Translator: Nastya Lichman Reviewer: Queenie Lee
66 million years ago,
a mountain-sized asteroid
traveling 10 times faster than a bullet from an assault rifle
slammed into the shallow seas
covering what is now the Yucatan Peninsula of Mexico.
The immense energy of that impact hurled rocks as far north as Canada,
and it vaporized the asteroid,
part of Mexico and part of the shallow sea.
Well, this fireball of vaporized rock and water
rose far above the earth's atmosphere
and spread over the planet.
As it cooled,
molten drops of rock about the size of a grain of sand solidified
into an immense swarm of shooting stars.
The shooting stars re-entered the earth's atmosphere
and heated the upper atmosphere to a thousand degrees Fahrenheit.
Standing at the ground,
the dinosaurs saw the blue sky become a sheet of red-hot lava.
The scientific artist David Hardy
imagines the fate of the dinosaurs in this painting.
They broiled to death under the glowing skies.
The energy in the sky is like that in the glow bar in an electric oven.
If you're dying to experience what the the dinosaurs did when they died,
turn your oven on broil and hop in.
(Laughter)
The glowing skies started everything on fire.
Great clouds of smoke
rose into the upper atmosphere and blocked the sun
so that no sunlight reached the ground.
It became cold and dark.
Photosynthesis stopped,
and plants and animals, in the ocean or on the land,
either starved or froze to death.
The dinosaurs didn't do anything wrong that caused their death.
It was just fate that an asteroid hit the earth
and killed 70% of the species that we know of on the planet.
Unfortunately, in our lifetimes,
we may experience the same fate as the dinosaurs.
But I'm not talking about another asteroid collision,
I'm talking about a nuclear war.
A nuclear war would have many of the same phenomena
that the dinosaurs experienced.
But this time it absolutely would be our fault.
Fortunately, there are things that we can do to prevent this from happening.
If you live in a city that has a military base,
there's a missile that's aimed at you right now.
If you live in a city that has an important industry,
a major university, a large airport,
an oil refinery or oil storage facilities,
there's a hydrogen bomb that's aimed at you right now.
We live in a perilous era.
There are 15,000 nuclear weapons on the planet.
And the 9 nuclear weapon states are in conflict with each other.
The United States and North Korea,
NATO and Russia, India and Pakistan.
We're just one misunderstanding,
one mistake, or one fanatic politician away from a nuclear conflict.
In World War II, fleets of hundreds or even a thousand airplanes
were used to bomb a single city.
But with the invention of the atomic bomb,
only one airplane and one bomb was needed.
The Enola Gay carried one atomic bomb
with the power of 15,000 tons of TNT.
And when it dropped that bomb on Hiroshima, Japan,
a hundred thousand people died.
Over time, even more powerful bombs were built.
Hydrogen bombs.
This 1960s airplane carried five hydrogen bombs,
the red and white things there,
and had the power of 500 Hiroshima bombs.
And of course the United States and Russia don't just use airplanes.
They have intercontinental ballistic missiles with hydrogen bombs on them,
and they have nuclear submarines with missiles.
A single Trident missile submarine
can carry a hundred hydrogen bombs
with the explosive power of a 1,000 Hiroshima bombs.
Knowing the power of the bombs and their targets,
we can understand the destructiveness and loss of life that might occur
if these were ever used.
Let us imagine, for example, that the United States
attacks Pyongyang, North Korea, the capital,
with the smallest bomb carried on a Trident missile submarine.
500,000 people - about the population of Sacramento or Baltimore - would die.
Nuclear weapons kill people in four different ways.
In this orange circle, there's a shock-wave so powerful
that it knocks down concrete buildings and kills everyone within that zone.
In the red circle,
there's radiation that's released from the atomic bomb as it fissions.
The radiation would kill 50 to 90% of the North Koreans,
over the next few weeks.
In this green circle, the shock-wave continues out
with enough power to knock down residential buildings.
And in this yellow circle, six miles in diameter,
there's a blast of light so bright
that if your skin was exposed,
you'd get third-degree burns, which can be fatal,
and flammable things like leaves, newspapers and your clothes
would burst into flames.
And of course, if we attack North Korea,
they're likely to attack us back.
If they use the same size weapon that we used,
and they've already tested one like this,
they could kill 150,000 people in this 6-mile diameter circle in Denver.
And these terrifying scenarios I'm talking about
are just each if side uses one nuclear weapon.
But Russia and the United States each have 4,000 strategic nuclear weapons.
That's enough to attack each city with more than 100,000 people,
in each country, with 10 atomic bombs.
In a war like that, 400 million people would probably die on the planet,
in China, in Russia, in Europe and in the United States.
But wait, that's not all.
(Laughter)
I've just been talking about the damage near ground zero.
That's all the military considers in their war plans.
But there will be collateral effects.
Remember the dinosaurs: it was the burning forests
that killed three quarters of the species we know about on the planet.
And the same would happen after a nuclear war;
cities would catch on fire and burn.
It's this damage,
the damage the military doesn't even consider,
the damage that's just thought of as an accident,
that might destroy human civilization.
Even a war between India and Pakistan,
two of the smallest nuclear powers,
with only a few hundred weapons of about the size of the Hiroshima bomb.
We might die as unintended consequences
that the Indian and Pakistani generals never even gave a thought about.
My colleagues Luke Oman and Alan Robock calculated the spread of smoke
after a war between India and Pakistan.
It only takes about two weeks for the smoke to cover the entire Earth.
And it would rise to altitudes between 20 and 50 miles above the surface.
At those altitudes, it never rains.
The smoke would stay there for years.
This farmer, maybe in Europe or in the United States,
but many thousands of miles from Pakistan and India,
is looking at the smoky sky above him and down at the crops
that have died in his field from lack of light and cold temperatures.
It's estimated that in a war between India and Pakistan,
we would lose 10 to 40% of the yields of corn, wheat and rice
for years afterward because of the bad weather.
The entire world only has enough food to feed the population for 60 days
unless agriculture produces more food.
Ira Helfand, a member of the Nobel Peace Prize winning
International Physicians for the Prevention of Nuclear War,
has estimated that one to two billion people would die
after a war between India and Pakistan, of starvation.
And after a full-scale nuclear war,
temperatures would plunge below ice age conditions.
We would be in a nuclear winter.
No crops would grow.
It is estimated that 90% of the population of the planet
would starve to death, and civilization would be destroyed.
And no one would be safe.
Not those in countries with no nuclear weapons,
not those in countries that didn't participate in war,
and not those on the other side of the planet
from where the explosions occurred.
No one would be safe.
I bet you're not getting a warm and fuzzy feeling out of this talk.
(Laughter)
But we don't have to just keep plodding on like we have been,
walking toward disaster.
We can do things to stop a nuclear war
and prevent global starvation and the end of human civilization.
In the 1980s, politicians recognized the dangers of a nuclear conflict
and did things about it.
Nowadays, politicians don't seem to understand the dangers of these wars.
And the younger generations hardly give nuclear conflict a thought.
We baby-boomers had this drummed into us.
In grade school, we were taught "duck and cover" drills
and how to get under our desk
in a hopeless attempt to avoid a nuclear explosion.
(Laughter)
In middle school, our mothers told us,
"You can't drink your milk anymore,
because the 500 atmospheric nuclear weapons test
had poisoned the earth with radiation.
And the popular culture was dominated by radioactive mutants,
such as Godzilla, which is a Japanese nightmare from Nagasaki and Hiroshima.
In the 1980s,
I worked with Richard Turco, Carl Sagan, Russian scientist and others
to tell Mikhail Gorbachev and Ronald Reagan
about the dangers of a nuclear war.
We told him a nuclear war would cause a nuclear winter
that could end civilization as we know it.
And they listened.
(Applause)
Ronald Reagan said, "A great many reputable scientists are telling us
that such a war could just end up in no victory for anyone
because we would wipe out the earth as we know it.
And Mikhail Gorbachev said, "Models made by Russian and American scientists
showed that a nuclear war would result in a nuclear winter
that would be extremely destructive to all life on earth;
the knowledge of that was a great stimulus to us,
to people of honor and morality,
to act in that situation.
In September of 2017, the United Nations passed a resolution
banning nuclear weapons like landmines,
chemical and biological weapons have been banned.
Unfortunately, the nuclear weapons states want to ignore that ban
and just plod on like they have been.
It's up to us to wake them up
before they sleepwalk into a nuclear disaster.
What can you do about this?
Talk to your political representatives.
Tell them you'd like the Department of Defense
to report to us on what would happen after a nuclear war.
They did this in the 1980s.
How many people would die in Korea
if we attack them with nuclear weapons?
How many people would die in Russia,
China, South Korea and Japan,
the countries that surround North Korea?
What will happen if like every other war we have ever fought,
it does not go as planned and expands beyond North Korea?
And you should ask your politicians to stop "launch on warning."
In launch on warning,
the American president can launch nuclear-armed missiles within minutes
without consulting anyone, using the nuclear football,
which is carried everywhere the president goes by a military officer.
In 1968, the United States and 190 other countries
signed the treaty to prevent a proliferation of nuclear weapons.
In that treaty,
we promised to build our nuclear arsenals down to zero as soon as we could.
We need to keep that promise.
All of our lives may depend on it.
(Applause)
Thank you.