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Across our planet, sea levels are on the rise.
And while our changing climate is a huge driver,
the movement of land, itself, is also an important factor.
Around 20,000 years ago, ice sheets covered large areas of our planet,
In many places, the weight of these massive ice sheets pressed down
on the planet’s crust and the viscous mantle underneath.
This weight caused the surrounding land to rise,
and the sea levels to fall relative to that rising land.
Over time, these ice sheets began to retreat
as part of Earth’s natural cycle of glaciation and melt.
and as a result, this land began to rebound.
Land rose up, and previously uplifted land sank, or subsided,
causing the sea level to rise relative to the ground.
This adjustment of the land in many previously glaciated regions
continues to this day,
particularly in areas like the East Coast of the United States.
Today, if we were to travel to a region like Greenland,
where massive ice sheets are now retreating due to a changing climate,
we can see the land readjusting in the same way to the lessening load.
This also alters the shape of corresponding ocean basins,
leading to additional subsidence along coastlines.
Subsidence also can result from human activity.
For example, we can see that many coastal cities rely on underground aquifers for fresh water.
However, when water is extracted, it causes sediment to compact
and the ground above to subside.
This leads to additional sea level rise for these communities.
We live on a dynamic planet that is constantly in motion.
And understanding the many drivers of sea level rise is critical
to anticipating and adapting to our ever-changing home.