Is the Melting of Polar Ice Caps Happening at an Accelerated Rate?

Since 1993, global sea levels have increased by 98 millimeters (nearly 4 inches) [source: NASA]. A significant contributor to this rise is the melting of ice caps in Greenland and Antarctica. NASA reports that these melting ice sheets account for one-third of the global sea level increase.

Icebergs and Rising Sea Levels

Icebergs are large pieces of glacial ice that detach from glaciers and enter the ocean. Due to global warming, glaciers are weakening, leading to more fractures and an increase in iceberg formation as ice breaks away more frequently.

Melting sea ice is often likened to ice cubes dissolving in a glass of water. Since melting ice cubes don’t raise the water level in the glass, how do melting icebergs contribute to global sea level rise?

Interestingly, the melting of sea ice in the ocean isn’t analogous to ice cubes melting in a glass. Glaciers consist of fresh water, which occupies more space than salty seawater [source: Huang]. Still, their effect is minimal compared to the massive ice sheets melting in Antarctica.

The Polar Ice Caps

Antarctica, located at the South Pole, is Earth’s largest ice-covered landmass, holding roughly 90% of the world’s ice and 70% of its freshwater. The ice sheet covering Antarctica averages 2,133 meters (7,000 feet) in thickness. If this ice sheet were to melt entirely, global sea levels would surge by approximately 61 meters (200 feet).

NASA reports that Antarctica is losing ice at a rate of 147 billion metric tons annually, a pace far exceeding earlier scientific predictions.

Unlike the South Pole, the North Pole lacks a landmass and is instead covered by a floating layer of sea ice. Arctic sea ice expands and contracts annually, with scientists monitoring its changes every September when it reaches its minimum extent.

Satellite imagery reveals that Arctic ice is diminishing at a rate of 12.6 percent per decade. Ice age is another critical indicator of climate change. In 1958, Arctic sea ice was primarily older and thicker. Today, over 70 percent of the ice is younger and thinner, classified as "seasonal," meaning it melts and reforms each year.

Greenland is home to a vast ice sheet, and its complete melting would raise global sea levels by an additional 7 meters (20 feet). Due to its proximity to the equator, Greenland experiences higher temperatures, making its ice more susceptible to melting. NASA states that Greenland is losing ice at a rate of 271 billion metric tons annually.

Rising Ocean Temperatures

Water reaches its maximum density at 4 degrees Celsius (39 degrees Fahrenheit). At temperatures above or below this point, water becomes less dense, occupying more space. As ocean temperatures rise, water expands slightly, contributing to the overall increase in sea levels.

The Intergovernmental Panel on Climate Change released a new report in 2019, outlining multiple scenarios for sea level rise by 2100. Their projections estimate an increase ranging from 0.43 meters (1.4 feet) to 0.84 meters (3.75 feet), driven by thermal expansion of oceans and the melting of glaciers and ice sheets. This rise is expected to severely affect coastal populations worldwide.