Climate Change

In Ancient Oceans That Resembled Our Own, Mass Extinction Was Triggered By Oxygen Loss

by Zachary Boehm, Florida State University

Roughly 430 million years ago, during the Earth's Silurian Period, global oceans were experiencing changes that would seem eerily familiar today. Melting polar ice sheets meant sea levels were steadily rising, and ocean oxygen was falling fast around the world.

At around the same time, a global die-off known among scientists as the Ireviken extinction event devastated scores of ancient species. Eighty percent of conodonts, which resembled small eels, were wiped out, along with half of all trilobites, which scuttled along the seafloor like their distant, modern-day relative the horseshoe crab.

Now, for the first time, a Florida State University team of researchers has uncovered conclusive evidence linking the period's sea level rise and ocean oxygen depletion to the widespread decimation of marine species. Their work highlights a dramatic story about the urgent threat posed by reduced oxygen conditions to the rich tapestry of ocean life.

See Full Article at Source: https://phys.org/news/2019-03-ancient-oceans-resembled-oxygen-loss.html

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Oceans Have Absorbed 60% More Heat Than Scientists Thought

By Olivia Rosane

Nov. 01, 2018 07:00AM EST

The landmark report from the UN's Intergovernmental Panel on Climate Change published last month warned that humans needed to reduce greenhouse gas emissions 45 percent below 2010 levels by 2030 for us to have a shot at limiting global warming to 1.5 degrees Celsius above pre-industrial levels.

Now, another study published in Nature Wednesday found we might have even less time than that. This is because the oceans have been absorbing much more heat than previously calculated, meaning the earth is more sensitive to carbon dioxide emissions than scientists thought.

"We thought that we got away with not a lot of warming in both the ocean and the atmosphere for the amount of CO2 that we emitted," research leader and Princeton University geoscientist Laure Resplandy told The Washington Post. "But we were wrong. The planet warmed more than we thought. It was hidden from us just because we didn't sample it right. But it was there. It was in the ocean already."

How Much More Warming Is This?

In the past 25 years, the oceans have warmed 60 percent more than previously thought.

What Does This Mean?

It means that policy makers now have even less leeway when it comes to reducing greenhouse gas emissions if they want to keep warming to 1.5 or even 2 degrees above pre-industrial levels. The findings reduce the total amount of carbon dioxide humans can safely burn before crossing those thresholds by 25 percent.

They also have implications for the ocean-related impacts of climate change: the health of marine life and the pace of sea level rise.

Read Full Article at Source: https://www.ecowatch.com/oceans-heat-absorption-climate-change-2617077826.html

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Climate Change Indicators: Oceans

Covering about 70 percent of the Earth’s surface, the world’s oceans have a two-way relationship with weather and climate. The oceans influence the weather on local to global scales, while changes in climate can fundamentally alter many properties of the oceans. This chapter examines how some of these important characteristics of the oceans have changed over time.

Read the full article at source:  https://www.epa.gov/climate-indicators/oceans

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