According to a recently published scientific study from Nature Climate Change, sea levels are not only rising but the rate of sea level rise is steadily increasing. This is at least the third study confirming sea level rise published in the past year.
While the ocean rose by 2.2 millimeters in 1993, it rose 3.3 millimeters in 2014. That is between 0.86 and 1.29 inches of sea level rising per decade, with further acceleration possibly in store.
Scientists based these estimates off of the mass changes of several key components of sea level rise, such as the melting of the Greenland and Antarctic ice sheets.
Antarctic and small glaciers have certainly melted at a faster rate over the decades. The Greenland ice sheet, however, has melted the most. In 1993, the sheet contributed to less than 5 percent of all sea level rise, but in 2014, it contributed more than 25 percent.
The researchers also re-examined the recent satellite record, wanting to see a clearer picture of the sea level rise. With these satellite images, they were able to observe each of the individual components of sea level rise, collectively called the sea level “budget.”
These components include thermal expansions of ocean water as it heats up, as well as the melting of Greenland, Antarctic and smaller glaciers around the globe. Terrestrial water storage and loss are also key components of sea level rise. Due to rainfall and other factors, the continents can store more water on their surfaces or lose it to the ocean.
The study found that the different parts of the budget matched up with the sea level changes observed over the past two decades.
“We’ve known the bottom line total sea level change over the last couple decades, and we’ve known the individual components on a year-by-year basis. We’ve known the two match up pretty well. The authors show that, when you look a bit more sharply at the year-to-year total, it’s quite close to the total of the individual components. The sums work, not just on average, but in each year. This increases confidence in the overall result,” stated Bob Kopp, a Rutger University sea level expert who is familiar with the study.
Researchers also discovered that ice melting is contributing more to sea level rise than thermal expansion. This discovery contrasted with research from the United Nation’s Intergovernmental Panel on Climate Change, the top authority on climate science, which predicted that thermal expansion would contribute more to sea level rise in 2013.
These findings “highlight the importance and urgency of mitigating climate change and formulating coastal adaptation plans to mitigate the impacts of ongoing sea level rise,” wrote Xianyao Chen of the Ocean University of China and Qingdao National Laboratory of Marine Science and Technology, and his colleagues from institutions in China, Australia and the U.S.
“We understand why the sea level is accelerating and we’re understanding what the components are contributing,” added University of Arizona researcher Christopher Harig, one of the study’s authors.
Earlier this year, another research group found that sea level rise was about 1.1 millimeters per year before 1990. Between 1993 and 2012, the rise increased to 3.1 millimeters per year.
According to current statistics from NASA, the rate of sea level now is at 3.4 millimeters per year.
Despite these differing estimates, researchers agree in general that the sea level rise is increasing and that it will negatively affect coastal regions, which will have less time to adjust to the rises.
Scientists also agree that there is no way to deny that the sea level is rising and will continue to rise at a faster rate based on scientific projections.
“I think it’s gotten to the point where the observation is pretty robust,” said Haring. “It’s no longer a projection, it’s now an observation. It’s not something that they can continue to put off into the future.”
