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X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:0

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Mhm, Mhm,

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and

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you can

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Yeah,

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bye.
Coral reefs are the jewels of the

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ocean communities of organisms

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as rich and diverse as any above or below the
surface of the planet.

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For at least 400 million years, reefs in one
form or another have circled the equator with

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an exquisite living necklace.

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But despite their apparent permanence, reef
building corals are remarkably fussy.

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They need the ocean to be not too cold and not
too hot.

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They like it just right much below 20 °C,

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and coral reefs fail to develop much above 30
degrees, and whole reef

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systems like this will start to die.

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This narrow thermal tolerance means that coral
reefs are sitting in the biological front line

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of a changing world.

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In July 1998 an Australian customs vessel set
course for a remote spot far off the north

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west Australian coast.

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Destination was Scott Reef.
A day and a night steam away in the tropical

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Indian Ocean,

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lying halfway between Indonesia and the
Kimberley coast.

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Scott Reef is a difficult place to reach.

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Hitching a ride with customs was a team of
biologists from the Australian Institute of

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Marine Science.

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They\'ve been coming out to Scott Reef since
1994 as part of a regular coral monitoring

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programme.
Surveys by the team had shown Scott to have

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some of the highest coral cover of any reef in
Australia, indeed,

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the world.
But by the middle of 1998 all that had changed.

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The survey team found a reef that was dead and
dying.

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Most of the few corals that were still alive
were bleached white as ghosts.

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For the rest, it was too late.

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Their bear skeletons were already smothered by
algae.

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Scott Reef was not alone.

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1998 Designated International Year of the
Oceans turned out to be the year in which

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marine biologists witnessed the biggest coral
die off of modern times.

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In 1998 the richest coral reefs of the Pacific
and the Indian Ocean have

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undergone a catastrophic mass mortality.

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Most of the Philippines, Indonesia, Maldives,
Seychelles, for instance seems that more than

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90% or up to 90% or more of the corals have
died.

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The branching corals, the ones that are rapidly
growing that rapidly recolonize new areas,

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have been been pretty much wiped out.
I mean,

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if suddenly you see your, um, 500 year old
coral generation dying off

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suddenly in this year, and they haven\'t in the
last 500 years.

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That does tend to suggest that this is a a very
severe event.

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Coral bleaching is a symptom.

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I it it\'s just one symptom on coral reefs, and
I think we have to start looking at coral reefs

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as being a a sentinel, something that is out
there giving us the signal that there there are

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changes in the marine environment.

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When talk of global warming first surfaced in
the late 19 seventies,

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there were dire predictions for Coral Island
nations.

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The concern was with melting ice caps and
rising sea levels.

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The low lying Maldives was singled out as
especially vulnerable to being washed away.

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Sometime next century, few people expected that
corals

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themselves were threatened, that the greatest
risk would come from rising sea temperatures

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and that it would come so soon in 1998.

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The common link everywhere that corals had
bleached was that sea temperatures were the

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warmest on record.

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Many scientists are now warning that a shift in
climate will render sites of healthy coral

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reefs like this increasingly rare in our
lifetime.

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One of those most convinced lives far from the
tropics here in New York State.

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But the outspoken doctor Tom Garre has an
impressive pedigree.

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Well, my grandfather was a science photographer
at Life magazine,

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and in 1950 51 he filmed up and down the entire
barrier reef he filmed underwater.

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There we are.
It\'s, uh I can\'t even go through these all but

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the Mickle mass key.
Um there, uh, Green Island

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Cairns.
Among these pictures are are really the first

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underwater photographs of the Barrier Reef

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as a science photographer, Fritz Gore\'s travels
took his young family around the world.

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Soon Tom Garreau senior became entranced with
corals as well.

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My father was the first scientist who used
scuba diving to record the Ecology reef

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organisms.
And my mother and my father did a lot of the

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basic work on on the growth rate, the
physiology of of corals.

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My father knew more about res than anyone I
think was ever lived.

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And, um, what I found was that there was a lot
of stuff that I knew just simply had learned

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by osmosis.
If you will as a child that, um,

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other people were not aware of un.
Unfortunately, my father died very young of

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cancer.
He died before he could write down most of what

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he knew.
Um, and it\'s just it was important to continue

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that and finish up some of the stuff that was
left undone.

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No carrying on the family tradition,

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Tom Garreau travels the tropics researching
corals and documenting the status of reefs.

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But to make sense of what you see on a reef,
you have to understand what kind of animals

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corals really are.

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Corals are animals in the sense that they, uh,
catch your food.

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They catch little swimming.
So plankton,

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animals that are a millimetre or so in size for
the most part,

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and they eat them.
And so you know, they\'re They\'re perfectly good

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animals in that sense.
But unlike most animals,

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they\'re they\'re not mobile.

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They sit in one spot.
They they there\'s about a millimetre or so of

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tissue.
It overlies a massive skeleton so a coral can\'t

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chase after its prey.
It can\'t run away from from stressful

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conditions.
It simply sits there and waits for its food to

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be washed to it, and then it catches it with
its tentacles and stuffs it in its mouth.

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Now at the same time, corals, Even though their
animals are almost half plants,

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they contain symbiotic algae, microscopic
single celled algae that live within their

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tissues.
So they\'re they\'re entirely within their

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interior, and it\'s almost as if we had little
plants growing inside of our skin.

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And we could simply, you know, stand out in the
sunlight and grow.

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You know our own food.
Internally,

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coral polyps literally farm algae within their
flesh.

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In this symbiotic relationship, the resident
algae, a type of dinoflagellate called Zola,

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are given a sturdy home, guaranteed sunlight
and a ready supply of carbon dioxide from the

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host pollen.
By harnessing the energy of the sun through

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photosynthesis, the Zola convert the carbon
dioxide into sugars and amino acids.

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About 90% of this is passed to the coral host.

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This is how corals get the wherewithal to build
their limestone skeletons day after day,

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year after year, millennia after millennia.

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Now, if corals are stressed for any reason,
what breaks down is the symbiotic association

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with the algae, and the algae are lost long
before the coral itself dies.

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Corals can\'t run away from stress all they can
do is lose their algae or die,

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and when they lose the algae, they, they then
become what is known as bleached.

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Now, the reason that it\'s called that is that
the algae give the corals almost all of their

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colour.
It can be browns, greens, yellows,

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blues, reds, tremendous range of colours.
Almost all of that colour comes from the little

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lounge, because when coral loses its algae, it
loses its colour,

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and at the same time it loses much of its food
supply.

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And the result is we coral, even if it\'s still
alive, even if the coral animal is still in

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good condition that it\'s starving.

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Corals can recover from bleaching, but only if
conditions return to normal before too much

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damage is done.
If not, they die.

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The phenomenon was first noticed by a scientist
almost a century ago,

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when corals trapped by extreme low tides turned
white after baking under the hot summer sun.

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Stress, like a sudden change in salinity, a
snap cooling or an oil spill can cause the same

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result.

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But for most of this century, all these
observed bleaching events were on small,

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localised scales.

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No one paid them much attention.

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The first signs of change were noticed in the
marine reserves of the Florida Keys

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Sanctuary Superintendent Billy Cosey watched
with interest,

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and we started observing coral bleaching in the
seventies.

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But throughout the decade of the eighties we
saw the most severe bleaching,

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and it occurs on the heels of some phenomenon
that sets up slick,

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calm water conditions.

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You go out and and the water is like a mirror.

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At that same time, the water starts getting
very warm,

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and in August and September of 1983 we had the
reefs in the lower keys.

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Bleach severely.
In fact, it looked like a snowfall on top of

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some of the shallow reefs san.

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Then, four years later, in 1987 Superintendent
Kozi saw the whole thing happening again.

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And in September we were getting reports all
over the Caribbean that the reefs were

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bleaching and it was really alarming to us
because it was so widespread.

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And then we started getting reports from the
Indo West Pacific and from Australia and all

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over the the western part of the Pacific that
the reefs were starting to bleach,

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and so then we went from a local phenomenon to
a regional phenomenon to a global event.

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Both 1983 and 1987 were strong El Nino years.

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The climatic effects were felt worldwide,
though there was obviously some

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link.
By the 19 nineties, mass coral bleaching was

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being reported on a nearly annual basis from
the Red Sea to Bermuda,

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including reefs far from populated areas.

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This was French Polynesia.
In 1994 Of the many

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theorised causes, from viruses to the hole in
the ozone layer,

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only one seem to explain it temperature.

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Since 1982 NOA, the US Oceanographic and
Atmospheric Administration has been recording

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sea surface temperatures from space.

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These earth observing satellites measure in the
infrared recording,

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the heat rising off the ocean during the night.

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Back on Earth, the data is beamed to the NOAA
Science Centre just outside Washington,

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to the Office of Al Strong.

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What\'s interesting?
What we found out, sort of by luck was that

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corals are very, uh, they\'re very much adapted,
obviously to the normal conditions,

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and the big one is temperature.

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Working with field data from Tom Garreau and
others, Al Strong has developed an interactive

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coral bleaching hotspot site Each chart plots
only where sea surface temperatures have risen

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above the average 15 year monthly maximum.

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Yellow signifies a hotspot where temperature is
one degree higher than normal.

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If the temperature exceeds the normal range
that they\'re adapted to by just one °C,

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then we\'ve seen bleaching happen in the corals.
And almost universally,

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this technique has worked to give sort of an
early warning or an indication that something

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is going on.
The temperatures are high.

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It\'s almost scary because it\'s it\'s so
responsible.

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In 1997 the NOAA satellite began to pick up the
tell tale temperature signals of a strong El

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Nino forming in the waters of Peru.

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For reasons which are still unclear in an El
Nino year,

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circulation patterns in the entire Pacific
Ocean change.

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Because of this, this El Nino Southern
oscillation can have effects far beyond the

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Eastern Pacific.

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From late 1997 Armstrong began to notice that
sea temperatures were becoming unseasonably

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warm in the Western Pacific as well.

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Hotspot anomalies started appearing along the
Great Barrier Reef.

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There\'s some hotspots that are just starting to
show up.

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Fiji\'s got it and Caledonia, it\'s all spreading
around there By

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early 1998 the corals began to respond.

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This was the scene at Heron Island on the
southern Great Barrier Reef.

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During the peak of the event, over 100 species
bleached and temperatures more than five

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degrees above maximum were recorded in the reef
flat at low tide.

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Marine Park Authority staff took to the air to
gauge the extent of the damage.

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At first, the bleaching was thought to have
been caused by heavy summer rains in the

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Townsville region.
But the aerial surveys confirmed extensive

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bleaching along the entire inner region of the
Great Barrier Reef,

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1000 kilometres from Heron Island north to
Cooktown.

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While many of the outer reefs escaped entirely.

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Mortality rates around some of the inshore
islands exceeded 90%.

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But the Pacific got off lightly compared with
what happened in the Indian Ocean.

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This is 1998.

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The way the Noah satellite saw it, what
happened in 1998 was that there was incredible

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hot water that stretched across the entire
Indian Ocean all the way from Mozambique to

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western Australia and Indonesia, and the whole
South Indian Ocean bleached very heavily.

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It stayed excessively hot for about 4 to 5
months.

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Not only did the corals bleach, but most of
them died.

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And in Seychelles, where I I\'d been filming the
coral reefs,

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working with the Marine Park Authority in
Seychelles in order to document reef condition

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in early 1997 I found beautiful reefs in
Seychelles.

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I mean, some of the loveliest I\'ve seen
anywhere.

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And there were areas that were were, you know,
95% or more beautiful life,

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healthy coral.
By May of 1998 80% of those calls were

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dead.

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By December of 19, 98/90 percent were dead.

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The disaster was that the best coral reefs were
the worst affected,

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and the the reefs that really were the most
beautiful of all.

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In some cases, more than 99.9% of all the
corals were dead.

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Every branch and coral was wiped out.
You could find us one or two partly alive.

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Head corals here or there.
And that was it

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5000 kilometres away.

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Aim scientists were about to discover the same
fate that struck Scott Reed,

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50 maidens, 25.

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What are you doing?
Came

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satellite records showed that the hot water had
sat on Scott Reef for nearly two months.

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By the time the team arrived, the branching
corals were dead and had already been colonised

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by fine filamentous algae.

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Devastation was most complete in the shallows.

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You could swim for hundreds of metres before
finding a single living colony.

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I didn\'t expect to find the amount that we have.
Many corals that live on the top sort of six

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metres of the reef just don\'t exist there
anymore.

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They\'re gone.
They\'ve all died and I didn\'t expect to find

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these these huge corals that are hundreds of
years old,

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either dead or in the process of dying.

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Previous bleaching in other parts of the world,
reefs have actually been able to bleach and

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then recover.
And Scott Reef, Um, as you\'ve seen just hasn\'t

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at all.
It\'s been knocked down in the

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lagoon.
Whole fields of corals were totally cooked.

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The mortality lessened with depth but extended
below 30 metres to the base of the reef.

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We\'re talking about an event that made the
corals bleach as deep as we could go,

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which was 30 metres.
So you\'re looking at like 100 and 10 ft of

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water, and we went down there and everything is
bleached.

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So it\'s a huge volume of water you\'re talking
about that\'s moved through.

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It\'s not just the the situation where the
surface layer has has warmed up

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on video.
The dead coral appears dark, those still alive

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pale.
Some bleached soft corals turn bright yellow

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instead of white before slumping off their
pedestals and dissolving

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on some of the tougher species.
Patches of tissue protected from direct

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sunlight remained unbleached.

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This shading effect is a confusing feature of
bleaching.

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If temperature is the cause, why does light
have an effect?

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Mhm.
In a few places near deep channels,

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Scott\'s ubiquitous sea snakes could hunt
through small patches of surviving coral.

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But for the most part, the reef was devastated.

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As the year progressed, the hot water swept
northwards with the summer sun.

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The Maldives suffered heavy bleaching similar
to Scott.

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So did Sri Lanka, and the latch wood es
bleaching swept the East Africa

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coast, the Persian Gulf and the southern Red
Sea.

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The hot water that had sat on Scott Reef surged
through Indonesia,

25:11.619 --> 25:16.989
eventually affecting the Philippines, Vietnam,
Palau, Okinawa,

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Taiwan, almost all of Southeast Asia

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in the Western Hemisphere.

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Extensive bleaching was reported from the
Galapagos, Costa Rica,

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the Bahamas, Florida and the Cayman Islands in
Belize.

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OK, by the end of 1998 some 60 countries and

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island nations had been affected.

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It took the world by surprise.

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Surely corals are tougher than this.

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After all, reefs have lived through all the
upheavals to life on Earth.

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For the best part of 400 million years, they
must have an escape plan for a bit of warm

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water.

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Here on the Great Barrier Reef, corals cast
their young adrift on a couple of fun filled

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nights in early summer.

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This is how coral reefs have beaten the
climatic odds for millennia.

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Released to the whims of the ocean currents,
the next generation can drift to more

27:01.819 --> 27:08.050
favourable locations, colonise new oceans and
escape fluctuating sea levels.

27:16.319 --> 27:19.180
This is a ritual affected in ancient seas.

27:20.729 --> 27:26.619
Sperm from any one of over 100 species have the
uncanny ability to pair up with the matching

27:26.630 --> 27:29.880
eggs and then battle it out for fertilisation.

27:33.859 --> 27:38.060
But from the moment a coral is born, it\'s at
the mercy of the elements.

27:41.270 --> 27:45.160
Coral lava cruised the Pacific Atlantic and
Indian oceans,

27:45.420 --> 27:50.359
hoping the sea will carry them somewhere with
the perfect combination of light and warmth,

27:50.489 --> 27:52.119
depth and cleanliness

27:58.770 --> 28:02.910
for aeons.
This is how these mighty mountains of life have

28:02.920 --> 28:05.640
risen to meet the sun at the surface of the sea.

28:13.180 --> 28:19.719
10,000 years ago, this was a dry, tree covered
hill on the Australian mainland being drowned

28:19.729 --> 28:20.880
by a rising ocean.

28:24.689 --> 28:30.699
Now it\'s one tree reef 100 kilometres from
shore at the southern end of the Great Barrier

28:30.709 --> 28:35.760
Reef.
Now look at that.

28:35.770 --> 28:39.089
That\'s interesting, isn\'t it?
Uh, this is still bleached.

28:39.130 --> 28:41.540
How many months after the bleaching event is it?
Four months,

28:41.550 --> 28:45.619
four months?
See the the bleached area up here,

28:45.630 --> 28:49.099
where the coral is still living.
But it hasn\'t gotten any 1000 telly and then

28:49.750 --> 28:52.040
all around the side, sort of a shade effect.

28:53.079 --> 28:58.810
And the pigmentation Marine biologist Ross
Jones and O Ho Guldberg followed the 1998

28:58.819 --> 29:03.069
bleaching event at the One Tree Island Research
station four months after the

29:07.979 --> 29:12.319
Hoegh Guldberg thinks they\'re getting close to
pinpointing the precise mechanism of bleaching.

29:13.349 --> 29:16.619
And it\'s all got to do with how the zoella
process light.

29:17.479 --> 29:21.250
OK, here\'s the next one.
One of the things that we\'re really interested

29:21.260 --> 29:25.869
in right now is how much of the light that
comes onto a coral is actually harvested by the

29:25.880 --> 29:30.479
zoelle.
At the moment, um, we\'re getting estimates of

29:30.489 --> 29:36.630
about 50% of what actually falls on.
A coral ends up going down the photosynthetic

29:36.640 --> 29:40.859
pathway.
It\'s almost as efficient as higher plants,

29:40.869 --> 29:43.219
which are sort of the ultimate specialists in
this,

29:48.260 --> 29:53.550
just as a tree in a forest needs to convert
sunlight as efficiently as possible to

29:53.560 --> 29:59.280
outcompete weeds or to survive the shading of
neighbours, so does a coral jostling for

29:59.290 --> 30:05.089
position on a reef or struggling to suck energy
out of the feeble sunlight at depth.

30:07.599 --> 30:09.739
But this efficiency comes at a cost.

30:10.599 --> 30:13.989
Corals push their biochemical pathways to the
limit.

30:34.900 --> 30:36.109
You sealed this properly, right?

30:36.510 --> 30:38.420
OK, it\'s $13,000 worth.
All right.

30:45.300 --> 30:48.790
Underwater science these days is getting quite
sophisticated.

30:50.180 --> 30:53.479
This lab in a box is called a Pam Fluorometer.

30:55.050 --> 31:00.079
Now the pan fleeter in literally a second tells
you of the light captured.

31:00.089 --> 31:04.510
How much of that light is actually being
transferred into photochemical energy?

31:04.520 --> 31:08.729
That\'s actually the energy that ultimately ends
up in sugars and photosynthetic products.

31:10.359 --> 31:15.979
Now that turns out to be very interesting
because one of the first impacts of thermal

31:15.989 --> 31:21.500
bleaching on corals is the fact that the
efficiency with which they process photons

31:21.589 --> 31:23.859
drops off at a phenomenal rate.

31:28.000 --> 31:33.739
The first stage in the photosynthetic process
is the chemical capture of energy from the

31:33.750 --> 31:40.489
photons of sunlight, the so called like
reactions a second

31:40.500 --> 31:45.339
stage of the biochemistry.
The dark reactions involves using this energy

31:45.349 --> 31:51.880
to convert carbon dioxide into sugars, but the
process is temperature

31:51.890 --> 31:56.239
dependent.
If the water gets much above 30 degrees,

31:56.449 --> 32:00.150
the algae seem to lose their capacity to
convert this trapped energy.

32:02.030 --> 32:07.530
It appears that the dark reactions of
photosynthesis are affected first,

32:07.839 --> 32:12.380
and that when you block those suddenly the
light energy that\'s being captured by the

32:12.400 --> 32:18.420
zoelle has nowhere to go.
And energy, as we know,

32:18.430 --> 32:22.020
has to go somewhere and it goes into electron
donation to oxygen.

32:22.069 --> 32:26.859
And it appears that they\'re very nasty forms of
oxygen, and I\'ll say nasty because they do have

32:26.869 --> 32:29.420
very deleterious effects on cells.

32:29.739 --> 32:34.290
This super oxide ends up essentially degrading
the zos andela.

32:35.089 --> 32:39.550
It looks like it poisons the host cell, and
then the host cell is then released from the

32:39.560 --> 32:46.160
coral as long as water temperature remains high,

32:46.579 --> 32:50.640
the very light for coral needs for growth has
become poisonous.

32:51.880 --> 32:56.189
The polyp\'s only hope of survival is to
jettison its own cells,

32:56.199 --> 32:58.300
together with the now toxic algae.

33:04.020 --> 33:08.989
This mechanism explains for the first time why
partially bleached corals often exhibit a

33:09.000 --> 33:14.670
shaded effect where those parts of the coral
exposed to the highest light levels suffer the

33:14.680 --> 33:16.550
most after a thermal stress.

33:19.199 --> 33:24.030
Interesting, it\'s still affected until some
damage going on.

33:29.050 --> 33:34.339
At the moment, we have very good information
saying that temperature is the primary variable.

33:34.640 --> 33:39.900
We also know a lot about what\'s driving those
small increases in temperature and that is

33:39.910 --> 33:44.329
largely connected to the El Nino cycle in the
Pacific and associated weather patterns in

33:44.339 --> 33:49.369
other oceans.
What we don\'t really have, um A a good handle

33:49.380 --> 33:55.369
on and this is really the realm of atmospheric
physics is whether or not the El Nino cycle

33:55.380 --> 33:59.069
that we\'re currently experiencing is unusual.
And, of course,

33:59.079 --> 34:02.750
that links into global climate change and the
implications for,

34:03.040 --> 34:05.270
um, the future of coral reef systems.

34:14.418 --> 34:15.918
This is the great dilemma.

34:16.888 --> 34:22.608
The evidence to link the 1998 coral bleaching
to human induced global warming is strong,

34:23.229 --> 34:24.749
but our records are short.

34:26.100 --> 34:32.239
In such a dynamic world as ours, it\'s difficult
to discriminate an unnatural event from the

34:32.250 --> 34:34.010
long-term rhythms of nature.

34:43.539 --> 34:46.019
Perhaps the corals themselves hold the answer.

34:48.070 --> 34:53.919
After spending a few weeks adrift, it\'s time
for our coral larvae to leave the plankton.

34:56.408 --> 35:01.218
If they\'re lucky, they\'ll pick up the scent of
a nearby reef and head for the bottom.

35:05.520 --> 35:10.379
A coral planular might spend an hour or so
nosing about for the perfect spot.

35:11.260 --> 35:15.149
But once settled, corals are stuck living where
they are.

35:17.820 --> 35:24.600
There They sit silently, recording in their
skeletons just how right or wrong the water

35:24.610 --> 35:26.050
around them makes them feel.

35:40.939 --> 35:45.479
While instrumental climate records only go back
about 100 years at best,

35:45.540 --> 35:51.449
certain corals, like the massive pets, can take
this history of the natural range of climatic

35:51.459 --> 35:53.439
variability back much further.

35:57.560 --> 36:03.300
They can sit in the one spot for up to 1000
years, laying down the local climate history in

36:03.310 --> 36:09.159
their skeleton, much like the way a tree in a
temperate forest lays down summer growth rings.

36:14.090 --> 36:18.330
It\'s a global tropical climate archive that
scientists have been eager to tap

36:21.780 --> 36:27.409
every time an El Nino forms, trade winds drop
in the Eastern Pacific and a tongue of hot

36:27.419 --> 36:29.439
water extends from South America.

36:30.820 --> 36:33.909
One isolated island group sits right in the
middle.

36:34.419 --> 36:35.429
The Galapagos.

36:38.419 --> 36:41.419
The corals here have an interesting story to
tell.

36:43.479 --> 36:46.709
The longest record we have from anywhere is the
Galapagos record,

36:46.719 --> 36:48.939
which nearly goes back 400 years.

36:49.199 --> 36:54.179
That record tells us that the frequencies of El
Ninos have indeed changed through time.

36:57.419 --> 37:01.969
Galapagos is a place where you have penguins
and sea lions and all these other things that

37:01.979 --> 37:03.830
you don\'t expect to see at the equator.

37:06.290 --> 37:10.270
The greatest changes in sea surface temperature
during El Ninos occur there.

37:10.280 --> 37:13.030
Biologically, it has the greatest impact.

37:16.010 --> 37:21.520
In the 16 hundreds, The El Nino frequency was
on the order of anywhere from every six years.

37:21.530 --> 37:27.129
Every 4.6 years you go up to the beginning of
the Industrial Revolution and in fact,

37:27.139 --> 37:33.409
you begin to see a change to about uh uh 4.6
and then finally,

37:33.679 --> 37:40.020
um, you see a change to about 3.3 which is what
lines have been through most of the 20th

37:40.030 --> 37:44.659
century.
And now, uh, we\'re beginning to see a shift to

37:44.669 --> 37:46.250
a 2.5 year interval.

37:49.510 --> 37:55.719
The Galapagos corals seem to be confirming a
shift first predicted in C SIRO climate models.

38:00.010 --> 38:05.939
By doubling the amount of CO2 in the atmosphere,
the computer model doubled the frequency of El

38:06.280 --> 38:07.280
Ninos.

38:15.209 --> 38:20.389
The El Nino of 1997 98 was arguably the
strongest on record.

38:22.479 --> 38:27.820
Much of Southeast Asia was drought stricken and
blanketed in smoke from fires burning out of

38:27.830 --> 38:32.139
control.
The Americas were lashed by storms.

38:37.770 --> 38:40.719
Few of us saw what was going on underwater at
the time.

38:50.389 --> 38:54.840
About the only part of the tropical world to
escape coral bleaching altogether was the

38:54.850 --> 39:01.590
central Pacific.
Here in the Cook Islands, the water tends to

39:01.600 --> 39:05.090
cool in an El Nino and warm during the La Nina.

39:07.590 --> 39:11.179
This makes it the perfect place to cross check
the Galapagos record.

39:15.250 --> 39:20.530
Gerry Wellington and Ove Hoegh Guldberg have
been sampling a 400 year old Pates colony here,

39:20.790 --> 39:22.340
the oldest in Rarotonga.

39:27.989 --> 39:33.000
Well, this about completes two thirds of the uh
length of the core we collected in Rarotonga.

39:34.159 --> 39:39.520
So far, analysis of the Rarotonga core is
completed back to about 1910.

39:40.959 --> 39:47.399
Wellington has confirmed a sudden increase in
water temperature around 1940 also detected

39:47.409 --> 39:48.959
from other cores in the Pacific.

39:54.669 --> 39:59.790
He\'s now looking for evidence of similar
warming episodes and intense El Nino cycles

39:59.800 --> 40:01.969
from the pre industrial past.

40:05.129 --> 40:11.149
If we find that there is no evidence of these
kind of large excursions in in temperature and

40:11.159 --> 40:15.229
severity of El Ninos, then it\'s likely to be
we\'re either one of two things.

40:15.239 --> 40:20.090
We\'re just going through a natural cycle and
that has a very long periodicity.

40:20.320 --> 40:25.790
Or in fact, these are the early warning signs
of of of a pending,

40:25.800 --> 40:30.820
uh, global climate change being driven in
eastern part by,

40:30.830 --> 40:34.310
uh, human.
Forcing the CO2 in the atmosphere

40:38.649 --> 40:44.530
1998 was the hottest year on record, eclipsing
the two previous record holders

40:44.550 --> 40:47.570
1997 and 1995.

40:50.649 --> 40:55.750
Just how much warmer than usual things are
getting is best judged from somewhere cool.

41:04.929 --> 41:10.870
Denro chronologist Ed Cook has found some of
the longest climate records in the sub alpine

41:10.879 --> 41:12.270
trees of Tasmania.

41:14.459 --> 41:19.840
From my own research, I\'ve been able to develop
a record of a warm season,

41:19.870 --> 41:25.000
uh, temperature variations from hue and pines
growing on Mount Reed in western Tasmania.

41:25.620 --> 41:28.399
This record now extends back about 3600 years.

41:32.969 --> 41:34.729
The most recent 30.

41:34.979 --> 41:39.870
Some odd years, uh, of tree growth are
consistent with an unusual warming,

41:39.879 --> 41:43.780
uh, in Tasmania.
That\'s consistent with larger scale warming in

41:43.790 --> 41:50.790
the Southern Hemisphere.
All right, uh, that\'s a good looking

41:50.800 --> 41:54.530
core.
If we go back in time in the treating record,

41:54.540 --> 42:00.459
we have to go back almost 2000 years into the
past to find another period of comparable

42:00.469 --> 42:04.489
warmth.
So while I can\'t say for certain that the most

42:04.500 --> 42:09.530
recent warming is unprecedented, I can say that
it\'s extremely unusual and certainly,

42:09.540 --> 42:14.209
uh uh is of some concern with regards to
possible greenhouse gas forcing.

42:17.850 --> 42:23.030
Whether or not this is human forcing of the
climate, temperatures underwater are clearly on

42:23.040 --> 42:27.570
the rise.
Sea temperatures in the Great Barrier Reef have

42:27.580 --> 42:29.929
risen by a degree in the last century.

42:31.689 --> 42:37.100
They\'re still within the range seen in the 800
year old coral record but are rising faster

42:37.110 --> 42:38.139
than ever before.

42:44.979 --> 42:51.679
In Florida\'s Penny Camp National Park, 300 year
old brain corals were heavily bleached and

42:51.689 --> 42:53.639
suffered substantial mortality.

43:03.580 --> 43:06.840
At Sarang, Pa.
Taif, next to Scott in the Indian Ocean,

43:07.280 --> 43:12.429
a PAA colony aged conservatively at 1000 years
was killed outright,

43:18.610 --> 43:23.219
swimming over dead pates, colonies that have
been silently putting down a centimetre of

43:23.229 --> 43:27.080
limestone\'s skeleton every year since the
Norman invasion of England.

43:27.979 --> 43:32.729
It\'s hard to accept that coral bleaching on
this scale is a frequent natural event.

43:39.260 --> 43:44.360
It\'s our coral reefs that have been so stable
over time that we\'re starting to see changes.

43:44.370 --> 43:50.280
And I think we\'re seeing intensified El Nino
events and I think the this intensification has

43:50.290 --> 43:52.080
to be linked back to global warming.

44:01.520 --> 44:06.020
Only 15,000 years ago, the world was in the
grip of an ice age.

44:09.459 --> 44:15.080
So much water was frozen in the polar regions
that the sea was 200 metres shallower than it

44:15.090 --> 44:22.010
is today.
No one is too sure why, but

44:22.020 --> 44:23.649
the ice age ended suddenly.

44:27.939 --> 44:33.570
Bubbles of ancient atmosphere trapped in ice
cores from Antarctica and Greenland have shown

44:33.580 --> 44:36.879
that the world\'s climate flipped to the current
warm interglacial.

44:37.120 --> 44:38.919
In the space of only 10 years,

44:45.959 --> 44:50.280
there were corals alive at the time, which also
recorded this very rapid change.

44:53.510 --> 44:58.350
Some of them have been discovered among the
vast collections of the American Museum of

44:58.360 --> 44:59.250
Natural History.

45:06.419 --> 45:11.879
Yeah, all the way of the 1350 species of modern
corals.

45:12.060 --> 45:17.419
Half of them live not on tropical reefs but in
the freezing darkness of the deep ocean.

45:22.610 --> 45:27.840
These species are small, mostly solitary, and
lack the symbiotic algae of their shallow water

45:27.850 --> 45:31.580
cousins.
But they, too, are linked to the tropics and

45:31.590 --> 45:35.959
the atmosphere above by the circulation
patterns of the deep ocean.

45:38.449 --> 45:43.689
The reason that we care about the deep ocean
circulation is that it\'s part of a global

45:43.699 --> 45:48.590
system of transporting heat around the planet.
And as almost everyone knows,

45:48.600 --> 45:53.489
the, uh, the equator is warm and the and the
poles are cold and that it sets a temperature

45:53.500 --> 45:58.010
gradient.
Uh, that, um, the ocean and the atmosphere work

45:58.020 --> 46:03.439
to try to erase, essentially by transporting
heat from the equator to the pole.

46:03.610 --> 46:07.669
Uh, you have currents in one particular one.
We call North Atlantic deep water,

46:07.929 --> 46:11.969
and the corals that that we\'ve been looking at
grew in that current in the past.

46:11.979 --> 46:17.429
And so as that current wax and wanes, we can,
uh, use the chemical signatures and the corals

46:17.439 --> 46:20.870
to understand where it\'s gone and how quickly
it\'s it\'s moving about.

46:22.830 --> 46:28.770
Analysis confirms that the corals, like the ice
cores show the same very rapid shifting climate

46:28.780 --> 46:30.629
at the end of the last ice age.

46:32.189 --> 46:35.729
But which changed first, the ocean or the
atmosphere?

46:36.939 --> 46:40.540
The name of the game.
In these times of questions of which came first,

46:40.550 --> 46:46.219
the deep ocean, the atmosphere is very well
dated records and the deep sea corals,

46:46.229 --> 46:49.760
because they contain uranium, allow us to have
a clock.

46:49.770 --> 46:52.929
We can measure that That uranium clock in the
corals, Uh,

46:52.939 --> 46:55.199
very precisely and very accurately.

46:55.500 --> 47:00.159
And the ice cores can be layer counted, just
like tree rings if you count density layers

47:00.169 --> 47:03.360
back in the in the course back 15,000 years.

47:03.770 --> 47:08.479
And if you believe those two different
chronologies, the corals seem to lead the ice

47:08.489 --> 47:10.209
cores by a few 100 years.

47:10.540 --> 47:14.310
This is a very controversial result, and I may
be one of the few people who actually believe

47:14.320 --> 47:17.699
it.
Uh, but, uh, uh, it\'s certainly very exciting.

47:17.709 --> 47:22.239
And for the first time, we\'re actually being
able to say something about which happened

47:22.250 --> 47:23.870
first.
The deep ocean, the atmosphere,

47:31.919 --> 47:37.639
perhaps the recent warming of tropical seas is
an indication of a rapid change brewing in the

47:37.649 --> 47:39.860
ocean atmosphere.
Circulation patterns.

47:42.689 --> 47:45.550
I feel as an oceanographer.
There\'s a lot of information in the ocean

47:45.560 --> 47:48.469
that\'s trying to tell us something, and I don\'t
know that we figured it out.

47:48.479 --> 47:54.800
Yet as we look at the Northern Hemisphere
tropics, we see an alarming increase in

47:54.810 --> 47:58.399
temperature.
Uh, something that\'s approaching a half degree

47:58.409 --> 48:00.199
Celsius per decade.

48:03.290 --> 48:08.320
Plotted in red is where satellites have
recorded a rise in average surface temperatures

48:08.330 --> 48:09.879
since 1984.

48:11.739 --> 48:13.810
Purple is where the oceans have cooled.

48:16.379 --> 48:21.820
This pattern of rapid warming in the northern
tropics has not been predicted in any climate

48:21.830 --> 48:22.830
change models.

48:36.020 --> 48:42.169
All of a sudden, it seems, the future of coral
reefs has taken a decidedly uncertain turn.

48:45.179 --> 48:50.199
One of the strangest twists has been discovered
in the most unlikely of places.

48:55.250 --> 48:59.850
The Biosphere two project in Arizona took its
name from Biosphere one,

49:00.239 --> 49:01.709
otherwise known as the Earth.

49:03.929 --> 49:08.389
It was an attempt to encapsulate some of the
major ecosystems of our planet.

49:08.899 --> 49:14.110
A desert, a rainforest, an ocean in their own
sealed atmosphere.

49:21.610 --> 49:26.590
Within the Self-supporting Biosphere ocean, a
small reef community of fish,

49:26.600 --> 49:29.540
coral and algae mimic life in the real world.

49:33.770 --> 49:38.659
It\'s here that an international team has been
investigating the way corals respond to the

49:38.669 --> 49:42.280
increases of carbon dioxide we\'re making to the
atmosphere.

49:44.510 --> 49:49.050
What we did was change the chemistry of the
water as we know that it will change in the

49:49.060 --> 49:56.030
next 100 years or so as CO2 in our atmosphere
increases that CO2 will dissolve in the ocean

49:56.040 --> 50:02.550
water and CO2 is a weak acid, so it\'s going to
increase the acidity lower the PH of the ocean

50:02.560 --> 50:09.540
waters.
At first, people thought corals

50:09.550 --> 50:11.929
would do quite well in the greenhouse world.

50:13.520 --> 50:20.120
The more carbon dioxide, the faster corals
would grow quite useful given the threat of

50:20.129 --> 50:21.350
rising sea levels.

50:23.770 --> 50:27.060
But the biosphere experiments have shown the
opposite is true.

50:28.750 --> 50:35.310
As CO2 rises and makes the ocean more acidic,
it reduces the concentration of carbonate ions

50:35.320 --> 50:40.239
in the water.
This makes it much harder for corals to build

50:40.250 --> 50:41.840
their limestone skeletons.

50:43.580 --> 50:49.040
Repeated experiments have shown a drop in
skeletal growth rates of at least 30 per cent

50:49.060 --> 50:53.399
in the next 100 years, and there\'s no real
smoking gun.

50:53.409 --> 50:57.820
There\'s no obvious whitening of the tissues.
These pearls are just going to grow more slowly

50:58.530 --> 51:05.239
and be less fit and able to to cope with the
other stresses like a rising sea level and may

51:05.250 --> 51:07.550
just drown without any obvious, uh, warning.

51:10.489 --> 51:15.469
The Biosphere results forecast that on current
projections in 50 years,

51:15.479 --> 51:20.810
reefs worldwide will be struggling in 200 years.

51:21.030 --> 51:22.639
They\'ll stop growing altogether.

51:27.719 --> 51:32.600
Already, increases in co 2 may explain why some
of the world\'s more marginal reefs,

51:32.889 --> 51:37.080
like those in Florida, seem to be so
susceptible to disease and pollution.

51:40.300 --> 51:45.159
And there\'s evidence from at least some coral
cause that growth rates have begun to decline

51:45.169 --> 51:46.719
over the last few decades.

51:50.050 --> 51:54.429
Everyone that\'s ever visited a reef 20 years
ago noticed the dramatic decline in the the

51:54.439 --> 51:59.500
state of the reefs.
And now something\'s done about the CO2.

52:00.290 --> 52:03.979
I think that the, uh, future for reefs in the
next 100 years or so is pretty,

52:04.100 --> 52:10.500
pretty glum.
Coral reefs seem to have been delivered a

52:10.510 --> 52:14.370
double blow.
If temperature doesn\'t get them,

52:14.780 --> 52:16.290
then the chemistry will.

52:28.530 --> 52:34.030
So what are the prospects for reefs like Scott
so heavily damaged in 1998?

52:38.100 --> 52:41.770
The corals, even though they they aren\'t the
food of the other organisms,

52:41.780 --> 52:45.979
For the most part, they provide the habitat and
the shelter which these other things grow.

52:49.669 --> 52:52.729
At the moment we\'re seeing all these corals
dead.

52:52.739 --> 52:55.770
But standing in place, the fish still look as
beautiful as ever.

52:55.780 --> 53:00.889
They\'re darting around between these dead
branches, so unless you really look closely,

53:00.899 --> 53:02.290
it\'s hard to tell the difference.

53:04.790 --> 53:09.050
The thing is, though, that they\'re now dead,
and at this point,

53:09.060 --> 53:13.409
boring organisms are beginning to settle in
them, and they\'re gradually going to be riddled

53:13.419 --> 53:19.179
out from the inside eventually.
And I can\'t tell you when.

53:19.189 --> 53:23.129
There\'s going to be a big storm that\'s going to
hit, and those weakened corals are just going

53:23.139 --> 53:24.439
to collapse into rubble.

53:26.030 --> 53:28.939
At that point, the habitat will be wiped out.

53:38.810 --> 53:42.229
Recolonization of a reef like Scot will be very
slow.

53:43.659 --> 53:48.959
Settlement plates recovered by the biologists
confirmed that there was a complete failure of

53:48.969 --> 53:50.370
the annual coral spawning.

53:54.689 --> 53:59.590
With little brood stock left, most new recruits
will need to come from reefs upstream.

54:01.090 --> 54:06.429
That probably means Indonesia, where reefs were
also bleached and under great pressure.

54:10.840 --> 54:16.100
It will be decades, perhaps a century before
Scott returns to its former glory.

54:17.060 --> 54:21.399
But even recovery on this timeframe depends on
two unlikely assumptions.

54:22.820 --> 54:28.540
That there will be no more bleaching events and
that carbon dioxide levels can be made to fall

54:28.550 --> 54:35.270
instead of rise, even if

54:36.030 --> 54:41.179
there was a supply of baby quarrels, and even
if the water quality was clean so that they

54:41.189 --> 54:45.649
could settle and begin to grow, then they will
survive only if it never gets hot again.

54:46.020 --> 54:48.949
And that\'s the real problem.
It\'s you see, it\'s easier for a place like the

54:48.959 --> 54:52.090
Barrier Reef to say, Well, there\'s great
management and so forth.

54:52.300 --> 54:55.919
But the fact is, even the best managed reefs
will die if they get too hot.

54:55.929 --> 54:58.389
It\'s got nothing to do with managing local
stresses.

54:58.399 --> 55:03.639
This is truly a global problem.
If, in fact the temperatures were to continue

55:03.649 --> 55:08.929
to increase in the tropics, as they have been
for another 15 or 20 years,

55:09.270 --> 55:15.560
Uh, not only would there be more bleaching, but
there would be a lot less reefs on a global

55:15.570 --> 55:18.260
scale.
We\'re seeing changes in the ocean environment.

55:18.270 --> 55:23.199
We\'re seeing changes in our atmosphere, and we
have to recognise that we\'re really

55:23.209 --> 55:25.639
economically dependent on the health of the
oceans.

55:25.659 --> 55:30.669
And if we let our coral reefs uh, disappear, if
we let our fisheries disappear,

55:30.679 --> 55:33.669
then we\'re going to see the economic impacts on
a global scale.

55:42.090 --> 55:47.449
The last time the world saw wholesale loss of
reefs was 65 million years ago.

55:51.780 --> 55:57.260
Whether it was a rogue asteroid or catastrophic
volcanism that saw the end of the dinosaurs,

55:57.669 --> 56:00.889
the atmosphere was left high in carbon dioxide.

56:03.510 --> 56:07.840
For a time, coral reefs completely disappeared
from the fossil record.

56:10.080 --> 56:16.379
Eventually, carbon dioxide levels returned to
normal, and so did the corals we see on reefs

56:16.389 --> 56:21.939
today.
But it took them over 10 million years to

56:21.949 --> 56:26.340
recover.
It\'s unlikely we can wait that long.