Since the early 20th Century, global air temperatures have shown an increasing trend. This pattern has coincided with the continuous release of greenhouse gasses into the atmosphere. The rising temperatures are already having negative effects on many of our natural environments including, oceans, deserts, and glacial landscapes, including Antarctica.
The warming stripes below show annual global average temperatures from 1850 to 2019. The more red the colour, the more above-average the temperature. You can see that recent years have been far warmer than any time in the last 100 years.
Exploring Antarctica’s climate changes in the past, present and future
Since the beginning of time, before humans were even present, climate has been changing. It has been switching between warmer than present periods, known as interglacials, and colder than present periods, known as glacials. Over the last million years, it has made this switch approximately every 100,000 years.
Archives of past climate change
We know this by using environmental archives, such as ice cores from Antarctica. These ice cores are long poles of ice which contain annual layers of ice from thousands of years ago – some even from 800,000 years ago! Each winter a new layer of snow is formed and over time it is compacted and forms an annual layer of ice.
Ice cores are often drilled from the centre of an ice sheet where there is the thickest and slowest-moving ice. This means the scientists can get really long records without the layers of ice being deformed.
These ice-core records provide important information about these past changes in the climate system, the ice thickness, and can also tell us about the change in atmospheric gasses over time, as shown in the figure below. This figure is showing the change in temperature and ice thickness from two different ice cores (EPICA and Vostok) from the East Antarctic Ice Sheet.
Antarctica and Present-Day Warming
The effects of increasing temperatures on environments can already be seen in some areas of the globe, including Antarctica. Antarctica is one of the fastest warming places on Earth because of a process known as polar amplification. Alongside air temperature rises, the oceans around Antarctica are also warming.
This rapid warming is causing oceans to warm allowing increased melt on the underside of ice shelves, causing them to eventually collapse. Ice shelves have an important role in holding back the ice on the land. Therefore, when ice shelves collapse, it causes the ice on the land to become unstable and flow faster.
The West Antarctic Ice Sheet
The West Antarctic Ice Sheet is of great concern to scientists as the bedrock beneath the extensive coastline of ice shelves is sloping. This means that the grounding line, which is the point at which the ice begins to float, is beneath areas of much thicker ice, as shown on the figure below. The thicker ice flows much faster, therefore causing a greater amount of ice discharge into the oceans.
Future Climate Change and Antarctica
Global sea levels since the industrial period (1850) have shown an increasing trend. Sea levels are increasing by more than 3 mm per year and are set to increase as global air temperatures rise. As Antarctica has the largest store of freshwater, it has the greatest potential to affect sea levels around the world.
Antarctica has a total sea level equivalent of almost 60m. This means that, that if the whole of the Antarctic continent were to melt, then there will be almost 60m of sea level rise. This would effect many coastal regions all around the world.
Antarctica has this much sea-level-equivalent because it is just so huge. It is bigger than the United States of America and has an average thickness of ice of 2.4 km, all over the continent. In some places, the ice is more than 4000 m thick!
|Ice Sheet||Sea Level Equivalent|
|The Antarctic Peninsula||0.2m|
|The West Antarctic Ice Sheet||4.3m|
|The East Antarctic Ice Sheet||53.3m|
Future sea level rise
Much of the British coastline is currently protected by a sea wall, promenade or another type of coastal defence. These have been built to protect the land from large storm events, however due to the rising sea level, storms surges are getting larger. This means that over time, coastal defences are not able to defend from storm events as the waves are able to topple over the defences causing more flooding inland.
Climate change in Antarctica StoryMap
You can learn more about climate change in Antarctica through this interactive ESRI StoryMap. It is free to use and will open in your browser, no need to download any special software.