Breaking the Ice

A block of ice the size of Gush Dan has started breaking away from the Antarctic continent and in a few weeks it is expected to cause a rise in sea level. Is it possible to stop this alarming process?

Racheli Vox, Angle - Science and Environment News Agency

In various cold corners of the world the ice is gradually disappearing from the landscape. In recent weeks it has been reported that the phenomenon has also reached the roof of the world: more and more of the ice that covers the formidable Mount Everest is melting due to climate change, and by the way also exposing the bodies of many climbers who perished on their dangerous way to the top of the world's highest mountain over the years. The melting of the ice does not miss the coldest place in the world: Antarctica. In the coming weeks, part of the Brunt Ice Shelf is expected to break off and detach from Antarctica, while releasing into the sea an iceberg whose area will be larger than the entire Dan Block. The breaking of ice shelves and the formation of glaciers that are carried by sea currents is a natural process that occurs when the land ice flows towards the sea. From 1915 when Ernest Shackleton explored the area, the edge of the Brant Ice Shelf developed and changed very slowly compared to other ice shelves in Antarctica, but in recent years the process of change has accelerated significantly, unusually for this area.

The ice is getting warmer
On most standard world maps, Antarctica is nothing more than a shapeless white line stretching across the southern edge of the world - that is if you even bother to mark it on a map. However, behind the distorted drawing on the flat map hides a fascinating continent, whose area is larger than the area of ​​Australia, Europe or the United States. When the few who get to see for themselves the unique landscape of Antarctica sometimes feel like they are on another planet, where the white color completely dominates the landscape (apart from penguins that dot the area, of course). The land of the continent is covered with huge layers of snow and ice, in the water around it float large and small pieces of sea ice in a variety of shapes, and along large parts of the coastline extend from the land ice shelves: huge extensions of ice that float on the surface of the water. These shelves, the thickness of which may reach hundreds of meters, are usually formed when ice from the land moves slowly towards the nearby sea water (due to the pressure created by the large weight of the ice on the bottom of the glacier and the friction with the ground, the lower layer of the ice passes through the mass and the glacier slides and moves to a lower area and finally reaches the sea).

In the ice shelves, a process known as "calving" naturally occurs from time to time, where a part of the shelf breaks into the sea. However, in recent years the frequency and speed with which such events occur has increased radically. This jump is attributed to the increase in air and water temperatures caused by climate change. The warm air turns the ice on the surface of the shelf into water, which seeps into the shelf, erodes it from the inside and creates cracks in it that keep growing. At the same time, the warmer seawater melts the bottom of the ice shelf, thus making it thinner and more vulnerable. It is also possible that the acceleration in the melting of the sea ice that surrounds Antarctica adds to the process: this ice protects the continent from large waves and storms, which could damage the ice shelves and increase their instability.

Two cracks meet

In the significant breaking event that is expected to occur in a few weeks, the Brunt ice shelf, located in the part of the continent south of the Atlantic Ocean, will be damaged. The break will occur when two cracks crossing the ice shelf intersect. One of these cracks, dubbed The Halloween crack, first appeared in October 2016, and is steadily spreading eastward. The second crack, Chasm 1, has been known for a long time and has remained stable for 1 year, but recently it began moving north rapidly.

When the two cracks meet, a huge chunk of at least 1,700 square kilometers is expected to break off from the ice shelf, which could be the largest ever to break off from the Brant Ice Shelf since measurements began in the area in 1915 (in relation to ice shelves from other regions of Antarctica, the iceberg that is expected to break off in April is located between the 20 The largest glaciers on record break up). NASA warns that the event may increase the instability of the Brant Ice Shelf, thus increasing the risk that more parts of it will break off later.

The expected break in the Brant Ice Shelf joins other significant breaks that have occurred in recent years. Thus, for example, in July 2017, a glacier measuring approximately 5,700 square kilometers broke off from the Larsen C ice shelf - more than a quarter of the territory of the State of Israel. The phenomenon is connected to the acceleration in the melting rate of the glaciers in Antarctica, which increased sixfold between the years 2009-2017 (compared to the situation in 1979-1990).

Islands disappear from the map

The cracking and breaking of the ice shelves could worsen the rise in sea level in the world. The reason for this does not actually lie in the new glacier that is released into the sea (this is because the ice shelves are still almost completely in the sea water and the detachment of glaciers from the edges of the shelf does not significantly change the mass of ice floating on the surface of the sea and therefore does not affect the level), but in its indirect effect of the ice shelf on the large ice that is on land. "The ice shelf is actually a kind of big plug that stops the ice on the land from flowing into the sea," says Prof. Yoav Yair, dean of the School of Sustainability at the Interdisciplinary Center in Herzliya. When the ice shelves break up and lose their mass, their ability to hold back the land ice decreases."

"The danger is that ice from the continent will slide into the ocean, melt and turn into liquid water, which will raise the sea level," says Yair.

The melting of the glaciers in Antarctica, the continental ice in Greenland and the glaciers on the mountain tops around the world is the main reason why the global sea level has risen close to 25 centimeters in the last 150 years - of which nine centimeters in the last 25 years alone. According to the reports of the Panel of Climate Scientists of the United Nations (IPCC), the estimates are that the sea level is expected to rise by the end of this century by 74-30 centimeters depending on the emissions scenario that will be realized. In other studies from the last few years, even a sharper and faster increase is expected.

The effects of sea level rise can already be seen today in various island countries around the world, such as Micronesia in the Pacific Ocean, where the area of ​​some of the islands has already shrunk significantly and some of them have even begun to completely disappear from the map. The rise in sea levels has caused many people to lose their homes in Bangladesh, and has also begun to affect parts of the US coastline: the city of Miami in Florida, for example, is struggling with flooding caused by the rise in sea levels. The phenomenon will not pass over Israel either, and the level of the Mediterranean Sea on the country's coasts is expected to rise as well It is 1.4-1 meters by the end of this century.

Around the world, attempts are currently being made to prepare as much as possible for sea level rise, but the only way to slow down the phenomenon is to slow down the pace of climate change, by reducing the emission of greenhouse gases into the atmosphere as a result of human activity and at the same time promoting preparation to protect coastal infrastructure and to deal with other elements of climate change . There are many actions that each and every one of us can perform for this purpose, such as turning the air conditioner on a few degrees less, traveling by public transport, by bicycle or walking instead of using our private car or reducing our meat consumption. "Sea level rise is one of the most obvious results of climate change," concludes Yair. "People can't argue with that, you can actually see it happening."