Another climate lie bites the dust: 2018 Florida Red Tide caused by ocean circulation, not climate change

From the UNIVERSITY OF SOUTH FLORIDA and the Gilda Radner School of Universal Climate Blame comes this “never mind” moment. You may recall that last year, blaming Florida’s red tide event was the low-hanging fruit for journos, like Angela Fritz of the Washington Post “Capital Weather Gang” who, without any direct evidence, speculated breathlessly: How climate change is making ‘red tide’ algal blooms even worse

Except when you wait for the science to catch up to headlines, Angela gets to have a Gilda Radner moment.

Ocean circulation likely to blame for severity of 2018 red tide

ST. PETERSBURG, Fla. (April 18, 2019)- The harmful algae that causes red tide is currently at near undetectable levels in Florida waters compared with the much higher concentrations at this time last year. The red tide algae, Karenia brevis, causes respiratory issues, is responsible for massive fish kills and is often blamed for damaging tourism.

While traces of the bloom are always present offshore in the Gulf of Mexico, a new study published in the Journal of Geophysical Research-Oceans finds ocean circulation made 2018 the worst year for red tide in more than a decade.

By affecting the nutrient levels offshore, marine scientists at the University of South Florida (USF) showed that the ocean circulation played a controlling role. If nutrient levels offshore are high in spring due to the upwelling of deeper ocean waters, then there tends not to be major red tide blooms along the shoreline in fall. Such upwelling did not occur in winter and spring of 2018, allowing a new bloom to form offshore in spring and summer 2018. An upwelling circulation then set in toward the end of July, ensuring that the newly formed bloom would be carried to the coastline along the bottom where it reinforced what had already been in place from 2017.

Data collected along the University of South Florida glider track shows trajectories and depth of contaminated water particles as they traveled toward the coast.
CREDIT University of South Florida

Tropical Storm Gordon temporarily disrupted the upwelling circulation, allowing some of the new bloom to be carried to the Florida Panhandle. After the passage of Gordon, the upwelling circulation then allowed the bloom to be transported offshore at the surface to eventually be carried to the Florida’s east coast by the Gulf Stream. Thus, the rare occurrence of Karenia brevis at three different locations (Florida’s west, Panhandle and east coasts) may be attributed to the ocean circulation.

“This further demonstrates that the ocean circulation is the major determinant of Florida’s, Karenia brevis harmful algae blooms, dispelling the myth that land-based fertilizers are to blame,” said Robert Weisberg, PhD, Distinguished University Professor of Physical Oceanography. “While pollutants can exasperate an existing red tide, they are not the root cause.”

In addition to ocean circulation models, the team at USF and collaborators with the Florida Fish and Wildlife Conservation Commission (FWC) deployed an autonomous underwater glider for a near month-long mission. Its sensors detected relatively high chlorophyll and low oxygen levels near the sea floor, along with upwelling circulation. On-site sampling also helped pinpoint the initiation zone for all three regions to be the middle shelf some 30 to 50 miles off the coast from north of Tampa Bay to Sarasota Bay.

Weisberg and his colleagues have accounted for the occurrence or lack of occurrence of major red tide blooms in 20 of the past 25 years based on the ocean circulation conditions. While recent sampling shows very low concentrations of Karenia brevis offshore, which is not a cause for immediate concern, it is too early to speculate on what future conditions may be. Weisberg expects to have a better idea of the possible severity of 2019’s red tide season in mid-June.


The paper:

The Coastal Ocean Circulation Influence on the 2018 West Florida Shelf Kbrevis Red Tide Bloom


Blooms of the harmful alga, Karenia brevis on the west Florida continental shelf are thought to initiate offshore before manifesting as a nuisance along the coastline. Contributing to such blooms are a complex sequence of events occurring within oligotrophic waters, which in any given year may or may not be facilitated by the ocean circulation. Once initiation occurs, the delivery from the region of offshore origination to the region of coastline manifestation requires an upwelling circulation, whereby Kbreviscells are advected shoreward along the bottom. The 2018 K. brevis bloom was particularly intense owing to cells from the preceding 2017 bloom being reinforced by a newly formed bloom in 2018, a year when the offshore conditions in spring through early summer were again favorable for bloom development. As an event response to determine the potential for new cells to be delivered to the shore, a glider was deployed from 24 August 2018 to 17 September 2018 with a track line designed to map water properties over the hypothesized initiation region. The coastal ocean circulation during the deployment interval was generally upwelling favorable, but the passage of Tropical Storm Gordon temporarily disrupted this flow, after which Kbrevis appeared along the Florida Panhandle coast. Strong upwelling then reestablished and Kbrevis was subsequently observed along Florida’s east coast. We describe the glider deployment, the Kbrevis observations, and we use a numerical circulation model to account for the K. brevis manifestation as occurred along Florida’s west, Panhandle, and east coasts.

Plain Language Summary

We account for the intensity and location of the 2018 Karenia brevis red tide outbreak on the west Florida continental shelf by a combination of water property observations and numerical circulation model simulations. These confirm the initiation region being offshore, the manifestation region being along the shoreline and the delivery mechanism (from initiation to manifestation) being an upwelling favorable coastal ocean circulation. The intensity is attributed to the cells remaining in the manifestation region from the prior 2017 bloom being reinforced by cells newly formed offshore in 2018.

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April 24, 2019 9:18 am

Science intrudes and brings reality to breathless imagination.

Bill Powers
Reply to  ATheoK
April 24, 2019 9:39 am

As thinking people knew it would.

Reply to  Bill Powers
April 24, 2019 12:54 pm


paul courtney
Reply to  ATheoK
April 24, 2019 6:29 pm

ATheo: If Climate Scientists had run this, the “ocean circulation” would have been found to be man-caused. Seems this corner of the research world hasn’t been given the hockey stick treatment. Yet.

Richard Anderson
April 24, 2019 9:31 am

Perhaps, but climate change made Tropical Storm Gordon worse, which, in turn, made the 2018 Florida red tide worse.

Reply to  Richard Anderson
April 24, 2019 9:48 am

Exactly, and Hurricane Gordon was a consequence of Catastrophic Climate Change, so, ipso facto, the Red Tide was a result of CCC. (Do I need a /sarc?)

Reply to  Richard Anderson
April 25, 2019 6:29 am

Climate change does not cause hurricanes to get “worse” (if by that you mean what, exactly? maximum sustained wind velocity? total energy released? duration? minimum eye pressure? maximum economic damages?).

It has been shown repeatedly that a warming climate has NOT caused any increase in hurricanes or cyclones.

April 24, 2019 9:33 am

Yes but she’s only claiming “GW made it worse” . A conveniently non falsifiable claim.

Joel Snider
Reply to  Greg
April 24, 2019 12:10 pm

I was just about to post that very thing.

April 24, 2019 9:33 am

not this simple guys….

it needs iron from Saharan dust too…high nutrient levels with no iron, allow other plankton to out compete it

…low nutrient levels…with added Saharan dust….lets K. bervis out compete

Reply to  Latitude
April 24, 2019 10:28 am

Good point Lat. We did have prolonged instances of the SAL reaching our atmosphere in Florida prior and during this episode, now that you mention it.

Reply to  ossqss
April 24, 2019 10:39 am

…and we know that’s the trigger….”red” should be obvious

Iron feeds Trichodesmium, the favorite food of K. Brevis..and practically nothing else eats it….plus these guys are not looking far enough west….start off the SE coast of Texas and go from there

April 24, 2019 9:36 am

But… but… but the ocean circulation is controlled by climate change, doncha know?

Nicholas McGinley
April 24, 2019 9:39 am

Got into it several times over the past year with people who did not know a single thing about red tides, oceans, and who have never lived near the Gulf of Mexico, but who knew…KNEW…that red tide was caused by “climate change”.
And could not even begin to guess what eutrophication was, or how oxygen and nutrient levels interacted and water temperatures interacted with each other.
When told that these events have occurred over the entire period for which we have documentation, back beyond 100 years ago, this was news to these people, but it did not have any effect on their opinion, whatsoever.
Everything is either caused by or gets worse due to climate change, although only in the minds of the panic mongers and their oh-so-willing to be duped sycophants.

AGW is not Science
Reply to  Nicholas McGinley
April 24, 2019 10:31 am

If you really want to twist their closed minds into a pretzel, you can pile on with the fact that the ocean circulation has a lot more to do with the causes of climate change than “climate change.”

bit chilly
Reply to  AGW is not Science
April 24, 2019 4:52 pm

I wish someone would let the clowns making huge climate change related claims on the demise of Scottish Salmon at the moment know that.They also seem to ignore a huge increase in Grey Seal numbers in the last 30 years.With it now being near impossible to control seal numbers as most of the salmon netting rights have been bought out, the impact of seals on Scottish Atlantic Salmon is only going to get worse.

Tom in Florida
April 24, 2019 10:04 am

I believe one of the contributing factors that made the outbreak so bad and so long was the overflow of the sewer system in St Petersburg. It happened in the fall of 2017 with Irma and again after a period of very heavy rains in June 2018. The system is old and would cost too much to repair. All those nutrients flowed down the coast to my area polluting the waters which became dark and disgusting, signaling to me that there was more going on than just red tide. Those waters had been crystal clear through June. Of course, this news was squashed as one can imagine the law suits against St Pete if this was proven.
As the bloom grew do to these extra nutrients the dead fish started to pile up adding to the stench. It was one terrible summer and fall for the beaches.

April 24, 2019 10:05 am

Those living on the Florida West coast at the time of the outbreak, as I do/did, noted that there was a consistent pattern of onshore winds for many weeks/months in advance of, and during, the major red tide outbreak, helping to concentrate the surface algae bloom even further by pushing it onto the gulf shorelines and further into the bays and estuaries. That is an observation, not just a guess.

Another note is the dump, where they trucked all of the nasty tidal debris that was collected from the shorelines, was a real stink spot also. Can Red Tide survive a trip from the dump back to the Gulf via rain runoff?

Reply to  ossqss
April 24, 2019 10:58 am


oss, here’s the long version…..high nutrients cause algae blooms…K. bervis is not an algae…dinoflagellate, it needs something to eat… feeds on trichodesmium
High nutrients and iron (SAL) cause algae blooms…..low nutrients and iron cause trichodesmium blooms
Trichodesmium is a cyano that fixes nitrogen from the atmosphere..but it needs iron to do that…high nutrients and it’s out competed and smothered by algae that grows a lot faster

…low nutrients…Tcod fixes it’s own nitrogen…once a Tcod bloom starts it locks up nutrients giving it the advantage…and also locks up the iron

So all this garbage about global warming….pollution…is just that…..garbage

You need the combination of low nutrients…and iron…to kick off the Tcod…and that feeds the K. brevis

Reply to  Latitude
April 24, 2019 11:02 am

“Trichodesmium is a cyano that fixes nitrogen from the atmosphere.”…

…and that’s why red tide blooms always start way off shore….low nutrients

Reply to  Latitude
April 24, 2019 6:56 pm

Is there any thought, by anyone, to seed the Gulf with the required nutrient to offset the negatives of red tide on the tourist trade at my most favorite place on Earth, Captiva Island? Same thing for small salmon population in Scotland. It seems there was a large, unauthorized, seeding of the Oregon/Alaska salmon feed biota that almost overwhelming increased the salmon population on the North American West Coast. Zubrin, if I remember correctly. We already influence ocean productivity with our waste, why not encourage increasing the biota in the ocean with our largesse? A long time ago I read that the determining factor in ocean productivity is the area of hard surface for the lowest in the food chain to attach themselves to, which led to a large number of derelect ships, after cleaning, to be sunk to form artificial reefs. We can be positive in the survivability of the progeny of thes hard surface huggers. Big tuna love a good meatball mid ocean.

John E Ford
Reply to  Latitude
April 25, 2019 2:24 pm

That is a fantastic explanation. Thanks you. As a reef aquarium keeper for 30 years this makes perfect sense. Nitrogen fixing dinos are the food. Wow.
Also, had no idea that dust deposits from the Sahara added iron to the GOM.

Cool stuff.

April 24, 2019 11:11 am

For much of my career I was on standby for red tides (Karenia brevis). Spent about two weeks sitting at the desk each evening for a local TV station giving the latest report on levels off the SE Florida coast one year when it came “around the corner.” One of the problems we faced relative to public relations was that there are other red tide blooms in the world caused a different organism often triggered by pollution events. So the news media was always putting the evil humans as the cause. We would then spend weeks explaining how that wasn’t the cause. Even though pollution is often blamed we have known for decades that Karenia brevis was a naturally occurring phenomenon. We had a pretty good idea that they came inshore due to eddies encroaching on to the West Florida Shelf. What was bad about this past years red tide in Florida was the news media, politicians and several prominent professors connected the red tide with long standing pollution problems in Lake Okeechobee and the Indian River Lagoon. Of course a couple threw in climate change as part of the problem. One suggested that we could have people dying from the red tide. Let no good crisis good to waste especially if I can get grant money (sarc).

Reply to  Edwin
April 24, 2019 11:17 am

+1 Edwin….first they equate K. bervis with a algae bloom…then it’s impossible to convince them it’s low nutrients that cause it

April 24, 2019 11:13 am

Been living in Florida for 66 years and been seeing Red Tides for just as long.

HD Hoese
April 24, 2019 1:13 pm

Written records go back to 1844 last I read, upwelling suspected for quite a while, 1916 event recorded as really bad. Karenia brevis was cultured in the 1950s in Galveston, so about time, great to see it. They are rarer in Texas, not sure it anyone knows for sure, but upwelling is a long overlooked condition, especially may occur near TX/Mexico border. Recent paper on Gulf temperature inversions, more common than expected! A couple of red tides were coincident with floods.

Not sure of their panhandle connection, but upwelling off the NE Florida Coast long known.

Pop Piasa
April 24, 2019 6:14 pm

Here’s what happens when a science-ignorant hippie musician with a penchant for pessimistic prophecy decides to write a song about red tides…

April 24, 2019 6:46 pm

But did any of the persons then admit that they were wrong, or did the
Media do the same.

Of course not, so this is now in the publics mind as just another proof of
the facts about “”Climate Change””.


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Pop Piasa
Reply to  jasa backlink permanen
April 24, 2019 8:56 pm

is the above a spam bot?

Tom in Florida
Reply to  jasa backlink permanen
April 25, 2019 4:57 am

This makes more sense than AOC.

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