Sea Level Rise: A Crash Course for All
The newest and most comprehensive Intergovernmental Panel on Climate Change (IPCC) report holds dire warnings. The report details how humans have been answerable for the 1.1 degrees C of temperature rise since the economic era. It also shows the impacts of this warming are already lethal and disproportionately harming the world’s most vulnerable people. But there’s also hope. The report concludes that it continues to be possible to carry off global warming’s worst consequences, but doing so will take global cooperation, billions of dollars, and profound societal changes.
With such high stakes, a lecture at Columbia Climate School‘s Lamont-Doherty Earth Observatory, “How Much Will Sea Level Rise? Diving into the Past to Predict Future Change,” drew a near-capacity crowd last week. Assistant Professor Jaqueline Austermann, an affiliate of the Seismology, Geology, and Tectonophysics Division of Lamont, delivered the talk.
“[Jacky] is an incredibly well-recognized young scientist,” said Lamont director and Columbia Climate School co-dean Maureen Raymo, who introduced the lecture. “She was named one in every of Science News’s 10 scientists to look at last yr. She is the winner of a Sloan Research Fellowship in 2021 to 2023, a prestigious fellowship given to scientists.”
Austermann framed the conversation by first describing the stakes — how sea level threatens infrastructure worldwide, and the homes and livelihoods of tens of millions of individuals. Then she dove into the evidence.
“If we have a look at [the rate of sea level rise from] 1900 to 1990, we’re about half an inch of sea level rise per decade, or a bit of over a millimeter per yr. And that has been accelerating to 3 to 3 and a half millimeters per yr during the last couple of a long time,” said Austermann, pointing to and describing the varied measurement technologies.
Austermann explained that sea level rise is a consequence of three dynamics: roughly a 3rd of that sea level rise comes from thermal expansion (as global warming heats the oceans, water naturally expands), whereas melting polar ice in Greenland and Antarctica and the melting of mountain glaciers are answerable for the opposite two thirds.
Looking closer at polar ice melt, Austermann noted that the Thwaites Glacier in Western Antarctica is probably the most significant concern to scientists.
“There’s good evidence that if it starts to melt, big parts of this Western Antarctic ice sheet will [also] melt,” she explained.
The talk also drilled down how and why sea level doesn’t rise at the identical rate in every single place. On the East Coast, for instance, the ocean is rising at roughly double the worldwide rate. And even along the identical coastline, this acceleration isn’t uniform.
“We’ve about two millimeters per yr of sea level rise in Florida over this time period and about 4 within the Carolinas,” said Austermann. “So, there’s very significant spatial variability on this sea level prediction, and that also implies that once we’re planning and adapting infrastructures for sea level change, this spatial variability is absolutely critical.”
Austermann said this variability might be traced back to the last ice age and the way land masses steadily rebound once relieved of their burden of ice. When ice sheets covered huge swaths of North America, their weight depressed the land under the ice, and caused the encircling land to bulge up. Now that the ice has disappeared, the land formerly under the ice sheet is slowly rising back up and the encircling bulges are lowering, flattening out. This so-called “post-glacial rebound” changes the coast’s character and relationship to rising seas.
“Sea level goes up, and it’s going up due to expansion but in addition since the land is coming down. That is most severe within the Carolinas for this reason very distinct shape,” said Austermann.
Climate researchers project a variety of future sea levels. Austermann displayed a map showing what the several predictions mean when it comes to inundation.
Digging deeply into paleoclimatology, the study of past climate, Austermann described how Lamont scientists — herself and Raymo included — have been capable of model predictions of future sea level rise by studying the markers of past tides, gauging sea levels during a time when Earth was warmer than today. Specifically, Austermann shared photos and data from a field expedition within the Bahamas. While there, the research team found clues to sea level rise within the distant past by examining fossilized dunes and corals. They concluded that sea level back then was likely no less than two millimeters higher than today and can have risen as much as five millimeters higher.
Amongst her final comments was a frightening conclusion. Sea level rise is projected to be on the order of a meter in Recent York City by the top of the century, reminding the audience of the critical importance of reducing carbon emissions to stave off probably the most drastic global changes.