This text is taken from the “Courrier de la planete” of May 24, 2022. To subscribe, click here.
The rise in the level of the oceans is one of the consequences of climate change that affects the most people on our planet. The World Bank estimated in 2020 that more than a billion people could be directly affected by a rise in the average sea level. In Quebec, the first regions affected will probably be the Gaspésie and the Îles-de-la-Madeleine.
This graphic created by The duty makes it possible to visualize the cumulative increase in the average level of the oceans compared to 1993. We can see that the rise of approximately 6 centimeters in 2012 is established at more than 10 centimeters in 2022. Taken by satellite altimetry, the data collected come from the European marine service Copernicus.
By measuring the altitude at a multitude of points in the Earth’s oceans, it is possible to calculate an increase in the average level of these. As with the rise in the average temperature on Earth, the rise in the level of the oceans will be more or less significant depending on the region of the globe.
For the next 30 years, the US National Weather Service estimates that the average water level could rise by 20 centimeters on the west coast and 35 centimeters on the east coast.
On the graph, we can distinguish a variation of the rate of increase; the pace seems to have accelerated in recent years. Previously estimated at about 2.8 mm per year, the annual increase is now estimated at more than 4.2 mm.
Although it is difficult to explain precisely the acceleration of recent years, the rise of the oceans is generally attributed in equal parts to two phenomena, namely the melting of ice, originating from glaciers and pack ice, and the thermal expansion of water, due to its heating.