Climate change in Antarctica: How rising temperatures are affecting the coldest place on Earth
Antarctica is renowned for its icy landscapes – but that could all soon change.
The southernmost continent is one of the fastest warming places on Earth, with untold impacts unfolding on its wildlife and the wider world.
For tens of millions of years, Antarctica has been a land of ice.
A vast ice sheet has covered the southern continent for over 30 million years, creating a harsh and forbidding polar desert for most animals and plants. But for those that can brave its cold winds and frigid waters, it’s a paradise.
The Southern Ocean that rings Antarctica is one of the most productive on Earth, providing a home for everything from microscopic algae to enormous whales. On land, species found nowhere else persist despite everything that the climate can throw at them.
But this wilderness, one of the planet’s last largely untouched ecosystems, could soon change beyond recognition.
Our greenhouse gas emissions are sending temperatures in Antarctica soaring. As the ice melts, it risks starting a chain reaction that won’t just impact a remote region of the planet, but the whole world.
Is Antarctica a desert? Yes – In fact, Antarctica is the largest desert on Earth as it only receives a small amount of precipitation every year. Public domain image by NASA/ Jim Ross via NASA Images.
Antarctica’s changing landscape
The Antarctic ice sheet is the largest on Earth, covering almost 14 million square kilometres. If it were a country, it would be the second biggest in the world.
In fact, the ice sheet is so big that scientists often divide it into three parts to help understand it. The east Antarctic ice sheet is the largest, covering the majority of the continent, followed by the west Antarctic ice sheet and the Antarctic peninsula – the section of the continent that stretches out towards South America.
When snow falls on the ice sheet, where subzero temperatures ensure it doesn’t melt. Antarctic temperatures regularly reach -40°C or lower in the interior, with the lowest ever temperature on Earth recorded as -98°C on the east Antarctic plateau. Towards the coast it gets a little warmer, where it’s a comparatively balmy -10°C on average.
These frigid temperatures mean that snow has been building up for millions of years. As more and more snow falls on top, the pressure gradually transforms it into solid ice that adds to the ice sheet below.
At the same time, the flow of the Antarctic ice sheet means that’s it’s always gradually moving towards the sea. When it reaches the water it begins to float, forming an ice shelf. On its leading edge, the shelf eventually breaks up and forms free-floating icebergs.
Antarctica’s ice shelves help to hold back the ice sheets behind them, limiting how much ends up breaking apart and melting into the ocean.
For millions of years, there’s been a natural balance between the amount of snow falling and forming new icesheet, and the rate of ice flowing off the continent and eventually breaking up in the ocean. However, this balance has been thrown off as the Earth has warmed.
Watch this video to find out how studying ancient Antarctic rock can help scientists understand future climate change.
While the east Antarctic ice sheet is largely stable for now, the west Antarctic ice sheet and Antarctic peninsula are much more vulnerable to higher temperatures. An increasing amount of ice from these areas is entering the ocean, causing sea levels to rise.
Across the entire continent, temperatures are rising fastest in the Antarctic peninsula. It’s warmed by over 3°C since the 1950s, which is more than three times faster than the rest of the world.
Western Antarctica is also rapidly heating up, putting areas such as the Thwaites ice shelf at particular risk of collapse. Dr Peter Davis, a British Antarctic Survey (BAS) scientist who has led research into the shelf and the glacier it supports, says warmer water is getting under the ice shelf and causing it to melt faster.
“It’s important to understand what will happen to the Thwaites ice shelf because climate models suggest it will cause sea levels to rise the most in the next century,” Peter explains. “If it melts away, global sea levels could rise as much as 70 centimetres.”
The Thwaites ice shelf is also a key support for the west Antarctic ice sheet. If the shelf is lost, it could trigger a wider collapse of this ice sheet that would make sea levels to rise even further. By 2300, this could cause global sea levels to rise by almost 4.5 metres – about the height of a double decker bus – and submerge low lying areas around the world.
How does Antarctica influence the world’s oceans?
The consequences of a warmer Antarctica extend further than rising sea levels. Antarctica’s ice sheet is an important source of nutrients for the world’s oceans.
As the ice melts, these nutrients are released into the surrounding waters and then distributed around the world through a process of ocean mixing and deepwater circulation. This means that Antarctica’s ice sheet can affect everything from coral reefs to seagrass meadows. For many years, it was thought this mixing was generally driven by four processes: winds, tides, currents and heat loss.
But Professor Michael Meredith, who explores the links between the ocean and the climate at the BAS, says that Antarctica’s ice sheet is now known to play a role.
“As glaciers calve ice into the water, they produce tsunami waves not just on the surface of the ocean, but also in the layers underneath it. These waves can travel for kilometres and break as they flow over undersea hills and canyons, causing mixing.”
“There are thousands of glaciers all around the world, and we now think that most of these can cause mixing. This process is likely to become more common as temperatures rise and glaciers melt, and we need to understand it better to work out how it will affect our climate and ecosystems.”
What is krill? Krill, meaning ‘small fish fry’ in Norwegian, is the name given to a group of crustaceans that play important roles in marine ecosystems across the world. © Gonzalo Giribet via iNaturalist, licensed under CC BY-NC 4.0.
How is climate change affecting Antarctic krill?
As the continent gets hotter, Antarctica’s animals which rely on sea ice lose their vital habitat. The most important inhabitants of all are Antarctic krill, whose trillion-strong populations are eaten by everything from small fish to enormous whales.
These crustaceans have a complicated lifecycle, with their eggs sinking hundreds of metres beneath the surface to overwinter before the newly hatched larvae swim up to the sea ice in spring. The ice shelters the larvae as they develop and provides a surface where the krill can feed on ice algae.
As rising temperatures make sea ice less abundant, young Antarctic krill are losing their nurseries and feeding grounds. Dr Sophie Fielding, a BAS scientist who studies krill and other zooplankton, says that the warming ocean also affects where krill live.
“Higher temperatures in Antarctica have an impact on the currents surrounding the continent,” explains Sophie. “This affects krill because, although they can swim to a certain extent, they’re also swept around by these currents.”
“If currents change, then young krill will come to the surface in different places away from shelter or access to food. This reduces their chances of survival to adulthood.”
Any impact on krill populations not only has serious consequences for the animals that feed on them, but also how the ocean captures carbon dioxide through what is known as the biological carbon pump. This natural process sees photosynthetic plankton take the gas out of the atmosphere before sinking into the deep ocean and locking the carbon away in the sediment.
The krill play a part in this process, as they eat the plankton and excrete dense pellets that sink quickly, burying carbon on the seabed. They’re incredibly good at this – the amount of carbon they lock away each year is on a par with all the world’s mangroves or salt marshes.
There are many Antarctic birds: penguins, petrels and skuas to name just a few. They’re all feeling the impact of climate change. © Sergey 402/ Shutterstock
However, as some areas of the Southern Ocean start to approach krill’s upper temperature limit, their populations are moving back towards the Antarctic mainland. As they do, new animals known as salps are moving into the region and changing the ecosystem.
“Salps are gelatinous zooplankton that feed with a mucus web,” Sophie explains. “They produce more fragile faecal pellets than krill, making them more likely to break apart before reaching the deep ocean. This affects the efficiency of the biological carbon pump.”
“The gelatinous bodies of salps also aren’t as energy rich as krill, so they’re less able to support a food web in the same way.”
How does climate change affect penguins and other Antarctic wildlife?
It’s not just krill that are under pressure in the Antarctic either. Stephanie Martin is a BAS researcher who has been visiting the region for over 30 years, and has experienced the changes in its wildlife first hand.
“A lot is changing in Antarctica,” Stephanie recalls. “I’ve seen glaciers and ice shelves disappearing, which has affected the distribution of many different animals.”
“Orca are shifting where they live, while the distribution of ice seals has also changed since I started visiting Antarctica in the 1990s. There used to be groups of crabeater and Weddel seals further north on the peninsula, but these have been declining over time.”
Rising temperatures are also affecting the continent’s weather patterns, with higher temperatures contributing to more powerful storms and heavier precipitation. In 2021, two important colonies of the Antarctic petrel were battered by unseasonally heavy storms and failed to breed.
Even Antarctica’s iconic penguins aren’t immune to the changes. Many species rely on sea ice for hunting, breeding and raising chicks, but it’s melting much faster than it used to. Colonies in the western Antarctic peninsula are particularly vulnerable, with thousands of emperor penguin chicks killed in 2022 after the sea ice broke up much earlier than normal.
Changes in the sea ice also affect their prey, leading to some Antarctic penguins doing better than others.
“Some species, like Gentoo, are doing well because they can feed on krill and fish, so they just focus more on fish as sea ice declines,” Stephanie explains. “But Adélie penguins are krill specialists, so they need the ice for ready access to krill. As sea ice changes, they’re just not as able to adapt as other penguins.”
The British Antarctic Survey takes its research vessel, the RRS Sir David Attenborough, on regular Antarctic cruises to understand how the continent is changing. © Phil Nash via Wikimedia Commons, licensed under CC BY-SA 4.0.
How will higher temperatures affect Antarctica?
Antarctica now faces an uncertain future, one based on how high we allow our emissions to rise. Some of these changes are already locked in because of how hot the Earth has already become, leading to global changes that are largely unavoidable.
For example, areas of the Southern Ocean such as the Amundsen Sea are set to warm around three times faster than they did 100 years ago and drive greater melting. The collapse of the west Antarctic ice sheet is also looking increasingly likely as global temperatures approach its tipping point of around 1.5°C.
Further changes are harder to predict, because Antarctica has been studied for much less time than the rest of the world. Scientists have been rushing to understand its complexities as part of international research projects, such as the International Thwaites Glacier Collaboration.
“We sent cameras underneath the Thwaites ice shelf in 2019 to look at the grounding line, where the ice lifts off from the seabed, as we believed the processes most important for sending heat into the glacier were located here,” Peter explains.
“It turns out it was much more nuanced than we thought. While there was a layer of freshwater that restricted melting in some areas of the ice shelf, there were also very rough surfaces that had much more intense melting. It’s one of the many things we don’t yet understand about what’s happening in Antarctica.”
“Climate change could impact many different species in ways we don’t yet know,” adds Stephanie. “For instance, we know that whale populations around Antarctica are currently recovering, but declines in krill could threaten them from a completely different direction.”
While there’s uncertainty in what comes next, researchers are universally agreed that slashing our greenhouse gas emissions is the best way to protect the region. Whether Antarctica remains a land of ice is now in our hands.
