It’s been a quarter of a century since the Earth Summit in Rio de Janeiro, one of the first steps towards a global environment policy. Since then there have been annual meetings of the parties to the Framework Convention on Climate Change (the latest, COP23, was met with almost complete indifference from the media) with complex negotiations that led to the signing of the Kyoto Protocol in 1997 and the Paris Agreement in 2015.
The idea what we need to do something to save the planet on which we live has made headway in the public consciousness, with films, rock concerts, awareness-raising campaigns and a growing understanding of good daily habits. Today the powerful images of swathes of trees chopped down in the Amazon or polar bears on drifting ice floes in the Arctic populate the collective imagination as much as the more celebrated shots of wars and revolutions.
But there is something missing from the debate on the climate and the environment: an acknowledgement of the health of the seas. We still know very little about what is actually going on in the vast stretches of water that cover 71% of the planet’s surface and encircle the dry land on which we live. To be honest few of us have any familiarity with this blue desert, beyond the first few meters offshore.
Think about this: The Scripps Institution of Oceanography at the University of California, San Diego has analyzed the commitments made by national governments after COP21, and found mention of the oceans in only 70% of them. While it’s not surprising to find out it is the island nations of the Indian Ocean, the Pacific and the Caribbean that are most concerned about marine waters, it is a shock to learn that 14 countries with coastlines do not mention the sea.
But are the oceans simply a backdrop to the climate change taking place on land? Nothing could be further from the truth, says marine biologist Silvio Greco, the president of the Slow Fish Scientific Committee. “It’s hard to talk about marine issues,” he said, “even though the sea is the true regulator of the planetary climate, absorbing an enormous quantity of CO2 and provides at least half of the oxygen we breathe.”
The real problem is that we know too little about what is going on in these places. “We have no real data, for example, about the actual functioning of the Gulf Stream or the Global Conveyor Belt, in other words the global circulation caused by the varying density of masses of water. And this absence of data and research makes it hard to evaluate the effects of climate change.”
For a century and a half, says Greco, we have been measuring the surface temperature of the ocean as well as the temperature of the atmosphere. But there is a whole world, deep underwater, that is mostly unexplored.
Only at the end of October 2017 did scientists from the French National Centre for Scientific Research (CNRS) and the Lausanne Federal Polytechnic School (EPFL) in Switzerland discover that the method used to determine historical marine temperatures might be completely wrong. To learn more about the climate in previous geological eras, we have been using Foraminifera fossils, analyzing the oxygen isotopes “trapped” in their shells to calculate climactic variations.
These calculations have suggested that 100 million years ago, the temperature at the depths of the ocean was around 15°C warmer than it currently is, and this finding is often used as a argument by those who deny the anthropic origins of climate change.
The problem, say the French and Swiss researchers who looked at the previous studies, is that it seems the levels of oxygen in the shells can vary without leaving obvious traces, and not necessarily because of the effect of variations in temperature. This led them to conclude that the average temperature of the oceans has actually been fairly stable over the past 100 million years and that, as a result, the warming of the waters is a much more serious phenomenon than previously believed.
What is certain is that the effects of this warming can be seen every day now. One of the most worrying is the invasion of Ctenophora (comb jellies), “a kind of jellyfish without tentacles,” explains Greco, “which are filling the Adriatic Sea. They feed on fish eggs and larvae, so their abnormal proliferation, due to the changing climate conditions, is having devastating impacts on the ecosystem, something that has already been seen in the Black Sea.”
The National Institute of Oceanography and Applied Geophysics in Trieste has documented the staggering rise in the populations of these creatures, which shows the suffering of marine ecosystems and will soon lead to a fall in stocks of mullet and cuttlefish.
As though all this wasn’t enough, the effects of climate change are being compounded by the pressure of industrial fishing. At the moment, according to the FAO, 30% of fish stocks are being exploited at a rate that prevents marine populations from renewing themselves.
While catches among countries with advanced economies have settled at around 20 million tons a year after a peak in the 1990s, in developing countries the total catch has passed from 3.6 million tons in 1950 to 39 million in 1988 and risen to 58 million in 2013. Most of this fish goes to supply our markets, where demand is neither falling nor paying any attention to the sustainability of consumption.
But even in this area, we are dealing not with certainties but with estimates, as programs for direct measurements have been reduced. Italy had one in the 1990s that followed fish populations trends in our seas, but now all that remains is a small EU program.
What can we do? It may feel like we have no way to change things, but we do have one tool at our disposal: our shopping bag. Greco has this to say: “As consumers, we must grasp the concept of seasonality. Buying eggplant or peppers all year round has an impact on energy consumption and therefore increases the production of CO2.” It’s the same with the sea: “Fish have their seasonality too, but almost nobody cares because, as I often joke, they were the only animals that didn’t need Noah and we still haven’t forgiven them. The truth is, choosing one species over another is a truly political choice.”
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