Copenhagen and Beyond

Jean-Michel CousteauDecember 8, 2009

Climate Change: State of the Ocean

We are all modern witnesses to both the miraculous and the incomprehensible. We have seen our planet from space, had access to the deepest canyons of the ocean, deciphered the infinitesimal DNA structure of life, and discovered unimaginable species—but we’ve also seen our own destructive influence on the planet’s complex network of life.

Nowhere is this more evident than with the current state of the world’s oceans.

Besides the devastating impact of overfishing, habitat destruction and ocean pollution, climate change is modifying the chemistry of the oceans in a way that has not been seen for tens of millions of years.

Since the pre-industrial age, the oceans have been absorbing more than one third (almost 130 billion tons) of human emissions from the burning of fossil fuels and deforestation.  Increased CO2 has wreaked havoc on our ocean’s chemistry. The oceans are naturally alkaline and when CO2 dissolves in seawater, it forms carbonic acid, which greatly increases ocean acidity levels.

There is no controversy about this, it’s just basic chemistry. Nor is there any question that increased acidity is fundamentally altering the ocean’s essential functions, such as regulation of the earth’s climate system or absorption of carbon.

The actual process of ocean acidification greatly decreases the ability of many marine organisms, such as coral reefs, to build their shells and skeletal structures, which provide the foundation for one of the most biologically diverse ecosystems in the world.

If we lose our precious corals, we will set off a deadly chain reaction causing extinctions of the important organisms that inhabit and depend on the reef systems. This will make the reefs less diverse, less resilient and far less productive for the hundreds of millions of humans who rely on them for food, protection and livelihoods. And when the loss of coral reefs is coupled with sea level rise, this will lead to the mass displacement of coastal populations, to increased world hunger as a result of depleted fisheries and other forms of food production, not to mention the decreased availability of fresh water in many parts of the world.


Ocean acidification is a critical warning sign of just how perilously close we are to destabilizing the earth's vital systems. And yet this ecological drama has not received much attention in the climate negotiations. What we do right now in terms of global efforts to reduce carbon emissions will affect the oceans for thousands of years to come. If we do not change our CO2 emissions trajectory, by 2050 the level of ocean acidity could increase three times above pre-industrial figures. At those levels, all coral reefs will stop growing and start dissolving and it would take thousands of years for the Earth system to re-establish ocean chemical conditions that even partially resemble those found today.

This is why it is so urgent for global leaders to take bold steps to significantly reduce CO2 emissions and to set reduction targets based on the latest science on ocean acidification and the vulnerability of marine ecosystems.

Losing the natural carbon functions of both the green and blue biospheres of our planet is not an option. By protecting the oceans, we protect ourselves.


Top Photo: © Karen Keltner, Ocean Futures Society.
Bottom Photo: © Richard Murphy, Ocean Futures Society.