Sea level rise rate doubled since 1850
This image shows the coast of Portland, Maine in 1853, at the beginning of the Industrial Revolution. Kenneth Miller's study indicates that sea level is rising about twice as fast now as it was in the 1850s, perhaps indicating a connection between sea level rise and human activities.
DB: This is Earth and Sky. Global sea level is rising twice as fast today, in contrast to 150 years ago.
JB: That’s according to Kenneth Miller, professor of geological sciences at Rutgers University in New Jersey. Miller and his colleagues took five core samples, drilled to a depth of 500 meters, or about 1600 feet.
DB: They studied the sediments, fossils, and isotopes of the core. By comparing them with other known measurements, Miller’s team constructed something that hadn’t existed before – a comprehensive record of sea level and climate changes that span 100 million years. Combined with other records, sea level changes can now be traced over 500 million years, according to Miller. The results are published in the journal Science.
Kenneth Miller: I think that the part that has caught most of the attention in a record that spans hundreds of millions of years, basically, is the past five thousand years, where our studies show that sea level, globally, has been rising at a rate of about a millimeter per year over the past five thousand years, while tide gauge data, which record things basically since 1850, shows almost double the rate of change. And that does imply that human induced warming has caused an increase in the rate of sea level rise.
JB: This summer, Miller will continue his drilling studies to detail sea level change. We have more at earthsky.org. Thanks today to NASA: explore, discover, understand. We’re Block and Byrd for Earth and Sky.
Additional Teacher Resources
EPA: Sea Level Rise Report
“The Cost of Holding Back the Sea” estimates the area of dry and wet land that would erode or be inundated from a 50, 100, or 200 cm rise in global sea level, for each of seven regions comprising the contiguous 48 states.
NASA: Seal Level Rise, After the Ice Melted and Today
Climate warming is expected to result in rising sea level. Should this occur, coastal cities, ports, and wetlands would be threatened with more frequent flooding, increased beach erosion, and saltwater encroachment into coastal streams and aquifers. Global sea level has fluctuated widely in the recent geologic past. It stood 4-6 meters above the present during the last interglacial period, 125,000 years ago, but was 120 m lower at the peak of the last ice age, around 20,000 years ago. A study of past sea level fluctuations provides a longer-term geologic context, which can help us better anticipate future trends.
