ocean carbon cartoon

Ocean Carbon Climate System Is Most Powerful And Important

The idea that the world’s climate changes the oceans is simply ‘bass ackwards’, it is the oceans that control the world’s climate.

The oceans are this blue planet’s most important “carbon sink”, helping manage both natural CO2 and those emissions from human activities.

A new study, published in Nature, reveals that loss of natural ocean cooling is changing the way they manage the world’s CO2.

It’s an obvious matter of scale, the earth and atmosphere manage 2,000 billion tonnes of carbon while the oceans manage 60,000 billion tonnes.

ocean carbon cycle pie

This science blog prefers the ocean-centric view of our Blue Planet’s carbon cycle as shown in this graphic

Strengthening ocean warming and thermal stratification, aka loss of plankton cooling, has reduced the amount of the vast reserve of CO2, the ocean carbon, contained in the deep ocean that was until recently reliably recirculated at the surface with the atmosphere. This has shifted the oceans climate control and is allowing the surface ocean to absorb more CO2 from the air.

That might sound like good news to the CO2/climate change community but it comes as desperately bad news for the oceans that make up 72% of our Blue Planet. The shift comes with parallel destruction of the ocean pasture ecology that converts deadly CO2 into ocean life, that added CO2 is becoming deadly acid instead of ocean life. It is the phyto-plankton of the world’s ocean pastures that are most important of all in keeping the oceans and the Earth in the ‘Goldilock’s Zone’. Follow Goldies link to read more about how life as we know it is able to survive and thrive here.

The authors of this Journal Nature paper dutifully use the profitable vernacular of ‘climate change’ in their ‘politically correct science’ commentary that punctuates the paper, a regrettable mistake on their part. But the science underpinning the paper is good stuff.

The popular terran-centric science posits that the oceans have absorbed about a third of the CO2 that humans have emitted into the atmosphere since the beginning of the Industrial Revolution. The terrans maintain that their world, the world of land, absorbs another third. That leaves the final third of humanities CO2 as the source of the climate crisis.

The vast cold Southern Ocean is a big part of the oceans for carbon storage – accounting for as much as 40% of the global ocean CO2 uptake. That’s simple physical chemistry as cold water can hold more CO2 than warmer waters. In the 1990s, strengthening winds circulating around Antarctica affected ocean currents, created more mixing at the surface, and brought more of the carbon-rich water in the deep abyss to the surface. This meant the surface ocean, in-spite of it being cold, was less able to absorb CO2 from the atmosphere as it was filled by the deep CO2.

In the 2000’s, the winds continued to be strong, yet the amount of atmospheric CO2 found in the Southern Ocean appears to have increased. This, combined with increasing presence of atmospheric CO2 in surface waters of other oceans, makes it clear there is are other potent factors affecting the ocean carbon capture and sequestration efficiency.

ocean CO2 cycling

Simplified conceptual diagram illustrating how changes in upper-ocean overturning circulation have affected the ocean CO2 sink. Figure shows the a) increased release and b) increased uptake of CO2 during the 1990s – with an overall reduced CO2 sink, and the opposite in the 2000s (c and d). Data show uptake/release of carbon (black) and the difference caused by the circulation change (red/blue), in billion tonnes of carbon. Source: DeVries et al. (2017)

The new study which focuses exclusively on the measure of new atmospheric CO2 vs. old CO2 in the oceans reveals changes in the circulation and exchange between the deep CO2 saturated ocean waters that make up 90% of the oceans and the top 1,000m of the world’s oceans. The researchers who are really mathematicians with an elegant computer model don’t go near the powerful biological carbon cycle of the oceans. It is the biology of life in the ocean pasture ecosystems that repurposes CO2 via photosynthesis into biological carbon that moves that carbon from the surface into the abyss. But it is useful to study the one side of the ocean carbon equation.

Ordinarily the mixing of deep ocean waters is limited by the fact that they are very cold and thus more dense. There is a natural division of the oceans into two parts, the cold dense deep waters and a warm layer that floats on that cold deep sea. The two oceans are divided by a remarkably distinct boundary layer, a wall preventing or at least greatly slowing the ‘immigration’ of the dangerous dark carbon carrying cold water into the warm lighted zone above.

Using years of observed data, the researchers built a computer model to simulate circulation patterns in the upper ocean. They ran their model to analyse the exchange of fresh CO2 at the surface and ancient CO2 at the surface to study how the ocean and atmosphere have been interacting over recent decades.

They found that in the 1990s, the ocean circulation patterns were “more vigorous” and coincided with a big dip in CO2 uptake. From around 2000, the circulation patterns then weakened, and ocean conversion of CO2 via photosynthesis and sinking also weakened, the combined forcing is seen as a rebound in the amount of fresh atmosphere derived CO2 in the surface waters.

In an accompanying “News & Views” article, Dr Sara Mikaloff-Fletcher, from the National Institute of Water and Atmospheric Research in New Zealand, writes:

“[The paper] is the first to robustly quantify the role of circulation change in the recent decadal shift in CO2 uptake, providing the missing piece of this puzzle.”  

As the strengthening stratification and weak circulation patterns continue, this will continue to promote the uptake of dangerous anthropogenic CO2 sink for some time is the conclusion one comes to in reading the paper.

But the absence of the most important biological processes of ocean ecology where photosynthetic conversion of anthropogenic CO2 from its harmful ocean acidifying form into safe, even beneficial new ocean life is utterly missing from the computer model.

Ocean Pasture Plant Life Are The Means By Which Oceans Control Our Climate

iceberg dust lichens

Iron rich dust accumulates in Antarctic Ice later to be released as icebergs drift and melt. Click to read more

Giant icebergs from Antarctica and their iceberg dust account for a vast amount of carbon dioxide captured and stored in the Southern Ocean, far more than was previously believed say a paper published recently in the scientific journal Nature Geoscience.

The research from the University of Sheffield’s Department of Geography studied the slow melting of giant icebergs, which contains an accumulation of aeolian, wind-blown, dust that contains iron and other nutrients vital to ocean pasture health and productivity. As the icebergs, both large and small, drift and melt in the seas around the frozen continent they leave broad green swaths of healthy vigorously growing ocean pasture phyto-plankton.

The researchers point out that of course these rich iceberg dust fed plankton blooms are responsible, via their photosynthesis, for absorbing enormous amounts of carbon dioxide from the atmosphere and converting that CO2 into phyto-plankton biomass that sustains the Southern Ocean ocean pasture ecosystem, feeds all of ocean life, and locks the ‘left overs’ for millennia into the frigid ocean abyss.

Ref: DeVries, T. et al. (2017) Recent increase in oceanic carbon uptake driven by weaker upper-ocean overturning, Nature, doi:10.1038/nature21068 Mikaloff-Fletcher, S.E. (2017) Ocean circulation drove increase in CO2 uptake, Nature