Robot probes the Red Sea’s carbon storage system


Research News


Warming waters and oxygen depletion in the Red Sea could slow the flow of organic carbon from the surface into the deep ocean where it can be stored, out of reach of the atmosphere. A KAUST team has used an underwater robot to investigate the little-studied mesopelagic, or “twilight,” zone, at depths of between 100 and 1000 meters.

The oceans absorb billions of tons of carbon dioxide (CO2) from the atmosphere each year that either dissolves or is transformed into organic carbon by plants and phytoplankton in the sunlit shallows (0 – 100m). Most of this organic carbon is converted back into CO2 by microorganisms as it falls through the mesopelagic zone, but some of it eventually sinks into the deep ocean, where it can remain for centuries.

Understanding what controls the fate of organic carbon at different depths could help scientists predict how the oceans will absorb and store atmospheric CO2 in the future. Malika Kheireddine and her team used an underwater robot equipped with bio-optical sensors to measure particulate organic carbon (POC) variations between the surface and the bottom of the mesopelagic zone in the northern Red Sea, where sea temperatures are rising particularly fast. “The Red Sea offers unrivalled opportunities as a natural laboratory for studying the impact of climate change on the fate of organic carbon,” says Kheireddine.

Throughout 2016, the device also measured water temperature, salinity, density and oxygen concentrations. “Our observations allowed us to estimate the rates at which POC is converted back into CO2 by marine microorganisms,” explains Giorgio Dall’Olmo, a co-author from the UK National Centre for Earth Observation, “and how these microorganisms are affected by temperature and oxygen levels.”

In the Red Sea’s warm and oxygen-starved waters, the conversion occurred mainly in the shallowest, most productive layer of the mesopelagic zone; only 10 percent of POC sank below 350 meters. “The conversion rates could be expressed as a function of temperature and oxygen concentration,” adds Kheireddine, “which could help us predict how climate change will affect these rates in the future.”

The team was surprised to find that more than 85 percent of POC was broken down within a few days of entering the mesopelagic zone, whereas the rest drifted for weeks to months before being consumed. There are multiple drivers of organic carbon transfer and transformation in tropical seas.

“Underwater gliders in the Red Sea are collecting continuous data that could reveal the effects of physical processes, such as eddies and coastal currents, on these biogeochemical processes,” says group leader Burton Jones, a marine scientist at KAUST.

“The fate of organic carbon in the oceans affects the global climate,” says Kheireddine. “Our findings will help refine models showing whether the amount of carbon sinking in the ocean is increasing or decreasing.” The deeper organic carbon sinks before it is converted to CO2, the longer it is likely to remain there, locked away from the atmosphere.


From EurekAlert!

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December 2, 2020 6:39 am

hey, I have a great idea…..let’s all plan some $c@m for a free dive vacation to the Red Sea

…the main outlier…..warmer and saltier than all the rest

Farmer Ch E retired
Reply to  Latitude
December 2, 2020 4:24 pm

I highly recommend it – was fortunate enough to snorkel in the Gulf of Aqaba in the late ’80s when my sister & family were living in Jordan. Way cool.

December 2, 2020 6:42 am

You mean Mother Nature can take care of herself?

December 2, 2020 7:01 am

There are huge gaps in our knowledge of how CO2 is dissolved in the ocean.


If global warming causes upwelling areas like the high latitudes or the equatorial Pacific to stratify, then the natural carbon dioxide that is normally released during venting may just stay in the deep ocean. Stratification might wind up having competing effects on the overall carbon cycle, with saturation slowing carbon dioxide uptake in surface waters, but also suppressing venting. link

The whole linked article is full of suppositions like the above.

When you look closely at CO2 processes in the ocean, you find huge uncertainties. In the face of that, the alarmists pretend to do a CO2 budget accurate to within one percent.

In the above quote, the idea of suppressing venting seems risible. Once again, we have a professional writer badly misunderstanding the science.

paul courtney
Reply to  commieBob
December 2, 2020 4:12 pm

commiebob: Well, they had to move their CO2 study to the deep ocean. If they were studying CO2 in the atmosphere, somebody might get the idea that it isn’t settled! Can’t have that kinda thinking.

December 2, 2020 7:36 am

“Warming waters and oxygen depletion in the Red Sea could …”

Stopped there.

Alasdair Fairbairn
December 2, 2020 7:43 am

All grant infused suppositions.

Ed Zuiderwijk
December 2, 2020 8:14 am

In the Red Seas warm and oxygen starved waters …. corals and other marine life thrive.

Bruce Cobb
December 2, 2020 8:21 am

The Warmatards are in a continual search for the Holy Grail of positive feedbacks which, they claim, will spell disaster for the planet. Sad to see to what depths “science” has sunk.

Ian W
December 2, 2020 8:32 am

Has anyone demonstrated warming of a volume of water using 3.7 Watts per square Meter of CO2 frequency infrared?

Around 75% of the Earth surface is water and at least another 20% of the surface is covered with transpiring plants. Infrared is absorbed by the first water molecule it hits and the extra energy added to surface molecules will allow them to evaporate faster taking latent heat of vaporization with them. The humid air just above the surface is lighter than dry air and will convect upward drawing in drier air over the surface further enhancing evaporation. The humid air will eventually rise to a level where the surrounding air temperature is low enough for the water to condense into water droplets releasing the heat from the surface well above the surface increasing the convection.

It is strange that there has been a lot of handwaving and thought experiments but nobody seems to have run a controlled experiment showing the effect of low level infrared in the CO2 band on the temperature of a volume of water. If the water is not warmed, as would seem to be the case, then the anthropogenic global warming hypothesis is falsified.

It would seem to be an extremely important experiment to run. Note not modeling – physical live experiment.

Null hypothesis: a volume of water irradiated by infrared in the CO2 frequency band at 3.7 Watts per Square Meter with still air above its surface at the water temperature, will reduce in temperature compared to an identical control that is not irradiated by infrared.

It is strange that the experiment has not been run. Perhaps it has and the result memory holed?

December 2, 2020 8:43 am

From the article:
“The team was surprised to find that more than 85 percent of POC was broken down within a few days of entering the mesopelagic zone, whereas the rest drifted for weeks to months before being consumed.”

From NOAA:

“The area between 200 and 1,000 meters (656 and 3,280 feet) is the mesopelagic or “twilight” zone. Light intensity in this zone is severely reduced with increasing depth, so light penetration is minimal. About 20 percent of primary production from the surface falls down to the mesopelagic zone. Consequently, the density or biomass of mesopelagic zone occupants is lower than at the surface, and mesopelagic organisms have an interesting variety of mechanisms that help them find food as well as avoid being meals for other species.”

So….. we’re talking 85% of the 20% that actually reaches that zone is broken down within days. And the rest drifts around for “weeks to months before being consumed”. So….none of the POC actually reaches the bottom to be stored?

Sounds like along with all of the other features that make the Red Sea an anomaly rather than the norm, this feature also makes it a lousy proxy for ocean carbon sinks.

December 2, 2020 10:09 am

Off Topic: Cramer, Overbye of the New York times reported yesterday that the “Arecibo radio telescope in Puerto Rico collapsed unexpectedly Tuesday morning, the National Science Foundation said.” Officials “said a 900-ton platform of girders and radio receivers suspended from mountaintop towers crashed into a 1,000-foot dish nestled in a valley below.” The “collapse came two weeks after the National Science Foundation said the telescope, a destination for astronomers perched in the mountains of Puerto Rico, was in danger of falling and would have to be demolished.” The cause “of the collapse was not immediately clear, but ‘initial findings indicate that the top section of all three of the 305-meter telescope’s support towers broke off,’ according to the foundation.”

December 2, 2020 10:22 am

“One of the UK’s best known architects Norman Foster has withdrawn from an environmental coalition in a dispute about the destructive role of aviation in the escalating climate crisis.
In his statement Foster called for a “sense of proportion and serious consideration of the facts” when discussing aviation’s impact on the climate crisis, pointing out aviation emissions account for 2% of the global total.”

Ian W
Reply to  Vuk
December 2, 2020 12:25 pm

That is 2% of the global human emissions total and now a lot less than that.

Gary Pearse
December 2, 2020 1:51 pm

Do they know that the Red Sea is a deep rift zone that split Africa off from Arabia in the Eocene and that it is still separating at about 1cm a year. The African continent is still rotating away – discernible even by inspection if the map! The Red is famous for ‘hot smokers’ on the seafloor with deposition of Zn, Cu and other metals in growing columnar carbonate structures.

Across larger areas of the central seabed are hot briny muds at 60°C! Yeah this sea is a wound penetrating the earth’s mantle so it is ‘warm’ and ‘polluted’. Yet, even in the hot smoker there are tiny shrimp and a whole ecology of critters able to withstand remarkable temperatures and base metal carbonates!

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