What does climate change mean for the Antarctic?
When we asked people what the Antarctic makes them think of, ‘climate change’ was one of the most common answers around the world.
If you Google news about the Antarctic it’s easy to see why – terrifying headlines warn about icebergs the size of Luxembourg breaking off, accompanied by slow-mo videos of ice crashing down into the ocean. But there’s more to this story than meets the eye.
To truly understand what climate change means for the Antarctic, we have to look at the Antarctic’s tallest glaciers and its deepest waters.
The Antarctic is also an important barometer for how climate change is impacting our planet. Scientists can read Antarctic ice cores like a record going back for hundreds of thousands of years, comparing levels of carbon dioxide in atmosphere from the past 800,000 years with today’s measurements. This sends us the important warning that carbon dioxide levels are higher now than they’ve ever been.
As a result, parts of the Antarctic are warming three times as fast as other parts of our planet. Scientists recently recorded its warmest day ever – a distinctly not-freezing 17.5°C.
Changing ocean temperatures are also important, because they warm the massive Antarctic glaciers from below, making them less stable. Glaciers form on the Antarctic landmass as snowfall compresses into ice over time, and they flow under their own weight towards the ocean – like a very slow river. But as these glaciers feel the heat of a warmer ocean underneath them, they speed up their slow march to the coast, causing big chunks of ice to break off into the sea as icebergs at a faster speed.
The melting and break down of glaciers into the ocean raises sea levels all around the world. Antarctic glaciers are now losing ice faster than snow is falling to add new ice. The rate at which Antarctic ice sheets melt under increasing temperatures will affect coastal communities globally, whether living in small island states or mega-cities.
Warmer seas also impact the iconic wildlife living in the Antarctic. Scientists have warned that a warmer Antarctic could also attract new species of animals and plants, creating competition for Antarctic life that is specially adapted to icy temperatures. They are also investigating whether warmer temperatures are increasing the risk of disease for the Antarctic’s most plentiful starfish.
Closer to the surface, the amount of seawater that freezes as sea ice around Antarctica during winter – and how long it stays frozen – affects many Antarctic animals. Sea ice normally covers an area twice the size of the United States by October each year, but new lows were recorded last year.
Emperor penguins that depend on sea ice for breeding could lose key areas of their home, while less sea ice could have massive implications for populations of krill, which particularly as youngsters cluster around sea ice for food and shelter. If we don’t take action to reduce warming, the biggest reductions in sea ice are unfortunately forecast for areas where most krill currently gather.
Scientists have also warned that tiny krill face challenges growing and reproducing in waters that are becoming more acidic from absorbing carbon. Carbon dissolves more easily in cold waters compared to warmer seas, so life in the polar regions is hit particularly hard by the ocean absorbing pollution caused by burning fossil fuels on land. Practically all Antarctic wildlife, from whales to penguins to seals, rely on krill as their main food source, so threats to krill will have knock-on effects throughout the Antarctic environment.
But the Antarctic – and the ocean worldwide – isn’t simply a victim of climate change. If we protect the ocean with a huge network of sanctuaries we will help sea life thrive. And thriving sea life can help slow climate change, benefitting us all.
How does this work?
Creating ocean sanctuaries provide a haven for marine life, safe from industrial activity. They not only give space for these creatures to recover from pressures facing our seas and build resilience to the impacts of a changing climate – but they allow this wildlife to keep storing carbon, helping all of us.
Carbon is absorbed and stored by marine plants and animals. Tiny plants at the surface of the sea absorb carbon for energy, which enters and travels up the ocean food chain. As that happens, scientists have suggested that krill poo, more glamorously known as carbon-rich fecal matter, moves carbon into deep waters where it remains over long periods – storing the same amount of carbon as all UK households combined emit each year.
We also find carbon in the bodies of much bigger ocean creatures like whales. In life, whale poo helps nourish those carbon-absorbing tiny plants near the sea surface, and in death, the carbon in whales’ bodies is buried along with them on the seabed. This can store carbon for thousands of years.
So we have a choice: a healthy Antarctic ecosystem can help us avoid the worst effects of climate change, but letting threats damage this icy wilderness would make climate change worse.
All this reinforces that we need to act now. Tackling the causes of climate change and protecting the ocean must go hand in hand. We need to transform our energy system away from polluting fossil fuels to 100% renewable energy, and we need to protect our oceans with vast ocean sanctuaries.
Scientists recently warned that decisions taken in the next decade will affect the future of the Antarctic – and, therefore, the whole planet. So we better make those decisions the right decisions. Call on governments to create an Antarctic Ocean Sanctuary this October, giving wildlife the space to build resilience to a changing ocean and help us all avoid the worst effects of climate change.
About Louisa Casson
I'm a campaigner in Greenpeace UK's oceans team, leading our campaign to create the world's largest protected area in the Antarctic ocean.