If all the salt in the ocean could be removed and spread evenly over the Earth’s land surface it would form a layer more than 166 metres thick – about the height of a 40-storey building. Adam Smith discovers why the salt of the Earth is so important.
Adam Smith: I don’t know about you, but, yum, I love a bit of salt on my fish and chips. And vinegar of course. Salt and seafood go hand in hand, perhaps because they’re both from the ocean. By some estimates, if all the salt in the ocean could be removed and spread evenly over the Earth’s land surface it would form a layer more than 166 metres thick – about the height of a 40-storey building. That’s a lot of salt, and it’s what I’m looking at in this podcast. I’m Adam Smith. Welcome to Pod Academy.
In addition to seasoning my fish and chips, the oceans’ saltiness, or salinity, plays another key role.
Liesl Hotaling: It’s a main driver of the physical processes in the oceans. Saltier water is more dense and that will start driving ocean currents in certain ways. Critters like different saltiness in different ways, so you’ll find different critters in different oceans, so it’s a very rudimentary and important parameter in the ocean to study.
AS: Liesl Hotaling is based at the College of Marine Sciences, University of South Florida. With salinity such an active driver in ocean behaviour, it’s important that the public understands that it’s not just about ‘shake to taste’.
LH: But then it also makes a very nice transition into reaching out to the public because it is a parameter, if you will, that he public can understand very easily. They understand salty, they understand not salty. So it’s a very easy way to kind of coax them into learning about the data.
AS: And there’s plenty of that. Like a toddler liberating crabs from a rock pool, oceanographers are collecting buckets and buckets of data on salinity – they can now even taste the sea’s saltiness from a great distance.
Eric Lindstrom: We launched the Aqaurius satellite last June to measure salinity from space.
AS: That’s Eric Lindstrom, physical oceanography programme manager at NASA headquarters in Washington, DC. I sat down with Eric at a recent oceanography conference in London to hear more about Aquarius. How does it measure salinity from space?
EL: Salinity is normally measured from a ship. We measure the conductivity of seawater. Well, we can get a estimate of the conductivity of the seawater from space. As the conductivity changes, the microwave emissions change and we put a very sensitive radiometer in space that measures the microwave emissions from the sea surface and we can back that out into a salinity estimate. It’s very daunting remote sensing measurement. We have to have a very sensitive radiometer and we have all sorts of conflicting issues: the roughness of the surface, the temperature of the surface, the galactic background radiation.
AS: Aqaurius is up there producing all this data. Who is using that data and for what purpose?
EL: At the moment, it’s just being used by salinity scientists trying to understand the measurement itself. It’s not quite ready for prime time yet but the reason it’s flying is to understand the water cycle on the planet, among other things. In this warming world that we have, the oceans are warming, the atmosphere’s warming, there’s the idea that the water cycle on the planet will accelerate, there’ll be more moisture in the atmosphere, more precipitation, more cycling of water through the system. And the ocean can be kind of integrated gauge for that – changes in salinity can indicate changes in evaporation and precipitation over the ocean.
In fact, if you look back over all the measurements that have been made from ships over the last 50 years and you map the changes in salinity you actually find that most of the saltier places in the ocean surface have gotten saltier and the fresher places have gotten fresher, which is exactly the fingerprint that you would think to see in an acceleration of the water cycle. So Aquarius is coming along ocean scientists are trying to diagnose if this is really true, that there is an acceleration. We have to like a doctor doing diagnostics on a human, we have to rule out other diseases so what we’re trying to do with salinity here is rule out that it’s not ocean processes fooling us to make it look like an acceleration of the water cycle.
AS: As Eric said, because Aquarius is not even one year into its new job tasting salt from orbit, the little satellite isn’t ready for prime time yet. Scientists around the world who are working with NASA to calibrate the data before they can start to use it properly for research purposes are due to meet in Buenos Aires in April, when they’ll decide how to start releasing the data. The wait is only heightening oceanographers’ enthusiasm…
Zdenka Willis: That’s just really exciting.
Scott McLean: It’s pretty cool.
LH: It’s quite amazing.
AS: One reason why the seadogs are so excited is because data on salinity can feed into research on another phenomenon that is affecting many residents of the ocean, including one our favourite seafoods.
ZW: Do you like to eat oysters?
AS: Yes, very much.
ZW: So we have an issue on the west coast of the United States that all of a sudden we raise the oysters and have the larval, they weren’t setting on the oysters and we had no idea why. And in 2005 we lost almost 80% of our crop and as it turned out it’s because the water had changed, the chemistry of the water become more acidic.
AS: That’s Zdenka Willis, who isn’t trying to put us off oysters – on the contrary! Zdenka is the director of the Integrated Ocean Observing System, or IOOS, a US agency that is part of the National Oceanographic and Atmospheric Administration, NOAA – the NASA of the oceans. Zdenka’s agency, IOOS, collates data on the oceans to help scientists, officials, residents and business people improve safety, grow the economy and protect the environment. So: she wants oysters and other ocean dwellers not to be threatened by acidification.
Now, I may like a splash of acetic acid, vinegar on my fish and chips, but acid in the ocean is another matter altogether. Yum.
About one quarter of the carbon dioxide we pump into the atmosphere is absorbed by the oceans. This leads to chemical reactions that make seawater more acidic which, among other things, makes it difficult for all sorts of sea critters to grow their shells. This is what was happening to the oysters on the west coast of the United States, when IOOS scientists stepped in.
ZW: As we started to have this dialogue with our oyster growers, we said we’ll we need to be able to observe what’s going on. So in fact we have worked with our group, our IOOS group out in the northwest and our Pacific Marine Environment Lab of NOAA to come up with sensors, where we can actually sense the water. They talk about bringing in good water or bad water, because you can’t replicate seawater very well, so you use the natural water. With the observing system we monitor the data for them, we have actually put up oyster pages, if you will, on our website and they monitor when they’re going to take water in which is good or bad and last year they were back up to 80% production.
AS: Of course, the oysters on America’s Pacific coast are the lucky ones. Acidification remains a huge problem elsewhere in the world – the Arctic Ocean is especially susceptible. So researchers are continuing to study it, and now they have a new helper: Aquarius. Here’s Eric Lindstrom again.
EL: One of the things that people studying ocean acidification want to know is the surface salinity because the dissolution of CO2 in the ocean is a function of salinity as well as temperature. And so we have a lot of interest from the ocean acidification scientists in our Aquarius measurements and I’ve actually funded people to try and work on the CO2 cycle with the Aquarius data.
ZW: What we’re trying to do from the observing perspective is get the instrumentation out there with these partnerships so that the scientists can actually understand what is going to happen. The shells for the oysters – it’s calcium, what’s that acid going to do, and what’s it then going to do for our beaches and coral reefs? So that research is just in its infancy. What we’re hoping to do from the observing capacity is provide the data for the scientists to do the research.
AS: Studying the ocean normally provides plenty of work for scientists who are looking at long-term changes in factors such as salinity and pH. But occasionally one single event can require second-by-second analysis in real time. When the Deepwater Horizon oil rig exploded in the Gulf of Mexico in 2010, for oceanographers it was all hands on deck.
Deepwater Horizon shows just how far technology has come in oceanography. The US has a network of high-frequency radars – which are just about to be hooked up with similar networks around the world – trained on the oceans, and banks of automated unmanned vehicles, little subs that swim about making measurements.
ZW: We were able to bring all of this capacity and technology in a coordinated fashion to a crisis. You can’t just show up at a crisis. What we were able to do was to bring this high frequency radar which was in the gulf, making sure that it was used by NOAA for their daily tracking of where the oil was on the surface. We did have to understand the sub-surface oil, which was a new phenomenon with Deepwater Horizion.
So we sent an individual down there from my office to coordinate the oceanographic sensors, most particularly the gliders, so seven of the nine gliders were brought to the community by this non-federal US IOOS partnership with new sensors on board these gliders that could measure carbon dissolved oxygen matter, CDOM, so what we were really able to do was understand the ocean state and most importantly where the oil wasn’t, so we could direct the high-value assets, the ships, to where the oi lwas for that clean up.
AS: As Zdenka implies, this network of 128 high-frequency radar units, which IOOS coordinates, is becoming more and more useful. And the data collected might be used in some surprising areas.
ZW: We’ve had a lot of solar activity here recently and because this is a signal that’s going out through the atmosphere there’s another group that through software they’ve developed they’re actually monitoring this solar activity, through CODAR. Who knew? And then we talk about marine protected areas, and what are the resources that we need to protect. So we can monitor from where water comes to and from and that doesn’t sound like its that important but if you’re looking at larval transport, which is what our ecosystems depend on, that food, we can kind of see where the water particles are moving and what areas of the world that we need to protect.
AS: There are many more examples of innovative ocean research going on around the world. In fact, we might be on the verge of a new era, according to some…
SM: Hi, I’m Scott McLean. I’m the director of ONCCEE. It’s a centre of excellence for the commercialisation of ocean research in Victoria Canada.
AS: As the nation with the longest coastline in the world, Canada pours money into ocean research. So in 2009 the government established ONCCEE to make sure the money also led to socio-economic benefits through commercialization and outreach programmes. As such, its director, Scott McLean, has somewhat of a birds-eye view of ocean research.
SM: Ocean research I’d say is in a transformative phase. Most of the 20th century we were cruising around in ships taking measurements and we get these tiny little snapshots of what was happening in the ocean and really it doesn’t give us a very good picture. Then with satellites you get the broader picture but what we lacked was the temporal scale.
And now we’re getting that with the newer technologies. Ad the key ones there are the cabled observatories, which provide very high data rates, video and acoustic – things that allow us to visualise the environment. But also AUVs and remotely operated vehicles that can actually go out and replace ships. And that’s really the trend I think in the future, less research ships, more autonomous vehicles, more cabled observatories.
AS: So AUVs, or automated unmanned vehicles, will be part of the future. I took a look around the London conference and came across one such little robot. It looked to me like a torpedo, broken apart with its guts spilled across the table.
I’m here in the busy exhibition hall at Oceanology International and I’ve just met Andy, who graduated from Cambridge but is still involved in a project that Cambridge University is doing at the moment. Andy, tell us what this instrument that I’m looking at on your table is.
Andy: So this is the start of our new AUV which is going to be called Barracuda. It’s going to be a shallow water AUV for operation up to about 80m with a number of sensors on it. So we’re going to have a forward-facing camera, upward-facing camera and downward-facing camera, and a multi beam sonar which has kindly been provided by Tritech. And it’s also got a vector thrust configuration, which means we can move in five axes.
AS: What are the applications for this kind of machine?
A: So the machine that you’re looking at here is designed for shallow water so that can include environmental surveys, pipelines surveys, anything shallow water where you want to look at something over a long distance basically.
AS: Do you work with any oceanographers or ocean scientists who actually tell you what you need from an AUV?
A: Yeah, there’s various departments in Cambridge that have uses for AUVs. So one is the Scott Polar Institute. We’ve spoken to them several times and then we’ve also got unversity adviser from the applied mathematics department who works in studying the oceans and studying ice caps, so one of our applications is going to be to study the Arctic ice and how it changes over time.
AS: Such adventurous research projects are, of course, connected to what many scientists describe as the biggest problem of our time – climate change. I asked Scott whether we’re joining the dots as well as drawing the arrows… We all do those hydrology models at school, at least I remember drawing them with all the arrows going up and the arrows coming down. And yet climate change and climate science seems at the moment from the public’s point of view to focus on the atmosphere, really. Do you think that the oceans are connected in the public’s mind enough to what’s going on in the climate?
SM: No I don’t think the public’s mind there’s a good connection there. Of course, there’s a very significant connection.
AS: And he thinks it’s because we haven’t been very good at measuring CO2 in the ocean. Zdenka and her crew may have saved the oysters from acidification, but there’s still a long way to go…
SM: The problem we’ve had in the past is that we can measure CO2 in the atmosphere quite well. We can measure the CO2 in the ocean fairly well. What we can’t do is measure the result of that in terms of the pH of the water and that’s critical, so technologies for measuring things for ocean acidification has been very difficult. There’s new technologies becoming available and that’s really going to show what the increase in CO2 in the atmosphere is doing to the oceans because it’s going to radically change things.
AS: And plenty of research projects are planned. Although NASA’s Eric Lindstrom used to be an ocean-going scientists, today he rides a desk. But in September he’ll be back on the bridge on an expedition… to do with salinity…
EL: Now we have a research programme in the Atlanic starting in September 2012 and extending for a year. So we’re doing a salt budget in the middle of what is the saltiest place in the open ocean, to understand how it gets to be salty. There’s a water mass that’s formed there from the salty warm waters, so we’ll spend about 35 days at sea deploying a sensor web of various kinds of salinity measurements: we have gliders and profiling floats and surface drifters and moored current meters.
AS: And what will be your job on this expedition?
EL: My job will be your job, Adam. I get to be the blogger on this ship, so you know, I’m sort of out of practice will all the technical aspects of the hardware but I am pretty good at doing all the different jobs on the ship. But I thought that maybe in this day, everybody wants to know what’s going on out on the ship. We have an internet connection, so I can write every day, take pictures everyday, and send all this information back. And NASA.gov has an awesome PR machine and they’ve all volunteered to help me get the word out.
AS: What an adventure that will be! We’ll have to stay tuned for Eric’s updates but, in the meantime, when your taste buds enjoy fish and chips with a dash of salt, you can think about how important salinity in the ocean is – and how Aquarius is circling above us to taste it.
Don’t forget you can read the full transcript, find useful links and hear more podcasts from the science and environment faculty at podacademy.org or subscribe via iTunes.
(Seagull sound courtesy of inchadney.)
AS: Damn seagull took my chip!
- Pacific Marine Environment Laboratory
- Ocean Networks Canada Centre for Enterprise and Engagement
- NEPTUNE Project – Acabled Observatory in the North West Pacific
- VENUS Project – Acabled laboratory in the North West Pacific
- Oceanology International
- Scott Polar Research Institute
- Centers for Ocean Sciences Education Excellence – Networked Ocean World
- College of Marine Science, University of South Florida
- Aquarius Mission and Data
- TED video: oceanographer Kate Moran
- Cambridge AUV project
- Cambridge AUV project paper 2011