Scientists are Concerned about Mysterious Rise in Ocean Salinity

Researchers are concerned about rapidly rising ocean salinity Scientists have observed unexpected changes in the seawater salinity and they are increasingly concerned about the potential impact on ocean currents.  The salinity of seawater can accelerate the water cycle which can cause extreme weather events like floods and drought.

To investigate the issue of ocean salinity scientists have boarded the research vessel Knorr, which set sail on September 6, 2012. NASA’s Aquarius instrument is part of a separate research project that has been measuring seawater salinity from space since August 2011.

In addition to ocean salinity, researchers are exploring the water cycle which involves the ways that water circulates between the Earth’s oceans, atmosphere, and land. This process involves precipitation and return to the atmosphere by evaporation and transpiration.

Although seawater is not uniformly saline throughout the world, the vast majority of seawater has a salinity level between 3.1 percent and 3.8 percent. Ocean salinity has been stable for billions of years, however scientists have observed that the salinity of seawater has been changing over the course of the last five decades.

These changes in salinity are accelerating the water cycle. As global temperatures get warmer, evaporation increases, altering the frequency, strength and distribution of rainfall around the planet.

Salinity, water cycle, temperature and weather are interconnected phenomenon. Ocean salinity is important because it affects ocean circulation; this in turn affects ocean temperatures, which can alter the weather.

Seawater which is high in saline can cause radical alterations in weather patterns. Salty water has a tendency to sink while warmer water rises to the surface, this impacts ocean currents which then impact the weather.

Research published in the journal Nature in 2006, indicated that sudden decreases in temperature over Greenland and tropical rainfall patterns during the last Ice Age are linked to rapid changes in the salinity of the North Atlantic Ocean.

Decades of research has demonstrated that the salty parts of the oceans have become saltier and the fresh regions have become fresher. Many scientists claim they do not know why this is happening, but on Wednesday September 5, 2012, Ray Schmitt, a senior scientist at the Woods Hole Oceanographic Institution, told journalists that he believes global warming may be driving these changes.

“Climate is changing all the time, and some of that change is due to natural variation,” Schmitt said. “The 50-year trend we are talking about, most of us believe is really due to the general trend of global warming.”

A warming planet can accelerate the water cycle making dry regions drier and high rainfall regions wetter. Although factors like wind can affect ocean salinity, the primary factor appears to be evaporation caused by warming. According to NASA’s Salinity Processes in the Upper Ocean Regional Study (SPURS), we see 86 percent of global evaporation and 78 percent of global precipitation over the world’s oceans. The oceans have more evaporation as compared to precipitation, which makes the water saltier, whereas in areas where there is more precipitation, the water is fresher.

According to 2009 research out of the UK, big shifts in salinity may indicate severe droughts and floods, perhaps even accelerated global warming. This research suggested that the amount of salt in seawater is varying in direct response to anthropogenic climate change. The UK study further indicated that global warming is changing precipitation patterns causing increased evaporation in subtropical zones; more precipitation towards the poles and higher concentrations of salt in the North Atlantic.

Evidence that the world’s water cycle has intensified is contained in 2010 research published in the American Journal of Climate. According to this study, co-authored by CSIRO scientists Paul Durack and Dr Susan Wijffels, the surface warming we have seen over the past 50 years has penetrated deep into the ocean.

“This is further confirmation from the global ocean that the Earth’s water cycle has accelerated,” says Mr Durack.

The salinity of the oceans is also connected to CO2. Changes in the salinity of the oceans contribute to global changes in carbon dioxide as waters with more saline are less soluble to carbon dioxide.

We are all intimately connected to the ocean; it is the ultimate source of much of the water we drink and much of the air we breathe. The ocean directly feeds millions of people and absorbs a great deal of the air and water pollution. Our oceans are under threat but no single threat is more daunting than the acceleration of the water cycle caused by increased seawater salinity.

Richard Matthews is a consultant, eco-entrepreneur, green investor and author of numerous articles on sustainable positioning, eco-economics and enviro-politics. He is the owner of The Green Market Oracle, a leading sustainable business blog and one of the Web’s most comprehensive resources on the business of the environment. Find The Green Market on Facebook and follow The Green Market’s twitter feed.


Richard Matthews
Richard Matthews
Richard Matthews is a consultant, eco-entrepreneur, sustainable investor, and writer. He is the owner of THE GREEN MARKET, one of the Web’s most comprehensive resources on the business of the environment. He is also the author of numerous articles on sustainable positioning, green investing, enviro-politics, and eco-economics.

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  1. says: “It looks like the delusional quasi-science of Global Warming is finally going to be defeated and seen for what it actually is – a deadly policy of genocide and de-industrialization. This is what lies behind the Green Agenda, commonly known as Agenda 21.”

    The only thing missing from your conspiratorial assessments are the facts.

    The green agenda not about de-industrialization it is about retooling our economies so that we can emit less carbon (and other GHGs).

    • Sea levels have risen by about 8 inches in 140 years but as the climate warms the rate of sea level rise appears to be increasing. In very simple terms sea level rise is attributable to two major factors:

      1. Melting ice
      2. Thermal expansion (warmer waters occupy more space)

      Evaporation redistributes water it does not make it disappear. It falls back to earth (although it does not always make its way back to the sea),.

    • David – To augment Richard’s response, I’ve obtained an answer to your question from Scott Mandia, an assistant professor of physical sciences. Here’s his response:
      Sea levels are rising due to thermal expansion and the addition of water from land ice melt. Because the climate is warmer it is expected that many regions will experience increased evaporation due to higher temps. When this happens on the ocean surface the salt content increases. Of course, when land-ice melts the salt content decreased because fresh water is being added. Changes in salinity are regional because some regions get hotter and drier while others get hotter and wetter.

      An analogy: I have a glass that is half full. I begin to slowly add new water while I also increase the room temperature. Both the water level and the rate of evaporation are increasing.

    • In all the bull they put forth nobody says a word about the world’s largest river not reaching thier natural destinations the oceans. So it only makes sense that the salinity of the oceans go up . And if you raise the salinity the sun would more easily raise the Temps of the oceans. You can Google how many of the world’s oceans don’t reach the original destinations of the world’s oceans.

  2. Why not let go of the trillions of gallons of freshwater trapped by man made lakes? Would not dropping more freshwater? into the ocean lower the level of salinity? Would it not also allow more water to freeze creating bigger ice caps that would bring colder winds and temperatures? Since it’s freshwater that actually freezes? When my salinity increases in my saltwater fish tank it’s because of the freshwater being evaporated from it. I just add the lost freshwater and a little salt and it’s fixed. Now according to this article letting go of the trapped freshwater would do the same to the ocean as it does to my tank.

  3. What is the mean change of salinity over all the oceans? In what time period? How can one say that salinity has been unchanged for billions of years? Evaporation is known to leave concentrated mixtures of elements in the solution behind, the clouds drift over the land and wash more salt from The land masses into the ocean. There not being a known mechanism for removing more salt than the amount washed into the ocean by streams and other similar runoff means logically salinity nessicarily increases over time. If the weather cycles are increasing, then salinity also must be increasing. So, this should not be a shock. What is shocking to me is the lack of specificity on a website that is supposedly science based.

    • Thanks for the comment, James. Shocking? The author of this post cited and linked to his sources. Did you follow those references for the specificity you seek? This piece is several years old. Upon rereading it I’m not sure where, or if, the claim is made that ocean salinity has “remained unchanged for billions of years”.

      Have a look at the byline of this article and the “about” page for the site.


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