Sea levels are on the rise, mainly due to climate change. This rise is caused by melting ice sheets and glaciers, as well as the warming of seawater, which expands and takes up more space. But changes in sea level can also happen over millions of years because of geological processes that change ocean basins.
Research by Dalton et al. explored a time between 15 million and 6 million years ago. During this period, ocean crust production dropped by 35%. This was largely due to a slowdown in seafloor spreading, which deepened ocean basins.
The researchers examined various factors related to the ocean crust and found that this slowdown would have led to a sea level decrease of about 26 to 32 meters. This is a significant drop, comparable to what we might see today if the East Antarctic Ice Sheet melted away.
They also discovered that heat coming from beneath the ocean decreased by around 8% during this time. Near oceanic ridges, this drop was even more pronounced at 35%. Such a reduction in heat could have altered ocean chemistry in important ways.
Earlier studies from some of the same researchers suggested that the slowdown in crust production might have led to reduced volcanic activity and less greenhouse gas emission. If that was the case, the sea level could have declined by an additional 60 meters due to the cooling of water and the increased amount of water stored in ice sheets.
Although there isn’t a lot of direct evidence of sea level changes from the past 15 million years, the new calculations align well with existing data from coastal areas in New Jersey and Nova Scotia.
This research marks a significant step in understanding how plate tectonic movements can influence sea level over time. It provides finer details and more accurate interpretations than many previous studies.
You can read more about this research and its findings at Eos.org.
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