Thursday, January 29, 2015

New research reveals extreme oxygen loss in oceans during past global warming

Since this was caused by global warming, it could (will?) happen from global warming from any cause, including the increase in greenhouse gases as is happening today.

Jan. 29, 2015
Sarah Moffitt, ocean and climate scientist with expertise in the marine ecological consequences of abrupt climate warming

New research published this week reveals that vast stretches of the ocean interior abruptly lost oxygen during the transition out of the last ice age that occurred 17,000–10,000 years ago. This event was the most recent example of large-scale global warming, and was caused primarily by changes in Earth’s orbit around the sun.

Past climate events provide informative case studies for understanding what is currently happening to the modern climate system. For this research, marine sediment core records across the Pacific Ocean were used to reconstruct the subsurface “footprint” of dissolved oxygen loss during abrupt global climate warming.


Like most of the life on the planet, the large majority of marine organisms need oxygen to live. Most marine life, from salmon, crabs, to shellfish, respires oxygen and many forms are intolerant of low oxygen seawater. Low oxygen zones have been incorrectly referred to as “dead zones.” In reality, they are host to bizarre ecosystems of extremophiles: worms, bacteria, and specialized urchins and bivalves colonize these harsh environments.

But, importantly, few commercially significant species of fish or shellfish can live within the low oxygen zones. So, if you are a microbial biologist you might be very excited to find a low oxygen zone, but if you are a commercial fisherperson, that low oxygen zone represents a no-go environment for fishing.


The new research, which I led, found that entire ocean basins can abruptly lose dissolved oxygen in sync with other global-scale climate change indicators: temperature rise, atmospheric carbon concentration increases, and sea level rise.


Major changes in the distribution of oxygen are already underway in the modern ocean. Modern losses of dissolved oxygen have been detected in every ocean basin by oceanographers and modern instrumentation.


[From the same author]

“From a human perspective,” she added, “what I want is for my son to be able to grow up in a world that has as much abundance and beauty as I have known. I really think that our jobs as people is to care for the beautiful planet that we have in front of us and pass that richness and beauty off to the generations in front of us, and I am really deeply concerned that my son will not have the same kind of planet and environment to enjoy the rich experiences that I’ve had.”

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