Researchers Find Global Cooling as Devastating as Global Warming for Marine Life

Global cooling can be just as detrimental to marine life as global warming, according to a new study.

Many studies have focused on the effects of global warming, Now, researchers have shown that a phenomenon called "global cooling" that occurred about 116 million years ago was associated with the loss of marine life.

The study was conducted by researchers from Newcastle, UK, Cologne, Frankfurt and GEOMAR-Kiel who found evidence of  major marine life loss when the earth experienced a brief cold spell during the mid-Cretaceous greenhouse period. The study also quantified the magnitude of the climate change.

For the study, researchers analyzed the geochemistry and fossilized records of marine species in the sediment core taken from the North Atlantic Ocean.

Global temperatures began to drop primarily after the super-continent, Pangaea began to drift apart, hence creating large oceanic basins. In the study, researchers showed how the rise of water bodies around continents reduced temperatures around the world by increasing the surface area for marine algae to grow. The dead algae were buried in the sediments and locked up a certain amount of carbon with them that reduced the atmospheric Carbondioxide. 

Low levels of the gas in the atmosphere led to a major shift in the carbon cycle with global temparatures dropping to 5 Celcius, about 2.5 million years ago.

This "cold snap" ended when intense volcanic activity in the Indian Ocean began adding high volumes of carbon back to the atmosphere. The warming began about 2 million years back.

The study shows that although research focuses on global warming, it is equally important to note that a global decrease in temperatures can dramatically affect marine life.

It is worth noting that the global cooling effect occurred over a period of a million years while human-induced global warming has occurred just over a few decades.

"As always it's a question of fine balance and scale," said Thomas Wagner, Professor of Earth Systems Science at Newcastle University, and one of the leaders of this study.

"All earth system processes are operating all the time and at different temporal and spatial scales; but when something upsets the balance - be it a large scale but long term natural phenomenon or a short and massive change to global greenhouse gases due to anthropogenic activity - there are multiple, potential knock-on effects on the whole system," Wagner added in a news release.

The study is published in the journal Nature Geoscience.