Keeping global warming below the threshold of 2°C would require halving greenhouse gas...
Climate Change : The ocean, our unsung ally
- Paris, France
Global warming would reach even more alarming levels were it not for the role of oceanic waters, as pointed out by Sabrina Speich, Professor of Geosciences at the Ecole Normale Supérieure in Paris and coordinator of the Southern Ocean Climate (SOCLIM) project supported by the BNP Paribas Foundation. The scientist spoke at the Climate Initiative conference at the Oceanographic Institute in Paris to stress the importance of preserving this precious shield.
Its territory covers two thirds of the surface of the planet, yet its internal dynamics remain largely unknown. Also, it is often referred to in the plural, as if to downplay its power. But Pacific, Atlantic or Indian, the ocean in fact one in the same. Although divided into several basins, its waters are interconnected and play a major role in our climate system. It is a buffer – a protector even - against global warming, a blight plaguing the collective consciousness.
The waters of the ocean are the primary captor of solar energy, transforming it into heat which is then transported in part by the currents to the polar latitudes. Despite some heat loss by the winds, the ocean retains a significant portion of it. The ocean also absorbs excess energy linked to greenhouse gas emissions. Without the ocean, global warming would be even more extreme. To illustrate its importance, the ocean contains in its depths 93% of the anthropic heat accumulated over the last 50 years. The ocean alone collects a quarter of carbon dioxide (CO2) injected by humans..
Without the ocean, global warming would be even more extreme.
Underlying warming, underlying threats
By default, the ocean cannot escape the effects of global warming for it generates within its waters a phenomenon known as thermal dilation. Unevenly distributed, it is responsible for up to 30% of rising sea levels (of which 40% is linked in parallel to the melting of the icecaps).
The increased concentration of CO2 raises the acidity of the water and decreases the oxygen reserves in its depths, with direct consequences on the ecosystems already mistreated by the overfishing of marine species by over 30%. While the barrier reef is dying, micro-plastics and other pollutants are being pulled up to the surface by the currents. How much longer will the ocean and its buffer effect withstand the strain inflicted on it by human activity? This is the question being asked.
How much longer will the ocean and its buffer effect withstand the strain inflicted on it by human activity?
In addition to increasing temperatures, global warming has also given rise to extreme rainfall, very often due to the release of excess water. The feared prospect is even more intense and frequent storms and cyclones. Ocean specialists currently do not have all the data they need to draw a clearer picture of the future.
Beacons of the future
New currents are emerging. The quantity of currents going towards the Arctic is changing. What impact will these new dynamics have on the ocean and the role it plays in the climate system? Exploration in this area is in its infancy and will need resources. The pioneering Argo programme unveiled in 2013 aims to expose the mechanisms of the ocean currents. As part of the SOCLIM project, in October 2016 a research campaign set sail in the Southern Ocean.
the Argo “rockets” have already shed light on new CO2 and heat-carrying currents.
Cutting-edge robotic transmitters – the unmistakable yellow rocket-shaped Argo beacons - were deployed in the raging waters of this remote territory. The beacons were sunk 1,000 metres underwater and ascend to 2,000 metres every 10 days. This is also the pace of the transmission of data, the processing of which is estimated to take up to five years. So far, the Argo “rockets” have already shed light on new CO2 and heat-carrying currents, as well as previously-unknown seasonal cycles.
More work needs to be done, but at 35,000 to 40,000 euros a day to charter a ship research campaigns are a costly affair. This cost is partly to do with the reluctance of governments to get involved, despite the urgency. The involvement of the scientific community aside, the ball is firmly in the court of governments and business to alter the adverse trends that are wreaking havoc in ecosystems and entire populations.
The ocean, our unsung ally, may well gain the recognition it deserves through scientific discovery and increased awareness of the climate imbalances at play. Its fate its being debated at the UN, and the international community’s reaction to the US pulling out of the Paris Agreement is another encouraging sign. While we don’t yet have all the knowledge to back this environmental awakening, we all know that it will take more than iron fertilisation to feed plankton and lime treatment to reduce temperatures.
A specialist in the understanding of ocean dynamics and their influence on climate change, Sabrina Speich is a globally recognised expert in modelling the oceans and in organising in situ observations on a large scale. She is a pioneer in the use of Argo floats for ocean observation.
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