New satellite is going to better monitor sea level rise

Today in California, a satellite is being launched to measure the rise in sea level. This is the Sentinel-6 Michael Freilich satellite, which monitors sea level rise more accurately than was previously possible from space.

Climate scientists mainly want to know whether and if so where sea level rises accelerated, as a result of the melting of glaciers and ice caps in Greenland and Antarctica.

For a few years, a slight acceleration in sea level rise has been observed, to the great concern of water managers and politicians. It is therefore important that the new satellite can continue the measurement series.

โ€œ Because only then can you clearly see how much acceleration in sea level rise is taking placeโ€, says Bart van den Hurk, professor of climate science at the Vrije Universiteit in Amsterdam and researcher at Deltares. For years, the sea level rise was about 2 millimetres per year, but it has now risen to an average of 4 mm.

โ€œ The big question is whether this increase will remain modest this century, or will increase sharply. In any case, it is no longer about the question of how many centimeters the sea will eventually rise, but by how many meters.โ€

No accelerated increase in North Sea level

Incidentally, this acceleration is not observed off the coast of the North Sea, says Marjolijn Haasnoot of Utrecht University, also working at Deltares. On behalf of the Deltacommissaris, she conducted a study on sea level rise in the future and its significance for the Netherlands.

In this animation you can see how Sentinel-6 will work:

โ€œ The fact that this acceleration is not seen here does not mean that it does not take place. These measurements give us a better understanding of when and how much we need to adapt,โ€ says Haasnoot. In any case, there are regional differences in the world, sea level does not rise equally hard everywhere.

For example, Pacific islands already notice the consequences, the rise in sea level is quicker than the global average.

Measuring sea level rise at the earth‘s surface is complicated, says Haasnoot. Rijkswaterstaat manages about twenty measuring stations, which continuously monitor the water level just along the coast. โ€œThere is a lot of variation. For example, if in a year there are many storms, the sea level is higher. But a year later, the sea may be lower again.โ€

That is why the new satellite is crucial, she says, in order to be able to make additional measurements.

Ice sheet Greenland melts

Most of global warming is absorbed by the oceans. Warmer water expands, which makes the most important contribution to the rise in sea levels today. In addition, in particular, the ice cap in Greenland has shown a fairly rapid loss of mass in recent years, causing sea levels to rise even harder.

โ€œ The question is whether the latter will continue, or whether it will be less fast in five years,โ€ says climate scholar Van den Hurk. โ€œAs with the capriciousness of the weather, the movement of these large ice caps also goes with a capricious pattern. There are many elements that play a role, which we are far from all of us.โ€

Van den Hurk compares the ice sheet to a truck that has to brake for a traffic light. It does not do so in a smooth movement, stopping is with small jerks. The melting of ice sheets seems to be the same way, but at a much lower pace.

โ€œ However, we know from historical climate research that sea level per degree of warming rises by a few metres. The world has already reached over a degree of warming, so there will be a few metres of sea level rise anyway. We just don’t know when that rise will come. This century, or only 500 years from now?โ€

โ€œ We can use that satellite to keep our finger on the pulse,โ€ says Van den Hurk. He also hopes that with the new observations computer models can be improved, which calculate how fast the sea level rises. โ€œBecause right now, melting is going to be harder than the climate models predict.โ€