Catastrophic Sea-Level Rise From Antarctic Melting Possible if Paris Climate Agreement Isn’t Met

Wilkins Ice Shelf

If Paris Agreement targets are not met, the collapse of melting Antarctic ice shelves — like the Wilkins Ice Shelf in 2009 — could cause catastrophic global sea level rise in the second half of the century. Credit: NASA

Antarctic ice sheet is more likely to remain stable if Paris climate agreement is met.

The Antarctic ice sheet is much less likely to become unstable and cause dramatic sea-level rise in upcoming centuries if the world follows policies that keep global warming below a key 2015 Paris climate agreement target, according to a Rutgers coauthored study.

But if global warming exceeds the target — 2 degrees Celsius (3.6 degrees Fahrenheit) — the risk of ice shelves around the ice sheet’s perimeter melting would increase significantly, and their collapse would trigger rapid Antarctic melting. That would result in at least 0.07 inches of global average sea-level rise a year in 2060 and beyond, according to the study published in the journal Nature.

That’s faster than the average rate of sea-level rise over the past 120 years and, in vulnerable coastal places like downtown Annapolis, Maryland, has led to a dramatic increase in days of extreme flooding.

Global warming of 3 degrees Celsius (5.4 degrees Fahrenheit) could lead to catastrophic sea-level rise from Antarctic melting — an increase of at least 0.2 inches per year globally after 2060, on average.

“Ice-sheet collapse is irreversible over thousands of years, and if the Antarctic ice sheet becomes unstable it could continue to retreat for centuries,” said coauthor Daniel M. Gilford, a post-doctoral associate in the Rutgers Earth System Science & Policy Lab led by coauthor Robert E. Kopp, a professor in the Department of Earth and Planetary Sciences within the School of Arts and Sciences at Rutgers University-New Brunswick. “That’s regardless of whether emissions mitigation strategies such as removing carbon dioxide from the atmosphere are employed.”

The Paris Agreement, achieved at a United Nations climate change conference, seeks to limit the negative impacts of global warming. Its goal is to keep the increase in global average temperature well below 2 degrees Celsius above pre-industrial levels, along with pursuing efforts to limit the increase to 1.5 degrees Celsius (2.7 degrees Fahrenheit). The signatories committed to eliminating global net carbon dioxide emissions in the second half of the 21st century.

Climate change from human activities is causing sea levels to rise, and projecting how Antarctica will contribute to this rise in a warmer climate is a difficult but critical challenge. How ice sheets might respond to warming is not well understood, and we don’t know what the ultimate global policy response to climate change will be. Greenland is losing ice at a faster rate than Antarctica, but Antarctica contains nearly eight times more ice above the ocean level, equivalent to 190 feet of global average sea-level rise, the study notes.

The study explored how Antarctica might change over the next century and beyond, depending on whether the temperature targets in the Paris Agreement are met or exceeded. To better understand how the ice sheet might respond, scientists trained a state-of-the-art ice-sheet model with modern satellite observations, paleoclimate data, and a machine-learning technique. They used the model to explore the likelihood of rapid ice-sheet retreat and the western Antarctic ice-sheet’s collapse under different global greenhouse gas emissions policies.

Current international policies are likely to lead to about 3 degrees Celsius of warming, which could thin Antarctica’s protective ice shelves and trigger rapid ice-sheet retreat between 2050 and 2100. Under this scenario, geoengineering strategies such as removing carbon dioxide from the atmosphere and sequestering (or storing) it would fail to prevent the worst of Antarctica’s contributions to global sea-level rise.

“These results demonstrate the possibility that unstoppable, catastrophic sea level rise from Antarctica will be triggered if Paris Agreement temperature targets are exceeded,” the study says.

Gilford said, “it’s critical to be proactive in mitigating climate change now through active international participation in reducing greenhouse gas emissions and by continuing to ratchet down proposed policies to meet the ambitious Paris Agreement targets.”

Reference: “The Paris Climate Agreement and future sea-level rise from Antarctica” by Robert M. DeConto, David Pollard, Richard B. Alley, Isabella Velicogna, Edward Gasson, Natalya Gomez, Shaina Sadai, Alan Condron, Daniel M. Gilford, Erica L. Ashe, Robert E. Kopp, Dawei Li and Andrea Dutton, 5 May 2021, Nature.
DOI: 10.1038/s41586-021-03427-0

Rutgers coauthors include Erica Ashe, a post-doctoral scientist in the Rutgers Earth System Science & Policy Lab. Scientists at the University of Massachusetts Amherst, Pennsylvania State University, University of California Irvine, University of Bristol, McGill University, Woods Hole Oceanographic Institution and University of Wisconsin-Madison contributed to the study.

5 Comments on "Catastrophic Sea-Level Rise From Antarctic Melting Possible if Paris Climate Agreement Isn’t Met"

  1. This is absurd…. they have been touting this for over 30 years… Al Gore thought we were going to be inundated with water 25 years ago…. This is all about control and the socialist revolution, not climate change. There is no significant climate change caused by human activity.

  2. Clyde Spencer | May 11, 2021 at 3:11 pm | Reply

    Lots of assertions with no support provided! First off, the ice shelf is floating and already displacing as much water as contained in its meltwater. That is, if the shelf ice ‘collapses,’ it will not raise sea level! It is implied by some researchers that the shelf ice acts as a buttress to the glaciers. I have not seen a rigorous defense of that assumption! The friction with the bedrock is the most important determinant in the speed of the glaciers. There is one anecdotal piece of evidence of an acceleration of glaciers after shelf ice broke off. On the other hand, the acceleration of the ice might have been responsible for the shelf ice breaking off! Glaciers commonly experience what is called “surging,” which is dramatic changes in the speed with which they move.

    Snow and ice don’t melt linearly with temperature. It must pass the threshold of 0 deg C to melt. The shelf ice is currently melting from below because the ocean water is a little above zero. The center of the land mass is as much as 4,000m above sea level. The dry adiabatic lapse rate is 1 deg per 100 meters of elevation change. That means, even if the AVERAGE Earth temperature increases 2 deg C, and the sea level air temperature in Antarctica were to reach 0 deg C, everything from the shore (0 deg C) to the interior (-40 deg C) would still be , well below the melting point of ice! And the water would no longer be able to melt ice in the water.

    The signatories to the Paris ‘agreement’ have not been keeping their promises. The USA, which Trump withdrew from the ‘agreement,’ has been doing a better job of reducing CO2 emissions than the pious participants.

    These academics should be ashamed of making assertions that are so poorly supported, and so easily countered. It is not the science I grew up with!

  3. Dr Robert El Zazi | May 11, 2021 at 10:23 pm | Reply

    Absolute balderdash. The core temp of the planet has risen less than 1C in over 2,000 years, but yet Rutgers claims it will go up double that amount in less than 30 years. Plus we fact we all have to pay billions of dollars to make it happen. What utter s#!te, and what gets me is people are falling for this. Humans do not, and will not control the temperature on this planet. The sun will and always will. CO2 is NOT the enemy of this planet for those that have studied geochronology they will find out that the more CO2 there is, the more oxygen that’s will be produced

  4. The 10th Man | May 12, 2021 at 7:21 am | Reply

    Nice hit piece you effin shill.

  5. Jared Anderson | May 16, 2021 at 2:23 am | Reply

    Greed wins freedom is the right to be a climate killer

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