Ocean health is a key to healing the climate

Howard Dryden of GOES has an important message that is both chilling and provides reason for some optimism. It is about the sea surface microlayer (SML). This is a thin “skin” of 1 to 1000 microns on the ocean’s surface. The SML is populated by plankton, diatoms, and other micro-organisms and a complex mixture of carbohydrates, lipids, and proteins derived from these organisms.

Sea surface microlayer as a biochemical microreactor  (I) Unique chemical orientation, reaction and aggregation  (II) Distinct microbial communities processing dissolved and particulate organic matter  (III) Highest exposure of solar radiation drives photochemical reactions and formation of radicals . Image credit: Oliver Wurl; Werner Ekau; William M. Landing; Christopher J. Zappa (from Wikipedia)

Why is the SML important for healing the climate?

This microlayer contains a high concentration of phytoplankton – and they provide the bulk of our oxygen. Just one genus, Prochlorococcus provides about 20% of our oxygen. The SML regulates gas exchange in and out of the ocean. This is another example of the planet developing complex systems to maintain an equilibrium and a good place to live! Another function is to promote clouds through the dispersal of aerosols into the air.

In a 2022 paper, Howard Dryden and Dianne Duncan warn that human-created pollutants are degrading the SML. These include black carbon (what you see following a diesel-powered vehicle up a hill), microplastics including fragments from tires, incompletely treated sewerage, biocides, and forever chemicals. Lipid sunscreens can contain oxybenzone, which is toxic to coral and plankton at 62 parts per trillion. Is it a bit selfish that we use this stuff to protect ourselves from melanoma while it kills marine life?

The degradation of the SML has dire consequences for climate disruption. Here is an extract from the paper revealing this problem.

The main Greenhouse Gas (GHG) is water vapor, which accounts for 75% of all GHGs; the second most important is carbon dioxide, followed by methane and particulates such as black carbon (BC) soot. The concentration of water vapor in the atmosphere is regulated by air temperature; warmer conditions lead to higher evaporation, which in turn increases the concentration of water vapor, the Clausius-Clapeyron relation. This means that as the oceans and atmosphere warm, a self-reinforcing feedback loop accelerates the evaporation process to cause further warming.

…This SML layer is known to promote the formation of aerosols and clouds; it also reduces the escape of
water molecules and slows the transfer of thermal energy to the atmosphere. The concentration of water vapor is increasing in our atmosphere, and 100% of this increase is evaporation from the ocean surface; water vapour from land systems is decreasing.

What can we do about it?

Two pathways are available to regenerate the SML. The first requires detoxification of the planet. Unfortunately, some of the pollutants have a very long life, but the least we can do is to stop them going into the ocean. This will require a complete lifestyle change including:

  • Stop burning fossil fuels.
  • Manufacture tires from biodegradable materials.
  • Ensure all sewerage is completely treated.
  • Detoxify our diets.
  • Stop using biocides – encourage regenerative farming practices.
  • Use only natural fibres for clothing, textiles and carpets.
  • Phase out the use of plastics.
  • Use mineral rather than chemical sunscreens.

The interesting thing about this list is that everybody can participate. The flipside of reducing inputs of pollutants is to clean up what is already there. This is a mammoth task but there are significant plastics removal projects happening around the globe.

A second pathway is to promote plankton growth by, for example, fertilising the ocean with the iron essential for plankton photosynthesis. I am cautious about replicating single-element solutions given our abuse of the world’s soils, but this is a plausible short-term solution. Perhaps there are clean organic wastes that could serve the same purpose?

A reason for optimism

In this podcast Howard Dryden relates that 60% of biomass in the ocean is from micro-organisms. They have incredibly fast reproduction rates, so the ocean can theoretically double its biomass in a few days. This consumes lots of carbon and the energy required for photosynthesis.

For two long climate conversations have focused on land and sky and paid scant attention to the sea. With our attention and support she may well be our saviour.

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