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Some say it will end in fire. | 0:00:02 | 0:00:05 | |
Others think there will be a flood. | 0:00:06 | 0:00:08 | |
Some tell of a great plague that will strike down humanity. | 0:00:12 | 0:00:16 | |
Destruction shall come upon this evil generation. | 0:00:16 | 0:00:19 | |
But all point to one thing - the world is going to end. | 0:00:19 | 0:00:24 | |
Armageddon is one of humanity's most powerful and enduring ideas. | 0:00:26 | 0:00:32 | |
Stories of the apocalypse stretch right back | 0:00:33 | 0:00:37 | |
to the dawn of civilization, and they still make blockbuster hits today. | 0:00:37 | 0:00:41 | |
It seems there is nothing we love more than a vision of the apocalypse, | 0:00:54 | 0:00:58 | |
imagining how our world might end | 0:00:58 | 0:01:01 | |
seems a fundamental part of being human, but where | 0:01:01 | 0:01:04 | |
we once might have looked to religion for answers, many now turn to science | 0:01:04 | 0:01:09 | |
both to predict what might happen and to protect us from impending doom. | 0:01:09 | 0:01:15 | |
For nearly 50 years the BBC's Horizon | 0:01:18 | 0:01:20 | |
has been at the forefront of science journalism. | 0:01:20 | 0:01:23 | |
Charting the breakthroughs and discoveries that would change our world. | 0:01:24 | 0:01:29 | |
Science and technology have enabled us to predict earthquakes, | 0:01:32 | 0:01:36 | |
defeat disease, and defend ourselves from the awesome power of nature. | 0:01:37 | 0:01:43 | |
Our understanding of the world around us is better now than ever before. | 0:01:45 | 0:01:50 | |
But are we any closer to knowing how it's all going to end? | 0:01:52 | 0:01:56 | |
And when Armageddon arrives, | 0:01:57 | 0:02:00 | |
will science be able to save us? | 0:02:01 | 0:02:03 | |
For thousands of years people thought the only force powerful enough to end the world was God. | 0:02:25 | 0:02:32 | |
But then in 1945, all that changed. | 0:02:34 | 0:02:37 | |
The horror of two world wars | 0:02:53 | 0:02:55 | |
and the phenomenal power of the Hiroshima and Nagasaki bombs | 0:02:55 | 0:02:59 | |
left little doubt that we were capable of annihilating ourselves. | 0:02:59 | 0:03:03 | |
The creation of atomic energy had been a scientific triumph. | 0:03:03 | 0:03:08 | |
But the sheer scale of death and devastation it had caused | 0:03:10 | 0:03:14 | |
left the scientific community in turmoil. | 0:03:14 | 0:03:18 | |
One of the earliest Horizon programmes | 0:03:27 | 0:03:30 | |
reported on the moral torment that many scientists now faced. | 0:03:30 | 0:03:35 | |
This week, Horizon looks at a dilemma, | 0:03:35 | 0:03:37 | |
the dilemma of the scientist who, try as he might, | 0:03:37 | 0:03:41 | |
cannot reconcile with his conscience | 0:03:41 | 0:03:43 | |
the fear that his discoveries may eventually be used to the detriment of mankind. | 0:03:43 | 0:03:48 | |
CHEERING | 0:03:48 | 0:03:50 | |
Victory over Japan brings a wild ecstasy to the ordinary men and women of the triumphant nations. | 0:03:51 | 0:03:56 | |
At Los Alamos, the place where the winning weapon was created, | 0:04:00 | 0:04:03 | |
most join in the general mood of celebration and relief, but not all the scientists | 0:04:03 | 0:04:08 | |
present at the victory parties there share the popular excitement. | 0:04:08 | 0:04:11 | |
There are some among them for whom the sweets of triumph are soured by | 0:04:11 | 0:04:15 | |
a frightful awareness of the evil forces their genius and efforts have released. | 0:04:15 | 0:04:19 | |
We knew the world would not be the same. | 0:04:24 | 0:04:26 | |
I remembered the line from the Hindu scripture the Bhagavad-Gita | 0:04:28 | 0:04:34 | |
"Now I am become death, the destroyer of worlds." | 0:04:36 | 0:04:40 | |
I suppose we all thought that, one way or another. | 0:04:43 | 0:04:46 | |
But there was no going back. The nuclear arms race had begun. | 0:04:48 | 0:04:53 | |
During the '50s and '60s, | 0:04:55 | 0:04:57 | |
the super powers built increasingly bigger bombs in a bid to defend themselves from each other. | 0:04:57 | 0:05:02 | |
The result was an arsenal of weapons that could wipe humanity off the face of the Earth. | 0:05:04 | 0:05:11 | |
The threat of Armageddon was real | 0:05:21 | 0:05:24 | |
and many people lived each day in fear of nuclear annihilation. | 0:05:26 | 0:05:30 | |
When I was a kid growing up in the 1970's and early '80s | 0:05:34 | 0:05:37 | |
I certainly remember information like this government handbook | 0:05:37 | 0:05:41 | |
about what to do in the event of a nuclear attack | 0:05:41 | 0:05:43 | |
and it's got hints like how to build a bunker in your sitting room, | 0:05:43 | 0:05:47 | |
how to protect your drinking water from fallout | 0:05:47 | 0:05:49 | |
and it's scary stuff because at the time | 0:05:49 | 0:05:52 | |
I remember thinking that Armageddon was just a button push away. | 0:05:52 | 0:05:56 | |
And the terrible responsibility of having to push that button | 0:06:04 | 0:06:07 | |
rested on the shoulders of just a handful of men. | 0:06:07 | 0:06:10 | |
In 1971, Horizon gained unprecedented access to their extraordinary daily lives. | 0:06:13 | 0:06:20 | |
Cherie, would you bring me a cup of coffee, please? | 0:06:25 | 0:06:27 | |
'Bryce Martenson is a missile commander | 0:06:29 | 0:06:31 | |
'with strategic air command.' | 0:06:31 | 0:06:33 | |
Chris, do you know we're going up to Grandma Jean's for Thanksgiving? | 0:06:33 | 0:06:37 | |
'Every four days he leaves his family to go to an underground | 0:06:37 | 0:06:40 | |
'bomb-proof command post to take charge of ten Minuteman missiles.' | 0:06:40 | 0:06:44 | |
'If necessary, he is fully prepared to take part in the destruction | 0:06:48 | 0:06:52 | |
'of whole nations and ultimately his family and himself.' | 0:06:52 | 0:06:56 | |
Once in the heavily guarded compound, | 0:07:02 | 0:07:05 | |
Martenson and his deputy are there for 36 hours of duty. | 0:07:05 | 0:07:10 | |
Both have been checked on by military intelligence and psychiatrists. | 0:07:10 | 0:07:14 | |
-Attention! -Carry on. | 0:07:14 | 0:07:16 | |
Both are armed. If one of them suffers a psychiatric breakdown, | 0:07:22 | 0:07:27 | |
it's the duty of the other to shoot him. | 0:07:27 | 0:07:29 | |
60 feet under the ground, Martenson and his deputy | 0:07:36 | 0:07:38 | |
have to pass through a seven ton steel door | 0:07:38 | 0:07:41 | |
before reaching the entrance to the command capsule itself. | 0:07:41 | 0:07:45 | |
They're now surrounded by thousands of tons of steel and concrete. | 0:07:45 | 0:07:49 | |
Protected from almost anything but a direct nuclear hit. | 0:07:49 | 0:07:53 | |
The red strong box contains the secret orders to be used in case of war. | 0:07:59 | 0:08:03 | |
In the box are two keys. | 0:08:03 | 0:08:06 | |
To fire the missiles, these have to be turned simultaneously | 0:08:06 | 0:08:09 | |
in locks thirty feet apart. | 0:08:09 | 0:08:11 | |
They have been trained to the highest peak of efficiency to carry out | 0:08:14 | 0:08:17 | |
a task which we hope they'll never be asked to perform. | 0:08:17 | 0:08:21 | |
A first strike by the total Russian missile forces would leave | 0:08:24 | 0:08:28 | |
almost all of the American Minuteman missiles undamaged. | 0:08:28 | 0:08:32 | |
If only half of them were used in retaliation, | 0:08:32 | 0:08:35 | |
they could destroy 80% of Russian industry and 100 million people. | 0:08:35 | 0:08:40 | |
They hum menacingly. If you touch them, they feel alive. | 0:08:43 | 0:08:46 | |
# Don't you understand what I'm trying to say | 0:08:53 | 0:08:57 | |
# Can't you feel the fears I'm feeling today | 0:08:57 | 0:09:01 | |
# If the button is pushed There's no running away... # | 0:09:01 | 0:09:04 | |
Thousands took to the streets in protest against the apparent insanity of the arms race. | 0:09:04 | 0:09:09 | |
We will campaign until | 0:09:09 | 0:09:13 | |
all the nuclear bases are cleansed from our soil! | 0:09:13 | 0:09:17 | |
APPLAUSE | 0:09:17 | 0:09:19 | |
The use of destruction leads to destruction. It solves nothing. | 0:09:19 | 0:09:24 | |
Europe without the bomb can solve its problems. | 0:09:24 | 0:09:27 | |
As far as the people were concerned, | 0:09:29 | 0:09:31 | |
decades of scientific achievement had only brought us closer to | 0:09:31 | 0:09:35 | |
Armageddon than ever before and there was little we could do to prevent it. | 0:09:35 | 0:09:40 | |
Three, two, one, zero. | 0:09:52 | 0:09:56 | |
We have commencement. | 0:09:56 | 0:09:58 | |
But then in 1969, one event transformed public opinion. | 0:10:04 | 0:10:09 | |
I'm at the foot of the ladder. | 0:10:14 | 0:10:17 | |
I'm going to step off now. | 0:10:20 | 0:10:22 | |
It's one small step for man, | 0:10:24 | 0:10:27 | |
one giant leap for mankind. | 0:10:27 | 0:10:32 | |
Around 500 million people watched Neil Armstrong | 0:10:36 | 0:10:39 | |
step out of the Apollo 11 spacecraft onto the surface of the moon. | 0:10:39 | 0:10:44 | |
It was a remarkable achievement. | 0:10:45 | 0:10:48 | |
But seeing the Earth from space brought home | 0:10:51 | 0:10:54 | |
just how vulnerable our planet really was. | 0:10:54 | 0:10:57 | |
The survival of the entire human race depended on this | 0:11:00 | 0:11:04 | |
tiny oasis in the vast emptiness of space. | 0:11:04 | 0:11:08 | |
It would be another two decades before the fall | 0:11:15 | 0:11:18 | |
of the Soviet Union would diminish the threat of nuclear war. | 0:11:18 | 0:11:22 | |
But by the early 1970s, a new branch of science was already emerging, | 0:11:24 | 0:11:30 | |
one based not on destruction, but on protection. | 0:11:30 | 0:11:34 | |
Washington DC, early morning of April 22nd 1970, Earth Day. | 0:11:36 | 0:11:41 | |
Young people, until this time characterised as inward-looking, | 0:11:41 | 0:11:44 | |
drug-orientated, campus-rioting | 0:11:44 | 0:11:47 | |
and disaffected from public life, had found a cause. | 0:11:47 | 0:11:50 | |
America had discovered ecology. | 0:11:50 | 0:11:53 | |
-Well, ecology is a balance of nature. -What do you mean by ecology? | 0:11:53 | 0:11:58 | |
Well, to clean it up, not to pollute the atmosphere, the land, the water. | 0:11:58 | 0:12:03 | |
It's the relationship between me | 0:12:03 | 0:12:05 | |
and plants and animals and the world in general. | 0:12:05 | 0:12:07 | |
People talk about it and that's what they do. They say, | 0:12:07 | 0:12:09 | |
"I'm really for ecology," but nobody really does anything for it. | 0:12:09 | 0:12:12 | |
-What is ecology then? -Going out and doing something! | 0:12:12 | 0:12:15 | |
This enthusiasm for ecology was echoed by many scientists | 0:12:17 | 0:12:22 | |
convinced that if we destroyed our environment, | 0:12:22 | 0:12:26 | |
we would ultimately destroy ourselves. | 0:12:26 | 0:12:29 | |
It's not enough to put bricks in your toilet to save water, | 0:12:30 | 0:12:35 | |
or recycle your tin cans ritually or so on. | 0:12:35 | 0:12:39 | |
The really critical thing, of course, is what you're doing | 0:12:39 | 0:12:43 | |
to the life support systems of the planet because those | 0:12:43 | 0:12:45 | |
are the systems which supply us with all of our food, maintain | 0:12:45 | 0:12:49 | |
the quality of the atmosphere, dispose of all of our waste. | 0:12:49 | 0:12:52 | |
If we get rid of them, we've bought the farm. | 0:12:52 | 0:12:55 | |
CHANTING AND SINGING | 0:12:56 | 0:13:00 | |
The ecology movement was based on working together | 0:13:00 | 0:13:03 | |
to build a better future. | 0:13:03 | 0:13:06 | |
Many scientists echoed this idea, believing that sharing ideas | 0:13:08 | 0:13:12 | |
was the key to becoming the masters of our destiny. | 0:13:12 | 0:13:16 | |
And it was this spirit of co-operation that gave them | 0:13:17 | 0:13:21 | |
the confidence and the courage to tackle one of humanity's biggest killers. | 0:13:21 | 0:13:27 | |
There are probably two diseases that have caused more fear | 0:13:32 | 0:13:36 | |
in the population of the world than any other, | 0:13:36 | 0:13:39 | |
and that is plague and smallpox. | 0:13:39 | 0:13:41 | |
Smallpox is probably one of the most frightening, | 0:13:44 | 0:13:47 | |
ugly diseases that one can imagine. | 0:13:47 | 0:13:49 | |
I had seen worms in wounds, I had seen all kinds of rashes, | 0:13:49 | 0:13:54 | |
and people amputated, but smallpox, it's the worst I've ever seen. | 0:13:54 | 0:13:59 | |
Half of them were dying and there's nothing we could do. | 0:13:59 | 0:14:04 | |
In the post-war era, the scourge of smallpox was still killing | 0:14:06 | 0:14:10 | |
15 million people a year. | 0:14:10 | 0:14:12 | |
So members of the World Health Organisation met to lay out | 0:14:19 | 0:14:23 | |
the plans of an extraordinary global challenge - to end smallpox forever. | 0:14:23 | 0:14:29 | |
I felt overawed by the task ahead, recognising we had | 0:14:31 | 0:14:36 | |
so many languages to deal with | 0:14:36 | 0:14:38 | |
that we had so many different countries to deal with, that we were | 0:14:38 | 0:14:41 | |
dealing with countries where there was famine, where there was war. | 0:14:41 | 0:14:45 | |
There were many scientists who said | 0:14:45 | 0:14:47 | |
that this was just not possible to do. | 0:14:47 | 0:14:50 | |
And in fact, at the time, even the Director General of WHO said | 0:14:53 | 0:14:56 | |
it just can't be done. | 0:14:56 | 0:14:58 | |
The task was immense. | 0:14:59 | 0:15:01 | |
No disease had ever been eradicated from the world before | 0:15:01 | 0:15:06 | |
and smallpox was endemic on every continent. | 0:15:06 | 0:15:09 | |
The challenge was to vaccinate every one at risk, | 0:15:09 | 0:15:13 | |
all one billion of them. | 0:15:13 | 0:15:17 | |
Doctors, nurses and health workers joined forces across the globe. | 0:15:19 | 0:15:24 | |
This was war and the troops worked around the clock. | 0:15:26 | 0:15:29 | |
People were dying like flies and if I sleep, | 0:15:32 | 0:15:35 | |
that means there is nobody else who is going to do the work. | 0:15:35 | 0:15:38 | |
The best that I ever did was in a prison, | 0:15:46 | 0:15:48 | |
I did 600 people in 20 minutes. | 0:15:48 | 0:15:50 | |
The best I ever did in a day was something over 11,000. | 0:15:50 | 0:15:56 | |
Oh, it was a real battle. | 0:15:56 | 0:15:57 | |
Hundreds of thousands of people were working - health workers, | 0:15:57 | 0:16:01 | |
volunteers, so many different people. | 0:16:01 | 0:16:05 | |
But no matter how hard they tried, it was just too big a task. | 0:16:08 | 0:16:14 | |
Vaccinating everyone at risk was impossible. | 0:16:14 | 0:16:17 | |
The team needed a new strategy. | 0:16:17 | 0:16:20 | |
And so we asked the question, what would we do if we were smallpox viruses? | 0:16:22 | 0:16:26 | |
What would we do if we were bent on immortality? | 0:16:26 | 0:16:30 | |
What we would do is, we would find another susceptible person to move to. | 0:16:30 | 0:16:33 | |
Using that idea, we got on the radio to missionaries in the area | 0:16:36 | 0:16:41 | |
to tell us where are the cases of smallpox. | 0:16:41 | 0:16:45 | |
We used our vaccine precisely around those cases and then what was left, | 0:16:46 | 0:16:52 | |
we used where we predicted the smallpox virus would go next. | 0:16:52 | 0:16:56 | |
By finding every case of smallpox and vaccinating | 0:16:58 | 0:17:02 | |
everyone in contact with them, they broke the chain of transmission. | 0:17:02 | 0:17:06 | |
We had out-thought the smallpox virus. | 0:17:08 | 0:17:11 | |
Having vanquished the disease in North America, | 0:17:12 | 0:17:15 | |
South America, Europe and Asia, | 0:17:15 | 0:17:18 | |
the team were finally on the trail of the very last strain in Somalia. | 0:17:18 | 0:17:24 | |
They tracked the virus to this village. | 0:17:28 | 0:17:31 | |
And then to this woman. | 0:17:33 | 0:17:35 | |
They traced all her contacts and that's when they found him. | 0:17:35 | 0:17:40 | |
Ali Maalin - the last person on the planet with smallpox. | 0:17:49 | 0:17:54 | |
A disease that had plagued humanity for thousands of years | 0:18:05 | 0:18:08 | |
was finally under our control. | 0:18:08 | 0:18:11 | |
It was a fantastic achievement. | 0:18:14 | 0:18:17 | |
In 1979, smallpox was officially eradicated | 0:18:17 | 0:18:21 | |
as a threat to human life. | 0:18:21 | 0:18:23 | |
Science had shown that it could put us one step ahead of Armageddon. | 0:18:23 | 0:18:27 | |
Perhaps we could be masters of our destiny. | 0:18:27 | 0:18:31 | |
But then in 1981, Horizon reported on a controversial new theory | 0:18:35 | 0:18:41 | |
that suggested the fate of humanity was beyond our control. | 0:18:41 | 0:18:45 | |
It had long been known that 65 million years ago, Earth had | 0:18:52 | 0:18:56 | |
suffered a catastrophe that had wiped out nearly all living things, | 0:18:56 | 0:19:03 | |
including the dinosaurs. | 0:19:03 | 0:19:06 | |
No-one had managed to pinpoint what caused this mass extinction | 0:19:15 | 0:19:20 | |
until a father/son team proposed a radical new idea. | 0:19:20 | 0:19:26 | |
My son Walt brought along this little sample of rock, | 0:19:28 | 0:19:33 | |
which he has put together in Lucite to keep it from crumbling. | 0:19:33 | 0:19:38 | |
He said, "Dad, do you see this clay layer here, | 0:19:38 | 0:19:40 | |
"it's about a half inch thick." | 0:19:40 | 0:19:42 | |
He said, "That's when the dinosaurs went out," and I said, | 0:19:42 | 0:19:45 | |
"Do tell me more about that," and so he said that not only the dinosaurs | 0:19:45 | 0:19:51 | |
but 65 or 75% of all species alive on the Earth then | 0:19:51 | 0:19:56 | |
suddenly disappeared. And I said, "Gee, Walt, | 0:19:56 | 0:19:59 | |
"that's about the most exciting thing I've ever seen in my life." | 0:19:59 | 0:20:02 | |
And he had to confess ignorance to some things, he said, | 0:20:02 | 0:20:05 | |
"We really don't know how long it took, why it's there," | 0:20:05 | 0:20:09 | |
and so I said, "Maybe some of the tricks that I know as a physicist might help unravel that story," | 0:20:09 | 0:20:17 | |
and then we talked about it for the next couple of weeks | 0:20:17 | 0:20:20 | |
and finally decided to look for iridium | 0:20:20 | 0:20:24 | |
as a measure of the deposition rate. | 0:20:24 | 0:20:27 | |
Iridium along with all the other elements | 0:20:27 | 0:20:31 | |
was present in the cloud of dust that was to form the solar system. | 0:20:31 | 0:20:34 | |
What little there is comes from the slow drizzle of the stuff | 0:20:34 | 0:20:38 | |
that's still falling on the Earth at a known rate. | 0:20:38 | 0:20:41 | |
Alvarez decided to measure how much iridium there was in the clay | 0:20:41 | 0:20:44 | |
and so calculate how long it had taken to fall. | 0:20:44 | 0:20:47 | |
The results surprised everyone. | 0:20:52 | 0:20:55 | |
Iridium was found in large amounts, | 0:20:55 | 0:20:58 | |
much more than a slow drizzle from space could explain. | 0:20:58 | 0:21:01 | |
Now, there was no way that we knew of that we could explain | 0:21:02 | 0:21:08 | |
such an increase by conventional, | 0:21:08 | 0:21:11 | |
terrestrial chemistry or geo-chemistry. | 0:21:11 | 0:21:16 | |
Luiz realised they had stumbled upon something important, | 0:21:16 | 0:21:20 | |
but what did it mean? | 0:21:20 | 0:21:21 | |
And I went through a lot of scenarios. | 0:21:21 | 0:21:23 | |
Some of them were so wild I wouldn't even dare mention what they were, | 0:21:23 | 0:21:27 | |
but I remember thinking at the time, each of them looked pretty good. | 0:21:27 | 0:21:32 | |
One idea was that the iridium was showered on the Earth | 0:21:32 | 0:21:35 | |
from a nearby exploding star, a supernova. | 0:21:35 | 0:21:37 | |
The idea was that if the iridium had come from a super nova, | 0:21:40 | 0:21:43 | |
it would have carried with it a rare type of plutonium | 0:21:43 | 0:21:46 | |
that no longer exists in the solar system, plutonium 244. | 0:21:46 | 0:21:50 | |
Nothing. | 0:21:53 | 0:21:55 | |
-He went on churning out the ideas. -He would come up with them. | 0:21:55 | 0:21:58 | |
These would be evaluated and discarded. | 0:21:58 | 0:22:02 | |
After about a month and a half, he came up with one that none of us | 0:22:02 | 0:22:07 | |
could knock down and that's the one that we're working on now. | 0:22:07 | 0:22:11 | |
What they're working on now also comes from space. | 0:22:16 | 0:22:21 | |
The vast majority of iridium-bearing meteorites | 0:22:21 | 0:22:23 | |
started life as asteroids. | 0:22:23 | 0:22:26 | |
Most of them in an orbit between Mars | 0:22:26 | 0:22:28 | |
and Jupiter never come anywhere near the Earth. | 0:22:28 | 0:22:31 | |
But the theory goes that a few are occasionally | 0:22:31 | 0:22:33 | |
swung out of line by the enormous gravitational pull of Jupiter. | 0:22:33 | 0:22:38 | |
A very few of these finish up in an orbit which crosses the Earth's. | 0:22:39 | 0:22:44 | |
Alvarez' theory is that 65 million years ago, a huge asteroid, | 0:22:44 | 0:22:48 | |
six miles wide, smashed into the Earth with devastating effects. | 0:22:48 | 0:22:53 | |
It was this collision, he believes, that covered the Earth | 0:22:59 | 0:23:02 | |
with iridium and wiped out the dinosaurs. | 0:23:02 | 0:23:06 | |
Ten years later, Alvarez' theory became widely accepted | 0:23:14 | 0:23:18 | |
when a 200 kilometre-wide impact crater the asteroid left behind | 0:23:18 | 0:23:22 | |
was identified in the jungles of Mexico. | 0:23:22 | 0:23:25 | |
When it became clear that a rock falling from the heavens | 0:23:36 | 0:23:39 | |
had exterminated nearly all life on Earth, | 0:23:39 | 0:23:43 | |
we realised just how vulnerable we were. | 0:23:43 | 0:23:46 | |
The mass extinction of the dinosaurs was proof that Armageddon was real. | 0:23:49 | 0:23:54 | |
If it had happened before, it could happen again. | 0:23:54 | 0:23:57 | |
Against the awesome might of nature, | 0:23:57 | 0:24:00 | |
our science and our technology seemed powerless, | 0:24:00 | 0:24:04 | |
but if we couldn't prevent the devastation, | 0:24:04 | 0:24:06 | |
we needed to get really good at something else, | 0:24:06 | 0:24:09 | |
the science of prediction. | 0:24:09 | 0:24:11 | |
Astronomers began scouring the heavens for killer asteroids | 0:24:13 | 0:24:18 | |
that might be heading our way. | 0:24:18 | 0:24:22 | |
And then radio telescopes captured the image everyone was dreading. | 0:24:23 | 0:24:28 | |
A one kilometre-wide asteroid with our name on it. | 0:24:33 | 0:24:37 | |
It's known as 1950 DA. | 0:24:40 | 0:24:44 | |
An interesting question is, is 1950 DA the most dangerous rock in space? | 0:24:47 | 0:24:52 | |
And at the moment, one could say it's the most dangerous | 0:24:55 | 0:24:59 | |
known rock in space. | 0:24:59 | 0:25:01 | |
Astronomers have tracked 1950 DA more closely than almost | 0:25:04 | 0:25:07 | |
any other asteroid in the solar system, | 0:25:07 | 0:25:12 | |
and all the indications are it is cosmic enemy number one, | 0:25:12 | 0:25:17 | |
expected to collide with or come perilously close to the Earth in 2880. | 0:25:17 | 0:25:25 | |
Its impact could kill hundreds of millions of people. | 0:25:30 | 0:25:34 | |
If 1950 DA hit the Earth, the energy released would be | 0:25:38 | 0:25:42 | |
roughly 100,000 megatons. | 0:25:42 | 0:25:46 | |
Ten megatons is a very powerful hydrogen bomb. | 0:25:48 | 0:25:51 | |
So this would not be a pleasant event for the Earth. | 0:25:53 | 0:25:57 | |
It seems that in the mere blink of a cosmic eye | 0:26:04 | 0:26:06 | |
we have a date with Armageddon. | 0:26:06 | 0:26:09 | |
The world of science now faced an awesome task. | 0:26:11 | 0:26:15 | |
What could it do to save the Earth? | 0:26:15 | 0:26:19 | |
Jay Melosh was part of an elite group of scientists | 0:26:27 | 0:26:30 | |
summoned by the US Government to tackle this new threat to humanity. | 0:26:30 | 0:26:34 | |
The solution they confidently proposed would be | 0:26:38 | 0:26:42 | |
to turn our weapons of mass destruction into weapons | 0:26:42 | 0:26:45 | |
of mass salvation - | 0:26:45 | 0:26:47 | |
attack an incoming asteroid with nuclear missiles. | 0:26:47 | 0:26:51 | |
It would seem that a big nuclear weapon detonated | 0:26:53 | 0:26:56 | |
either on the surface or drilled inside an asteroid | 0:26:56 | 0:27:00 | |
would be the answer to this problem. | 0:27:00 | 0:27:02 | |
We've been trained from watching movies like Star Wars that | 0:27:07 | 0:27:12 | |
if we were to do that, | 0:27:12 | 0:27:14 | |
the asteroid would disappear in a cloud of vapour. | 0:27:14 | 0:27:17 | |
But then Melosh and his fellow scientists | 0:27:26 | 0:27:28 | |
pointed to one very obvious snag. | 0:27:28 | 0:27:32 | |
Those movies ignore the really gigantic scale of these objects. | 0:27:32 | 0:27:39 | |
Even a nuclear weapon of the normal yield, 20 megatons, | 0:27:39 | 0:27:43 | |
would not disperse it. | 0:27:43 | 0:27:46 | |
Firing even our most powerful missiles, | 0:27:57 | 0:27:59 | |
20 megaton warheads would be useless. | 0:27:59 | 0:28:03 | |
In fact, it could just make matters worse. | 0:28:05 | 0:28:08 | |
Scientists calculated that the explosion could simply | 0:28:11 | 0:28:14 | |
shatter the asteroid, causing huge pieces of rock | 0:28:14 | 0:28:19 | |
to rain down across continents and oceans. | 0:28:19 | 0:28:23 | |
One huge killer would be turned into something every bit as deadly - | 0:28:23 | 0:28:27 | |
a cluster bomb. | 0:28:27 | 0:28:30 | |
Even if we could break it up into fragments, it's not clear that | 0:28:32 | 0:28:36 | |
that would help things unless all of the fragments missed the Earth. | 0:28:36 | 0:28:41 | |
Because if they didn't, | 0:28:44 | 0:28:46 | |
gigantic fires could be ignited by those fragments hitting land. | 0:28:46 | 0:28:51 | |
Large fragments that hit the sea could raise tidal waves | 0:28:55 | 0:28:58 | |
up to four kilometres high. | 0:28:58 | 0:29:00 | |
It would be utterly devastating. | 0:29:05 | 0:29:07 | |
It seemed no existing nuclear weapon could save the Earth. | 0:29:14 | 0:29:18 | |
What was needed was something much bigger, something that | 0:29:19 | 0:29:22 | |
wouldn't just fragment an incoming asteroid, but completely vaporise it. | 0:29:22 | 0:29:28 | |
Nothing that we have in our arsenals can release that much energy. | 0:29:30 | 0:29:36 | |
Nevertheless, the nuclear weapons designers assure us that there | 0:29:36 | 0:29:40 | |
is no theoretical limit to how big you can build a nuclear weapon | 0:29:40 | 0:29:44 | |
and many were eager to try. | 0:29:44 | 0:29:46 | |
So they set to calculating just how big a weapon they would need. | 0:29:51 | 0:29:55 | |
The answer was staggering. | 0:29:57 | 0:30:00 | |
The biggest bomb ever made would have to be | 0:30:01 | 0:30:04 | |
placed on the biggest rocket ever made. | 0:30:04 | 0:30:07 | |
And the whole contraption fired out of the Earth's atmosphere | 0:30:10 | 0:30:14 | |
at 40,000 kilometres per hour. | 0:30:14 | 0:30:17 | |
We're talking something on the order of a thousand megatons. | 0:30:21 | 0:30:26 | |
Such weapons constitute a bigger threat to us | 0:30:26 | 0:30:30 | |
than the asteroids themselves do. | 0:30:30 | 0:30:32 | |
This weapon, if mishandled or misused, would itself be | 0:30:34 | 0:30:39 | |
capable of causing a global catastrophe. | 0:30:39 | 0:30:43 | |
The idea was dismissed as insane. | 0:30:43 | 0:30:47 | |
Nuclear weapons, it seemed, were not the answer. | 0:30:47 | 0:30:51 | |
Science had to find a better way. | 0:30:51 | 0:30:53 | |
So Melosh put forward an extraordinary idea. | 0:31:06 | 0:31:09 | |
He suggested building a device | 0:31:15 | 0:31:17 | |
that would act like a giant magnifying glass. | 0:31:17 | 0:31:21 | |
We imagine this is the asteroid. | 0:31:24 | 0:31:26 | |
We get it lined up, focus it | 0:31:26 | 0:31:29 | |
and we can start to vaporise the surface of the asteroid. | 0:31:29 | 0:31:33 | |
If we focus the solar energy in a narrow spot on the surface | 0:31:36 | 0:31:40 | |
we can actually vaporise rock, generate a jet, | 0:31:40 | 0:31:43 | |
kind of like a little rocket motor, a solar-powered rocket motor, | 0:31:43 | 0:31:47 | |
that will then gently push the asteroid away. | 0:31:47 | 0:31:50 | |
His name for this device was a solar collector. | 0:31:50 | 0:31:54 | |
This solar collector would focus | 0:31:57 | 0:31:59 | |
an intense beam of the sun's energy onto the asteroid. | 0:31:59 | 0:32:04 | |
The heat would burn away the surface of the asteroid, releasing energy | 0:32:04 | 0:32:09 | |
which would gradually push the asteroid off course. | 0:32:09 | 0:32:13 | |
It might sound like science fiction | 0:32:16 | 0:32:18 | |
but it offered hope that science could save the Earth. | 0:32:18 | 0:32:22 | |
But there was a problem. | 0:32:33 | 0:32:35 | |
It would take at least ten years to build and deploy the solar collector | 0:32:36 | 0:32:41 | |
and many asteroid hunters believed that we might not have that long. | 0:32:41 | 0:32:47 | |
They estimated there could be up to 600 kilometre-wide asteroids | 0:32:47 | 0:32:51 | |
still undiscovered near Earth. | 0:32:51 | 0:32:54 | |
And any one of them could be heading straight for us. | 0:32:54 | 0:32:58 | |
While astronomers trained their telescopes on the skies, | 0:33:08 | 0:33:12 | |
other scientists were fine-tuning their instruments to find out | 0:33:12 | 0:33:16 | |
what might be lurking here on Earth. | 0:33:16 | 0:33:18 | |
And they discovered that nature was far more dangerous | 0:33:20 | 0:33:24 | |
than they'd ever imagined. | 0:33:24 | 0:33:26 | |
Increasingly sophisticated seismological research | 0:33:27 | 0:33:32 | |
found that a single earthquake | 0:33:32 | 0:33:34 | |
could trigger a chain reaction of devastating quakes | 0:33:34 | 0:33:38 | |
capable of bringing entire nations to their knees. | 0:33:38 | 0:33:42 | |
And in the Canary Islands | 0:33:46 | 0:33:49 | |
an unstable volcano could cause a massive landslide, | 0:33:49 | 0:33:53 | |
creating a huge tidal wave far higher than any normal tsunami. | 0:33:53 | 0:33:58 | |
It would race across oceans, killing millions. | 0:33:58 | 0:34:02 | |
And then, hidden beneath Yellowstone Park in Wyoming, | 0:34:11 | 0:34:15 | |
geologists found an even bigger threat. | 0:34:15 | 0:34:18 | |
A super-volcano. | 0:34:23 | 0:34:25 | |
We realised that Yellowstone had been an ancient volcanic system. | 0:34:30 | 0:34:35 | |
We suspected that it had been a caldera volcano | 0:34:35 | 0:34:38 | |
but we didn't know where the caldera was or how large it was. | 0:34:38 | 0:34:42 | |
It wasn't until photographs were taken from the air | 0:34:45 | 0:34:48 | |
that the true scale of the caldera was revealed. | 0:34:48 | 0:34:51 | |
It was a monster. | 0:34:55 | 0:34:57 | |
70 kilometres across, 30 kilometres wide. | 0:34:57 | 0:35:01 | |
Beneath it lay a vast magma chamber | 0:35:04 | 0:35:06 | |
that encompassed almost the entire park. | 0:35:06 | 0:35:09 | |
The question was, when would it erupt? | 0:35:16 | 0:35:20 | |
To find out, geologists needed to work out | 0:35:24 | 0:35:27 | |
when it had erupted in the past, | 0:35:27 | 0:35:30 | |
so they examined the ancient sheets of hardened ash | 0:35:30 | 0:35:34 | |
and they discovered something unexpected - | 0:35:34 | 0:35:39 | |
three different layers from three different eruptions. | 0:35:39 | 0:35:45 | |
Quite amazingly, we realised that there was a cycle of caldera-forming eruptions, | 0:35:45 | 0:35:49 | |
these huge volcanic eruptions, about every 600,000 years. | 0:35:49 | 0:35:53 | |
Yellowstone was on a 600,000-year cycle | 0:35:59 | 0:36:02 | |
and the last eruption was 600,000 years ago. | 0:36:02 | 0:36:06 | |
And there were worrying signs that the volcano was once again beginning to stir. | 0:36:08 | 0:36:14 | |
Professor Bob Smith has been working in the park for most of his career. | 0:36:18 | 0:36:24 | |
I was working at the south end of this lake in a place called Peale Island. | 0:36:27 | 0:36:32 | |
I was standing on the island one day and I noticed a couple of unusual things. | 0:36:32 | 0:36:37 | |
The boat dock that we would normally use at this place seemed to be under water. | 0:36:37 | 0:36:42 | |
That evening, as I was looking over the expanse of the south end | 0:36:43 | 0:36:47 | |
of the lake, I could see trees that were being inundated by water. | 0:36:47 | 0:36:51 | |
I took a look at these trees and they were being | 0:36:53 | 0:36:56 | |
inundated with water a few inches, maybe a foot deep. | 0:36:56 | 0:36:59 | |
What does it mean? We did not know. | 0:37:01 | 0:37:03 | |
Bob commissioned a survey to measure the elevation of the park | 0:37:07 | 0:37:11 | |
above sea level. | 0:37:11 | 0:37:12 | |
He compared these figures to those of a survey carried out in the 1920s. | 0:37:14 | 0:37:17 | |
The results were surprising. | 0:37:20 | 0:37:22 | |
They seemed to show that the ground was heaving upwards. | 0:37:22 | 0:37:26 | |
The surveyor said, "There's something wrong." | 0:37:33 | 0:37:35 | |
And he said, "It's not me. It's got to be something else." | 0:37:35 | 0:37:39 | |
So we went through all the measurements again, | 0:37:39 | 0:37:41 | |
trying to be very careful | 0:37:41 | 0:37:43 | |
and the conclusion kind of hit me in the face. It said this caldera has uplifted, at that time, | 0:37:43 | 0:37:49 | |
740 millimetres in the middle of the caldera. | 0:37:49 | 0:37:53 | |
The ground beneath the north of Yellowstone was bulging up, | 0:37:57 | 0:38:01 | |
tilting the rest of the park downwards. | 0:38:01 | 0:38:05 | |
This was tipping out the south end of the lake, | 0:38:05 | 0:38:07 | |
saturating the shore-side trees with water. | 0:38:07 | 0:38:11 | |
The scientists realised there was only one thing that could | 0:38:14 | 0:38:17 | |
make the earth rise up in this way - | 0:38:17 | 0:38:21 | |
a vast, living magma chamber. | 0:38:21 | 0:38:23 | |
The Yellowstone super-volcano was alive. | 0:38:26 | 0:38:28 | |
And if the calculations were correct, the next eruption was already overdue. | 0:38:31 | 0:38:36 | |
They predicted that when this super-volcano erupts again | 0:38:45 | 0:38:48 | |
it will have a devastating impact across the whole world. | 0:38:48 | 0:38:53 | |
Gigantic plumes of ash and debris will be thrown into the atmosphere, | 0:39:03 | 0:39:08 | |
blotting out the sun. | 0:39:08 | 0:39:10 | |
Global temperatures will plummet, devastating agriculture | 0:39:24 | 0:39:29 | |
and pushing humanity to the brink of extinction. | 0:39:29 | 0:39:32 | |
It seemed the more scientists scrutinised nature | 0:39:40 | 0:39:43 | |
the more terrifying threats they found. | 0:39:43 | 0:39:47 | |
Increasingly sophisticated scientific techniques might have | 0:39:47 | 0:39:51 | |
brought us greater knowledge but we were scaring ourselves stupid. | 0:39:51 | 0:39:55 | |
And as the millennium approached we were gripped by Armageddon fever. | 0:39:55 | 0:39:59 | |
We even convinced ourselves that the turn of the new year itself | 0:39:59 | 0:40:03 | |
would spell our doom. | 0:40:03 | 0:40:05 | |
Patients' lives could be at risk because the Health Service | 0:40:05 | 0:40:08 | |
may not be ready to deal with the so-called Millennium Bug. | 0:40:08 | 0:40:13 | |
At the stroke of midnight, the Millennium Bug would cause computers to crash, | 0:40:13 | 0:40:18 | |
power grids to seize | 0:40:18 | 0:40:20 | |
and planes to fall from the skies. | 0:40:20 | 0:40:22 | |
Three, two, one. | 0:40:24 | 0:40:26 | |
BELL CHIMES | 0:40:26 | 0:40:29 | |
When the New Year arrived uneventfully, | 0:40:38 | 0:40:41 | |
hysteria turned to apocalypse fatigue. | 0:40:41 | 0:40:44 | |
We'd believed all the hype and now started to wonder | 0:40:47 | 0:40:50 | |
if the scientists were crying wolf. | 0:40:50 | 0:40:53 | |
But then, just when we thought we were safe, an event witnessed by millions changed everything. | 0:40:53 | 0:40:59 | |
Nearly 3,000 people died in the terrorist attacks of September 11th 2001. | 0:41:22 | 0:41:28 | |
It was a stark reminder that there were some things we could never predict | 0:41:29 | 0:41:34 | |
and that Armageddon could yet be a man-made catastrophe. | 0:41:34 | 0:41:38 | |
These shocking acts of violence put the world on red alert. | 0:41:39 | 0:41:43 | |
And then on Boxing Day, 2004... | 0:41:50 | 0:41:54 | |
..the Indian Ocean Tsunami, | 0:42:00 | 0:42:02 | |
one of the most devastating natural disasters in living memory, | 0:42:02 | 0:42:05 | |
claimed over 200,000 lives in a single day. | 0:42:05 | 0:42:11 | |
Dire warnings of the apocalypse can sometimes feel dramatic | 0:42:21 | 0:42:26 | |
and unreal. | 0:42:26 | 0:42:27 | |
But these events were a chilling reminder that our lives | 0:42:27 | 0:42:30 | |
could be snuffed out in an instant. | 0:42:30 | 0:42:33 | |
Science was powerless to prevent these tragedies, | 0:42:40 | 0:42:42 | |
but one year later, | 0:42:42 | 0:42:44 | |
when devastation looked set to strike again, | 0:42:44 | 0:42:47 | |
scientists made sure they were ready. | 0:42:47 | 0:42:50 | |
Good evening, European governments have been told to take urgent action | 0:42:54 | 0:42:58 | |
to prepare for a possible flu pandemic. | 0:42:58 | 0:43:01 | |
The virus found is H5N1 - highly pathogenic virus. | 0:43:01 | 0:43:07 | |
Any bird flu could cause a pandemic. | 0:43:10 | 0:43:14 | |
But hidden inside H5N1, is something that makes it a more dangerous virus | 0:43:14 | 0:43:18 | |
than any we've seen before. | 0:43:18 | 0:43:20 | |
This particular H5N1 virus | 0:43:21 | 0:43:25 | |
falls into the category of what we call a highly pathogenic virus. | 0:43:25 | 0:43:29 | |
Um, much, much more deadly | 0:43:29 | 0:43:31 | |
than your run-of-the-mill avian influenza viruses. | 0:43:31 | 0:43:35 | |
When we analysed it, we found a tiny extra piece | 0:43:38 | 0:43:41 | |
of genetic material | 0:43:41 | 0:43:43 | |
that's in one of the genes of the virus. | 0:43:43 | 0:43:46 | |
The tiny genetic anomaly turns H5N1 into a particularly nasty killer. | 0:43:48 | 0:43:54 | |
What is different about the H5N1 virus | 0:43:56 | 0:44:00 | |
is that this very small change | 0:44:00 | 0:44:01 | |
allows the virus to spread throughout the body | 0:44:01 | 0:44:04 | |
infecting various organs and tissues around the respiratory tract. | 0:44:04 | 0:44:08 | |
And of course, we've seen the result quite clearly, | 0:44:08 | 0:44:12 | |
many of these people who have become infected with H5N1 | 0:44:12 | 0:44:15 | |
are dying from multi-organ failure. | 0:44:15 | 0:44:17 | |
The idea that a killer bird-flu virus could | 0:44:29 | 0:44:33 | |
take hold in the human population isn't scientific theory - | 0:44:33 | 0:44:37 | |
it's historical fact. | 0:44:37 | 0:44:38 | |
Medical archives reveal a pattern of flu pandemics | 0:44:38 | 0:44:41 | |
stretching back through the centuries. | 0:44:41 | 0:44:44 | |
The most devastating outbreak of all occurred in 1918, | 0:44:44 | 0:44:48 | |
shortly after the end of the First World War. | 0:44:48 | 0:44:52 | |
A deadly strain of avian flu spread rapidly across the globe, | 0:44:52 | 0:44:56 | |
carried in the lungs of soldiers returning home to their families. | 0:44:56 | 0:45:00 | |
The death toll was terrifying. | 0:45:02 | 0:45:04 | |
Within 14 months, the virus had taken 15 million lives. | 0:45:08 | 0:45:12 | |
'The biggest shock, I guess, about 1918 was | 0:45:20 | 0:45:23 | |
'the way the virus turned its face and attacked | 0:45:23 | 0:45:26 | |
'young people between the ages of 25 and 35.' | 0:45:26 | 0:45:29 | |
They are not the sort of young people who were normally killed | 0:45:29 | 0:45:32 | |
by an influenza virus, but in 1918 they were. | 0:45:32 | 0:45:36 | |
'The virus spared the elderly - | 0:45:38 | 0:45:40 | |
'they're usually the most vulnerable - and attacked the young group. | 0:45:40 | 0:45:43 | |
'Whenever you think about 1918, you think,' | 0:45:43 | 0:45:46 | |
"Oh, my goodness, I hope that's not going to happen again." | 0:45:46 | 0:45:48 | |
The flu strain responsible for the 1918 pandemic was H1N1. | 0:45:51 | 0:45:55 | |
Not the same virus that is threatening us today, | 0:45:55 | 0:45:58 | |
but the similarities between the two are striking. | 0:45:58 | 0:46:02 | |
'At the moment, with H1N1, | 0:46:05 | 0:46:07 | |
'140 people have died, in a population of six billion. | 0:46:07 | 0:46:10 | |
'People come to me and they say, "That's not many."' | 0:46:11 | 0:46:14 | |
But my answer to that is, go back to the year before 1918. | 0:46:14 | 0:46:17 | |
There, you had 140 people dead, 140 soldiers dead. | 0:46:17 | 0:46:21 | |
'There you had a virus that didn't seem to spread at all,' | 0:46:21 | 0:46:24 | |
but within a year it had exploded, and killed 50 million people. | 0:46:24 | 0:46:31 | |
So, there's a warning there. | 0:46:31 | 0:46:34 | |
We cannot ignore a virus that's done that in the past. We really can't. | 0:46:34 | 0:46:39 | |
The predictions surrounding avian flu were truly apocalyptic. | 0:46:42 | 0:46:46 | |
Virologists warned that millions could become infected and die, | 0:46:48 | 0:46:52 | |
plunging society into chaos. | 0:46:52 | 0:46:55 | |
But in the end, the pandemic never came. | 0:46:59 | 0:47:02 | |
Scientists are keen to warn us when they spot a looming disaster, | 0:47:06 | 0:47:09 | |
but when their predictions don't come true, | 0:47:09 | 0:47:12 | |
they're often accused of scaremongering. | 0:47:12 | 0:47:14 | |
Yet their most persistent warning, the one they've been shouting about | 0:47:14 | 0:47:18 | |
for decades now, is still something that many people don't want to hear. | 0:47:18 | 0:47:23 | |
It's a story Horizon has been following since the '80s. | 0:47:24 | 0:47:27 | |
Our world is getting hotter. | 0:47:32 | 0:47:35 | |
The atmosphere is changing, trapping more heat from the Sun. | 0:47:35 | 0:47:39 | |
Changing with it may be climate, agriculture and the level of the sea. | 0:47:39 | 0:47:43 | |
The cause is odourless, colourless and non-toxic, and it's man-made. | 0:47:44 | 0:47:49 | |
Some of the trouble comes from this power station at Vesteros in Sweden. | 0:47:51 | 0:47:55 | |
The emissions should be harmless - water vapour | 0:47:55 | 0:47:59 | |
and carbon dioxide, or CO2 - but carbon dioxide is the problem. | 0:47:59 | 0:48:04 | |
Burning coal, or any fossil fuel such as oil or gas, makes CO2. | 0:48:06 | 0:48:12 | |
We put 18 billion tonnes of it out into the atmosphere each year. | 0:48:12 | 0:48:16 | |
CO2 traps heat like a giant greenhouse, | 0:48:16 | 0:48:18 | |
and it may be changing the climate of the Earth. | 0:48:18 | 0:48:21 | |
'20 years ago, when this matter was discussed among scientists, | 0:48:26 | 0:48:30 | |
'the response was one of dismissing it - | 0:48:30 | 0:48:33 | |
'"This is fiction, we don't believe it." | 0:48:33 | 0:48:36 | |
'Today, many are concerned, and that's a major difference.' | 0:48:36 | 0:48:41 | |
It's been an evolutionary process in people's mind | 0:48:41 | 0:48:44 | |
as well as with regard to our knowledge about the phenomenon. | 0:48:44 | 0:48:48 | |
What is happening is that we as human beings are | 0:48:48 | 0:48:52 | |
bringing about a climatic change. | 0:48:52 | 0:48:56 | |
We are emitting things into the atmosphere now with a rate | 0:48:56 | 0:48:59 | |
that will change the climate more rapidly | 0:48:59 | 0:49:03 | |
than it has changed naturally during the last hundred thousands of years. | 0:49:03 | 0:49:07 | |
# I've got the brains | 0:49:09 | 0:49:10 | |
# You've got the looks | 0:49:10 | 0:49:13 | |
# Let's make lots of money | 0:49:13 | 0:49:15 | |
# You've got the brawn... # | 0:49:16 | 0:49:18 | |
But the apocalyptic warnings fell on deaf ears. | 0:49:18 | 0:49:23 | |
The 1980s were the boom years of optimism and progress, | 0:49:27 | 0:49:32 | |
and consumerism was running wild. | 0:49:32 | 0:49:34 | |
The idea that our success and progress could be harming | 0:49:38 | 0:49:41 | |
the planet wasn't something that people really wanted to hear. | 0:49:41 | 0:49:45 | |
After all, if global warming was making Britain | 0:49:45 | 0:49:48 | |
a few degrees warmer, what was there to worry about? | 0:49:48 | 0:49:51 | |
But as the years passed, | 0:49:56 | 0:49:57 | |
the complexities of climate change started to unfold. | 0:49:57 | 0:50:01 | |
Scientists began to think that a few degrees of warming | 0:50:03 | 0:50:06 | |
in some parts of the world could trigger global chaos. | 0:50:06 | 0:50:11 | |
This is the cleanest place on Earth, | 0:50:18 | 0:50:20 | |
the Clean Air Facility at the South Pole, | 0:50:20 | 0:50:23 | |
where the impact of human civilisation is measured - | 0:50:23 | 0:50:27 | |
the Earth's environmental oracle. | 0:50:27 | 0:50:29 | |
CFCs... | 0:50:31 | 0:50:32 | |
It was in Antarctica that the hole in the ozone layer was first spotted. | 0:50:33 | 0:50:37 | |
It is here the increase in carbon dioxide levels is measured, | 0:50:40 | 0:50:44 | |
and it is here that scientists are prophesying doomsday... | 0:50:44 | 0:50:48 | |
-35.5. | 0:50:48 | 0:50:49 | |
..global warming at the end of the Earth. | 0:50:49 | 0:50:53 | |
For it has been predicted that, if temperatures rise, | 0:50:55 | 0:50:58 | |
part of the vast ice sheet that covers Antarctica | 0:50:58 | 0:51:02 | |
might suddenly collapse. | 0:51:02 | 0:51:04 | |
And Antarctica is warming up. | 0:51:06 | 0:51:07 | |
# We're all going on a summer holiday... # | 0:51:11 | 0:51:15 | |
We're heading for Leonie Island over there. | 0:51:16 | 0:51:19 | |
It's a small island about four kilometres square | 0:51:19 | 0:51:21 | |
with a thin ribbon of vegetation along one side of it. | 0:51:21 | 0:51:23 | |
Head of terrestrial life sciences for British Antarctic Survey, | 0:51:33 | 0:51:37 | |
David Walton has been measuring climate change, | 0:51:37 | 0:51:40 | |
and on Leonie Island the evidence is irrefutable. | 0:51:40 | 0:51:43 | |
The desert that is Antarctica is blooming. | 0:51:48 | 0:51:51 | |
There's a tremendous amount of Colobanthus up here, | 0:51:51 | 0:51:54 | |
growing amongst the mosses. | 0:51:54 | 0:51:56 | |
It looks really good, lots of vegetation. | 0:51:56 | 0:51:58 | |
Lots of grass all along here, colonising all the bare ground, | 0:52:00 | 0:52:03 | |
and in the cracks up amongst the rocks. | 0:52:03 | 0:52:05 | |
'We've been mapping these plants for some time.' | 0:52:05 | 0:52:08 | |
Over 25 years, we've noticed a tremendous increase | 0:52:08 | 0:52:11 | |
in their spread, into areas they'd previously never colonised, | 0:52:11 | 0:52:14 | |
and this paralleled measurements that we were making which showed | 0:52:14 | 0:52:18 | |
that the mean temperature was going up year on year. | 0:52:18 | 0:52:21 | |
The records show that, in the last 50 years, | 0:52:21 | 0:52:24 | |
the Antarctic Peninsula has warmed by an unprecedented 2 degrees Celsius. | 0:52:24 | 0:52:29 | |
The Antarctica team feared this increase in temperature might | 0:52:36 | 0:52:40 | |
cause the ice sheet to collapse. | 0:52:40 | 0:52:42 | |
And if that happened, | 0:52:46 | 0:52:48 | |
they predicted global sea levels could | 0:52:48 | 0:52:50 | |
rise by as much as three metres, | 0:52:50 | 0:52:52 | |
swamping coastal towns and cities across the world. | 0:52:52 | 0:52:55 | |
And there was evidence it was already beginning to happen. | 0:53:06 | 0:53:09 | |
..have discovered that an ice shelf which used to be | 0:53:11 | 0:53:14 | |
the size of East Anglia has completely collapsed... | 0:53:14 | 0:53:18 | |
Since that programme was made, a further 2,500 cubic kilometres | 0:53:18 | 0:53:23 | |
of the polar ice sheets have melted into the sea. | 0:53:23 | 0:53:25 | |
That's more fresh water than could flow over Niagara Falls in 40 years. | 0:53:30 | 0:53:35 | |
But scientists realised that rising sea levels might only be | 0:53:46 | 0:53:50 | |
half the problem. | 0:53:50 | 0:53:51 | |
Fresh meltwater flooding into the oceans could also disrupt | 0:53:51 | 0:53:55 | |
a natural cycle we all depend upon... | 0:53:55 | 0:53:58 | |
..the Gulf Stream. | 0:54:04 | 0:54:06 | |
Britain bathes in its heat. | 0:54:06 | 0:54:07 | |
It begins south of the Equator, absorbs heat from the tropics | 0:54:09 | 0:54:12 | |
and delivers it to our shores. | 0:54:12 | 0:54:14 | |
It means we can swim in the sea at the same latitude | 0:54:14 | 0:54:18 | |
that Canada has polar bears. | 0:54:18 | 0:54:20 | |
But the most important thing about it happens further north. | 0:54:22 | 0:54:27 | |
It sinks. | 0:54:27 | 0:54:28 | |
This sinking is caused by the salt in the water. | 0:54:28 | 0:54:31 | |
The dense salty water plunges to the bottom and is pushed back south, | 0:54:32 | 0:54:37 | |
where it warms and rises, and the whole cycle begins again. | 0:54:37 | 0:54:40 | |
For thousands of years, the current has circulated without interruption. | 0:54:53 | 0:54:58 | |
But then a fisheries researcher working off the coast of Scotland | 0:54:58 | 0:55:03 | |
discovered something alarming. | 0:55:03 | 0:55:05 | |
This graph shows the salinity, or saltiness, of the bottom water. | 0:55:07 | 0:55:12 | |
It's the saltiness from 1900 to the present day. | 0:55:12 | 0:55:15 | |
Until the 1970s, the salinity had been almost constant, | 0:55:18 | 0:55:22 | |
but then it began to fall. | 0:55:22 | 0:55:23 | |
After the late '70s, we began to see a freshening of the bottom water, | 0:55:28 | 0:55:32 | |
so much so that we began to doubt our own results. | 0:55:32 | 0:55:35 | |
We took further samples, | 0:55:35 | 0:55:37 | |
we checked with other countries who were sampling the same water, | 0:55:37 | 0:55:40 | |
until eventually we became convinced that | 0:55:40 | 0:55:42 | |
this change was actually happening. | 0:55:42 | 0:55:45 | |
Fresh water flooding down from the melting Arctic ice caps was | 0:55:51 | 0:55:55 | |
threatening to disrupt the Gulf Stream's cycle. | 0:55:55 | 0:55:57 | |
And scientists warned that if the Gulf Stream shuts down... | 0:56:01 | 0:56:06 | |
..global weather patterns would be thrown into turmoil. | 0:56:08 | 0:56:11 | |
Europe would be plunged into a bitter winter | 0:56:15 | 0:56:17 | |
that could last 100 years. | 0:56:17 | 0:56:19 | |
The lush forest of the Amazon would wither and die. | 0:56:23 | 0:56:27 | |
The life-giving monsoon rains would fail, | 0:56:29 | 0:56:32 | |
leaving hundreds of millions of people | 0:56:32 | 0:56:34 | |
to face drought and starvation. | 0:56:34 | 0:56:36 | |
It could be the end of the world as we know it. | 0:56:42 | 0:56:45 | |
Right now, many scientists regard climate change | 0:56:50 | 0:56:52 | |
as the single greatest threat to our survival. | 0:56:52 | 0:56:57 | |
It's not as dramatic as a supervolcano | 0:56:57 | 0:56:59 | |
or as immediate as a killer virus, | 0:56:59 | 0:57:01 | |
but the consequences of climate change could be just as apocalyptic. | 0:57:01 | 0:57:05 | |
Life on Earth has been wiped out in the past, | 0:57:07 | 0:57:09 | |
so we know it could happen again. | 0:57:09 | 0:57:11 | |
All we can do is hope that, this time, we'll have enough warning. | 0:57:14 | 0:57:17 | |
Over the last 50 years, science has done everything it can to try | 0:57:21 | 0:57:26 | |
and keep one step ahead of Armageddon - | 0:57:26 | 0:57:29 | |
to predict, to prevent or simply to dispel every likely threat. | 0:57:29 | 0:57:33 | |
But the facts still remain. | 0:57:33 | 0:57:35 | |
However advanced our science, however hard we try and prophesise, | 0:57:35 | 0:57:40 | |
we can never be sure what might be lurking around the corner. | 0:57:40 | 0:57:43 | |
# It's the end of the world as we know it | 0:57:48 | 0:57:52 | |
# It's the end of the world as we know it | 0:57:52 | 0:57:56 | |
# And I feel fine | 0:57:56 | 0:57:59 | |
# It's the end of the world as we know it | 0:58:02 | 0:58:05 | |
# It's the end of the world as we know it | 0:58:06 | 0:58:11 | |
# It's the end of the world as we know it | 0:58:11 | 0:58:15 | |
# I feel fine... # | 0:58:15 | 0:58:17 | |
Subtitles by Red Bee Media Ltd | 0:58:18 | 0:58:20 | |
E-mail [email protected] | 0:58:20 | 0:58:22 |