🌊 Climate: scientists predicted it 30 years ago, it's now confirmed

The melting of polar ice and rising sea levels are phenomena that have concerned scientists and citizens for decades. A recent study provides striking insight into the reliability of climate predictions made nearly thirty years ago, by comparing them with current satellite observations.

Researchers from Tulane University compared sea level rise projections made in the 1990s with data measured by satellites since that time. They found remarkable agreement, despite the technological limitations of the era. The climate models of that time, although rudimentary, correctly anticipated the global increase in sea level, demonstrating a solid understanding of the mechanisms at play.


The study, however, highlights some shortcomings in the initial predictions, particularly an underestimation of the contribution from melting ice sheets. Scientists at the time did not fully grasp the impact of warming ocean waters on the destabilization of ice shelves, particularly in Antarctica. This unexpected acceleration of ice loss has added more than 2 cm (0.8 inches) to the observed rise.

The authors emphasize the importance of continuing monitoring efforts, particularly through NASA space missions and programs of the US National Oceanic and Atmospheric Administration. These data are crucial for refining future projections and adapting coastal strategies, as sea level rise varies considerably from one region to another.

Persistent uncertainties regarding the behavior of ice sheets raise questions for the future. Scenarios now include the possibility, although unlikely, of a catastrophic collapse of Antarctic ice by the end of the century, which would have dramatic consequences for low-lying coastal areas, such as in Louisiana.

Ice sheets and their role in sea level rise

The ice sheets of Greenland and Antarctica contain enormous amounts of frozen water. When they melt, this water flows into the oceans, directly contributing to sea level rise. The melting process is accelerated by climate change, which affects both air and water temperatures.

Ice melts not only on the surface due to warmer temperatures, but also from below, where warmer ocean waters erode the bases of glaciers. This phenomenon, less well understood thirty years ago, explains why the initial projections underestimated the contribution of ice sheets.

Modern satellites allow precise measurement of the thickness and flow velocity of these ice masses. These data help scientists better predict their future evolution and anticipate impacts on global sea levels.

Satellite monitoring of sea level

Since the early 1990s, specialized satellites have continuously measured the height of the ocean surface. These instruments use radars to send signals toward Earth and measure their return time, enabling extremely precise calculations.

This technology has revolutionized our understanding of sea level rise by providing global and homogeneous data. Before this, measurements relied on coastal tide gauges, which were geographically limited and subject to local variations.

Satellite data have confirmed that the average sea level is rising by about 3 millimeters (0.12 inches) per year on average, with recent acceleration. They also allow the study of regional variations, enabling the adaptation of coastal policies to local specificities.