The impact of Antarctic ice melt on future sea levels

The ground beneath the Antarctic Ice Sheet is on the move, and this rising earth could become a significant factor in future sea level changes, according to a recent study.

While it may seem like the solid ground is stationary, it's constantly deforming, sinking, and rising in response to environmental factors. In Antarctica, as the ice melts, the weight on the bedrock decreases, causing it to rise. How this rising earth will interact with the overlying ice sheet and contribute to sea level changes is not well understood, says Terry Wilson, a senior research scientist at the Byrd Polar and Climate Research Center at The Ohio State University.

A team of researchers at McGill University has developed a model to predict these interactions and their potential impact on global sea levels. If efforts to reduce greenhouse gas emissions are successful and global warming is slowed, the model suggests that the upward movement of the earth could reduce Antarctica's contribution to sea level rise by approximately 40%.

This scenario would significantly improve the best-case projections for global sea level rise. In this low-emissions scenario, the rising land would slow the flow of ice from land to ocean, allowing more of the ice sheet to remain intact.

However, if emissions continue unchecked, ice retreat will outpace the uplift, pushing ocean water away from Antarctica and exacerbating sea level rise. This outcome could significantly worsen the most severe projections for sea level rise along densely populated coastlines, according to Wilson.

“Our measurements show that the solid earth beneath the Antarctic ice sheet is changing shape surprisingly quickly,” Wilson explains. “The land uplift from reduced ice on the surface is happening in decades, rather than over thousands of years.”

This study, published in Science Advances, highlights how the earth beneath Antarctica is responding to environmental changes much faster than previously thought. The research team developed a 3D model of the Earth’s interior using geophysical data collected by the Antarctic Network (ANET) of the Polar Earth Observing Network (POLENET) project. This project focuses on studying the polar regions by gathering GPS and seismic data from an array of autonomous systems across Antarctica.

Using this model, the researchers ran several simulations to explore various possible futures for Antarctica’s ice sheet and the resulting global sea level rise through the year 2500. These simulations reveal the potential impact of different carbon emissions scenarios on the ice sheet and sea levels.

Wilson emphasizes the importance of these projections: “We can now project the difference that a low-emission scenario could make compared to the ‘business as usual’ emissions.”

One of the key strengths of the model is its detailed incorporation of data from Antarctica. GPS stations monitor land movement, while seismometers measure the speed of seismic waves from earthquakes, providing valuable insights into where land uplift is occurring rapidly or slowly. Wilson notes that the Antarctic Ice Sheet is currently experiencing solid earth uplift at a rate of about 5 centimeters per year—five times the rate seen in North America.

The study also explores how changes in Antarctica under different carbon emissions scenarios could affect coastlines worldwide. Because sea level change is not uniform, nearly 700 million people living in coastal regions around the world are at risk of being impacted by rising seas due to Antarctic ice loss.

Wilson stresses the importance of addressing environmental conditions like atmospheric and ocean warming to protect vulnerable regions, such as small island nations. “Many people are now more aware they’re experiencing the effects of climate change,” she says. “This work reinforces that our actions as individuals, nations, and globally can make a difference in what kind of Earth our offspring will experience in their lifetimes.”

The study underscores the complexity of the relationship between the solid earth and the processes occurring atop it, highlighting the need for continued data collection to make accurate predictions about our planet's future.

“There’s a lot of uncertainty in every model and every prediction,” Wilson acknowledges. “But to document how fast our world is changing, it’s crucial to keep advancing our ability to make predictions that are more certain. This is the only path that will allow us to tend to our future in a meaningful way.”

The findings from this research not only provide a glimpse into the future of our planet but also serve as a reminder of the critical role that human actions play in shaping that future. By understanding and addressing the factors that contribute to sea level rise, you have the power to influence the trajectory of climate change and protect the planet for generations to come.

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