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Oceans suffocating as huge dead zones quadruple since 1950, scientists warn

Areas starved of oxygen in open ocean and by coasts have soared in recent decades, risking dire consequences for marine life and humanity

 

"Ocean dead zones with zero oxygen have quadrupled in size since 1950, scientists have warned, while the number of very low oxygen sites near coasts have multiplied tenfold. Most sea creatures cannot survive in these zones and current trends would lead to mass extinction in the long run, risking dire consequences for the hundreds of millions of people who depend on the sea. [...]"

Source: The Guardian

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Declining oxygen in the global ocean and coastal waters

Abstract.

"Oxygen is fundamental to life. Not only is it essential for the survival of individual animals, but it regulates global cycles of major nutrients and carbon. The oxygen content of the open ocean and coastal waters has been declining for at least the past half-century, largely because of human activities that have increased global temperatures and nutrients discharged to coastal waters. [...]"

Source: Science
Authors: Denise Breitburg et al.
DOI: 10.1126/science.aam7240

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Patterns of deoxygenation: sensitivity to natural and anthropogenic drivers

Abstract.

"Observational estimates and numerical models both indicate a significant overall decline in marine oxygen levels over the past few decades. Spatial patterns of oxygen change, however, differ considerably between observed and modelled estimates. Particularly in the tropical thermocline that hosts open-ocean oxygen minimum zones, observations indicate a general oxygen decline, whereas most of the state-of-the-art models simulate increasing oxygen levels. Possible reasons for the apparent model-data discrepancies are examined. [...]"

Source: Philosophical Transactions of the Royal Socie
Authors: Andreas Oschlies et al.
DOI: 10.1098/rsta.2016.0325

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Deep oceans may acidify faster than anticipated due to global warming

Abstract.

"Oceans worldwide are undergoing acidification due to the penetration of anthropogenic CO2 from the atmosphere. The rate of acidification generally diminishes with increasing depth. Yet, slowing down of the thermohaline circulation due to global warming could reduce the pH in the deep oceans, as more organic material would decompose with a longer residence time. [...]"

Source: Nature Climate Change
Authors: Chen-Tung Arthur Chen
DOI: 10.1038/s41558-017-0003-y

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Function of the High Seas and Anthropogenic Impacts Science Update 2012 - 2017

The Zoological Department of Oxford University has reviewed and synthesised major marine science findings which have been published since Rio+20 in 2012.

The purpose of this synthesis is to determine how our understanding of the ocean at an Earth System level, with a particular focus on the role of the high seas, has changed in the last five years.

Summary:

"During the last five years scientists have utilised novel technologies and methods to explore new locations and investigate both the fundamental processes of the ocean and the mounting anthropogenic impacts on the marine environment. Studies have highlighted the important functions that the high seas perform for the planet and have often focused on the complexity and interconnected nature of these processes."

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Report: High seas in high danger as ecological tipping point nears

"As delegates convene at the United Nations to work out an international treaty to preserve the biodiversity of the high seas, a new report underscores the need to protect the remote ocean.

Scientists at Oxford University in the United Kingdom reviewed 271 research papers published between 2012 and 2017 and synthesized the latest data on the impact of climate change, fishing and pollution on the high seas. Their findings are not encouraging: Even the most distant reaches of the ocean are suffering from chemical and plastic contamination, a loss of biodiversity and the consequences of rising temperatures. [...]"

Source: UPI

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