Technology Some Climate Tipping Points May Be Reversible, If We Act Fast
Atlantic Ocean circulation weakens, sparking climate worries
New study finds evidence of an unprecedented slowdown in North Atlantic Ocean circulation, likely to due to human-caused climate change. © Provided by CBS News / Credit: Climate Central Recently scientists have noticed a cold blob, also known as the North Atlantic warming hole, in a patch of the North Atlantic around southern Greenland — one of the only places that's actually cooling on the planet. The fact that climate models predicted this lends more evidence that it is indicative of excess Greenland ice melting, more rainfall and a consequent slowdown of heat transport northward from the tropics.
In the already-glum world of climate research, tipping points are one of the least rosy areas of study. The collapse of crucial systems in response to passing certain levels of planetary heating isn’t exactly uplifting stuff.
Aout in Nature on Wednesday is about as good as it gets, showing that we may be able to bring some key aspects of the planet back from the brink if we reduce warming in a timely enough manner. So, uh, cheers to that.
The researchers focused on a handful of climate buffers that keep Earth’s climate in balance and also provide sustenance and livelihoods for billions of people. Among them are the Amazon rainforest, the polar ice caps, the Indian monsoon, and a key ocean current in the Atlantic. All are vital life support systems, yet they’re under threat by the experiment the oil industry and other polluters have decided to conduct in the atmosphere.
The US has a chance fix its broken climate risk disclosure system
If companies ignore their vulnerability to climate change, the global economy is at risk.Financial regulators in the US are grappling with that question now. The Securities and Exchange Commission (SEC) opened a 90-day public comment period in March that will inform the first update to federal climate risk disclosure guidelines in a decade. Shareholder groups and asset managers like BlackRock (CEO Larry Fink wrote in February that “climate risk is investment risk”) are pressuring boardrooms to improve corporate transparency around climate risks.
Rising carbon dioxide levels are pushing global temperatures higher. And the worry for each of these key systems—as well as others, such as the Great Barrier Reef—is that, once you cross a certain temperature threshold, they collapse or shift into a new state that humans have never dealt with. If enough heat and attendant drought cook the Amazon, for example, it could permanently turn into savannah in a relatively short period of decades. Figuring out what thresholds of warming could lead to this and other tipping points is important.
The new research looks at another key element: timescales. Specifically, if the world crosses a warming threshold and then cools back below it, can these systems be saved? To undertake the study, researchers created simple models that identified when tipping points would be reached for each of these systems. For the researchers, simplicity here was actually a major plus compared to more complex climate models.
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“Simple models allow us to study the key underlying dynamics (which allows us to identify that the structure is similar across multiple types of tipping point), whereas the more sophisticated climate models tend to be a bit more of a mystery/’black box’ in understanding all the processes,” Paul Ritchie, a postdoc at the University of Exeter who led the research, said in an email.
With the current in the Atlantic—known as the Atlantic Meridional Overturning Circulation, or AMOC, if you want to impress your friends—previous research pegged the key threshold as around 5.4 to 9 degrees Fahrenheit (3 to 5 degrees Celsius). The model they created for that pegged the tipping point right in the middle of that, at 7.2 degrees Fahrenheit (4 degrees Celsius).
They then ran their models and explored what would happen if the world crosses that threshold and then cools below it to levels outlined in the Paris Agreement. The results showed that the tipping point for big, slow systems like the AMOC actually take hundreds of years. The ocean would enter what researchers have dubbed a “melancholia state” (relatable) as the circulation shuts down relatively slowly from human standpoint but quickly from a geological one. The results also show that reducing warming fairly rapidly after crossing the 7.2-degree-Fahrenheit threshold could actually pull the system back out of collapse. Recent research has also shown that the AMOC may, so clearly this an active area of research.
Biden wants to convince the world America can be trusted on climate change
It’s going to be a tough sell.Senior administration officials spoke with reporters on a Wednesday call ahead of two days of remote meetings featuring world leaders like Biden, Chinese President Xi Jinping, and Russian President Vladimir Putin. While they didn’t confirm reports that the US hopes to cut emissions by 50 percent from 2005 levels by 2030, they did answer Vox’s question on why other nations should trust America to keep its climate promises — given the US government has swung wildly on climate policy depending on who the president is.
The findings show similar results for the ice cap at the top of the world. That’s where the kinda-sorta-good-news ends, though. The Amazon and Indian monsoon are both relatively smaller systems. Research on the Amazonfound it could collapse in the coming decades, and the threshold of warming for that tipping point is much lower. Should that tipping point occur, it would last only on the order of decades or even years. Once that tipping point is passed, there’s likely no coming back. The monsoon is slightly more robust, but it still isn’t likely to recover if peak heat above the collapse threshold is sustained for a few decades.
The other piece of bad news here is that, if we’ve reached the AMOC tipping point threshold of warming, we’re probably going to have bigger things to worry about. A world that’s 7.2 degrees Fahrenheit warmer is one where swaths of the planet are uninhabitable, billions of people are food insecure or forced to migrate, and sea level rise has essentially made Florida an archipelago. The century-long collapse of the AMOC will be among the least of humanity’s problems.
Given the importance of knowing which key systems could shut off or change and when, it’s clear more research is urgently needed to pin down tipping points—and if they can be reversed. Ritchie noted that the distinction between the temperature threshold that can trigger a tipping point and when the tip itself starts to happen is an important one to understand. Of course, it would be in everyone’s best interest to not ever test which of these research hypotheses is actually true, which means reducing carbon emissions ASAP.
“This is a ‘good’ news story, but still requires climate action to be taken now,” Ritchie said. “Ultimately, the safest option is not to cross climate tipping thresholds in the first place.”
Update, 4/21/21, 11:12 a.m.: This post has been updated with comments from Paul Ritchie.
Daily on Energy: Biden working to integrate climate into every agency’s work .
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