Here’s what you’ll learn as you read this story:
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Research shows that the Pacific Hemisphere is losing heat faster than the African Hemisphere.
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Heat flows from the Earth’s molten interior, causing continental drift.
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The landmass holds more heat than the sea floor, indicating a past Pacific warm zone.
Scientists at the University of Oslo say one side of the Earth’s interior is losing heat much faster than the other – and the culprit is practically as old as time itself.
A study published in Geophysical Research Papers It uses computer models of the past 400 million years to calculate how “insulated” each hemisphere was by continental mass, a key property that keeps heat in instead of escaping it. The pattern goes all the way back to Pangaea.
Earth’s interior contains a red-hot liquid that warms the entire planet from the inside. It also rotates, generating both gravity and Earth’s magnetic field. This keeps our protective atmosphere close to the Earth’s surface.
Over the long term, this interior will continue to cool until Earth resembles Mars. What’s surprising about the study is how unevenly the heat is spreading, but the reason makes intuitive sense: Parts of the Earth are insulated by more terrain, creating something of a thermos layer that traps heat.
This contrasts with how Earth loses most of its heat: “Earth’s thermal evolution is largely controlled by the rate of heat loss from the oceanic lithosphere,” the study’s authors write. Why is this the site of the greatest damage? For that, we need a quick and dirty run-through of continental drift.
Earth’s mantle is like a convection oven that powers a treadmill. Every day, the sea floor moves slightly; New seafloor is born from magma erupting along continental rifts, while older seafloors crumble and melt beneath existing continental landmasses.
To study how Earth’s interior heat behaves, scientists modeled the Earth by dividing it into the African and Pacific hemispheres, then dividing the Earth’s entire surface into half-degree latitude and longitude grids.
The scientists combined several previous models for things like the age of the seafloor and continental position over the last 400 million years. Then, the team crunched the numbers to see how much heat each grid cell would contain over its long life. This paved the way for calculating the rate of cooling overall, where the researchers found that the Pacific side cooled much faster.
Accumulated mantle heat loss (oceanic + continental) over the past 400 Myrs. Areas above the Pacific and African large low shear velocity provinces are shown using blue and orange lines. The dashed, light-colored meridian indicates the division of the Pacific and African hemispheres. Carlson, et al. al./Geophysical Research Letters
The ocean floor is much thinner than the bulk of land, and the temperature inside the Earth is “quenched” by the vast amount of cold water above it. Think of the vast Pacific Ocean compared to the landmasses of Africa, Europe, and Asia—it makes sense that heat dissipates quickly from the world’s largest ocean floor.
Previous research into this seafloor impact only went back 230 million years, meaning the new model, which goes back 400 million years, nearly doubles the time frame studied.
There is a surprising contradiction in the conclusion. The Pacific Hemisphere has cooled about 50 Kelvin more than the African Hemisphere, but “the consistently higher plate velocity of the Pacific Hemisphere during the past 400 [million years]”Suggest the Pacific was Very hot at a certain moment in time.
Was it covered by a landmass at some point in the not-too-distant past, trapping more heat inside? There are other possible explanations, but either way, the high tectonic activity of the Pacific today points to a heat asymmetry. As the mantle melts, the plates can slide and slam together.
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