Comment by NeedMoreTea | Hacker News Reader

Comment by NeedMoreTea | Hacker News Reader

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Page 109 is a summary specifically relating to estuaries and semi-enclosed seas. There are multiple other summaries relating to other ocean types preceding it.

From the executive summary at the beginning:

The loss of oxygen in the ocean can broadly be put down to two overlying causes – eutrophication as a result of nutrient run-off from land and deposition of nitrogen from the burning of fossil fuels, and the heating of ocean waters as a result of climate change, primarily causing a change in ventilation with the overlying atmosphere so that they hold less soluble oxygen, and compounded by reduced ocean mixing and changes in currents and wind patterns. Ocean deoxygenation is but the latest consequence of our activities on the ocean to be recognized. Ocean warming, ocean deoxygenation, and ocean acidification are major ‘stressors’ on marine systems and typically co-occur because they share a common cause.

Then from Section 2.1, Global Evidence of ocean deoxygenation:

+ Open-ocean deoxygenation is resulting mainly from a warming ocean, increased stratification and changing circulation which interact with eutrophication-induced hypoxia (oxygen concentration below ~60 to 120 µmol O2 kg-1) and biological activity in shelf regions.

+ Oxygen loss is closely related to ocean warming and acidification caused by CO2 increase driven by CO2 emissions as well as biogeochemical consequences related to anthropogenic fertilization of the ocean; hence a combined effort investigating the different stressors will be most beneficial to understand future ocean changes.

Yes! That's the problem! Read the BBC article again: Do they mention that the 700 ocean sites are specifically related to estuaries and semi-enclosed seas? They don't? Hm.

I'm responding to something presented in the BBC article, something they mention context-free, because they want to(?) imply that the problem is related to open ocean temp changes, when... it's not. It's a problem of eutrophication.

It's still a man-made problem, maybe its exacerbated by additional forces, but its dishonest to paint it as if warming has caused these 700 dead zones. Warming did not. Eutrophication did. Most people who read this:

> While nutrient run-off has been known for decades, researchers say that climate change is making the lack of oxygen worse.

> Around 700 ocean sites are now suffering from low oxygen, compared with 45 in the 1960s.

Will think that climate change caused the 700 ocean sites, up from 45, and not run-off. It's how they are couching it. It is bad and we should scrutinize that.

But the whole report, and the whole article mentions both eutrophication and climate heating as joint contributors.

To take the part you criticise, the preceding sentence is "While nutrient run-off has been known for decades, researchers say that climate crisis is making the lack of oxygen worse.", and the following sentence "The threat to oceans from nutrient run-off of chemicals such as nitrogen and phosphorus from farms and industry has long been known to impact the levels of oxygen in the sea waters and still remains the primary factor, especially closer to coasts."

Are they painting that as warming? Not by my reading. Does every single sentence have to correlate to the title when most do? Hm. No.

Then the article goes out into the wider oceans and talks of deoxygenation there, and the lack of mixing. Suitably dumbed down for their target audience. Could they have spelt it out better whilst meeting the needs of their non-scientific audience? Probably - it's sloppily worded, which can be said about just about every science article in every mainstream publication.

But the core point remains - the report, and the article point to a joint cause, and from my fast skim of summary sections of a 500+ page PDF a majority of the problem stems from heating.

I think they are though. If someone says in succession:

"While X has been a known issue, we now know about Y making things worse"

"What was [a little bad] in the 1960's is now [really super bad]"

The implicit finger is pointed at Y, I think. I sincerely think that's the takeaway most audiences would get from a setup like this.

Maybe I'm being too hard on the article. But the really damning thing (700 dead zones) seems way too context-free for me.

Well if you read it in isolation, perhaps so. in context, the three sentences taken together, the last closing with "and still remains the primary factor, especially closer to coasts." seems to point to the correct main cause.

Sure it's sloppily written, but so is nearly every article on astronomy or medicine etc. But I'd generally like more science in my science reporting than I'm ever going to get.

And as it's a longer one, I wonder how much time they get to boil down a 500 page report to 1 page pop-science piece.

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