Florida and Alaska: A 5,000 Mile Connection

Anyone who has lifted a jug of water, or a cooler full of ice, knows that water, or ice, is pretty heavy. Now imagine the weight of a glacier sitting on land. How heavy must that be?

During past ice ages, glaciers reached further south, midway into North America. As temperatures warmed and glaciers retreated over time, the land experienced something called “isostatic rebound.” This is the rise of land masses that had formerly been under the enormous weight of glaciers and ice sheets. As ice melts, land that had been pressed down under the weight of the ice slowly “rebounds,” or rises, as it supports less and less weight. In recent decades, as we have seen the climate changing at a much faster rate than in the past, scientists are actually seeing this rebound effect occur before our eyes. Using GPS deformation measurements, as well as gauging tides and shorelines, scientists have directly observed that shorelines have been rising, and have also been able to determine that this has been occurring since around the time that the massive Glacier Bay Icefield began melting substantially.

Florida may not have any glaciers, but it is also experiencing isostatic rebound in a different way. Scientists have observed marine fossils in Florida’s limestone up to 250 feet above sea level. If sea level was never that high, the conclusion is that there must have been some rising of the ground itself. Geologists have been able to show that as Florida’s Swiss cheese-like limestone base slowly dissolves into networks of caverns and sinkholes over time, the land becomes lighter and rises upward.

Is there a connection between Alaska and Miami? They are on opposite sides of the continent, separated by nearly 5,000 miles. Alaska straddles the Arctic Circle, and Miami is close to the Tropic of Cancer. Alaska has glaciers and mountains. South Florida has coral reefs and the Everglades. But warming temperatures and climate change directly link these two regions in multiple ways.  As climate change raises global temperatures and affects precipitation patterns, Alaskan glaciers (and others around the world) are unable to maintain the balance of ice mass over time. And as that melted ice, which is cold fresh water, runs off the land and into the salty oceans, it raises the sea level – not to mention that it affects ocean temperature, chemistry, and circulation. Unfortunately Florida’s natural isostatic rebound due to the nature of the Swiss-cheese-like limestone under our feet is about 100 times too slow to protect against how fast sea levels are projected to rise due to glacier melting. And with much of coastal Florida very close to sea level, Alaskan glacier melt is a very real connection.

This is not the only way that Florida and Alaska are connected. Can you think of any other ways? Check back here and learn more about what the scientists here are studying, and how it might affect you and your environment, wherever you are!