 > 0:19:48Shall I serve you a lovely chilli?
0:19:48 > 0:19:52It might seem weird to eat spicy food on such a hot day,
0:19:52 > 0:19:57but food like this can help to cool you down.
0:19:57 > 0:20:01The spiciness makes you sweat, that evaporates in the wind,
0:20:01 > 0:20:06which helps to cool your body down. Let's give it a go.
0:20:08 > 0:20:10Quite spicy, yeah!
0:20:10 > 0:20:12Whew!
0:20:12 > 0:20:17Nothing's better after a spicy meal than some cool ice cream.
0:20:17 > 0:20:20- Cheers.- It wasn't the tastiest meal I've ever had in my life.
0:20:20 > 0:20:24But, we can say, in the hottest place in the world,
0:20:24 > 0:20:26it's possible to cook from the power of the sun.
0:20:26 > 0:20:30- I think we can call that a success. - -Ish.
0:20:32 > 0:20:35I know all about life on the edge.
0:20:35 > 0:20:39I've climbed to the top of the world's highest mountain...
0:20:40 > 0:20:42..frozen in the Antarctic,
0:20:42 > 0:20:46and parachuted off some of the planet's biggest cliffs.
0:20:47 > 0:20:52I'm ready for the challenge. What do the team have in store for me today?
0:20:54 > 0:20:57I'm nervous about this one. I hate running.
0:20:57 > 0:21:00In Death Valley, runners come together to compete
0:21:00 > 0:21:03in one of the most extreme races on the planet -
0:21:03 > 0:21:05the Badwater Ultramarathon.
0:21:06 > 0:21:09It's five times longer than the London Marathon
0:21:09 > 0:21:15and it hits 55 degrees C - that's like running in very hot soup.
0:21:15 > 0:21:18And check it out, they're all wearing white.
0:21:18 > 0:21:19Now we know why.
0:21:19 > 0:21:22In fact, it gets so hot during the race,
0:21:22 > 0:21:25people can only stop their trainers from melting
0:21:25 > 0:21:28by running on the heat-reflecting white lines!
0:21:31 > 0:21:35I'm running a section of the race to find out what it's like.
0:21:35 > 0:21:38I find running boring. It's not extreme enough for me,
0:21:38 > 0:21:42but in Death Valley, it's going to be plenty extreme.
0:21:42 > 0:21:45A little bit of suffering makes for a good story.
0:21:45 > 0:21:49What I'm doing today isn't just tough, it's dangerous.
0:21:49 > 0:21:53Exercising in this heat can put incredible strain on the body.
0:21:53 > 0:21:58Dr Maz is here again to run some tests to make sure my body can cope.
0:21:58 > 0:22:02There's one important test to find out if I am allowed to run.
0:22:02 > 0:22:06Dr Maz has got to test my wee. Nice(!)
0:22:06 > 0:22:09- It's time for the blue cup, isn't it?- I'll go round the van.
0:22:10 > 0:22:15I'll be sweating a lot, so my body's water levels will go down,
0:22:15 > 0:22:18- which can be really dangerous. - Thank you!
0:22:18 > 0:22:22Dr Maz will test my urine to see if there's enough water
0:22:22 > 0:22:25in my system to complete the challenge.
0:22:25 > 0:22:29If it's a light colour, that's a good thing as it means I'm hydrated.
0:22:29 > 0:22:32If it's dark and orange, that's bad,
0:22:32 > 0:22:34and it means I need to drink more.
0:22:34 > 0:22:39I suspect I'm going to be quite a bit more dehydrated in 10K's time.
0:22:39 > 0:22:42We are looking at these different strips here.
0:22:42 > 0:22:44You're a little dehydrated,
0:22:44 > 0:22:47so I would like you to drink more fluids.
0:22:47 > 0:22:53You might want to drink another litre or another bottle of water.
0:22:53 > 0:22:55I want to keep you safe.
0:22:55 > 0:22:57How can you stay hydrated when running?
0:22:57 > 0:23:00It's impossible to drink continually?
0:23:00 > 0:23:03We'll hand you water if we can keep up with you.
0:23:03 > 0:23:07- Just drink as much water as you can. - Drink as much as you can.
0:23:08 > 0:23:12It's the middle of the day and oppressively hot.
0:23:12 > 0:23:15What Leo's going to be attempting is dangerous,
0:23:15 > 0:23:18so we're going to be following him, me and Dr Maz.
0:23:18 > 0:23:19I'm ready!
0:23:19 > 0:23:21Three, two,
0:23:21 > 0:23:24one, zero!
0:23:24 > 0:23:26Mo Farrah, eat your heart out!
0:23:27 > 0:23:29All right!
0:23:31 > 0:23:35It's 44 degrees C, I've only been running for five minutes,
0:23:35 > 0:23:38and already I'm dehydrated.
0:23:38 > 0:23:41I'm struggling to swallow.
0:23:41 > 0:23:45It's so hot and dry, your body loses water at an incredible rate
0:23:45 > 0:23:48and replacing it is difficult.
0:23:48 > 0:23:51It's really hard to drink,
0:23:51 > 0:23:53cos it makes you feel sick.
0:23:53 > 0:23:56It's like someone has a hairdryer on you.
0:23:56 > 0:24:02Perhaps running is a more extreme than I gave it credit for. Brutal.
0:24:02 > 0:24:06If you were to run the London Marathon,
0:24:06 > 0:24:09you should drink 3.5 litres over 26 miles.
0:24:09 > 0:24:10For the Ultramarathon,
0:24:10 > 0:24:14due to the extreme temperature, if I was running it all,
0:24:14 > 0:24:17I would need to drink up to 36 litres.
0:24:17 > 0:24:20This is one of the toughest things I've done.
0:24:20 > 0:24:22You're not just battling the heat,
0:24:22 > 0:24:26you're forcing your body to move when all it wants to do is stop.
0:24:26 > 0:24:31We've got to watch Leo doesn't push himself and develop heatstroke.
0:24:31 > 0:24:34One sign of this condition is mental confusion.
0:24:34 > 0:24:37We're going to test for that with a quick quiz.
0:24:37 > 0:24:41- What's the capital of England?- London.
0:24:41 > 0:24:44- What's the boiling-point of water? - 100 degrees Celsius.
0:24:44 > 0:24:49Who won gold at the 10,000-metre race at the London Olympics?
0:24:49 > 0:24:51Mo Farrah! Come on!
0:24:52 > 0:24:55But Mo wasn't running in this heat,
0:24:55 > 0:25:00and five kilometres from the start, there is a serious moment.
0:25:01 > 0:25:04Ah, hang on a minute, Dr Maz, Dr Maz. He's stopped.
0:25:04 > 0:25:07'The fierce heat has taken its toll on Leo.'
0:25:07 > 0:25:10- How you doing?- I'm OK. Is there any ice?
0:25:10 > 0:25:13- Let's get some ice water.- I am on it.- I think he's exhausted.
0:25:13 > 0:25:18I'm giving it five minutes, and then it would be foolish to continue.
0:25:19 > 0:25:24Yeah, we'll see how far we've got. Right, then, I'm set.
0:25:27 > 0:25:32A scary moment, and I don't think I've ever felt that bad before.
0:25:32 > 0:25:35But I've never let anything beat me in the past,
0:25:35 > 0:25:36and I'm not going to now.
0:25:36 > 0:25:39His pace is still incredibly fast.
0:25:39 > 0:25:42I've run 8km in 48 minutes,
0:25:42 > 0:25:45and the finishing line is just 500 metres away.
0:25:45 > 0:25:49Come on, you're almost there! This is the finishing line.
0:25:49 > 0:25:52He's our hero.
0:25:52 > 0:25:56He picked up the pace at the end, I don't know how he did it.
0:25:56 > 0:25:58It's just relentless.
0:25:58 > 0:26:01It really feels like you're a chicken in an oven.
0:26:01 > 0:26:04But a chicken that's running in an oven.
0:26:04 > 0:26:06You are in an oven.
0:26:06 > 0:26:08That was epic.
0:26:08 > 0:26:11I've taken on the heat of Death Valley and won.
0:26:11 > 0:26:13But only just.
0:26:13 > 0:26:16The temperature hit 44 degrees.
0:26:16 > 0:26:20I had to drink seven bottles of water.
0:26:20 > 0:26:26I battled the desert for 8km and refused to admit defeat.
0:26:26 > 0:26:29That's one of the toughest things I've done.
0:26:29 > 0:26:32Running is far more extreme than I gave it credit for.
0:26:32 > 0:26:35Especially here in Death Valley.
0:26:35 > 0:26:39There aren't many tougher places than Death Valley -
0:26:39 > 0:26:41the hottest place in the world.
0:26:41 > 0:26:45But if you do, there are ways to maximise your chances of survival.
0:26:45 > 0:26:47Here's our Fierce Earth Guide.
0:26:49 > 0:26:52The intense heat saps water from your body,
0:26:52 > 0:26:56so drink plenty of fluids - at least a litre of water an hour.
0:26:56 > 0:26:59You need to have some energy drinks.
0:26:59 > 0:27:03They replace the salts and sugar you lose through sweating.
0:27:05 > 0:27:08Wear light-coloured, reflective clothing,
0:27:08 > 0:27:10however silly you might look.
0:27:12 > 0:27:14Get up early to avoid the heat of the day
0:27:14 > 0:27:18and seek shelter from the sun.
0:27:18 > 0:27:20This is how you maximise your chances
0:27:20 > 0:27:22of surviving the Fierce Earth.
0:27:25 > 0:27:27Next time on Fierce Earth,
0:27:27 > 0:27:32we explore the powerful and destructive force of a tsunami.
0:27:39 > 0:27:43Subtitles by Red Bee Media Ltd