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Dr Jean-Pierre Gattuso
CNRS Research Director and President of the Monegasque
Association on Ocean Acidification (AMAO)

Unfortunately, species such as corals and
gorgonians are attached to the seabed and cannot
move. Their larvae are not attached to the seabed,
but move very slowly. Excessively high temperatures
have already caused large-scale mortality within
certain corals, such as the Great Barrier Reef
in Australia where two thirds were affected by
bleaching in 2016 and 2017.

How does acidification affect oceans?
Acidity levels have already risen by 34% in the past
two centuries. Increased sea water acidity has
Why is the ocean at the heart of the climate reduced carbonates which are an essential building
regulation system? block in generating calcareous skeletons and shells.
The carbon dioxide which we emit into the Acidification, therefore, is impacting many organisms
atmosphere increases the greenhouse effect and with calcareous skeletons and shells, such as
generates heat. The ocean stores more than 90% oysters and corals.
of this excess heat, and in doing so, limits air
warming. It also stores a quarter of carbon dioxide
emissions, which is 26 million tonnes of CO per day.
2
This also limits global warming. Lastly, the ocean
receives almost all the global ice-melt water. Sea-
water warming and acidification, including
increasing sea water levels, create mainly
negative consequences.

How can the ocean be
a global warming victim? RISING SEA LEVELS
+0,2m since 1900
Sea-water warming causes +0,3 to 1m in 2100
massive migrations,
large-scale mortality
and the demise of
certain species. We GLOBAL WARMING
have witnessed impressive +0,5°C since 1971
species migrations of several +0,6 to 2°C in 2100
hundred kilometres per
decade. This is the case, for
example, for tropical species
which tend to migrate to cooler ACIDITY
waters. The balance in biodiversity +30% since 1900
is disrupted and creates a predicted +150% in 2100
weakening in the tropics and an
increase in the polar regions.