As ocean oxygen levels dip, fish face an uncertain future

[1] https://www.pnas.org/doi/10.1073/pnas.1909726116

Mass fishery death: "won't someone think of the seafood!"

We deserve this

That is one of those books, you hate that his vision of the future looks so plausible.

It is a shame that in recent years he went full an anti-vax with Covid even though he explained why that kind of thinking had issue in that very book. He has also started engaging in bizarre conspiracy theories about a lot of things.

As water heats, the solubility of gases (O2, CO2, etc.) goes down.

Humanity coming from initial blissful ignorance about CO2 emissions eventually became concerned about rising atmospheric CO2.

Most emitted CO2 was actually being absorbed by oceans. This also makes the ocean acidic.

So the oceans acted like a "landfill" buffering a large amount of CO2 emissions.

Consider a duplicate earth, where Carbon is added to atmospheric O2 oxygen molecules. As long as its surface waters are not saturated with CO2, it can buffer a large fraction of the resulting CO2, with an equilibrium constant between aqueous CO2 and atmospheric CO2. At a certain point this "CO2 landfill" or rather "CO2 seafill" saturates. Assuming for simplicity a constant CO2 emission rate, thus without increasing the rate of CO2 emission, atmospheric CO2 rises at an initial rate (slower than CO2 emission rate, since a large fraction is initially absorbed by the ocean surface waters); until surface waters are (near) saturation, at which point atmospheric CO2 starts rising at a much higher rate since the surface waters no longer absorb significant amounts of CO2.

If one then desparately and miraculously succeeds in somehow halting continued excess CO2 emissions, the globe will still heat due to the added atmospheric CO2, also heating these surface waters, decreasing gaseous solubilities, resulting not just in aqueous O2 depletion but also sadly in "CO2 blowback": the large fraction of CO2 historically dissolved in the surface waters turns back into the atmosphere, even though miraculously excess antropogenic CO2 emissions were halted!

From a "carbon credits" perspective, where players are traditionally viewed as nations and corporations, surface waters rear their head and releases the historical CO2 debth.

The primary hydrogen carrier in water is oxygen.

Are deoxygenation & acidification different problem, or different slants on the same problem?

Between catastrophic climate change and resource depletion, AI, the danger of nuclear war, COVID and other potential pandemics, economic insecurity for most of the population, and farmed irrational extremist political movements, we seem to have quite a lot to deal with.

Might as well just have Carrington Event 2.0 and be done with it.

Take ocean deoxygenation: it happens locally due to fertiliser runoff in places that have a history of low oxygen. It’s good to put some resources towards fixing this, but it’s not useful to think of it as an extinction level problem that we “now have.”

It's difficult to overstate just how quickly we are destroying the planet.

I spend a lot of time snorkeling and I tell my kids to really take in what they see because it probably won't be there when they're parents themselves.

Paperclips are at least real objects.

Money doesnt even exist if everyone isndead, its not real.

Everything else can be sacrificed as long as the line keeps going up (GDP, stock market, revenue, profit, share price - take your pick). No politician will risk doing anything that makes the line go down even if it boosts 'non line' metrics like happiness, health, social connections, free time, any environmental measures, home ownership, min wage)

Could spin it as an angry piece condemning the fossil fuel lobby, but that probably gets you cut off the next time there's a burning oil rig to report on.

From your wikipedia link:

---8<---

A study in 2020 estimated that the average global temperature during the warmest 200 year period of the HCO, around 6,500 years ago, was around 0.7 °C warmer than the mean for nineteenth century AD.

The HCO consisted of increases of up to 4 °C near the North Pole (in one study, winter warming of 3 to 9 °C and summer of 2 to 6 °C in northern central Siberia).[8] Northwestern Europe experienced warming, but there was cooling in Southern Europe.[9] The average temperature change appears to have declined rapidly with latitude and so essentially no change in mean temperature is reported at low and middle latitudes.

---8<---

So, the effect then was localized to the waters where there's more oxygen anyway, and having temperature going in different directions in different parts of Europe and at a much slower rate than current changes, would make it easier for the fish to migrate? Unclear how water temperatures behaved at different depths though.

It was not 1.5—4 °C warmer. Mean air temperatures around the peak of the HCO were less than 1 °C elevated relative to preindustrial temperatures and were below last decade's mean air temperature. And those aren't ocean temperatures. Regionally, surface waters around the great barrier Reef was ~1 °C elevated relative to modern day.

Anyway, the answer to your question is the rate of change since was much slower than recent temperature /pH changes. Populations, even sessile ones like corals can more successfully redistribute and move toward the poles to find optimal thermal conditions with a slower rate of change. And we are also putting the ocean under a few other confounding stresses like overfishing, eutrophication, acidification, coastal development and habitat loss, etc, which is novel territory relative to previous climactic shifts.

Also I'll note what might be a blip in the geological record in terms of fossil richness could still have profound consequences for species on which we depend on for economic livelihood and food security, e.g. say you have a well managed fishery harvested at close to maximum sustainable yield. If conditions change such that the environment rapidly shifts to support only 80% of the original carrying capacity due to growing OMZs, the fishery now needs to be managed such that it will support a lot less jobs and produces less food (or, mgmt doesn't adapt and the stock gets severely overharvested, and then the job and production loss necessarily follow).

> I suspect this balance between higher atmospheric CO₂ which leads to an increase in vegetation which then leads to an increase in oxygen production is what kept ocean life from succumbing due to oxygen deprivation.

The article mentions why this suspicion is wrong. In fact, proliferation of the main oxygen producing taxa in the ocean is one of the primary mechanisms that exacerbates oxygen minimum zones. Phytoplankton blooms, then dies, sinks, and get eaten by microbes that consume oxygen.

Life did not manage sudden changes of climate, there yave been 6 mass extinctions. 99% of spieces that have ever existed are now exticlnct and we are on an express to join them

A study in 2020 estimated that the average global temperature during the warmest 200 year period of the HCO, around 6,500 years ago, was around 0.7 °C warmer than the mean for nineteenth century AD, immediately before the Industrial Revolution, and 0.3 °C cooler than the average for 2011-2019.

(Scrubbing CO2 from the atmosphere would also work, but would take longer to address ocean acidification.)

1. stop overfishing by switching to plant based diets

2. stop fishing ... even fish we don't fish, but decimate (as bycatch) will rebound

3. stop fishing ... there won't be as much plastic to entangle fish, mammals and turtles (49% of great pacific garbage patch is fishing nets)

4. stop animal ag ... minimize agricultural runoff from farms and fields to stop creating dead zones in the ocean

5. stop animal ag ... use technology to reforest pastures and store all excessive carbon in them

6. reform agriculture ... use technology to improve ag methods and improve our soils, storing even more carbon in them

7. stop fossil fuels

8. give nature time to repair itself

9. enjoy healthy ecosystems, saved for future generations

Or explain the scorched earth to your children.

https://www.ebbcarbon.com is one company building it.

Fish do indeed often contain heavy metals (mercury, lead, cadmium, arsenic, copper), PCBs, dioxins, and furans, as well as microplastics.

Young dolphins are dying because the mother's milk may be poisonous for the same reason.

https://phys.org/news/2018-12-toxins-mother-young-european-d...

Banned toxins passed from mother to young in European dolphins

https://www.poisoningchildren.com/blog/2014/02/05/bioaccumul...

Bioaccumulation and Dead Baby Dolphins

"Because female dolphins off-load most of their toxic exposure to their first-born calf, their levels after sexual maturity are lower than males; but a very high percentage of first-borns die"

"It is not astonishing that native women in the Arctic Circle, who eat high levels of marine mammals, pass these chemicals on to their babies with dire effects"

"Childbirth and breastfeeding are some of the few ways the body can rid itself of persistent chemicals. It is usually still best to breastfeed, but children who are breastfed continue to inherit the mother’s exposures, as shown in a study of testicular cancer in Denmark and Finland"

Btw, human and cow milk has similar problems.