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The Oceans Link to Climate Change

An estimated 35,000 walruses are resting on land because the sea ice has melted Photo credit goes to: Corey Accardo NOAA/NMFS/AFSC/ANML.

An estimated 35,000 walruses are resting on land because the sea ice has melted
Photo credit goes to: Corey Accardo NOAA/NMFS/AFSC/ANML.

Hold on to your hats folks, we can all agree that most of the concerns about climate change have focused on the amount of greenhouse gases that have been released into the atmosphere. But in a new study a group of researchers have found that circulation of the ocean plays an equally important role in regulating the earth’s climate. Keep in mind this doesn’t mean global warming isn’t a man-made problem, please.

The researchers say the major cooling of Earth and continental ice build-up in the Northern Hemisphere 2.7 million years ago coincided with a shift in the circulation of the ocean – which pulls in heat and carbon dioxide in the Atlantic and moves them through the deep ocean from north to south until it’s released in the Pacific.

The ocean conveyor system, the team believe, changed at the same time as a major expansion in the volume of the glaciers in the northern hemisphere as well as a substantial fall in sea levels. It was the Antarctic ice, they argue, that cut off heat exchange at the ocean’s surface and forced it into deep water. They believe this caused global climate change at that time, not carbon dioxide in the atmosphere.

“We argue that it was the establishment of the modern deep ocean circulation – the ocean conveyor – about 2.7 million years ago, and not a major change in carbon dioxide concentration in the atmosphere that triggered an expansion of the ice sheets in the northern hemisphere,” says Stella Woodard, lead author and a post-doctoral researcher.

Their findings, based on ocean sediment core samples between 2.5 million to 3.3 million years old, provide scientists with a deeper understanding of the mechanisms of climate change today.

The study shows that changes in heat distribution between the ocean basins is important for understanding future climate change. However, scientists can’t predict precisely what effect the carbon dioxide currently being pulled into the ocean from the atmosphere will have on climate. Still, they argue that since more carbon dioxide has been released in the past 200 years than any recent period in geological history, interactions between carbon dioxide, temperature changes and precipitation, and ocean circulation will result in profound changes

Scientists believe that the different pattern of deep ocean circulation was responsible for the elevated temperatures 3 million years ago when the carbon dioxide level in the atmosphere was arguably what it is now and the temperature was 4 degree Fahrenheit higher. They say the formation of the ocean conveyor cooled the earth and created the climate we live in now.

“Our study suggests that changes in the storage of heat in the deep ocean could be as important to climate change as other hypotheses – tectonic activity or a drop in the carbon dioxide level – and likely led to one of the major climate transitions of the past 30 million years,” says Yair Rosenthal, co-author.

The study is the first of it’s kind to suggest that the ocean currents  and not just CO2 in the atmosphere has caused climate change in the past. Keep in mind that they stop short of saying that the climate change we are experiencing now has been caused by the same mechanisms. I strongly urge any of my readers to remember that we do have a huge role in the shaping of our climate and the research behind that is still very sound.

The paper is merely offering another link in the complex web of our planet, not suggesting that we say “screw it”, and start burning more coal and oil. Even if we could, do we really want to go backwards instead of forwards?

Sources
Woodard SC, Rosenthal Y, Miller KG, Wright JD, Chiu BK, & Lawrence KT (2014). Antarctic role in Northern Hemisphere glaciation. Science PMID: 25342658

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