In 15 years the Earth has accumulated more heat than absorbed in the previous 45 years
(sustainabilityenvironment.com) – Can warming of the oceans change the global climate in ways we do not expect? It is the question at the center of a study published in Earth System Science Data. It starts from a fact that is catching on with climate scientists: the surface temperature of the seas this year has set a new record, and we are not yet sure why it happened. Nor how this event can interact with other climatic phenomena, starting from El Niño.
Where does ocean warming come from?
The most worrying aspect is that this heating is incredibly fast. To quantify it, the authors of the study started from the energy imbalance of the Earth, that is the difference between the amount of heat that the Planet receives from the Sun and what is reflected in space.
Most of the solar radiation, 89 percent, is absorbed by the ocean masses. The result: in 15 years we have doubled the Earth’s energy balance. The amount of heat absorbed in the last three decades is almost equal to that retained in the previous 45 years. And in the last 40 years the warming of the oceans is increased of +0.6°C, two thirds of the recorded total increment from 1850 to today (+0.9°C). Between 1971 and 2020, the heating rate averaged 0.48±0.1 W m2. But since 2005 the value has risen to 0.76±0.2 W m2.
A key climate indicator
What does it depend on? Is there the hand of man or is it just a phenomenon linked to the natural variability of the Planet? Or a mix of the two causes? Scientists do not yet have an answer, but, data in hand, stress that the Earth’s energy balance should automatically enter among the indicators used by climate diplomacy to calculate the results on emissions and calibrate future actions.
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“The Earth’s energy imbalance is the most fundamental global climate indicator that the scientific community and the public can use as a measure of how well the world is doing in the task of bringing anthropogenic climate change under control”, write the authors. “Moreover, this indicator is highly complementary to others already established, such as the global average surface temperature, as it represents a robust measure of the rate of climate change and the future one to which we are already bound today“.