In the depths of the ocean, where not even sunlight is able to reach, the environmental destruction of man is managing to gain a foothold. Almost a third of the CO2 particles emitted into the atmosphere by oil industries or exhaust pipes – together with other polluting sources – are absorbed by the sea. Its presence changes its chemical characteristics, making it a more acidic liquid which is incompatible with some forms of life.

Like the face of the Earth, the seabed has its own trees: corals. The best known are the ones we are used to seeing in documentaries, which can sometimes also be seen diving thanks to the fact that they are very close to the surface. Called tropical coralsThey are very colorful and they are inhabited by algae that feed through photosynthesis. Of course, they are not the only ones home to the vast ocean.

“There are other corals that are the great unknown to the general public and also to science, which are the deep corals. They do not photosynthesize because they are at depths of 500, 700, 1,000 or more meters – and sunlight does not reach. They are in cold waters, that’s why they are also called cold water corals“, explains Marcos Fontela (Asturias, 1987), postdoctoral researcher at the Algarve Sea Science Center (CCMAR).

Marcos Fontela, postdoctoral researcher at the Algarve Sea Science Center.

During the last five years of his life, Fontela has been part of a team of scientists that has been investigating since 1997 how the cold-water corals that surround the Peninsula are being victims of ocean acidification. The results of these two decades of work have recently been published in the magazine Nature. The conclusions they have reached are stark: if humans do not curb CO2 emissions, deep-sea corals could die in the not-so-distant future.

The bodies of corals, both in shallow waters and in deeper waters, have a kind of skeleton made up of the same material as shells: calcium carbonate. They are one of the oldest animals on the planet. Throughout their existence they have been able to develop in waters that were chemically favorable to them. Paradoxically, its equilibrium depends on there being a “Excess carbonate” in the water, but acidification is killing him. The nuance is important: “The carbonate will not run out, the excess carbonate will run out,” emphasizes Fontela.

Coral reef (Lophelia pertusa). Bank of Cabliers, Alboran Sea.
‘Lophelia pertusa’ from the bank of Cabliers, in the Alboran Sea.
Oceana Europe / Flickr

When excess carbonate ceases to exist, the following will happen: the skeletons of corals will corrode and those of those that are already dead will dissolve like aspirin in a glass of water. As living corals grow on top of dead ones, collapses will occur when these are diluted, like a building that collapses because the pillars have been removed.

These creatures have an irreplaceable ecological value and their destruction would not only deal a severe blow to biodiversity, but would directly affect our food dishes. Many commercially valuable fish “use cold-water corals as nurseries for eggs and small fish […] Imagine all the species associated with it in a forest. If we remove the trees, they will no longer be there ”, clarifies Fontela.

“Awareness of climate change was very high at the beginning of the year. Now it is obvious that there are other concerns “

In the Northeast Atlantic (the waters that surround the Peninsula), acidification is already expanding “from the surface to 2,500 meters deep.” The corals that live in this Atlantic region do so right in the middle of that interval, that is, around 1,000 meters deep.

Only governments can prevent what oceanographers are predicting. Depending on the determination with which they act, they can be given three scenarios. The most pessimistic happens because “the atmospheric concentration of CO2 reaches 700 parts per million (now we are at 410)”, according to the study. So, the waters would become “chemically hostile”.

Lophelia pertusa are necessary for a multitude of species to develop their lives.
Many species depend on cold-water corals for life.
Penn State / Flickr

A second circumstance would be that emissions evolve at the same rate as they are currently doing. If so, “50 years from now the deep coral reefs in our area will be in waters that are chemically unfavorable”.

The only hopeful scenario would be if governments fulfilled the 2015 Paris Agreement. That year, nearly 190 governments around the globe agreed to reduce CO2 emissions so that temperatures would not rise more than 2 ° C in the long term. Only if they fulfill this pact, “cold-water coral communities will continue to live in chemically optimal For their develpment”.

Marcos Fontela is confident that things will change for the better: “Awareness of climate change was very high at the beginning of the year. Now it is obvious that there are other concerns in the environment, but we must try to seize the moment to fulfill the objectives of the Paris Agreement. In this way, we would keep the water chemistry in good condition. We have no choice but to try to be optimistic ”.