How Ocean Currents Shaped Earth’s Climate in the Age of Dinosaurs

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A new study has revealed a previously unknown mechanism that influenced Earth’s climate during the Cretaceous period, when dinosaurs roamed the planet. The study shows how the movement of continents affected the ocean currents that carried warm water from the tropics to the poles, and how this impacted the temperature difference between these regions.

The Cretaceous Climate Puzzle

The Cretaceous period, which spanned from about 145 to 66 million years ago, was a time of high atmospheric carbon dioxide levels and warm global temperatures. However, geological evidence suggests that there was a significant increase in the temperature gradient between the poles and the tropics during this time, meaning that the poles were much colder than expected. This is puzzling because higher carbon dioxide levels should have warmed the whole planet uniformly.

How Ocean Currents Shaped Earth’s Climate in the Age of Dinosaurs
How Ocean Currents Shaped Earth’s Climate in the Age of Dinosaurs

Scientists have proposed various explanations for this phenomenon, such as changes in cloud cover, ocean circulation, or continental configuration. However, none of these factors alone could account for the observed temperature gradient.

A Novel Analytic Model

To solve this mystery, a team of researchers from the Hebrew University of Jerusalem and the University of Bristol, UK, applied a novel analytic model that they developed two years ago. The model focuses on wind-driven circulation at the ocean’s surface and highlights the pivotal role of ocean basin geometry.

The model allows the researchers to explore how large ocean swirls, called gyres, transport warm water from the equator to the poles. These gyres are driven by the wind and depend on the shape and size of the ocean basins. The model can also simulate how changes in ocean current patterns affect the surface temperature distribution.

A New Mechanism Revealed

Using their model, the researchers analyzed how changes in continental configuration during the Cretaceous period affected ocean gyre circulation and temperature gradients. They found that the movement of Earth’s continents during this time caused a slowdown in the large swirling ocean currents responsible for carrying warm water from the equator to the poles. This slowdown disrupted the way the ocean regulated its surface temperatures, resulting in a significant increase in temperature differences between the poles and the tropics.

The researchers compared their model results with computer simulations of ancient climates and geological data from the Cretaceous era. They found that their findings aligned well with both sources of evidence, providing a more comprehensive understanding of past climate dynamics.

Implications for Contemporary Climate

While the study primarily focuses on the Cretaceous period, it has implications for our understanding of contemporary climate systems. It highlights the importance of ocean gyres in shaping climate dynamics, both in the past and today.

The study also shows how sensitive Earth’s climate is to changes in ocean current patterns, which can be influenced by various factors such as wind, sea level, or ice cover. These factors can change over time due to natural or human-induced causes, such as global warming or geoengineering.

The researchers hope that their study will inspire further research on how ocean gyre circulation affects Earth’s climate over different timescales and under different scenarios.

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