If Paris Goals Are Not Met, Sea Level Rise May Become Unstoppable By 2060

We hear a lot about the importance of meeting the carbon emissions reductions agreed to by the global community in Paris in 2015. If we do, we are told, we face a world that will only be 1.5º C hotter. That in and of itself will trigger significant changes in storm intensity, elevate the risk of drought in many parts of the world where the crops that sustain us are grown, increase wildfire activity, increase the amount of flooding in other parts of the world, and subject many of the world’s largest cities to higher sea levels that could make parts of them uninhabitable. And that’s the good news!

The bad news is, humans have nearly a zero chance of limiting global heating to less than 1.5º C above pre-Industrial Revolution numbers. Business is too interested in making money and is spending billions to spread lies about climate science. Most governments depend on the support of voters and since there are virtually no limits on campaign finance spending, the wealthy get their way every time, even though ultimately they are going to be just as dead as the rest of us. The truth is, as long as the money keeps rolling in, what we get is lip service to the idea of making our planet sustainable while business as usual continues to be the modus operandi of societies everywhere.

Researchers at the University of Massachusetts, Penn State, Rutgers, McGill, and several other well known universities have published a new study in the journal Nature that examines what most likely will happen to global sea levels if the average global temperature increase reaches 3º C. If that happens, they say, the Antarctica ice sheet will begin to melt and nothing will stop it from disappearing completely over time.

The ice covering Antarctica holds enough water to raise global sea levels by 57.9 meters. For those of you who don’t do the metric system, that is equivalent to 190 feet. [Goodbye, Florida!] It doesn’t take a Rhodes Scholar to figure out what effect that much sea level rise will have on the world’s major cities, most of which are clustered on the edge of the oceans. Sea level rise will be 17 cm to 21 cm — double the current rate — by the end of this century if average temperatures increase by 3º C. If the Paris targets are met, the rate of sea level rise would be about half that number. Here is an excerpt from the executive summary to the study:

“The potential for the implementation of the Paris Agreement temperature targets to slow or stop the onset of these instabilities has not been directly tested with physics-based models. Here we use an observationally calibrated ice sheet–shelf model to show that with global warming limited to 2 degrees Celsius or less, Antarctic ice loss will continue at a pace similar to today throughout the twenty first century.

“However, scenarios more consistent with current policies (allowing 3 degrees Celsius of warming) give an abrupt jump in the pace of Antarctic ice loss after around 2060, contributing about 0.5 centimetres [global mean sea level] rise per year by 2100 — an order of magnitude faster than today. More fossil fuel intensive scenarios result in even greater acceleration. Ice sheet retreat initiated by the thinning and loss of buttressing ice shelves continues for centuries, regardless of bedrock and sea level feedback mechanisms or geo-engineered carbon dioxide reduction. These results demonstrate the possibility that rapid and unstoppable sea level rise from Antarctica will be triggered if Paris Agreement targets are exceeded.”

Robert DeConto, an expert in polar climate change at the University of Massachusetts and lead author of the study, tells The Guardian, “If the world warms up at a rate dictated by current policies we will see the Antarctic system start to get away from us around 2060. Once you put enough heat into the climate system, you are going to lose those ice shelves, and once that is set in motion you can’t reverse it. The oceans would have to cool back down before the ice sheet could heal, which would take a very long time. On a societal timescale, it would essentially be a permanent change. It’s really the next few decades that will determine the sea level rise from Antarctica. These ice shelves won’t be able to just grow back.”

Hello? Is anybody paying attention? Or are we too caught up in debates about cancel culture and the wrong sort of people voting to care?

A Contrary View

Image credit: NOAA

Another study published in Nature on Wednesday, by scientists at King’s College in London, says sea levels will rise by just 0.5 cm every year by 2100 if average global temperatures rise to 3º C. DeConto calls that other paper an “impressive piece of work” but noted it did not factor in the compounding impacts from the loss of ice shelves. “Neither of these papers are the last word, this is ongoing work,” he says. “Basically, we are going to have to cope with continued sea level rise. The real question is whether it will be at a manageable or unmanageable rate for us.”

Climate scientists are particularly concerned about the deterioration of the Thwaites glacier on the western edge of the Antarctic ice sheet, which is roughly the size of Britain and one kilometer thick. Some refer to is as the “doomsday glacier,” because if it is lost, that alone would raise the level of the seas by 65 cm — a little over 2 feet.

Antarctica is being eroded by a warming atmosphere as well as the heating oceans, with warming seawater entering crevasses and gnawing away at pinning points that hold enormous bodies of ice to submerged bedrock. A rapid acceleration of melting could cause a cascading effect where huge amounts of ice and water flow uninterrupted into the Southern Ocean, according to The Guardian. DeConto says the King’s College study fails to take into account the knock on effects of such destabilizing factors.

Once the train of events is set in motion, dramatic ice loss would occur over the next several centuries. “In the century after 2100, it’s potentially catastrophic,” he says. “If we did nothing at all to reduce emissions we could get 5 metres of sea level rise just from Antarctica by 2200, at which point you’d have to remap the world from space. It would be unimaginable.”

Orrin Pilkey, a sea level rise expert at Duke University who was not involved in the research, tells The Guardian the UMass research is an “important attempt to relate the Paris agreement to reality. I would consider this a thoughtful and even frightening but credible contribution which should provide a very strong basis to get on with implementation of the Paris agreement.”

Andrea Dutton, an expert in sea level rise at University of Wisconsin–Madison, who was a co-author, says the research “addresses an important and pressing question” of what the Paris climate targets will mean for future sea level rise. We are already struggling with the amount of sea level rise that has occurred over the past century.” A major acceleration in Antarctic melting will “bring about coastal retreat and migration on a scale that we have never before witnessed. We will not be able to just adapt because it is impossible to just engineer our way out of this,” she adds. “The conclusion is a stark reminder of the urgency in making deep and sustained cuts in our greenhouse gas emissions.”

Who’s In?

“Deep and sustained cuts in our greenhouse gas emissions.” Hmmm, who do we know who is doing that? If you said “no one,” go to the head of the class. Lots of political leaders are making flowery speeches about cutting emissions, but the will to do so is hard to find. China says it will get there by 2060, but that will be much too late, according to DeConto. The US says it is ready to do some heavy lifting, but there are only 18 months left before the balance of power in Congress shifts. The party that is currently out of power is much more concerned with locking up black and brown people and preventing them from voting than it is with cutting emissions.

Vanuatu is willing. So is Costa Rica. Does anyone think their efforts, no matter how sincere, will be enough? In a world where being popular on social media is more important than survival of our species, the odds of solving the dilemma of an overheating planet are decreasing with every passing day.

The Biden administration recently pledged to cut US carbon emissions by 50% compared to 2005 levels by 2030, a goal that some say is not nearly enough. “Science and justice demand that we reduce emissions by 70% from 2005 levels by 2030 on the road to zero emissions by mid-century,” Janet Redman of Greenpeace USA said last month, according to a report by AlterNet. “The White House can get this done by removing government subsidies to fossil fuel companies, investing in an equitable and sustainable economic recovery, and stopping fishy carbon offset deals.”

But will it? Now that the speeches are over, the hard work begins. Will the Biden administration take on Big Oil? Don’t bet the farm on it, and so the loss of ice at both poles is pretty much guaranteed to happen at this point. Don’t expect geo-engineering or carbon capture to save us. Both are band-aids designed to present the appearance of progress while business as usual remains the primary focus of the global economic system. Half measures will lead inexorably to a full blown climate crisis for those as yet unborn to deal with. What a legacy we are leaving to those who follow in our footsteps.

Hat Tip to Dan Allard

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