Coastal sea levels in many parts of the world are probably higher than previously assumed by scientific studies. This is what two scientists from Wageningen University & Research (WUR) stated in an article published on Wednesday in the trade journal Nature appeared.
According to the researchers, in many studies there is an average difference of twenty to thirty centimeters between the assumed and actually measured sea level heights. However, the deviation can amount to more than 1 meter.
The discovery has consequences for millions of people, the researchers say. According to WUR calculations, a sea level rise of 1 meter will place coastal strips and river deltas below sea level, where around 130 million people live. There are currently twice as many people living below sea level as suggested in previous studies.
The researchers studied hundreds of scientific studies and concluded that more than 90 percent of them are based on incorrect models. Less than 1 percent of the 385 studies examined calculated the actual sea level height on the coast completely correctly, according to them.
Vietnam
The errors result, among other things, from the use of an outdated calculation model. The sea level height is determined on the basis of, among other things, satellite measurements of the land height, data on gravity and rotation of the earth. This model does not take sufficient account of factors such as currents, tides and water temperature.
The differences are much greater in certain regions, such as countries in Southeast Asia and the Pacific, where ocean dynamics are more complex. There, the sea level along the coast is up to several meters higher than is generally assumed, the pair said.
Philip Minderhoud, responsible for the study, speaks to the NOS of “a blind spot.” He discovered the error when he visited the Mekong Delta in Vietnam about ten years ago, an area where many rivers flow into the sea. There he saw that the water level was much higher than indicated on the coastal maps.
