The enormity and complexity of climate change is a source of endless debate and argument, with conflicting viewpoints all too easy to find.
As politicians argue ideology and business and industry dodge responsibility instead of taking positive action, anthropogenic (human caused) climate change is a real and active threat in the Subantarctic and Southern Ocean.
There are currently large scale international programs working to study and understand the complex processes of climate change in the Southern Ocean. The Southern Ocean Observing System (SOOS) was established to coordinate and share information from these studies, which benefit the global understanding of climate change.
The Australian Antarctic Division is conducting extensive, long term climate research, and in 2009 initiated the Southern Ocean Sentinel program. This program, like SOOS, is part of larger international efforts to measure and understand the changing climate. The Southern Ocean Sentinel program made the key point that baseline measurements of Southern Ocean ecosystems are needed as soon as possible, so changes from climate change or other causes can be tracked and their root cause identified. Establishing base-line measurements in the Southern Ocean, after 2 centuries or more of exploitation by whaling, fishing, sealing and marine pollution, is a challenge in itself, but one being tackled by dedicated researchers.
The best known impact of climate change in the Southern Ocean, and across the globe, is an increase in air and sea water temperatures, and rising sea levels. While on paper an increase of 0.8 degrees Celsius might not sound like much, even slight increases in temperatures can have far reaching consequences for wildlife, earth systems, agriculture and so on human society.
Climate change is impacting the polar regions of the world faster than anywhere else. The Arctic ice cap is melting at an unprecedented rate, and polar bear numbers are dropping. Meanwhile in Antarctica, although the air and sea temperatures are increasing, winter sea ice is also increasing. Coupled with this, the perpetual winds of the Antarctic and Southern Ocean are increasing in velocity, not just in the far south but through the Subantarctic as well. These anomalies are not yet fully understood, but are explored in this short video from NASA.
Increasing temperatures have been identified as a current cause of impacts on Subantarctic plant and animals species. In 2009 the French Observatoire National sur les Effets du Réchauffement Climatique (National Observatory on the Effects of Global Warming, or ONERC) published the Technical Report Climate Change Impacts in the sub-Antarctic Islands, which gives a brief overview of the current and potential impacts of climate change in all the Subantarctic island groups.
Macquarie Island’s endemic cushion plant Azorella macquariensis has been suffering from such severe and fast paced dieback in recent years that is has been listed as Critically Endangered by the Australian government. It is not fully understood why this plant is dying off, but increased winds and changes in rainfall patterns are suspected causes. The loss of native plants in the small and isolated ecosystems of Subantarctic islands can have devastating effects. The cushion plant is considered a key-stone species on Macquarie Island, and the void left from its dieback can be filled with invasive species like the non-native tussock grass Poa annua.
The range and breeding habits of marine animals are also being altered by climate change. Breeding populations of Southern Elephant seals Mirounga leonina on Macquarie Island have dropped considerably in the last 30 years, and the change is thought be due to an increase in sea ice in eastern Antarctica (as mentioned above), which is impacting on their winter feeding grounds. However, the Elephant Seal population in the West Antarctic Peninsular is said to be increasing, possibly due to a reduction in sea ice in that region. This seeming contradiction demonstrates the complex and non-linear nature of climate change impacts on our complex and non-linear planet.
Rising global temperature are caused by increases in greenhouse gases in the atmosphere, primarily carbon dioxide (CO2). These gases are emitted naturally by the environment – we breathe it out and plants absorb it – but human activities, primarily burning fossil fuels, drastically increase their production and release. The increased gases trap more heat from the sun’s radiation in the atmosphere, rather than allowing to escape back into space, causing the planet to warm up.
The levels of CO2 in the earth’s atmosphere fluctuate throughout the year, and have gone up and down over millennia with the progression of ice ages and other planetary change, which can be measured from ice cores and the fossil record. But the last 100 years have seen CO2 levels more than double, rising at the fastest rate ever recorded. This progression has been named the Keeling Curve, after the scientist who first charted the long-term rise in CO2.
Elevated levels of CO2 in the atmosphere result in increased amounts of CO2 being absorbed into the ocean. The deep oceans are the largest carbon sink on the planet, storing an enormous amount of carbon deep below the surface. This carbon slowly cycles through the ocean systems over thousands of years, providing nutrients for ocean life. But the massive increases in atmospheric CO2 have led to a major increase in the CO2 levels of the ocean. And CO2 is acidic.
Oceans, are of course, salty. And salt is alkaline. All marine organisms, from blue whales to plankton and tiny snails, are adapted to living in an alkaline environment. As the oceans absorb more CO2, they are becoming more acidic, and this is already having a negative impact on ocean life. Small animals, like krill and plankton, are suffering from the corrosive effects of CO2 on their calcium carbonate shells and bodies. Over time, it is possible that these small, essential organisms at the core of the food web will become scarce due to ocean acidification, with dire consequences for the wider ecosystems of the Southern Ocean.
The cold waters of the Southern Ocean absorb 40% of human-emitted CO2, and so changes from ocean acidification are first felt by the marine plants and animals in the cold south. The Australian Antarctic Division has been running a world-first experiment in Antarctica to understand the impacts of increased CO2 in Antarctic waters. The experiment involved exposing marine organisms under the ice to the levels of CO2 that are predicted for the year 2100, and measuring their response.
Communicating the effects of climate change in Antarctica and the Southern Ocean to the wider world requires many voices, and benefits from a variety of approaches to sharing information. Since 1988 the Australian Antarctic Division has run the Antarctic Arts Fellowship, a program which gives artists, writers, musicians and others with a ‘non-science background’ the opportunity to travel to Antarctica with a scientific expedition and “communicate this unique experience and understanding to other Australians”. Dr Lisa Roberts, an Australian artist, travelled to Antarctica on an Antarctic Arts Fellowship in 2002 and has gone on to create Living Data, an on-going collaborative project between artists, scientists and other creatives to explore our responses to a changing climate. This type of cross-discipline collaboration has huge potential for sharing information, increasing our knowledge and understanding of the global processes that shape our world and how we can participate and contribute to positive change.