NASA study: Floods on US coasts are expected to increase significantly in mid-2030


A study by the NASA Sea Level Change Science Team at the University of Hawaii sees an increasing risk that from around mid-2030 the tidal floods on the US Atlantic and Gulf coasts will cause the flood thresholds in coastal cities to be exceeded more frequently. The number of flood days should then be three to four times higher than today. According to NASA, the study takes into account all known oceanic and astronomical causes for the first time.

Coastal US cities repeatedly struggle with flooding. As the US weather and oceanography authority National Oceanic reported to Atmospheric Administration (NOAA), more than 600 tidal surges occurred in 2019. This will increase in the future. On the one hand, the effects of climate change would contribute to this, such as the melting of the polar ice cap caused by global warming, which is causing the sea level to continue to rise.

From 2030 would come according to a study by the Seal Level Change Science Team In addition, an astronomical effect of the lunar cycle to wear: the pendulum or tumbling of the moon (libration) as a result of its elliptical orbit. The position of the moon changes in a cycle of 18.6 years relative to the earth and thus has an impact on the tides. Daily tides are suppressed about halfway through the Moon’s 18.6 year cycle. The high tide is then lower than normal, the low tide higher. The rise in sea level is thus counteracted. In the other half of the cycle, however, the effect increases, writes the science team. Then the tide is higher and the ebb is lower.

The Sea Level Protection Tool shows the development of the flood days in Honolulu.

(Bild: NASA Sea Level Change)

The moon is already in the tidal part of its cycle. The effects, together with the rise in sea levels due to climate change, are not yet so strong that the tide is so high that the flood thresholds are exceeded. However, the next tidal part of the cycle is due in mid-2030. Then the global rise in sea levels will also have progressed further, and the floods will inundate the coasts of the USA, Hawaii and Guam more intensely. Climate phenomena such as El Niño could intensify this effect. Only the coasts in the far north and Alaska are likely to be spared for another decade or more. The reason for this is the fact that the land areas there are increasing due to long-term geological processes, according to the researchers.

In view of these possible effects, the scientists are already warning to prepare for them and take measures to protect against flooding. In order to be able to plan better, it is important to know in advance whether floods will occur in one month or whether there will be more floods in the second half of the year than in the first, summarizes Ben Hamlington, head of the NASA Sea Level Change Team and co-author of the Study the need for continuous observation together. An already existing tool that shows the development of the floods, is to be supplemented with findings from the study in the near future.


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