Antarctica registers record marine melting – 02/16/2023 – Environment

Melting ice in the Antarctic sea has reached a new record, according to scientists at the National Snow and Ice Data Center at the University of Colorado Boulder (USA). On the 13th, the extent of sea ice in Antarctica fell to 1.91 million km², below the previous record of 1.92 million km², set on February 25 last year.

As the annual minimum usually occurs between February 18 and March 3, this index is expected to fall further in 2023.

Much of the Antarctic coast is ice-free, which exposes the ice shelves that line the continent to wave action and warmer conditions. This is the second year that Antarctic sea ice extent has been below 2 million km², a record in more than four decades of measurements.

The researchers point out that since the beginning of summer, ice levels have been well below average and last year’s records. “Climate conditions brought warm air to the region on both sides of the Antarctic Peninsula”, they explain. This caused the ice to melt almost completely on both the southwestern and eastern portions of the Antarctic coast.

The scientists also point out that the extent of Antarctic sea ice has been highly variable over recent years. Even though 2022 and 2023 were record lows, four of the five lowest melting levels occurred in the last 15 years.

Still, the sharp decline in sea ice extent since 2016 has been the focus of research investigating whether sea ice loss in the Southern Hemisphere is developing a significant downward trend.

On another front, two studies published this Wednesday (15) in the journal Nature analyze the integrity of the Thwaites Glacier, dubbed the “end of the world glacier”.

This mass of ice is the size of Great Britain and has become increasingly unstable. If it melts, it has the potential to raise —alone— up to 65 cm in sea level. Since the industrial revolution, the sea has risen by about 18 cm.

The study was carried out using equipment to observe, under the ice, the point where the glacier stops resting on the continent and starts to float in the sea. It is the retraction of this line that indicates how much ice and fresh water has already been dumped into the sea by the glacier. Since the end of the 1990s, it has retreated 14 km.

The researchers found that melt rates at the base of the glacier range from 2 to 5.4 meters per year, far less than the 14 to 32 meters estimated by mathematical models.

Despite this, they also observed that areas under the ice where there were cracks and steep structures melt faster, compromising the integrity and causing the accelerated retreat of the glacier to continue.

_{The Planeta em Transe project is supported by the Open Society Foundations.}