Two separate studies found that the activity of the undersea volcanoes intensified during ice-ages, but it slowed down during the following intermittent warm periods. A boost in underwater volcanic activity resulted in more carbon dioxide gas being released into the atmosphere, thus leading to an acceleration of the natural process of global warming, scientists reported.
Scientists based their findings on the data gathered from long-term analysis of the volcanic valleys and ridges on the ocean floor. Dr. Maya Tolstoy, the lead author of one of the studies said her team was amazed to learn that deep seafloor had so much to tell about “long-term climate cycle”.
Past studies had shown that new oceanic crust is constantly produced by the deep sea volcanic chains called spreading ridges, which are located along the line where tectonic plates meet. The magma spewed by volcanoes solidifies and creates the ridges and new crust. As tectonic plates move farther away, the new crusts sinks and form valleys between the volcanic chains (see image above). These two formations are the most visible features on oceanic floor.
Until now, scientists believed that the process of forming crust was constant throughout the geological ages, but the new findings show that undersea volcanic activity was linked to the pressure of the volume of oceanic water upon the volcanoes. And the volume fluctuated over long periods of time according to the amount of water resulted from the thawing of the planetary glaciers.
Tolstoy’s team analyzed the spreading ridge at the East Pacific Rise off the coast of Mexico. Scientists found that the thicker oceanic crust was formed when the sea level dropped due to a 100,000-year long ice age. A lower sea level triggered more energetic volcanic activity, so the resulting ridges were thicker, researchers explained. But the thinner crust was formed by slower volcanoes during periods of higher sea level caused by a global meltdown, according to the findings.
The results of the study were published this week in ‘Geophysical Research Letters’.
Another study analyzing the spreading ridges located at the Antarctic and Australia tectonic plates revealed the same mechanism: during periods of high sea level, undersea volcanic activity slowed down, but, when glaciers expanded and sea level was lowered, the volcanic activity got a boost. Researchers used a computer model to prove their theory, which was published Feb. 6 in the journal Science.
The computer model also suggested that the water’s weight affects how fast the magma, or molten rock, oozes at the spreading ridges.
Both teams of scientist currently think that the bursts in volcanic activity may accelerate the natural climate change over an ice age due to the large amounts of carbon dioxide gas released in the atmosphere. But more research is required to see how much of this gas can emerge from the ocean and cause a natural global warming.
Image Source: HNGN