One of the most profound insights I gained from my voyage to Antarctica with Homeward Bound was about Antarctica itself. Did you know that Antarctica affects the climate of the the entire planet? Whatever we collectively do to Antarctica will soon enough come right back at us — no matter where we are located on Earth. Because Antarctica is the beating heart of the global ocean’s current systems.
The Antarctic region is encircled by the clockwise flowing "Antarctic Circumpolar Current" (ACC). It is the temperature difference between cold Antarctica and the warmer climate further North that keeps the ACC "conveyer belt" system moving freely around Antarctica with no land mass to block it. In fact, the ACC is the strongest current system within the Earth’s oceans. It feeds and connects all oceans with each other. The gulf stream, too, is a part of this network of currents.
Part of the ACC is the "Antarctic convergence", a narrow region where cold northward-flowing waters meet warmer waters. The cold Antarctic water sinks towards the bottom and pushes the warmer water up. A mixing zone is created with the capability of flushing vital nutrients up to the surface which is pivotal for Antarctic marine life. Abundant krill growths is particularly dependent on these surface nutrients since it is the most important component of a healthy and sustainable food chain across Antarctica. Altogether, the ACC acts as a natural border of Antarctica. It is nature’s fantastic way of keeping Antarctica cold and separate from everything else.
But what will happen if this current system and the convergence zone move, weaken, and/or change?
Global warming has already caused significant warming of Antarctica and its ocean. More icebergs are breaking off, diluting the salt water with freshwater and changing its density. Being less cold and less salty makes it harder for that water to sink. This has impacted the "Antarctic Bottom Water," a mechanism to fill the deepest basins across all oceans with the coldest water via the ACC’s global current system. Effectively, this means that our deep oceans have been warming up, absorbing some of the effects of climate change.
How much warmer should the deep ocean become? The steady warming of Antarctic water will eventually lead to the ACC breaking down. Impacting this pumping force will alter the global current system with dramatic effects. Around the world, we can expect drastic shifts in weather and climate zones, including Europe whose moderate climate is largely due to the gulf stream delivering warm water up North. Not to mention floods that will endanger island nations, wild fires, and massive storms that have already been impacting many regions and millions of people.
Understanding this fragile yet critical connection between Antarctica and the rest of the planet is a first step towards understanding the "global" part of climate change. The other part pertains to the need for a global effort in order to keep Antarctica cold and the ACC going strong.
On our way back to Ushuaia, we passed through the convergence in early morning fog. It was the moment when we truly left Antarctica. For me, it was both calm and intense — a profound moment of letting go, simply by steadily moving forward. Just being carried by the waves, without resisting.
As we sailed on, the fog lifted. The new day brought on clarity, purpose and reflection about what "Antarctica" means to me, to us, to our planet. And that we all have to make changes to keep it, and us, safe. That must be our collective Plan A!