Ocean Lighting as a tool for marine Carbon Dioxide Removal

The Ocean Lighting project

Summary

Carbon dioxide is increasing in the atmosphere driving one of the fastest environmental changes in the Earth´s recent history. Cutting emissions will not suffice to limit global warming, and marine carbon dioxide removal (mCDR) should be urgently explored. Several mCDR technologies, such as iron fertilization or artificial upwelling were proposed to reduce atmospheric CO2. Other carbon sequestration processes such as the active flux, the carbon transported by diel vertical migrants (DVMs) remain underexplored. We have strong evidence that DVMs feed at night upon epipelagic zooplankton, except during the days around the full moon. During this period, DVMs remain deeper (below 80-100 m depth) to reduce predation risk, releasing epipelagic zooplankton from predation, allowing their biomass to increase during this antipredation window (APW). We propose to extend this APW using weak artificial light to promote a bloom of zooplankton as a new procedure for mCDR. During the extended APW, carbon from small cells typical of oligotrophic systems will be transferred through the food web into zooplankton biomass and into large sinking particles (e.g., fecal pellets) increasing passive flux. Switching off the light will allow DVMs to resume their normal migration, feed on the zooplankton crop transporting carbon to deep waters. This mCDR method will increase the efficiency of the biological carbon pump enhancing carbon sequestration. Indirect effects will also be studied to determine environmental impacts of this approach. In Ocean Lightingwe seek to answer: (1) Can we promote increased zooplankton biomass using weak artificial light to enlarge the natural APW? (2) Can this procedure provide the basis for a new mCDR approach without the addition of large amounts of substances (e.g., iron or lime) to the ocean? and (3) What are the ecological impacts of moon-like lights in the ocean? Ocean Lighting will change the paradigm of mCDR as this procedure is based on a natural process.

Ocean Lighting as a tool for marine Carbon Dioxide Removal

Oral communication presented at the "Marine Carbon Dioxide Removal emerging views and challenges", 56th International Liège Colloquium on ocean dynamics. Liège, Belgium, 26-30 May, 2025.

marine Carbon Dioxide Removal (mCDR)

Carbon Dioxide Removal and Emissions Offsetting

Climate change is the main problem facing humanity and the planet. The massive emission of carbon dioxide (CO2) and other greenhouse gases into the atmosphere following the Industrial Revolution is driving the most rapid environmental and social changes in Earth's recent history. A significant and urgent transformation of our economy is required. The use of renewable energy is the immediate solution to stabilize global temperature. However, even if we stop emitting CO2, a significant amount of this gas will still remain in the atmosphere. An important amount of greeenhouse gases will have to be artificially removed from the atmosphere if we want to maintain or reduce the planet's temperature. Furthermore, some sectors of the economy will find quite difficult the transition to renewable energy (e.g., maritime and air transport), so these emissions will need to be offset with specific technologies. The oceans have the greatest potential for storing carbon, as they represent 70% of the Earth's surface, but also because carbon could be exported and sequestered in the deep-sea, retaining large quantities of CO2 for hundreds or even thousands of years. Therefore, several marine carbon dioxide removal (mCDR) technologies have been proposed, such as iron fertilization, alkalization, artificial upwelling, and ocean lighting. These negative emissions technologies, currently being tested in parallel with renewable energies, should lead our planet and our society toward a sustainable environment.

Relevance for the Canary Islands

The Canary Islands should reduce its emissions to allow a balance between our greenhouse gases release to the atmosphere and the carbon storage on land and the deep ocean (Net-Zero). It is mandatory to promote mCDR technologies in order to offset emissions, but also to avoid the taxes imposed by the European Union for pollution. For instance, the ports, airports, and industry should reduce but also to offset emissions. If no action is taken, the result will be that many companies operating in our islands will relocate to neighbor countries (e.g., Morocco) to avoid EU taxes. The Canary Islands are one of the best places in the world to conduct and implement this mCDR research, avoiding additional costs for our economy. Its application could be carried out in a relatively short period. The Government of the Canary Islands should lead this research by implementing specific projects and negotiating with the EU to offset these emissions. The development of this research will result in significant cost savings for our economy.

Objectives

The overall objective of Ocean Lighting is to determine whether light is an efficient, safe, and low-cost solution for exporting and sequestering carbon by enhancing the efficiency of the biological carbon pump.

Sampling

Glider equipped with UVP6

Besides zooplankton nets and sediment traps, Ocean Lighting will use a glider equipped with the Underwater Plankton Proflier 6 able to record zooplankton abundance and biomass estimates, as well as the particle profile to assess passive flux.

Time-series Sediment trap

One of the objectives of the study is to know how an increase in zooplankton promotes an increase of large particles such as feca pellets, molts, and carcasses. Our hypothesis is that small cell typical of subtropical systems are converted in large particles due to top-down controls. We will use the 24 cups PPS3/3 sediment trap below the mixed layer in order to study the increase in passive flux.

Micronekton Optical Profiler System (MOPS)

We have built a video system equipped with different cameras to record micronekton species using infrarred lights. Estimation of mesopelagic fish biomass is nowadays a challenge as they are able to avoid samplers as they can see the promoted bioluminiscence at large distances (>15-20 m) in the water column. So, any camera mounted on a net, trawl, or rosette will generate bioluminiscence and these organisms will avoid them. Our system is able to record mesopelagic fish in a quite stable position in the water column avoiding bioluminiscence. In this way, mesopelagic fish will swim in front of the camera in their migration to the shallower layers or vice versa (see Video and Figure below).

MOPS

Mesopelagic fish passing in front of the MOPS at 176 m depth in the subtropical waters off the Canary Islands. Observe the diel vertical migration of mesopelagic fish just after sunset. The estimated biomass in a series of measurements provide evidence of higher values than assesed using nets or trawls (Hernández-León et al., unpubl.)

Indirect effects

We wonder whether illuminating the ocean could affect organisms from fish larvae to cetaceans.

Are cetaceans affected by ocean lighting?

Detections of sperm whale (Physeter macrocephalus) echolocation "clicks" during the different missions of the project MacPAM (Loro Parque Fundación and Canary Island Government, IP Cabrera-Gámez). The size of the marks is proportional to the number of signals grouped over a continuous time interval.

Ocean Lighting Efficiency

(Under construction)

The ocean is heavily illuminated

Lights produced by the squid fishery in the oceanic realm

Do we know what is the ecological impact of artificial lights in the ocean?

Remote sensing view of the illumination promoted by the squid fishery in the Pacific Ocean

IP candidate for Ocean Lighting

Santiago Hernández-León is a biological oceanographer at the “Instituto de Oceanografía y Cambio Global (IOCAG)” in the Canary Islands. He obtained the degree in biology in 1980 and received a Ph.D in Oceanography in 1986 from the Universidad de La Laguna (Canary Islands). He is professor (chair) of zoology in the Marine Sciences School at the “Universidad de Las Palmas de Gran Canaria”. He was Vice-Dean of this Faculty from 1994 to 1998, and Dean from 2004 to 2005, and at present Director of the IOCAG. His research interest is related to the effect of climate on the ecology and physiology of plankton communities. He is working on the role of micro-, mesoplankton, and micronekton in the oceanic carbon flux from the Arctic to Antarctica, but he is especially interested in the assessment of the biological carbon pump and how the ocean is exporting and sequestering carbon. He is also interested in the study of trophic cascades and how they affect the ocean biogeochemistry. At present, he works on the development of a new technology to remove and sequester carbon dioxide in the deep ocean.

¿Questions?

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