Much of our concerns about climate change focus on the impacts it will have on humanity and the land-based habitats of non-human animals. In doing so, the largest area of the world’s surface, the ocean, is at risk of being forgotten. Alanna Mitchell sets out the case for why the consideration of oceans and ocean life must be integral to any deal on climate change
As the world’s leaders gather to hammer out a do-or-die deal on global climate change in the coming months, they are ignoring a problem that is even worse.
The carbon dioxide we’re putting into the atmosphere by burning ancient plants and animals – we call them fossil fuels – is making not only the atmosphere and climate sick, but also the global ocean.
Here’s the problem by the numbers. A third of that ancient carbon we’ve put into the atmosphere has been absorbed into the ocean. In the atmosphere, the carbon dioxide hangs there, creating a greenhouse effect over the surface of the globe. It is dangerous but chemically inert.
So today, the proportion of carbon dioxide gas in the atmosphere is 387 parts per million by volume. Before we started burning fossils, it was 280. We know it hasn’t been above 300 for at least 20 million years.
In the ocean the carbon dioxide gas reacts chemically with water to form a mild carbonic acid. We’ve put so much carbon gas into the atmosphere – and therefore into the ocean – since the industrial revolution that we have begun to acidify the global ocean. We’re changing its chemistry.
This phenomenon was unknown until about 1999, when the first paper on ocean acidification came out in the peer-reviewed journal Science. Before that, scientists didn’t believe that such a key chemical characteristic of the ocean could change, short of a cataclysm.
But it has. The pH, or level of acidity, of the ocean’s open water has been about 8.2 for millions of years. In just a couple of centuries, we’ve lowered it to 8.05. Scientists estimate that it hasn’t been that low for 55 million years.
The chemical marker of the human-burned fossil carbon that is changing this acidity can be tracked to 1000 metres deep in the ocean, and, in some parts such as the North Atlantic, to 3000 metres.
It’s quite a feat. The ocean is vast, making up 99 per cent of the living space on the planet. It is also the planet’s major life support system. That means that those who are focusing just on the damage from climate change have a 1-per-cent view of the world.
Boris Worm, a marine scientist at Dalhousie University in Halifax, Nova Scotia in Canada puts it this way: If everything on land were to die tomorrow, life in the ocean would be fine. But if everything in the ocean were to die, everything on land would also perish.
That’s because plankton, those tiny wanderers of the ocean’s surface, control the planet’s carbon cycle, nitrogen cycle and part of its oxygen cycle, in other words, its critical chemical functions.
Take oxygen. The planet first became hospitable to life 3.6 billion years ago because plankton began to produce oxygen. Today, every second breath you take is oxygen produced by plankton. They are the true lungs of the planet. How will plankton fare as the ocean becomes more acidic? Sadly, that’s unknown.
Some have shells made of limestone, just as the plankton whose shells made up the white cliffs of Dover were made of limestone. As the ocean becomes more acidic, the calcium needed to make those shells becomes less available to creatures that need it.
For example, when the concentration of carbon dioxide doubles from pre-industrial levels to 560 parts per million by volume, which could easily happen by mid-century unless we do something, ocean creatures will have access to 30 per cent less calcium than they do now.
If the ocean becomes acidic enough, it will actually dissolve shells made of calcium. That would affect every creature in the sea with a shell, as well as the planet’s coral reefs, whose structures are also made of limestone.
What are the implications? Researchers are racing to find out, including many at the UK’s internationally famous marine institutions in Plymouth.
It’s possible that other plankton that don’t need calcium shells will take the place of those that do. But will they perform the same functions in the planet’s chemical cycles? Again, unknown.
And it’s not just plankton or the calcium problem. All the creatures that live in the sea have evolved in the pH we had before the great modern acidification. Early research shows that some of them will adapt quite nicely to a more acidic environment.
Others fall to pieces, quite literally, beginning with their digestive and reproductive systems.
We are setting the stage for a mass extinction on our planet, the like of which has happened only five times before in the history of life. The last time was 65 million years ago when the dinosaurs died out.
And we know that in each of the five, the ocean became acidic, as well as warm and short on dissolved oxygen, two other phenomena happening now too, also as a result of too much carbon dioxide in the atmosphere.
So, is there hope? We have power in knowledge, which means taking a 100-per-cent view of the world instead of a 1-per-cent view. That includes the world leaders who are meeting in the critical run-up to the Kyoto Protocol talks in Copenhagen in December.
It is at these talks that the world’s politicians will have to decide how fast and how far to cut carbon gas emissions. If they don’t come up with a solid plan and committed targets at that meeting, many scientists believe that the concentration of carbon dioxide in the atmosphere will hit the critical doubling – 560 parts per million by volume – in just a few decades.
At this point, despite all the scientific knowledge of the dangers of climate and ocean change and the treaties in place to curb carbon-gas emissions, those emissions are increasing faster than at any time since humans showed up on the planet.
Many of these leaders seem to understand that global climate change is severe enough to warrant swift and deep cuts. The kicker, though, is the change happening in the global ocean. It is invisibly ill. Critically ill. Little understood and therefore unpredictable.
This is an unusual time in the planet’s history. The next few months may well tell the tale of whether we lurch into another mass extinction or avoid it by the skin of our teeth, having only to adapt to the vast changes we’re making to the climate system. In itself that will be a huge task fraught with danger.
Which way will we go? It’s hard to read the signs. But my research tells me that unless we believe that transformation can happen, it will not happen. It’s also clear that we don’t have time for the luxury of despair.
My preference is, armed with knowledge and urgency, to cast our generation as the one that will alter our relationship with our planet.
It is up to us. The window for action is miniscule. But it is still open. This, and this alone, is our time for preserving life as we know it here on Earth.
Alanna Mitchell is a Canadian journalist and author of the international bestseller Seasick: The Hidden Ecological Crisis of the Global Ocean, published in the UK by Oneworld.
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