Antarctica ice melt remains worrisome

We keep coming across reports saying that the Antarctica is melting due to global warming. Human activity has led to this phenomenon, and purging carbon from the atmosphere seems to be the only solution.

A study published last year showed the world could lose most of the West Antarctic Ice Sheet, which rests on the seabed and is fringed by floating ice, in a warmer world.

A recent report said the volume of water loss from Antarctica’s floating ice shelves over the past 25 years would fill the Grand Canyon.

The continent’s ice shelves were found to have lost nearly 4,000 gigatons since 1994 due to melting from increased heat in the ocean as a result of the climate crisis.

Although there was much variation in the rate at which the ocean is melting the ice shelves, overall the ice is melting faster than it is being replaced in Antarctica.

However, a new study gives a new twist to theories that abound over Antarctica and its melting ice sheets.

Antarctic ice is melting, contributing massive amounts of water to the world’s seas and causing them to rise, but that melt is not as linear and consistent as scientists previously thought.

The analysis, of 20 years’ worth of satellite data, shows that Antarctica’s ice melts at different rates each year, meaning the models scientists use to predict rises in sea levels might also need adjusting.

From 2016 to 2018, for example, the ice sheet in West Antarctica actually grew a bit because of a massive snow. During that same time period, though, the ice sheet in East Antarctica shrank because of melt.

“The ice sheet is not changing with a constant rate – it’s more complicated than a linear change,” said lead author Lei Wang, Assistant Professor at the Ohio State University in the US. A 2019 report said Antarctica’s annual ice losses have accelerated six-fold in the past 40 years in a trend that could push sea levels metres higher in coming centuries amid man-made global warming.

It remarked the East Antarctic ice sheet is thawing at the fringes and adding to rising seas, unlike many past reports which have concluded that the eastern sheet has so far resisted a melt seen on the western side.

Ice losses from the frozen continent surged to a net 252 billion tonnes a year in the period 2009-17 from an average 40 billion tonnes from 1979-90, according to the study in the US journal Proceedings of the National Academy of Sciences (PNAS).

Overall, the scientists said that the melt of Antarctica added water equivalent to 13.2 millimetres (0.5 inch) of sea level rise over the past four decades.

The study, published in the journal Geophysical Research Letters, is built on data from Nasa’s GRACE (Gravity Recovery and Climate Experiment), a two-satellite mission that measures changes in the world’s oceans, ground water and ice sheets.

Models that predict sea-level rise are typically built around the assumption that ice is melting from the world’s largest ice fields in Antarctica and Greenland at a consistent rate.

Overall, the researcher said, the volume of ice in Antarctica is decreasing. But a chart of the decline on a line graph would have spikes and valleys depending on what happened in a given time period.

To understand those changes, the team evaluated data on the gravitational field between the satellites over Antarctica and ice on the continent. Changes to the ice’s mass – either increases from big snowfalls or decreases from melt – change that gravitational field.

Whatever may be the theories, the fact is that like the pandemic, global warming does not seem to go away. It is here to stay.