QUANTUM hitches a ride on the icebreaker 'Aurora Australis' towards Antarctica. We're travelling with an eclectic and energetic bunch of young Australian scientists at the frontline of research into global warming. The destination is Macquarie Island, a tiny island in the middle of one of the most powerful climatic forces on the planet: the Southern Ocean. As carbon dioxide levels continue to rise, the climate changes and researchers are picking up worrying signs. In Hobart, climate modellers are examining the impact of warming on the Southern Ocean. Regarded as the powerhouse of the world's climate, the Southern Ocean links all the world's main oceans - and between them, they absorb 40% of the world's CO2 emissions. If present levels of CO2 emission continue, climate modellers from the Antarctic Cooperative Research Centre predict ocean circulation will start to slow and within 100 years the deep ocean will start to stagnate. The impact of that will be felt on islands like Macquarie. What happens there is an indicator of the change that could eventually flow on to the rest of the world.