Sea level rise is more severe than at any point in the last 100 years, according to a new study out of Harvard University. Over the last century, observed increases in sea level were greater than would be predicted by current climate models. Overall change has also dramatically increased in the last two decades, according to researchers.
This difference between climate models and historical records could be the result of measurements taken in the early 20th Century using devices known as tide gauges, and these records were less reliable in the early 20th century than today. Another possibility is that current models have a vital flaw that would account for the discrepancies. Climatologists have known about these differences for several years, but the degree of the discrepancy may not be as great as suspected, according to the new study.
Between 1900 and 1990, tide gauges recorded a rise of around 0.05 inches each year, the new analysis revealed. Researchers had previously measured the sea level increase during that time at 0.06 inches. Climate models utilized by the Intergovernmental Panel on Climate Change (IPCC) calculate the sea level rise during that time should have measured just 0.02 inches.
Sea levels are seen rising at a dramatic rate in this new investigation. In the years between 1993 and 2010, the instruments recorded an increase of 0.12 inches every year, highlighting climate change in recent years.
"What this paper shows is that sea-level acceleration over the past century has been greater than had been estimated by others. It's a larger problem than we initially thought," Eric Morrow, a recent doctoral graduate from the Department of Earth and Planetary Sciences (EPS) at Harvard University, said.
Although this new study shows the rise in sea level since the year 1900 was not as great as once believed, the results also show the increase has become far more severe since 1993. Patterns linking the distantly-placed tide gauges were determined using sophisticated analysis, which could have presented some problems with the final analysis.
"Tide gauges are located along coasts, therefore large areas of the ocean aren't being included in these estimates. And the records that do exist commonly have large gaps," Carling Hay, a postdoctoral fellow at EPS, said.
Sea level change occurs for a number of reasons, including global warming and other climate change brought about by the release of greenhouse gases into the atmosphere. Ocean circulation patterns, expansion of the ocean, and continuous warming from the latest ice age also contribute to the rise. These conditions were utilized in the new study in order to arrive at the new conclusions.
