The ocean at Biosphere 2 is ideal for making... precise studies in a controlled environment.

The CO2 in the ocean is also increasing.

But most of the earth is covered with... uncontrolled and untamed ocean.

Not many sites are conducive to laboratory type research.

We use stalagmites for determining climate change.

One though is found in the Bahamas on Eleuthera Island.

Funding for In the Americas with David Yetman was provided by Agnese Haury ♪ Funding for In the Americas with David Yetman was also provided by the Guilford Fund.

♪ ♪ In the Americas with David Yetman theme This is the Biosphere, located north of Tucson, Arizona.

It's the world's largest earth science research center.

It focuses especially on water... and its effect on human habitation and natural habitation.

Ranging from tropical rainforests... To deserts... To Oceans.

Most of the earth is covered with ocean.

It is a vital part of the overall planetary system... that allows us to survive.

At the biosphere the ocean is being studied... in that flat area beyond the big building This is our ocean.

How much water are we looking at, here?

About two point six (2.6) million liters or 780,000 gallons.

This is not a natural beach.

So where does this come from?

No, this beach is not native to Arizona.

In fact this beach, like the whole ocean, was assembled from parts and pieces from everywhere.

So some of what we're seeing on the beach here ... came from Central America, other parts came from Florida, and the water itself started off with... a little bit of water from the Pacific Ocean, but has been supplemented by freshwater and... the addition of marine salt to fill the whole ocean.

The Biosphere 2 Ocean is limited in size certainly, but it is a nice intermediary between experimenting... in little aquaria or beakers or test tubes and... experimenting in the real ocean where you don't have any control.

So, we like the biosphere because it spans that gap... between what you can do in a lab and... what you can do in the real ocean, with all the uncertainty and unpredictability... and lack of control that's there.

As humans add CO2 to the atmosphere, through the burning of fossil fuels... and the deforestation of large tracts of tropical forests.

The chemistry of the atmosphere changes with higher C02 levels, of course, but those higher CO2 levels also... are translated into the ocean and the Co2 in the ocean also increasing.

That leads to higher acidity in the ocean, this is problematic for organisms in many ways.

The most obvious ways are that any organism that makes a shell... out of calcium carbonate, those organisms have a lot more trouble... making their calcium carbonate shells in a more acidic ocean.

But the impacts of the ocean acidification go beyond that.

They include things like how well sound translates in the ocean.

So, a more acidic ocean is a noisier ocean.

And marina mammals that communicate with sound, will have more confusing environment.

Now we're not going to put whales and dolphins... in the biosphere 2 ocean of course.

But, I just want to give you some examples ... of how the ocean is changing in ways you might not expect, as climate warms and as the ocean becomes more acidic.

We see also a de-oxygenation of deeper waters... that is problematic... for organisms that live there.

There are many different factors that are... affecting how the ocean is evolving right now.

So for example, there's overfishing, there's pollution, there's plastics dumping.

All kinds of things that humans are doing to change the ocean.

As well, we got climate change on top of that... and it's very hard to separate those effects in the real ocean.

One of the things we can do here in the biosphere is try to tease... out those different impacts.

So for example, we're not going to be polluting... this with plastic, we're not going to be over- fishing it.

We're only going to change the things that we know we're changing... and we're going to record those changes carefully.

And that allows us to disentangle that thorny problem... of cause and effect that we have... in the real complex system in the real ocean.

These kids are from North Carolina and... actually they're helping us with our salinity levels in the ocean.

Our ocean's dropped well below ambient salinity of the open ocean, so what they're doing is, we ordered some salt and they're mixing it up on the pier... and adding in solution into the ocean.

In the hope of raising our salinity.

Once we get the salinity up we can add more species.

The Biosphere's ocean is a research facility, and there is a lot of scientific work that can be done.

But the real test lies in the real ocean.

The best place for us to see how a laboratory... in real-life works, is in the Bahamas.

The Bahamas is an ideal place to study climate change... from the ocean's standpoint Because it's flat, it's limestone, which is very sensitive to changes in how water affects things.

It's convenient.

And in the Bahamas, it's a former British colony, you drive on the left -side of the highway.

And I'm left-handed so that works fine.

♪ I'm heading to the island's school which is home to a research facility where scientists can study... a wide variety of marine topics, including coral reefs and what is happening to them.

The coral reefs are not doing very well, because the corals themselves are extremely sensitive to temperature, and temperatures are rising because of global climate change.

So, in the news of very, very recently, this week in fact, people in Australia were reporting that about a... third of the Great Barrier Reef, had been lost... over the space of just a few weeks because... of a very, very intense El Niño.

We are approaching what we call a tipping point, very very rapidly, which is a temperature or environmental conditions where the corals and coral reefs in general, simply won't be able to survive.

Coral reefs are an ecosystem that probably holds... the most species per square meter of any ecosystem in the world.

The diversity of species is absolutely enormous.

But in human terms, they also have a great importance, Because they give us lots of goods and services.

Millions of people around the world depend on fisheries, catching fish on coral reefs and... and they depend on that for their subsistence.

Coral reefs are also really important in terms... of coastal protection, and so they break waves when there are storms... and they protect beaches.

So, they hold great attraction for tourism... in lots and lots of countries, particularly in developing countries... where other sources of income are relatively rare.

There are many manifestations of climate change, one of the key ones for coral reefs is increase in temperature, and that causes coral bleaching.

So within in their tissues coral have little algae, which are little plants that photosynthesize, so they make sugar and they exchange this sugar... for other things that the coral gives them.

So it's a sort of two-way, very very close interaction that the coral depends on for its nutrition And when the temperature is very high, corals expel these little algae, and in doing so they lose their color, so they turn white.

Hence the term bleaching.

If the warm water conditions hold for an extended period of time, the coral effectively starves to death.

I have visited enough coral reefs to know... that they harbor the greatest biological diversity... per square yard of any ecosystem in the world.

The number of species is staggering.

The next thing I learned about ocean acid- ification astounds me.

I had no idea.

Dr. Côté is explains the world is now... experiencing a rise in ocean acidification, all that carbon dioxide we are putting in the atmosphere... is affecting water in the ocean, making it more acid.

Under most conditions we think that corals will be able... to keep up with sea level rise.

So in most places we're less concerned about that, but temperature increase and acidification are really the two main things about climate change... that are really threatening reefs.

But every time there is a big bleaching event... we lose a sizable proportionof the reefs, 1998 and 2005, each time we lost 10-15%.

These events are coming, sort-of closer and closer together, so the whole ecosystem simply does not have time to recover... in between these events.

Dr. Côté studies climate change that we can see in our lifetimes.

Other scientist examine the geological record... for ancient signs of climate change.

History of climate change in the Bahamas... is recorded in many different records, archives.

Of course coral skeletons.

There are also stalagmites.

Bahamas is made of calcium carbonate.

Thousands of meters of calcium carbonate have been deposited here, over the last 100 million years.

And this is the only place in the modern world, where a particular a type of carbonate is forming in the present.

That carbonate, which might have been present in earth's early history.

So it's actually a crucial place to study the processes... of calcium carbonate deposition.

This cave has three layers.

This one is mainly accessed by the public, there a lot of graffiti in here.

Stalagmites in the Bahamas form when sea evel was much lower, over the last 100,000 years sea level gone down 120 meters, then it came back up again.

And at this time, stalagmites formed deep within the Bahamas bank, when they were exposed to fresh water.

So these stalagmites record a history of the water composition... and the temperature during those time periods, and also they give us unique insight from how the tropics behaved... during the period of very cold weather in the northern hemisphere.

We use stalagmites for determining climate change by analyzing the chemistry of the stalagmites, and then dating them, so we know precisely what happened at a particular time in history.

We date them with either carbon fourteen or uraniumthorium.

We can go back, you know, maybe a couple hundred thousand years... depending on what method we use.

Right now I'm sitting next to an actively forming stalagmite.

So, if you can see that the top of this is actually wet with... dripping from the stalagmites above.

When we go back into the lab with these stalagmites pores... and actually look at how the chemistry of the rock has changed through time, We can see periods of warming and cooling, on orders of thousands of years, tens of thousands of years, and sometimes even a little bit longer than that.

We see evidence that the earth is actually starting to get warmer... and we see, we can go back into the climate records and see what... happened when we actually see that same kind of pattern... in the past history.

We can analyze these... and we can tell all sortsof interesting phenomenon about how... the climate changed during these periods when the sea-level was much lower than it is today.

And one particular example is that we know... that the sea-level was down, about 120 meters, it was a period when therewere large glaciers... in the northern part of the United States.

So, these stalagmites gives us clues about how the climate changed, in response to these very cold periods, which were experienced by the northern part of the U.S. and Europe.

In the modern era, the risein carbon dioxide... comes from fossil fuel burning, oil and coal.

And has a very distinctive carbonized signature, and we can pick that up in the stalagmites.

So the timing at which they stop growing, gives us a record of the sea-level rise.

So by looking at the level of the stalagmite and the age of the top, we can actually refine howsea-level increased in the Bahamas... over the past 20,000 years or so.

So we have other students working on... other unrelated types of problems, such as how the chemistry of the ocean... affect the chemistry of corals.

How rapidly rocks change from one phase to another.

What the geochemical signatures are, which accompany that type of phase change?

If you have a limestone terrain and it's close to sea-level, then it will be affected by sea-level rise and fall and there will be a lot of dissolution in the subsurface.

So you can expect to find blue holes in any limestone terrain, which is close to sea-level.

So as sea-level moves up and down it dissolves carbonate, particularly at the interface between the freshwater and saltwater.

And as sea-level moves up and down over thousands of years, when it gets close to the surface, the surface becomes weak enough... it just simply collapses in a circular structure, and that's a blue hole.

They can go down, maybe 200, 240, 280 meters.

The Bahamas make fora fine outdoor laboratory, not just because of their geological make-up, but also because there are so many of them.

The Bahamas are a number of islands around the world, which are very close to sea-level.

Large portions of the Bahamas would be essentially wiped out, with only a small rise of sea-level.

So basically looking at how the Bahamas actually have responded... to the recent sea-level rise, will enable us to predict how future sea-level rises... will impact certain areas.

South Florida is very susceptible to sea-level rise, just like the Bahamas, not so much for the physical indentation of the land, but because the limestones are so preamble... and the seawater will come and destroy the aquifers.

Bahamas for example, the aquifers are disappearing... Because of saltwater intrusion.

That's going to happen in Miami.

Where are they going to get all that freshwater they need for the crops?

And for the industry and for just to survive?

We can use the Bahamas as a guide to what the future will look like... in south Florida in terms of the water resources.

Because the Bahamas are experiencing it right now.

And I didn't realize that they show up this much in the boat, but here we can see three different colors.

So what do we attribute that ethereal glow of the Bahamas water.

The different colors are resulting... from the different types of bottom.

Over here, we see the white ooid sands, okay, there's very little vegetation growing on the sands.

Yeah, it's pretty barren.

That's pure white and the sand waves are moving constantly, so things don't get established.

Probably just below the boat here though, there are many sea grasses and types of vegetation growing on the bottom.

So it's a more blue-green color?

Right so there's, you know chlorophyll, there's plants photosynthesizing down there, it just gives it a slightly different color and if the water was deeper, of course, it be adark blue.

So you wouldn't actually reflect off the bottom.

So it's really just a function of how deep the water is... and what's on the bottom.

Exactly.

And how clear it is.

♪ People of the world over are attracted to the Bahamas.

Because of that luminescent aqua-marine blue.

It is everywhere in the Bahamas.

But it's not everywhere in the Bahamas.

We're here on the margin of The Great Bahama Banks, on one side we have the Atlantic Ocean, on the other side we have the shallow waters of the Bahamas.

This margin here representsan old fault boundary.

To hear the Atlantic with all its power just break through the island and branches over into the Bahamas' side, the bank side Yeah, it's a truly amazing sight here This use to be a natural bridge here, they called itthe glass window.

It was destroyed by a hurricane.

They put a bridge up.

That was destroyed.

They put a bigger bridge up, that whole bridge was moved over several feet.

The whole bridge just moved?

Exactly.

And it looks like it may fall down again, soon.

Wow, the power of the hurricane and the ocean.

The landscape on a lot of theBahamas, is varying shadesof grey.

And dreary at times, but often you're walking along and you come upon red.

And that red is extraordinary, because it comes from the Sahara Desert.

Three to four thousand miles to the east, it lays down a layer and... several times in its deep history here we can find dust from the Sahara and that way we can find out a lot about old time climates.

In modern day we know the dust comes over, we keep records of this, we've been doing this for the past fifty 50 years.

And all the red soils we see throughout the Bahamas, are actually, come from the Sahara.

So how old are those bands?

Okay, we think that the sediments below the lower orange layer, represent sediments formed during glacial stage nine so about 300,000 years ago, plus or minus.

Then sea-level fell, it was exposed to freshwater, it's cemented up the rock, it formed a nice hard surface.

So then sea-level came up again and another sediment package was deposited on top So you only see the grey bands when it's below the ocean, dropping the sediment.

These packages all represent sea-level rises and falls.

When the sea-level is high, it basically forms beaches... and it forms dunes.

When the sea-level comes down, there's no more sources of sediment, because all of this is exposed.

So there is no more new sediment production and that's when everything turns into rock.

But down here in the pools is where the sediments... were deposited below the water surface... and all the stuff on top here is deposited by air, what we call eolianites As we go down towards the pool, were going down through the dunes through the airborne deposits into sediment, which was deposited below the surface of the marine water.

When you go to a modern beach you see... a lot of little bubbles in the sand.

Yeah, yeah.

Sure.

And that's basically what, you know we can see that's fossilized... in the record, we know it sort of identifies it as... As a beach.

As a beach.

I mean when it was deposited it was a beach... and then on top of it we had you know the airborne sediments.

And that's just dunes and stuff on the top.

They all have different characteristics and we can tell that.

You can just look at that as a geologist and say, that's what going on here.

Part of the geological history of the Bahamas... is the story of formation and breakdown of limestone Part of that history is readily visible... only on some of the tinier islands.

Some of the more than 700 in the Bahamas.

This island will move around... and it will be brought up to the surface of the ocean... regardless of where the surface is.

The trip to one tiny island gives me a chance to find out everything...

I've ever wanted to know about ooids.

Another form of limestone.

This whole island and all the sediment around here are made up of ooids.

Or ooids.

And they're really like little mini pearls.

So they have a center, a nucleus and then coated by layers and layers of cement.

Their geological history is, trenchesback over 600 million years, so these were around before there were any skeletal organisms... anywhere in the world.

And so we can go back into the pre-Cambrian... and actually look at the ooids, and they very similar to what we found today.

And they're very of immense interest to all sorts of industries because the holes between the ooids are great for... storing things like oil and gas and water.

So in fact all the aquifers in Florida... are actually in this type of material.

I bet they would look great under a microscope.

Oh, fantastic.

They look like a whole bunch of white, like pearls and marble.

Little pearls, yeah.

Uh-huh.

They even imported ooids from the Bahamas... to Florida to re-nourish beaches.

Ooids make the white sand which Florida must now import, as the sea-level rises and beaches erode.

The level the sea has been rising, about 3 millimeters a year... for the last hundred years, and so that mean 30 cms of increase since 1900... and it's projected to basically... double that rate during the 22nd century.

You already see evidence of the beaches... retreating in certain areas, like Eleuthera.

There's nothing really you can do about it.

Except, you know build your houses higher, that's only a short term measure.

The biggest impact perhaps is on the aquifers, the freshwater aquifers.

So where do they get their freshwater from?

eventually all the aquifers will be inundated... with marine water and then the only option is desalinization... really or to collect water from rainfall.

♪ The Bahamas Islands are flat, lie out in the middle of the ocean... and have a relatively small population.

It turns out it's an ideal place to do climate science.

What they are finding is something... of great importance to people in the Bahamas and to all the low lying areas throughout the world.

And we ignore them at our peril.

Join us next time on in the americas with me, David Yetman.

Right along the border that separates Mexico from Southwestern Arizona, is a land of fire, ash and lava.

It's called the Sierra Pinacate.

For some people, it is a land of brutal heat and pitiless isolation.

This is vast.

For me, and many others, it's a wild land of unparalleled beauty ♪ When I was a boy I served a term as office boy... to an attorney's firm.

I cleaned the windows and I swept the floor.

And I polished up the handles of the big front door.

He polished up the handles of the big front door.

I polished up the handles so carefully that now...

I am the Ruler of the Queen's Navy!

I polished up the handles so carefully that now... he is the Ruler of the Queen's Navy!

This boy had made such a mark that... they made me the post of a junior clerk.

I wore clean collars and a brand-new suit... No that's not.....

I passed examinations for the institute.

Funding for In the Americas with David Yetman was provided by Agnese Haury Funding for In the Americas with David Yetman was also provided by the Guilford Fund.

Copies of this and other episodes of In the Americas with David Yetman are available from the Southwest Center to order call 1-800-937-8632 Please mention the episode number and program title Please be sure to visit us at intheamericas.com or at intheamericas.org