Tuesday, August 17, 2010

Struggling to breathe underwater

"Unless we find a way to rein in our carbon emissions very soon, a low-oxygen ocean may become an inescapable feature of our planet."

- Carl Zimmer, "A Looming Oxygen Crisis and Its Impact on World's Oceans".

Carbon dioxide emissions from human activities are destabilising the climate under which human civilisation has developed. That is well known and widely discussed. They are also acidifying the oceans ten times faster than during a mass marine extinct event 55 million years ago. That is less well-known, but possibly just as serious. But there is yet another global threat from rising carbon dioxide levels: a decline in oceanic oxygen levels. Not simply the local devastation caused in an increasing number of sites from fertiliser run-off creating marine "dead zones" starved of oxygen, but a global issue. Warmer water can hold less oxygen and warmer water is more stratified, making the mixing of surface oxygen with deeper water slower. Although the absolute drop in oxygen may seem slight (single digit percentages over many decades), this could have severe effects on many marine creatures for whom oxygen intake represents a primary limiting factor. The winners? Jellyfish and certain bacteria that thrive in oxygen-depleted conditions. The former are presently experiencing a population explosion (largely due to overfishing removing competition, amongst other causes). The latter are a source of yet more potent greenhouse gases.

Take a deep breath and read the full article.
"And God said, 'Let the waters bring forth swarms of living creatures, and let birds fly above the earth across the dome of the sky.' So God created the great sea monsters and every living creature that moves, of every kind, with which the waters swarm, and every winged bird of every kind. And God saw that it was good. God blessed them, saying, 'Be fruitful and multiply and fill the waters in the seas, and let birds multiply on the earth.'"

- Genesis 1.20-21.

Are we undoing creation and denying the blessing of God?


Peter Lockhart said...

Or to ask another question, 'so how is that dominion thing working out for us human beings in relationship to the oceans?'

byron smith said...

Yeah, not too well.

Heard a great quote the other day from a marine biologist: "We're fighting a war against fish. And we're winning!"

byron smith said...

Global fisheries worth $246 billion (Canadian dollars, I think) and tens of billions of damage being done every year through over-fishing.

byron smith said...

Sir David Attenborough has a new programme being aired on Monday called The Death of the Oceans on BBC2.

byron smith said...

DD: Jellyfish in Israel. I could multiply this story with other stories in many other places - Japan, Scotland, the USA and on and on. I probably need to do a post just on jellyfish sometime.

byron smith said...

Oh, I also meant to say that the invasion of this species from the Red Sea into the (previously less salty) Med has been facilitated by a 90% drop in the flow rate of the Nile over the last few decades based on megadams that lead to vastly increased evaporation rates and so to somewhat more salty water in the Eastern Med that previously, which opens it up to invasive species coming through the Suez Canal from the Red Sea. Fun and games.

byron smith said...

See Something New Under the Sun, chapter six for the references.

byron smith said...

Vancouver Sun: Jellyfish on the rise, a new study apparently contradicting this one, though I haven't looked at the details.