Sea Level Rising Faster
Sea levels could rise faster than previously expected in the coming decades. This is the conclusion of a new study by the German ocean expert Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research (PIK). Using measurement data from the 20th century, the researcher demonstrated a close connection between global temperature increases and the speed at which sea levels are rising: the warmer it gets, the faster sea levels are rising. If this correlation found for the last century remains valid for the next 100 years, the global sea level could rise by 50 to 140 centimeters by the year 2100.
As a result of global warming, global sea levels will rise in the 20th century. Century increased by almost twenty centimeters. So far, scientists assumed a further increase of 9 to 88 centimeters, depending on how much greenhouse gas mankind emits and how sensitive the climate system reacts to it. According to Rahmstorf, however, computer models of the climate clearly underestimate the rise in sea level that has already occurred today, so future projections of sea level development based on these models are not yet reliable. Instead of climate models, the new study is therefore based on empirical observations of air temperatures and sea level changes.
"The fact that we get such different estimates using different methods makes it clear how uncertain our current sea level forecasts still are," says the Potsdam climatologist. A major reason for this uncertainty is the behavior of the large continental ice masses in Greenland and of Antarctica, which is difficult to calculate. Rahmstorf therefore warns: "For a given warming scenario, we could also get double the rise in sea level than previously expected."
A sea level rise of one meter or more would be very bad news for large coastal cities as it would greatly increase the risk of storm surges. Cities on the North Atlantic coasts such as London or New York are particularly at risk – sea levels could rise more here than elsewhere if the North Atlantic Current weakens. This was already shown in an earlier study by Rahmstorf's working group in 2005. Sea-level rise can be limited by significantly reducing greenhouse gas emissions in the coming decades. In addition, the consequences of sea-level rise can be reduced through forward-looking coastal protection. © Potsdam Institute for Climate Impact Research
