Temperatures over the records, year after year, extreme weather events in continuous increase, desertification, crazy rains. The effects of global warming are there for all to see. The bad news is that the situation could get worse faster than previously thought, according to the journal Science: a report by a team of experts led by Chinese climatologist Lijing Cheng reveals how the warming of the oceans has been accelerating for several decades. It would not be a coincidence if 2018 seems destined to be a passage to history as the hottest year ever for the oceans.
A worrying situation, especially since that oceans are considered the main brake at the increase in atmospheric temperature. Global warming is based on a imbalance between the Sun and the Earth caused by the greenhouse effect, and about 93% of the excess energy is absorbed by the waters.
Even so, the consequences for the mainland are quite obvious. At the increasing of surface waters’ temperatures, global warming effects gets tougher: ice melting, increasing frequency of extreme events such as hurricanes, tsunamis and heat waves. And when, inevitably, the difficulty of absorption of the oceans is slowing down, problems will only intensify. To survey changes in global warming is much more important, also because – the experts point out – sea temperatures are less variable than atmospheric temperatures, so they give clearer data to estimate global warming evolution.
How have the oceans warmed up because of human activity? And how fast? The answer comes from the most recent measurements made by Argo, a network of over 4,000 sensors positioned in the waters around the globe. As result of an international collaboration, Argo has been operating since the early 2000s, and today, after 13 years of activity, has allowed us to accumulate accurate measurements of the water situation, and to refine the models.
According to the data, average temperatures are growing, and they have surged since the 1960s. And the more recent models say that temperatures are growing faster than we thought in 2015, when the Paris climate agreement was negotiated. In the absence of interventions, the increase of energy in the waters within two km of depth will reach 2,020 zetajoules for 2100. In this case, it is not difficult to imagine that the consequences for the planet are catastrophic.
The good news is that the actions promised by the Paris agreement could still be effective. If the emissions of greenhouse gases are reduced, as stated in Paris climate agreement, it is possible to halve the accumulation of energy in the water (it would stop at about 1,037 zetajoule), enough to hit the target anyway, and limit the average temperature increase below two degrees.
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