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CO2 threatens the oceans

Monday, July 6, 2015

In December 2015 a new round of climate talks will take place in Paris. 

Climate change is arguably the greatest threat to human life on Earth. There is no drama in writing that the negotiators from governments around the world hold existence, as we know it, in their hands. While the Caribbean is a small contributor to absolute CO2 emissions, the region has a greater exposure to climate change than many parts of the world due to our status as Small Island Developing States (SIDS) and often limited resources to mitigate the effects of climate change.

Trinidad and Tobago has a special position as both a SIDS and the second highest per capita producer of carbon dioxide in the world (CO2).  

As islanders, Caribbean people know about the ocean. It is always there, present on the edge of our vision but I wonder if we truly appreciate the size of it, or its importance to life on Earth. Ask most people how big the ocean is and they will probably tell you “two thirds of the planet”, or if they are really knowledgeable you might get the more accurate answer of 71 per cent of the surface of the world. 

Neither of those figures reflects how important the ocean is to life. Think of the planet in terms of biosphere, or the really thin sliver of our planet and atmosphere where life is possible. The ocean is a whopping 99 per cent of the liveable part of Mother Earth. Or should we call her Mother Water? The ocean gave us life and it sustains life. Life evolved in the ocean billions of years ago and today the ocean provides half of the oxygen in the atmosphere. The ocean absorbs and retains heat, regulating atmospheric climate. 

We have read a lot about science warning us that the Caribbean will be impacted by rising sea levels, more extreme weather and longer droughts due to climate change, but what about the effect on the ocean? Twenty two of the world’s leading marine scientists warn that we are not paying enough attention to the importance of the ocean or the effect that carbon dioxide emissions is having on it. 

Writing in Science they warn that even if the world reduces carbon emissions in line with the Copenhagen Accord’s goal of a maximum of 2°C temperature rise marine ecosystems will still be negatively impacted. Our ocean will become less productive, less able to sustain life. If we opt for a ‘business as usual’ carbon dioxide emission scenario then we will cause “massive and irreversible” damage to what is a vital component of the life support system on our one and only planet.  

Since the start of the Industrial Revolution in 1750, the international baseline year for atmospheric CO2, the ocean has absorbed about 93 per cent of global warming caused by humans. Without the ocean the temperature on Earth would have been much higher than it is today. The ocean has also absorbed about 30 per cent of anthropogenic CO2 emissions since 1750.

The amount of CO2 going in to the ocean now is about 22 million tons per day. CO2 is slightly acidic and when dissolved in the ocean it causes ocean acidification. Ocean acidification affects animals that produce calcium carbonate shells and skeletons like corals, clams, oysters, phytoplankton and zooplankton, the tiny plants and animals that form the base of the marine food chain and on which everything else survives, right up to the whales. Let’s not forget about the 1 billion people who depend on the ocean for protein. 

So what we are doing is we are changing the chemistry and the temperature of the ocean. That has caused ocean warming, acidification and deoxygenation. Ocean warming causes species to shift their range as their native habitat becomes too hot for them. This shift in range can be dramatic, up to 400km per decade. Coral reefs, those rain forests of the sea, are at special risk. They are slow growing cannot pick up and move very easily. 

A warming ocean is able to hold less oxygen, which in part results in deoxygenation and can be exacerbated by nitrate runoff from agricultural pollution.  

Some species might thrive in the altered ecosystem but the overall impact will be predominantly negative. Studies have shown that many species can adapt to some changes, but few species will be able to deal with acidification, warming and deoxygenation all at the same time.

This is a call for Caribbean and global leaders to treat the Paris climate talks with a dedication that reflects the peril posed by anthropogenic climate change. Radical policy changes are needed and we need our policy makers to lead the charge.


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