Climate change has caused sea levels around the world to increase at a much faster rate during the 20th century than in any other period in the last 3,000 years, a new study says.
Scientists from Rutgers University and other research organizations in the United States have discovered that during the period between the 1900s and the 2000s, the water levels in the Earth's seas rose by as much as 5.5 inches at a rate of 1.4 millimeters annually.
This represents the fastest rate of global sea level increase that the planet has ever experienced over the past three millennia.
Data from NASA shows that the current rate of increase is at 3.4 millimeters every year, which suggests that the rise in sea levels is only continuing to accelerate in recent years.
Global Warming
According to the researchers, the abnormal rise in water levels during the 20th century occurred as a result of the planet's warming. They calculate that had it not been for climate change, there is little reason for sea levels to increase as much as they did during the period.
Water levels would only have experienced a fall of three centimeters (1.18 inches) and a rise of seven centimeters (2.76 inches), and not the 14 centimeters (5.5 inches) that was recorded.
The researchers' analysis of sea level increase in the past 3,000 years produced a "hockey stick" graph that depicts a long period of fairly flat sea levels, which serves as the "handle" followed by a sharp turn upward during recent periods, which serves as the "blade".
The patterns observed by the research team mirror those outlined in another climate study[pdf] conducted by scientists at Penn State University (PSU) in 1998. The PSU team discovered a similar hockey stick graph during their study of changes in the Earth's temperatures in previous years.
Limiting The Impact Of Sea Level Increase
In the recent global sea level study, the researchers calculate that water levels will continue to increase at a rate much faster than those observed during the 1900s, regardless of how much carbon dioxide is released into the atmosphere.
However, there are two prevailing scenarios that depict how the rise in sea levels could occur in the coming years, depending on the course of action taken by nations of the world.
The first one is known as a low emissions scenario, which shows that sea levels could only increase by as much as 24 to 61 centimeters (9.44 to 24 inches).
The second one is the high emissions scenario, which shows that the seas could rise by as much as 52 to 131 centimeters (20.5 to 51.6 inches). This last scenario is what nations that took part at the Paris climate summit agreed to prevent.
The researchers note that the methods they used to calculate for these figures may not fully capture what could occur over the next few decades.
"We have a model that's calibrated against a period when a certain set of processes, largely thermal expansion and glaciers, were dominant," Robert Kopp, a climate scientist from Rutgers and lead author of the study, said.
"We're looking forward to a period when other factors will be dominant."
The findings of the Rutgers University-led study are featured in the journal Proceedings of the National Academy of Sciences.
Photo: Liam Quinn | Flickr
