Over the past century, the burning of fossil fuels and other human and natural activities has released enormous amounts of heat-trapping gases into the atmosphere. These emissions have caused the Earth’s surface temperature to rise, and the oceans absorb about 80 percent of this additional heat.
The rise in sea levels is linked to three primary factors, all induced by this ongoing global climate change:
- When water heats up, it expands. About half of the past century’s rise in sea level is attributable to warmer oceans simply occupying more space. This process is called Thermal expansion.
- Large ice formations, like glaciers and the polar ice caps, naturally melt back a bit each summer. Recently, persistently higher temperatures caused by global warming have led to greater-than-average summer melting as well as diminished snowfall due to later winters and earlier springs. This imbalance results in sea levels rising.
- Increased heat is causing the massive ice sheets that cover Greenland and Antarctica to melt at an accelerated pace. Scientists also believe meltwater from above and seawater from below is seeping beneath Greenland’s and West Antarctica’s ice sheets, effectively lubricating ice streams and causing them to move more quickly into the sea. Moreover, higher sea temperatures are causing the massive ice shelves that extend out from Antarctica to melt from below, weaken, and break off.
Maryland’s coastal areas are experiencing land subsidence (sinking). Sinking land, continued glacier melting, and climate change are causing sea level rise to accelerate. Sea level rise rates in Maryland are nearly twice the global average. Sea levels are expected to rise another 3-5 feet by the year 2100.
Oceans will likely continue to rise as, but predicting the amount is an inexact science. A recent study says we can expect the oceans to rise between 2.5 and 6.5 feet (0.8 and 2 meters) by 2100, enough to inundate many parts of Baltimore. More dire estimates, including a complete meltdown of the Greenland ice sheet, push sea level rise to 23 feet (7 meters), enough to submerge massive portions of the city (National Geographic).