Shows that global warming is already hurting the Pacific Islands.
Silent Sentinels

- Description
- Reviews
- Citation
- Cataloging
- Transcript
Coral reefs are the jewels of the ocean. Communities of organisms as rich and diverse as any above or below the surface of the planet, they encircle the tropics like an azure necklace.
1998 was designated 'International Year of the Oceans'. It turned out to be the year that coral reefs around the world began to die. Unprecedented mass bleaching swept the world's tropical oceans, in places leaving hundreds of miles of coral coastline - the fringes of entire countries in places - severely damaged. Following a number of similar but lesser events since the 1980s, this latest bleaching event is being touted as unequivocal proof that global warming has begun, and that it will have a greater impact than many think.
This program reveals disturbing evidence that even if coral can survive continually rising temperatures, they won't be able to escape the chemical effects of high levels of carbon dioxide in the atmosphere. Experiments in Arizona's Biosphere II show that as the ocean is becoming more acidic, corals will grow more slowly and with weaker skeletons.
SILENT SENTINELS examines these claims and takes a step back to take a broader look at the coral organism and how it has coped with climate change over time. How coral both defines its environment and is created by it. It is a story of a polyp and a plant - one of the most successful biological relationships in the history of the earth.
SILENT SENTINELS was filmed in three oceans; on the Great Barrier Reef in Australia; the remote Scott Reef in the Indian Ocean; in the Maldives, the Red Sea, the USA and the Caribbean.
"This is the most important movie on global warming to date...Has a much stronger impact than any written report." —Rafe Pomerance, key US global warming negotiator, former Deputy Asst. Secretary of State for Environment and Development
"Drawing connections between the biological processes of life and death in the reef ecosystem with climate patterns, the viewer directly experiences the evidence that has convinced the scientific community that global warming is having significant impacts on coral reefs...Silent Sentinels combines the dire predictions of the future with strategies for staving off massive disaster, making it an important film for anyone concerned with the marine environment." —Stuart Sandin, Coral Reef Ecologist, Princeton University
"A comprehensive introduction to this subject that is both understandable to the layman and sufficiently penetrating to interest the professional." —Steve Coles, Bishop Museum, Honolulu
"Excellent program...Highly recommended for earth science and ecology classes." —Booklist
"Excellent...make(s) a compelling case that action is urgently needed to respond to global change, above all climate change...I strongly believe we will only have governments act when their citizenry is well enough informed and pressing for action...A significant contribution. It is important (it) be widely viewed." —Gordon Smith, Director of the Centre for Global Studies, University of Victoria
"An essential film for scientists and students of all grade levels who want to understand the critical impacts global warming is having of one of the earth's most biologically diverse, climatically sensitive ecosystems...Watching this film will put to rest any disagreement that rising global temperatures are killing tropical coral reefs." —James M. Cervino, Marine Biologist, University of South Carolina
"Science is one of the few human endeavors that still depends primarily on the printed word for reporting...The power of near-real-time satellite data to produce testable predictions of the location and intensity of coral bleaching is particularly well presented with computer graphic 'movies' of evolving hotspots. The message simply could not be as well presented in any other medium...In summary, the quality of the science presented in Silent Sentinels approximates that of the work done by the scientists it features: i.e. a very high standard." —Bruce G. Hatcher, Dept. of Biology, Dalhousie University
"There are literally dozens of videos available that relate to coral reefs, but Silent Sentinels...belongs in every school, college and public library. It is an excellent educational film...and it is very highly recommended." —Barbara Butler, Oregon Institute of Marine Biology, MC Journal
"This is an outstanding film." —David M. Anderson, Institute for Arctic and Alpine Research, University of Colorado
"Perhaps the greatest 'wakeup call' environment film I've ever seen." —Ceferina G. Hess, Political Science, Lander University
Citation
Main credits
Smith, Richard (film director)
Smith, Richard (film producer)
Smith, Richard (screenwriter)
Smith, Richard (narrator)
Other credits
Cinematography, Richard Smith; editing, Lile Judickas; music, Jeremy Smith.
Distributor subjects
Atmosphere; Climate Change/Global Warming; Conservation; Earth Science; Environment; Life Science; Marine Biology; Oceans and Coasts; SustainabilityKeywords
WEBVTT
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
01:00.520 --> 01:07.389
ocean communities of organisms
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as rich and diverse as any above or below the
surface of the planet.
01:17.500 --> 01:23.769
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.
01:27.940 --> 01:33.199
But despite their apparent permanence, reef
building corals are remarkably fussy.
01:34.790 --> 01:38.389
They need the ocean to be not too cold and not
too hot.
01:39.349 --> 01:46.150
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
01:53.180 --> 01:55.730
systems like this will start to die.
01:59.449 --> 02:05.790
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
02:46.539 --> 02:47.929
west Australian coast.
02:55.699 --> 03:00.860
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
03:37.119 --> 03:38.270
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.
04:36.250 --> 04:40.519
Most of the few corals that were still alive
were bleached white as ghosts.
04:42.420 --> 04:44.529
For the rest, it was too late.
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Their bear skeletons were already smothered by
algae.
04:55.200 --> 04:56.859
Scott Reef was not alone.
04:57.980 --> 05:04.019
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.
05:12.589 --> 05:19.260
In 1998 the richest coral reefs of the Pacific
and the Indian Ocean have
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undergone a catastrophic mass mortality.
05:23.089 --> 05:29.429
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.
05:32.959 --> 05:38.230
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.
06:17.019 --> 06:21.070
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.
06:33.179 --> 06:38.179
The low lying Maldives was singled out as
especially vulnerable to being washed away.
06:38.329 --> 06:44.859
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.
07:06.239 --> 07:10.970
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.
07:31.679 --> 07:34.809
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.
08:12.910 --> 08:16.609
Soon Tom Garreau senior became entranced with
corals as well.
08:19.260 --> 08:24.559
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.
08:33.140 --> 08:36.080
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.
09:24.369 --> 09:28.450
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,
09:34.039 --> 09:36.590
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.
09:40.750 --> 09:44.799
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.
10:01.840 --> 10:06.059
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.
10:18.380 --> 10:21.820
And we could simply, you know, stand out in the
sunlight and grow.
10:21.830 --> 10:23.380
You know our own food.
Internally,
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coral polyps literally farm algae within their
flesh.
10:37.840 --> 10:43.190
In this symbiotic relationship, the resident
algae, a type of dinoflagellate called Zola,
10:44.320 --> 10:50.479
are given a sturdy home, guaranteed sunlight
and a ready supply of carbon dioxide from the
10:50.489 --> 10:57.159
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.
11:04.900 --> 11:07.960
About 90% of this is passed to the coral host.
11:12.469 --> 11:19.229
This is how corals get the wherewithal to build
their limestone skeletons day after day,
11:19.799 --> 11:23.409
year after year, millennia after millennia.
11:28.299 --> 11:34.690
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.
11:39.200 --> 11:42.820
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,
11:55.159 --> 12:00.520
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
12:30.010 --> 12:32.719
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
13:45.609 --> 13:49.619
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.
14:37.099 --> 14:41.150
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.
14:45.260 --> 14:48.770
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.
15:00.669 --> 15:05.770
Both 1983 and 1987 were strong El Nino years.
15:06.460 --> 15:13.010
The climatic effects were felt worldwide,
though there was obviously some
15:13.020 --> 15:16.570
link.
By the 19 nineties, mass coral bleaching was
15:16.580 --> 15:21.020
being reported on a nearly annual basis from
the Red Sea to Bermuda,
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including reefs far from populated areas.
15:26.659 --> 15:33.169
This was French Polynesia.
In 1994 Of the many
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theorised causes, from viruses to the hole in
the ozone layer,
15:37.320 --> 15:41.299
only one seem to explain it temperature.
15:51.690 --> 15:58.369
Since 1982 NOA, the US Oceanographic and
Atmospheric Administration has been recording
15:58.380 --> 16:00.650
sea surface temperatures from space.
16:02.599 --> 16:07.039
These earth observing satellites measure in the
infrared recording,
16:07.049 --> 16:09.520
the heat rising off the ocean during the night.
16:15.859 --> 16:20.919
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.
16:24.880 --> 16:28.859
What\'s interesting?
What we found out, sort of by luck was that
16:28.869 --> 16:35.020
corals are very, uh, they\'re very much adapted,
obviously to the normal conditions,
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and the big one is temperature.
16:38.289 --> 16:43.559
Working with field data from Tom Garreau and
others, Al Strong has developed an interactive
16:43.570 --> 16:50.150
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.
16:54.960 --> 16:59.869
Yellow signifies a hotspot where temperature is
one degree higher than normal.
17:01.690 --> 17:07.329
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
17:38.109 --> 17:40.880
Nino forming in the waters of Peru.
17:44.989 --> 17:48.930
For reasons which are still unclear in an El
Nino year,
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circulation patterns in the entire Pacific
Ocean change.
17:53.839 --> 17:59.109
Because of this, this El Nino Southern
oscillation can have effects far beyond the
17:59.119 --> 18:00.180
Eastern Pacific.
18:02.670 --> 18:08.709
From late 1997 Armstrong began to notice that
sea temperatures were becoming unseasonably
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warm in the Western Pacific as well.
18:13.060 --> 18:16.770
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.
18:33.859 --> 18:37.800
This was the scene at Heron Island on the
southern Great Barrier Reef.
18:40.040 --> 18:45.660
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.
18:57.209 --> 19:01.709
Marine Park Authority staff took to the air to
gauge the extent of the damage.
19:10.859 --> 19:14.780
At first, the bleaching was thought to have
been caused by heavy summer rains in the
19:14.790 --> 19:20.910
Townsville region.
But the aerial surveys confirmed extensive
19:20.920 --> 19:24.569
bleaching along the entire inner region of the
Great Barrier Reef,
19:25.439 --> 19:29.500
1000 kilometres from Heron Island north to
Cooktown.
19:31.719 --> 19:34.430
While many of the outer reefs escaped entirely.
19:34.739 --> 19:39.030
Mortality rates around some of the inshore
islands exceeded 90%.
19:43.680 --> 19:48.140
But the Pacific got off lightly compared with
what happened in the Indian Ocean.
19:51.030 --> 19:52.729
This is 1998.
19:53.050 --> 19:59.739
The way the Noah satellite saw it, what
happened in 1998 was that there was incredible
19:59.750 --> 20:05.300
hot water that stretched across the entire
Indian Ocean all the way from Mozambique to
20:05.310 --> 20:10.619
western Australia and Indonesia, and the whole
South Indian Ocean bleached very heavily.
20:10.630 --> 20:13.739
It stayed excessively hot for about 4 to 5
months.
20:14.510 --> 20:18.010
Not only did the corals bleach, but most of
them died.
20:18.130 --> 20:22.199
And in Seychelles, where I I\'d been filming the
coral reefs,
20:22.260 --> 20:26.270
working with the Marine Park Authority in
Seychelles in order to document reef condition
20:26.709 --> 20:30.310
in early 1997 I found beautiful reefs in
Seychelles.
20:30.319 --> 20:32.130
I mean, some of the loveliest I\'ve seen
anywhere.
20:32.819 --> 20:38.310
And there were areas that were were, you know,
95% or more beautiful life,
20:38.319 --> 20:45.089
healthy coral.
By May of 1998 80% of those calls were
20:45.099 --> 20:46.099
dead.
20:59.170 --> 21:04.069
By December of 19, 98/90 percent were dead.
21:06.630 --> 21:10.290
The disaster was that the best coral reefs were
the worst affected,
21:10.530 --> 21:13.969
and the the reefs that really were the most
beautiful of all.
21:13.979 --> 21:18.849
In some cases, more than 99.9% of all the
corals were dead.
21:18.859 --> 21:23.270
Every branch and coral was wiped out.
You could find us one or two partly alive.
21:23.280 --> 21:25.530
Head corals here or there.
And that was it
21:32.270 --> 21:34.329
5000 kilometres away.
21:34.709 --> 21:38.750
Aim scientists were about to discover the same
fate that struck Scott Reed,
21:40.910 --> 21:45.579
50 maidens, 25.
21:47.270 --> 21:48.569
What are you doing?
Came
21:55.699 --> 22:00.599
satellite records showed that the hot water had
sat on Scott Reef for nearly two months.
22:02.920 --> 22:08.819
By the time the team arrived, the branching
corals were dead and had already been colonised
22:08.829 --> 22:10.599
by fine filamentous algae.
22:15.229 --> 22:17.709
Devastation was most complete in the shallows.
22:18.959 --> 22:23.339
You could swim for hundreds of metres before
finding a single living colony.
22:26.410 --> 22:33.109
I didn\'t expect to find the amount that we have.
Many corals that live on the top sort of six
22:33.119 --> 22:35.609
metres of the reef just don\'t exist there
anymore.
22:35.619 --> 22:39.209
They\'re gone.
They\'ve all died and I didn\'t expect to find
22:39.219 --> 22:42.910
these these huge corals that are hundreds of
years old,
22:42.920 --> 22:46.069
either dead or in the process of dying.
22:46.819 --> 22:51.420
Previous bleaching in other parts of the world,
reefs have actually been able to bleach and
22:51.430 --> 22:56.329
then recover.
And Scott Reef, Um, as you\'ve seen just hasn\'t
22:56.339 --> 23:02.800
at all.
It\'s been knocked down in the
23:02.810 --> 23:06.500
lagoon.
Whole fields of corals were totally cooked.
23:10.609 --> 23:16.510
The mortality lessened with depth but extended
below 30 metres to the base of the reef.
23:18.369 --> 23:22.569
We\'re talking about an event that made the
corals bleach as deep as we could go,
23:22.579 --> 23:26.199
which was 30 metres.
So you\'re looking at like 100 and 10 ft of
23:26.209 --> 23:30.339
water, and we went down there and everything is
bleached.
23:30.380 --> 23:34.510
So it\'s a huge volume of water you\'re talking
about that\'s moved through.
23:34.520 --> 23:38.689
It\'s not just the the situation where the
surface layer has has warmed up
23:42.130 --> 23:47.140
on video.
The dead coral appears dark, those still alive
23:47.150 --> 23:52.760
pale.
Some bleached soft corals turn bright yellow
23:52.770 --> 23:57.270
instead of white before slumping off their
pedestals and dissolving
24:02.349 --> 24:06.569
on some of the tougher species.
Patches of tissue protected from direct
24:06.579 --> 24:08.569
sunlight remained unbleached.
24:10.670 --> 24:13.689
This shading effect is a confusing feature of
bleaching.
24:14.689 --> 24:18.650
If temperature is the cause, why does light
have an effect?
24:21.989 --> 24:28.199
Mhm.
In a few places near deep channels,
24:28.209 --> 24:32.969
Scott\'s ubiquitous sea snakes could hunt
through small patches of surviving coral.
24:36.219 --> 24:39.099
But for the most part, the reef was devastated.
24:42.829 --> 24:47.410
As the year progressed, the hot water swept
northwards with the summer sun.
24:48.739 --> 24:51.630
The Maldives suffered heavy bleaching similar
to Scott.
24:52.400 --> 24:59.390
So did Sri Lanka, and the latch wood es
bleaching swept the East Africa
24:59.400 --> 25:02.989
coast, the Persian Gulf and the southern Red
Sea.
25:07.119 --> 25:11.349
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,
25:17.000 --> 25:20.060
Taiwan, almost all of Southeast Asia
25:27.479 --> 25:28.930
in the Western Hemisphere.
25:29.140 --> 25:33.369
Extensive bleaching was reported from the
Galapagos, Costa Rica,
25:34.089 --> 25:38.939
the Bahamas, Florida and the Cayman Islands in
Belize.
25:44.099 --> 25:50.869
OK, by the end of 1998 some 60 countries and
25:50.880 --> 25:52.979
island nations had been affected.
26:00.229 --> 26:02.119
It took the world by surprise.
26:03.380 --> 26:05.640
Surely corals are tougher than this.
26:06.689 --> 26:10.270
After all, reefs have lived through all the
upheavals to life on Earth.
26:10.280 --> 26:17.219
For the best part of 400 million years, they
must have an escape plan for a bit of warm
26:17.229 --> 26:18.229
water.
26:39.670 --> 26:45.079
Here on the Great Barrier Reef, corals cast
their young adrift on a couple of fun filled
26:45.089 --> 26:46.579
nights in early summer.
26:48.979 --> 26:52.839
This is how coral reefs have beaten the
climatic odds for millennia.
26:56.780 --> 27:01.810
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,
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coral and algae mimic life in the real world.
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It\'s here that an international team has been
investigating the way corals respond to the
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increases of carbon dioxide we\'re making to the
atmosphere.
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What we did was change the chemistry of the
water as we know that it will change in the
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next 100 years or so as CO2 in our atmosphere
increases that CO2 will dissolve in the ocean
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water and CO2 is a weak acid, so it\'s going to
increase the acidity lower the PH of the ocean
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waters.
At first, people thought corals
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would do quite well in the greenhouse world.
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The more carbon dioxide, the faster corals
would grow quite useful given the threat of
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rising sea levels.
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But the biosphere experiments have shown the
opposite is true.
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As CO2 rises and makes the ocean more acidic,
it reduces the concentration of carbonate ions
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in the water.
This makes it much harder for corals to build
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their limestone skeletons.
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Repeated experiments have shown a drop in
skeletal growth rates of at least 30 per cent
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in the next 100 years, and there\'s no real
smoking gun.
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There\'s no obvious whitening of the tissues.
These pearls are just going to grow more slowly
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and be less fit and able to to cope with the
other stresses like a rising sea level and may
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just drown without any obvious, uh, warning.
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The Biosphere results forecast that on current
projections in 50 years,
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reefs worldwide will be struggling in 200 years.
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They\'ll stop growing altogether.
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Already, increases in co 2 may explain why some
of the world\'s more marginal reefs,
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like those in Florida, seem to be so
susceptible to disease and pollution.
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And there\'s evidence from at least some coral
cause that growth rates have begun to decline
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over the last few decades.
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Everyone that\'s ever visited a reef 20 years
ago noticed the dramatic decline in the the
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state of the reefs.
And now something\'s done about the CO2.
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I think that the, uh, future for reefs in the
next 100 years or so is pretty,
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pretty glum.
Coral reefs seem to have been delivered a
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double blow.
If temperature doesn\'t get them,
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then the chemistry will.
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So what are the prospects for reefs like Scott
so heavily damaged in 1998?
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The corals, even though they they aren\'t the
food of the other organisms,
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For the most part, they provide the habitat and
the shelter which these other things grow.
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At the moment we\'re seeing all these corals
dead.
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But standing in place, the fish still look as
beautiful as ever.
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They\'re darting around between these dead
branches, so unless you really look closely,
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it\'s hard to tell the difference.
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The thing is, though, that they\'re now dead,
and at this point,
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boring organisms are beginning to settle in
them, and they\'re gradually going to be riddled
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out from the inside eventually.
And I can\'t tell you when.
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There\'s going to be a big storm that\'s going to
hit, and those weakened corals are just going
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to collapse into rubble.
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At that point, the habitat will be wiped out.
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Recolonization of a reef like Scot will be very
slow.
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Settlement plates recovered by the biologists
confirmed that there was a complete failure of
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the annual coral spawning.
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With little brood stock left, most new recruits
will need to come from reefs upstream.
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That probably means Indonesia, where reefs were
also bleached and under great pressure.
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It will be decades, perhaps a century before
Scott returns to its former glory.
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But even recovery on this timeframe depends on
two unlikely assumptions.
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That there will be no more bleaching events and
that carbon dioxide levels can be made to fall
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instead of rise, even if
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there was a supply of baby quarrels, and even
if the water quality was clean so that they
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could settle and begin to grow, then they will
survive only if it never gets hot again.
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And that\'s the real problem.
It\'s you see, it\'s easier for a place like the
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Barrier Reef to say, Well, there\'s great
management and so forth.
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But the fact is, even the best managed reefs
will die if they get too hot.
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It\'s got nothing to do with managing local
stresses.
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This is truly a global problem.
If, in fact the temperatures were to continue
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to increase in the tropics, as they have been
for another 15 or 20 years,
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Uh, not only would there be more bleaching, but
there would be a lot less reefs on a global
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scale.
We\'re seeing changes in the ocean environment.
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We\'re seeing changes in our atmosphere, and we
have to recognise that we\'re really
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economically dependent on the health of the
oceans.
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And if we let our coral reefs uh, disappear, if
we let our fisheries disappear,
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then we\'re going to see the economic impacts on
a global scale.
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The last time the world saw wholesale loss of
reefs was 65 million years ago.
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Whether it was a rogue asteroid or catastrophic
volcanism that saw the end of the dinosaurs,
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the atmosphere was left high in carbon dioxide.
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For a time, coral reefs completely disappeared
from the fossil record.
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Eventually, carbon dioxide levels returned to
normal, and so did the corals we see on reefs
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today.
But it took them over 10 million years to
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recover.
It\'s unlikely we can wait that long.