Global Weirding Horizon

THUNDER CLAP

'Something strange is happening to our weather.

'It seems to be getting more extreme.'

Yeah, it could be a record-breaking cold night...

'Britain recently shivered through two

'back-to-back record-breaking cold winters.

'Last year, Scotland splashed through its wettest year on record.

'Yet earlier in the year,

'parts of eastern England had their driest spring ever.

'But the UK's not alone.

'Records are being broken all over the planet.'

I have never, ever seen anything like this before.

'Storms appear to be getting bigger.'

Hurricane power has more than doubled

between the decade of the '80s and this past decade.

'The weather's been getting so weird

'that in some places, record-breaking rain

'has been followed by record-breaking drought.'

We've never had

this kind of steep oscillation go from one year to the next.

'Some scientists are calling it global weirding.'

Events that used to be random and extreme

are becoming much more frequent and severe.

We are going to live in a different world than the one we grew up in.

'Our weather is hypnotically beautiful.

'It's constantly changing,

'famously difficult to predict.

'But why does it seem to be getting weirder?

'The world's leading weather scientists are trying to understand what's happening.

'It's part of a global investigation.

'Because however local your weather feels,

'it's a small part of what plays out across the planet as a whole.

'It may seem obvious, but one place scientists are trying to get to grips with global weather extremes

'is in one of the most extreme weather events on Earth.

'And there's no bigger weather event than a hurricane.

'That's where people like Jason Dunion come in.

'He's a hurricane scientist

'who's turned in his white coat

'for a blue jumpsuit, and left the lab for the MacDill Air Force base

'in Tampa, Florida.

'Because Jason and his colleagues

'fly these aircraft into the middle of the weather madness.

'It's the best way to work out what really makes hurricanes tick.'

COMMUNICATIONS ON RADIO

You can't get everything you need to know about a hurricane

by looking at it from satellites or a buoy that's measuring the storm.

So we've got to fly into that storm.

Whether we're dropping instruments into it

or using radars to get a three-dimensional picture of what's going on.

You can't do that in any other way.

'Carrying out complicated scientific experiments in a hurricane

'creates its own set of unique problems.'

You're coming in at 10,000 feet,

passing through outer rain bands, getting jostled around in the plane.

Then you go through the eye wall,

that doughnut around the eye of a storm that's really intense.

You're tossed around pretty good.

You can lose a few hundred feet of altitude in a few seconds.

Pop through that eye wall and it's incredible.

You're in what looks like a football stadium.

The biggest one you've ever seen. It can be ten, 20, 30 miles across.

And it's very still.

It's a surreal spot in the storm, after what you've gone through.

And you know this is a beast.

But you're only through half the storm. There's still halfway to go.

'The hurricane chasers produce mountains of data from every flight.

'One of the things they've discovered is that hurricanes pulse at night.

'More significantly, they've also recorded an increase in the number of category five storms,

'the most extreme and powerful hurricanes.'

We've seen many category fives over the years.

We certainly have better tracking capabilities.

We can see category fives in the middle of the ocean

that we would have missed 50 years ago.

There have been more major hurricanes in recent years

and we're trying to understand why, but we have to keep an eye on those.

Those are the storms that can cause all the damage.

'So, Jason and his fellow hurricane chasers are recording more category five storms.

'This is a development that scientists are starting to grapple with.

'North Atlantic hurricanes only account for about 11%

'of the world's tropical cyclones.

'But Professor Kerry Emanuel,

'one of the world's leading hurricane experts,

'has started to see something of a pattern in his own backyard.'

This last decade was the worst in the record books.

2005 was especially bad. We had a record number of hurricanes.

So many they ran out of letters and had to go to the Greek alphabet.

'Professor Emanuel is trying to figure out why this might be happening.

'One crucial factor is the mechanism

'that's at the core of what makes them work in the first place.

'Hurricanes are driven by heat.

'In fact, they're quite simply massive heat engines.

'They effectively transfer warmth from the ocean...

'..into the atmosphere.

'As all of that heat drifts upwards,

'it gets whipped into huge hurricane-force winds.

'This is a process we all have personal experience of.'

When people go outside, one of the main reasons we feel cool is water evaporating from our skin.

And when water evaporates from us, it chills us.

That energy doesn't disappear. It goes into the atmosphere.

When water evaporates from the oceans it takes heat out the oceans and puts it into the atmosphere.

'Hurricanes are so powerful

'because the heat energy transferred from the ocean to the atmosphere

'is unimaginably huge.

'They take heat from hundreds of thousands of square miles of ocean.

'The average hurricane turns that

'into three trillion watts of kinetic energy.

'The equivalent of a ten megaton nuclear bomb exploding

'about every 20 minutes.

'Because they are driven by heat, hurricanes are sensitive

'to any changes in the temperature of the Atlantic ocean.

'And that's recently been on the rise.'

Part of this increase in hurricane power

from the '80s to recent times, is related to sea surface temperature.

As the temperature goes up, this thermal disequilibrium between the ocean and atmosphere also goes up.

It goes up at a rate that would increase the wind speed

of hurricanes maybe 7% for every one degree C.

But we've seen a lot more than 7% for half a degree.

So we're trying to understand that.

'But he's not just interested in what's happened in the past.

'He's trying to get a sense of what the future might be

'if ocean temperatures continue to rise.'

If we look at the distribution of hurricanes in the present climate,

with weak storms over on this side

and strong storms over on this side,

what we see is lots of weak events.

And as you go towards stronger events the numbers decline,

until you get to a speed limit

which, in today's climate, is about 200 miles per hour.

Now, after the climate warms, the distribution's expected to look

more like this...

..with fewer weak storms up here,

but more strong storms.

We expect that speed limit will go up to something like

220 miles per hour.

'But the weirding of hurricanes doesn't stop there.

'Professor Emanuel believes

'that in the future, we can expect hurricanes in parts of the world

'that have never seen them before.

'He calls these "black swan events".'

I spends a lot of time

modelling hurricanes in the current climate and future climates.

When we do that, we begin to see hurricanes

that haven't happened yet in history, but could happen on physical grounds.

We call those "black swan events", the particularly bad ones.

This worries me because there are places around the world

that are at great risk from hurricanes.

Some of which don't know they're at great risk from hurricanes.

'It seems scarcely credible,

'but one of the places he thinks could be hit by a hurricane

'is here in Dubai

'in the Persian Gulf.'

The Persian Gulf is a body of water that gets very hot in the summer.

Really hot. The hot water runs very deep, as well.

To our knowledge, in the limited history of the region,

there hasn't been a hurricane there.

There may have been one in the distant past that wasn't recorded.

Our models tell us there could be.

They'd be rare, but if a hurricane ever happened there, it could get very intense. Even today, it could.

Winds well over 200 miles per hour.

It worries us

because we see a lot of building going on

with no thought that there might be a risk from hurricanes.

'One of the important things about the weather

'is that small changes in temperature that we hardly notice

'can whip up storms we can't avoid.

'But how are these small changes

'having an impact on weather events in other parts of the world?

'This is west Texas,

'where they're very comfortable with extremes.

'Big cars.

'Big hats.

'And big farms aren't the exception, but the norm.

'But this isn't normal.

'These fields should be white, covered in blooming cotton.

'But all that's blowing in the wind...

'..is dust.

'Matt Farmer has been growing cotton here for most of his life,

'and he's been looking in desperation for any sign of rain.'

I'm 51 years old.

I was raised not far from the farm that we're sitting on right now.

I've never seen it... I've seen it be dry.

I've never seen it be dry for this length of time, you know.

Never have seen anything like this at all.

'And it just keeps getting worse.

'Matt recorded this raging dust storm on his camera phone.'

WIND BLOWS

Just a reminder how dry we are

and the condition that our land is in.

'This dust storm was so huge it made the local news -

'55 miles away.'

-REPORTER:

-Look at this incredible video, folks.

I have never, ever seen anything like this before.

This is where we live,

and this is what we're in for until we get some moisture.

It's gonna take a pretty significant rain event.

You know, we need moisture and we need a bunch of it

before we can do something to this land.

'It's now officially the worst drought on record here.

'It's fast becoming like the dust bowl of the 1930s,

'which forced thousands people off their land.'

Let's jump to the weather lab and take a look.

The storm system is departing...

'Local weatherman Ron Roberts, who's been at KAMC for over 30 years

'hasn't been able to forecast rain for nearly all of 2011.'

..What does all the blue mean? It's a freeze warning...

We are seeing an incredible drought.

This is the worst drought in climate history for this region.

Only four inches of precipitation.

The worst drought before this - eight inches about 70 years ago.

That should give you a pretty good idea of how severe this is.

We've never had a drought like this.

'It's yet another example of a weather record being broken.

..pets out there in the morning...

'It doesn't make forecasting the weather any easier.'

I think this has been one of the toughest years to forecast.

It is a drought, but everybody wants the drought to end.

"When's it going to rain?"

There's more pressure during a drought to know what they need to do.

'The stakes couldn't be higher.

'Trying to get to the bottom of this

'is one of the world's leading climate scientists.

'Professor Katharine Hayhoe has a more than academic interest in figuring out what's happening.

'She lives and works in west Texas.'

What we are experiencing ourselves,

in the places where we live our day-to-day lives,

is changes in the average conditions that we're used to.

One of the first things we're seeing is changes in our extremes.

We're seeing global weirding.

'Global weirding is a phrase she helped popularise.

'One of the clues to the weirding of the west Texas weather

'lies right under her feet.'

Here's some west Texas dirt, good dirt,

even though it's blowing away like sand - it's just very dry.

We're below 99% below average right now -

so far below average we can't measure how dry it is.

'As the soil becomes drier and drier,

'the drought gets worse and worse.

'That gets amplified because there's no moisture left in the soil

'to evaporate into rain.

'But the weird thing about the weather in west Texas

'is that the year before this record-breaking drought,

'these bone-dry fields were awash in rain.

'So much rain that it broke all records.

'Two record-breaking years back-to-back is unheard of in this part of the world.'

..the dew points are going to be a little higher...

'We have 100 years of climate history in Lubbock.'

In those 100 years we've never had this steep oscillation from one year to the next.

Something is impacting our natural variabilities we have every year.

'Over the years, the weather here naturally swings between wet

'and dry.

'But the swing has never been this extreme -

'rewriting the record books in the space of 12 months.

'So how can it be record-breaking wet AND dry

'at virtually the same time?'

Our planet has warmed by almost one degree Celsius over 100 years.

A tiny change in temperature.

How could that make a difference?

That temperature change, in and of itself, makes no difference to our lives.

It makes a huge difference to what we're used to.

'The weather here has all the hallmarks of global weirding.

'It may not rain as often

'or as regularly,

'which makes droughts possible.

'But when it does rain...'

THUNDER BOOMS

'..it's heavier

'and more intense.'

One of the changes we've seen

is that the average humidity of our planet has increased by 4%.

Warmer air holds more water vapour.

So, on average, our atmosphere is 4% more humid

than it used to be 30 or 40 years ago.

What does this mean for us in west Texas?

Our humidity's 10%, probably, so we don't feel that so much here.

But what happens is there's more water vapour in the atmosphere.

So when storms come through, there's more water to pick up and dump.

CLAP OF THUNDER

'It's these storms, or lack of them,

'that trigger the extreme dry and wet weather in west Texas.

'In the future, scientists expect this pattern of drought and flooding

'to be played out across the planet.

'It's the small change in average temperature that's behind

'the predicted increase in some extreme weather events.

'Scientists believe it's all a question of balance.

'As the Earth struggles for climate stability,

'the weather begins to get extreme.

'And weird.'

Our planet's a really complex place.

So as we increase the temperature of our planet,

we are changing the dynamics of our atmosphere, the way our weather systems move across the country.

We're changing... Our sub-tropical zones are expanding.

Our dry areas of the world are growing.

We are changing how water gets distributed around our planet.

Places that are dry are getting drier. Places that are wet are getting wetter.

Extremes are getting stronger in both directions.

'Whether this warming is natural or man-made,

'as the vast majority of scientists believe...

'..it's triggering global changes.

'And they are expected to play out in Britain.

'This year's government report on climate change risk

'says we are likely to see more flooding on the one hand,

'and longer drier spells on the other.

'The record-breaking rains in Scotland last year

'and the worst spring drought ever in parts of eastern England

'could be a taste of things to come.

'But the intriguing question is the effect it might have been having

'on our winters.

'As Christmas 2009 approached, Britain started to shiver.'

Yeah, it could be a record-breaking cold night tonight...

'The cold went on, day after day.'

..temperatures are going to plunge as the day goes on...

'It was the coldest winter for 30 years.

'Just a year later, records were being broken again.

'December 2010 was the coldest for over 100 years.'

..brought to a standstill as heavy snow continues to fall...

'The weather was so brutal,

'Heathrow Airport was closed at one of the busiest times of the year.'

..the temperature's set to plummet even further...

'But how was this possible

'when the world was supposed to be getting warmer, not colder?

'The British weather is so complicated, has so many variables

'that scientists believe that really understanding what was going on

'was well nigh impossible.

'But that didn't deter the weather experts at the Met Office.'

The view in my research group is that we shouldn't give up on this

because there are key pieces of this puzzle that may be predictable.

It's our job to squeeze as much predictability

out of the climate system as we can,

so that we can advise people about the possibility of extremes.

'There's a number of clues to unravel in this mystery.

'They lie buried away in the Arctic...

'..in the long history of the sun...

'..and, possibly, the contents of this case.

'This is a Stradivarius violin.'

PLAYS MELODY

'They are the most expensive violins in the world.

'They're worth so much because they have a unique sound.'

They have an incredible singing quality and also incredible depth

and richness.

I think they reach closer than any instrument to the human voice,

which touches people.

'The body of this violin has a remarkable connection to the weather.

'Stradivarius violins are defined, in part,

'by the exceptionally fine-grained wood they're made from.

'This violin was made in 1721,

'nearly 300 years ago.

'The comparison with the grain of a 20th-century tree is startling.

'Intrigued, scientists in America have conducted a series of tests,

'which seem to suggest that the unique sound of the Stradivarius

'is down, in some ways,

'to the fine-grained wood they're made from.'

I think that's extremely interesting. That's fascinating.

I have thought about the quality of the wood,

but not particularly the closeness of the grain.

It does make sense.

A lot of the violins from the golden period of Stradivarius

have this very tight grain.

'Whatever the truth about why the Stradivarius sounds so beautiful,

'the fact is, trees grow slowly in the cold.

'So the closer the grain,

'the colder it was.

'The fine grain on this instrument

'is evidence that the climate at the time was freakishly cold.

'But what caused this bout of extreme winters 300 years ago?

'Could the same thing be responsible for the record-breaking winters of the last few years in Britain?

'Solar scientist Mike Lockwood

'went looking for clues in the most obvious place.

'The sun.

'The sun's energy exerts the most important influence on the Earth's climate.

'It defines the seasons, creates weather patterns

'and drives the oceans' currents.

'And it's what was happening to the sun 300 years ago

'that's brought him to the River Thames and the crucible of British science.'

We're just coming up to Greenwich on the river here.

Greenwich is a really important place in the history of science.

It was the first ever purpose-built laboratory,

built to solve the longitude problem.

But they did other things as well.

They observed the sun.

They made a great sequence of data

that's incredibly useful for understanding the sun.

'Hidden away in the dusty archives

'were tantalising clues that would help Mike understand

'what was happening to our nearest star.

'Because 300 years ago, men of science

'were carefully observing the face of the sun.

'The records show

'that they were mystified by something they hadn't seen before.

'The sun's spots, which they had known about for years,

'seemed to have unexpectedly vanished.'

Initially, it was thought this was because people weren't looking properly at that time.

As more and more observers' records were found, it became quite clear

that wasn't the case, there just weren't spots there.

People carried on looking for sun spots for 50 years,

despite the fact they hardly ever appeared.

Those records are invaluable because they tell us about the state of the sun 300 years ago.

'Sun spots are important

'because scientists now know that they can affect the British climate.

'The sun's spots, shown here in white,

'come and go on an 11-year cycle.

'When there are no spots,

'when solar activity is low,

'there is a reduction in the amount of ultraviolet light

'hitting the Earth.

'Low solar activity has the potential to disrupt the jet stream

'and the flow of warm air over Britain,

'allowing the wind to blow cold winter air from the east.'

Our work suggests that, statistically,

if you have low solar activity you will get more of these cold winters.

It seems to be a phenomenon that's very much prevalent in Europe

but not really so significant anywhere else.

'But 300 years ago, the sun's spots didn't just vanish for a few years

'in the 11-year cycle.

'They disappeared for two generations.

'The impact on Britain's winter weather was recorded by 17th-century weathermen all over the country.

'This period coincided

'with a series of exceptionally cold winters in Britain.

'The Thames froze over and frost fairs were held on the river.

'The period from 1650 to 1700 has become known as the Little Ice Age.

'In fact, the coldest winter ever recorded

'was in 1683-84.'

It's interesting to see the care

with which things are recorded, but also the colourful language people use

that we don't use nowadays.

"Profound cold" is wording that we can't use in a modern scientific paper,

but actually means quite a lot.

'So why did the sun's spots disappear for 50-odd years?

'To answer that question, Mike had to go back even further in time,

'back before the beginning of civilisation.

'One of the best places to get that long view of the history of the sun

'is in ice.

'He and his fellow scientists analysed ice cores

'because they contain a signature

'of what's been happening to the sun over thousands of years.'

We can effectively look back in time.

Roughly speaking, there are 20 to 30 grand maxima

and grand minima in the 9,000 years that we can look at.

'So what the ice showed

'was something nobody could have predicted.

'The sun had a secret rhythm.

'As well as an 11-year time frame,

'it also operated on a much longer timescale -

'the grand solar cycle,

'averaging every 300 years or so.

'And Mike Lockwood's ground-breaking research

'helped explain what was happening in the 17th century.

'Because that was a time of a grand solar minimum,

'where UV light would be at its lowest.

'Not just for years,

'but decades.

'And that would create the conditions to allow the wind

'to blow from the east -

'leading to frost fairs

'and the production of beautiful violins.

'Could that help explain the recent cold winters?

'Have we reached another grand solar minimum?

'The answer was a convincing...

'..no.'

We seem to be coming out of a grand maximum of solar activity.

And we will, past experience tells us, go into a grand minimum.

It's just a question of how soon. It could be as little as 40 years.

It could take a couple of hundred years.

But the long-term record from cosmogenic isotopes tell us

that it will, eventually, go back into a grand minimum again.

'We now know for sure that it wasn't the grand solar cycle that was responsible for Britain

'shivering through two record-breaking cold winters.

'Of course, the end of the regular 11-year cycle

'combined with other natural weather factors, played a part

'in these record-breaking winters.

'But some experts didn't think that was enough.

'Something was missing.

'Over the last few years,

'climate scientists from around the world have been trying to figure out

'what might have been happening.

'One of the leading lights of that group is Dr Adam Scaife.

'He and his team have been accumulating and analysing

'mountains of weather data.

'Weirdly, they believe the answer to the problem lies in the Arctic.

'Even weirder,

'they think the warming of the Arctic may be holding the key.

'But how can it be getting warmer in the Arctic, yet colder in Britain?'

If you melt the Arctic ice,

you might think that would give warmer conditions further afield.

For example, over Europe.

It is, indeed, true that when you reduce the ice

that lets lots of heat out of the ocean, so in the Arctic,

you see several degrees of warming in the lower part of the atmosphere.

'And there's little doubt that it's been getting warmer in the Arctic.

'In the last ten years, the sea ice has reached record low levels.

'According to the Met Office's sophisticated computer models,

'a hotter Arctic doesn't equal a warmer Britain.'

That warming that's happening over the Arctic is not seen over Europe.

The reason is because the circulation changes, the wind changes.

When you remove the Arctic ice,

the winds become more easterly.

The winds start to circulate from east to west around the Arctic

and south of the Arctic, and that dominates the response over Europe.

So instead of warming in the winter over Europe when the ice is depleted

we get cooling because we're dragging the air from Siberia over northern Europe.

'They're still trying to understand the mechanism that produces this effect,

'but when you add this new factor to variables like the sun's solar cycle

'what happened to our winters starts to make sense.

'And perhaps what's even weirder is that as the world gets warmer,

'some bits of it can get colder.'

Of course, Europe and the UK is only one region of the globe.

There are many other regions, and when you average those up

you still see warming.

So the fact that Europe is cold and the US is cold at the same time,

is balanced by the fact that Canada and the Mediterranean tend to be milder in those winters.

When you integrate up this change in the winds, the extra easterly winds,

when you average it over the whole globe, it cancels out.

Global warming can continue unaffected,

but the regional temperatures over, say, UK and Europe,

can go down, at least for a few years, as the globe warms up.

Even though, in the end, global warming will, of course, win, if we continue on that trend.

'This is why, as the world gets warmer,

'it makes sense to talk about the weather getting weirder.

'It affects different parts of the planet in different ways.

'But every extreme weather event isn't an example of global weirding.

'Freak weather still happens.

'The difference is, in the future, there's likely to be more of it.

'The dice are now being loaded.'

Dice are a great way to picture

what climate change is doing to our world.

We always have a chance of rolling that six, whether it's extreme heat

or record-setting rainfall, or the longest drought on record.

That could happen naturally.

What climate change is doing is, one by one,

taking those sixes, those weather extremes,

and adding a few more to the dice.

So now our chances of a record-breaking heatwave are twice what they used to be.

Our chances of record-setting rainfall events have increased,

relative to the last 50 years.

We'll never know if that six we roll, that extreme weather event,

is the natural one or the climate change one.

But we do know that the chances of rolling those sixes are increasing.

'More extreme weather appears to be the new normal.

'So what, if anything, can we do about it?

'One strategy is on display here, in Holland.

'It's not exactly visible.

'Half the country lies below sea level,

'which makes it vulnerable to weather extremes.

'Not surprisingly,

'they've come up with a few clever solutions to the problem.

'This car park in the city of Rotterdam

'might look like any ordinary car park,

'but hidden away in the bowels of the building

'is an unusual approach to dealing with the consequences of weather weirding.

'There's nothing to advertise where is is.

'Access is through this nondescript door.

'Inside, it looks like a series of interlinked concrete bunkers.

'This man has created something that's dark, cold and functional.'

What we saw in the last years

is that we had an increased amount of heavy rainfall events.

With these heavy rainfall events,

the centre of the city has water problems.

'If the weather gets weird in the streets above,

'it can be dealt with at the press of a button...

'..that pulls a plug in the sewer system

'and the excess floodwater is siphoned off down here.

'For Daniel Goedbloed, the man who designed and built these bunkers,

'they're an essential element in the city's defence

'against the new weather extremes.'

We had streets flooding, basements flooding.

We had the canals more or less overflowing.

So we calculated how much extra storage we needed in the city centre

just to face this problem of extra rainwater.

'This space is big enough to deal with ten million litres of water,

'enough to cope with the worst flood in a century.

'The whole project cost 11 million euros,

'about ten million pounds.

'But for Daniel and Rotterdam, that's a small price to pay

'for the level of protection it brings.'

Rainfall events are going to increase, there are going to be more heavy showers.

Over a year, we're going to have less rainfall,

but it's going to come in shorter amounts of time, in heavier rain showers.

So we have to deal with this rain water in a short amount of time.

Then you can just let it flow here quickly, and store it.

'After the flood,

'the stored water can be released back into the sewer system,

'and the tanks can be flushed and cleaned -

'ready to deal with the worst of the weather patterns of the future.

'But Rotterdam's adapting to a wetter future

'in even more ingenious ways.

'They're so concerned about flooding, that they're making plans

'not just to continue living by the water,

'they actually think it's possible to live on it.

'This futuristic looking building

'is floating in the city's docklands area.'

It's a pilot,

and a sort of showcase to show to the people floating constructions.

Floating living and working is possible. It's really stable.

I think in Rotterdam, in the heart of the city, there's an opportunity

to make new city parks

with a nice way for living and working possibilities.

'Most of the world's biggest cities are built near water.

'The Dutch think their plan to fill this dockland area

'with a raft of these buildings

'could be a blueprint for urban living in the future.'

We are now planning in this harbour a new floating community.

The city has announced a competition

for international architects to think about

this new floating community.

It could be a sort of new Venice.

'That's all well and good for small rich countries like Holland,

'who can afford to build the infrastructure to cope with the future of weather extremes.

'However, there is another solution that's more about brain than brawn.

'An example of that strategy

'had its finest hour when the future of the world was in the balance.

'In a quiet corner of the Met Office library hangs a map,

'probably the most famous weather map in the world.

'It's the forecast for D-Day.

'It played a critical role in the outcome of the Second World War.'

The weather forecast might well have won the war.

They were trying to predict, within a window of a few days,

with the right amount of moon, the right tides,

as to whether the weather would be flat enough for the landings.

The forecast was for this ridge of high pressure

to move in across the western part of the Channel.

As you can see, it hadn't got quite as far in as was expected.

So conditions weren't perfect,

but they knew that if they didn't go at the beginning of June,

they'd have to wait another month.

'If this forecast was wrong, the consequences could have been catastrophic.

'So it's no exaggeration to say that the D-Day weather forecast

'didn't just help to change the course of history,

'it also saved countless lives.

'And getting an accurate forecast is vital in our new weather future,

'because the hope is prediction will lead to protection.'

The point of the weather forecast,

when you get down to the nitty-gritty,

is getting extreme weather events - heavy rainfall, high temperatures -

the forecasts for those spot-on

so people can get correct warnings in the right timescales

so they can take precautions to save themselves, if they need to.

'And the one thing forecasters have managed to improve over the years

'is the accuracy of the forecast.

'The five-day forecast is now as accurate as the one-day forecast was 30 years ago.

'That could be vital in a future predicted to be dominated by extreme weather events.

'The technological development that's driven the improved accuracy

'floats thousands of miles above us.

'Satellites.'

We've got so much more information because of all the satellites.

You need to know what's going on globally to get a good forecast

of what's going to happen in the UK for the next five days.

You can't do it without global coverage. Satellites have given us that global coverage.

'Satellites provide huge amounts of information

'about the world's most extreme weather events.

'But making sense of them...

'..requires one of these.

'This is the Met Office's computer behemoth.

'It only came online three years ago.

'It can do 100 trillion calculations a second.

'That's the equivalent of 100,000 PCs.

'It makes it one of the biggest number crunchers in the world.'

We need that power.

We've got millions of observations coming in every day.

It's also trying to calculate what the weather's going to be like on that grid around the globe

up to five days ahead and beyond.

We use the same model that we do our day-to-day forecasts on

for our climate forecasts hundreds of years into the future.

'And that computing power could be a vital weapon in the coming struggle

'with global weather extremes.

'Allowing the Met Office to develop new kinds of weather forecasts.'

The big new idea in climate science

is not just to look at the distant future 100 years ahead.

That's very important. It tells us what road we're on.

But in the near term, on planning timescales years or months ahead,

when people make real decisions,

the big thing is to increase the skill of the forecast on those timescales.

Maybe give some warning weeks or months ahead of impending extremes.

Perhaps even unprecedented extremes. That's what we're trying to do.

'The new science of weather extremes highlights the profound links

'between our climate and the way we live.

'It also underlines just how vulnerable our civilisation is.'

We're playing a kind of dangerous game with the climate.

The last 7,000 or 8,000 years

has been a remarkably stable climate.

Very unusual in the last two million years of Earth's climate history.

It was during that time that human civilisation developed.

So we should be clear about something.

Climate change, whether it's natural or we're doing it,

is no danger to the planet.

The planet has gone through much worse. The danger is to us.

Our civilisation developed in a very unusually stable climate,

and it's very well adapted to that climate.

We change it - again, whether the change is natural or man-made -

it's going to cause dislocations and problems.

'However we choose to deal with global weather extremes,

'be it protection or prediction, one thing is clear -

'the world has changed.'

The past is no longer a guide to the future.

The average conditions that we grew up with. It's not the same as 30 years ago.

Events that used to be random and extreme are becoming more frequent

and more severe.

We're living in a different world than the one we grew up in.

We have to adapt to those changes.

Subtitles by Red Bee Media Ltd