Tipping Points: Part 1 – Climate Change and the Log Stack Moment

What is a climate tipping point, what happens when we hit them and why should you care? In this episode, we dig into the science and stakes of passing critical thresholds in Earth’s systems. Plus, a metaphor you won’t forget: the “log stack moment.”

Transcript

Good morning, afternoon or evening, whatever it is wherever you happen to find yourself right now. 

I’m gonna start off with a quick story today. 

I love mountain biking, I’m not that good at it and I don’t get out anywhere near as often as I’d like, but it’s fun. When I was first starting out, my brother, who’s a much better rider than I am, was continually prodding, goading me to go out with him. And, I was kind of embarrassed at my ability, or lack thereof, so I kept putting him off but eventually, it hit a point at which I just couldn’t put him off anymore so I went out with him. 

When we finally went out, the first half hour or so was fine, we were climbing up a long, slow ascent, and I was good with that. Then, we started the downhill section and, about 5 minutes into this downhill section, we arrived at a log stack, which is basically some logs that are stacked up to form a vertical triangle, and they’re supposed to be really fun to go over…ya, key word being “supposed” to be. 

The log stack, as far as log stacks are concerned, wasn’t all that big, but this is the first one that I had ever attempted, that I had ever gone over, had absolutely no idea how to get over it. 

So, my brother, we stopped and he talked me through it and he rode down and went over it, and it looked really easy. I mean, how hard could it be, right? 

Then, I started downhill, and I was heading to those logs and, the closer to those logs I got and, they just looked like a log wall to me, the more freaked out I became. And I remember thinking…”I can still bail on this…I can still get out of it…I can st…”, but then I hit that point where I was committed, that point of no return. And I was going over whether I liked it or not.

You know how one of the main goals when riding a bike is staying on two wheels? Ya, I didn’t do that. I don’t exactly know what I did wrong, I think my that brain freaked me out to a point that, it just caused me to slow down too much and, suffice to say it didn’t go all that well. 

So I got up and dusted myself off and continued down…very. very slowly with my freshly broken ribs. Gained a little bit of wisdom that day but what does this have to do with climate change? Hang on and we’re gonna talk about that. 

I’m Dave and thank you so much for joining me on running my mouth off about climate change, where we, usually, talk about some of the lesser discussed issues that surround climate change, and today, that topic is tipping points. 

Before starting off, I decided to break this into two separate episodes, simply because there’s so much info in this first one, and it can be a bit overwhelming, at least it gets that way for me. So, I’ll be laying a foundation today and we’ll be talking a little bit about that first tipping point that you hear about, that 1.5° Celsius. And then we’ll look at 2° and beyond next week. Now because we’re breaking this down into to separate podcasts, these will be a tad shorter, but let’s get into it! 

A few weeks ago, I was listening to a podcast that had a guy named Bjorn Lumborg as a guest. Bjorn, he’s primarily a political scientist, but he does a lot of speaking on the topic of climate change. He says some  pretty cool stuff, some stuff I truly find interesting. But then he has a tendency to say things that make me, and a lot of other people, go, “wait, what?” — his approach doesn’t exactly line up with conventional thinking in a few different areas. One of the things that he said is that these tipping points, these 1.5 and 2 degrees celsius tipping points as outlined in the Paris Agreement, that these were just kind of randomly selected numbers, almost as if there wasn’t a lot of thought put into them. 

To be fair, I’d be shocked if there wasn’t a bit of rounding up or down to make things easier to digest, I mean, 1.5 sounds a lot better than 1.4792148…you get the picture. But I was a little taken back by just the casualness that he exhibited about these numbers, and a few other things. But how hard and fast are these numbers, how randomly selected are they, and what happens when we hit 1.5° celsius and 2°? Well, let’s check it out. 

Ok, starting off, let’s look at tipping points. 

There was a point on my journey over these logs, that I hit a point of no return and no matter how much I tried to stop, I was committed, I was going over. Momentum from speed, my bike, my body weight, etc… just took over and I was going for a ride whether I liked it or not. And, the longer this ride lasted, the more I was going to get hurt. Had there been a rocky downhill section right after those logs, it would’ve been pretty bad, but fortunately my fall didn’t last that long.

That’s basically how climate tipping points work—we hit that point of no return, and things shift into a whole new gear, it begins to take on a life of its own and once this process starts, it’s incredibly hard—if not impossible—to reverse.

And this is what scientists mean when they say “irreversible.” You’d think they’d have a better, more impressive word for that, and they do, and we’ll mention that in a moment, but, even If we stopped all emissions today, some of the changes that we’re seeing would still keep happening, would still keep unfolding for centuries or, thousands of years even. Once we hit that point on the log stack, there’s just no easy way to keep a lot of bad stuff from happening. 

Now, most people think of climate change as this long, slow, steady process. Temperatures rise little by little, sea levels creep up little by little—it’s predictable. That’s referred to as  linear change—add a certain amount carbon to the atmosphere, and get a proportional temperature rise. But tipping points? These don’t work like that. They’re non-linear. Instead of slow and steady, we get these sudden accelerations, these chain reactions if you will.  

And this is where we bring up that term that’s more impressive than “irreversible”, and that’s feedback loops.

Feedback loops, what are they. Essentially, they’re when a system has an input, which influences and output, and that output then influences the input, and then the whole thing forms a loop. Feedback loop.  And the desired outcome for this loop is that things stay stable, they remain in a state of homeostasis. 

For a very loose example of a feedback loop, think of a teeter toter, the person on one side and pushes up, and it provides input to the second person, they push up and that impacts what the first person does, and it forms a loop. Again, very loose example, but when we talk about feedback loops, there are two different types: there are negative, and there are positive feedback loops. The negative feedback loop? It’s pretty much the kind that we want when it comes to our climate. 

Think of a negative feedback loop as something like a thermostat in your home that you set to a certain temperature. When the temperature drops, the thermostat will tell the heater to warm things up, and the temperature in your home remains stable. Negative feedback loops create systems, and in this case, the temperature in your home, that are nice and stable, it keeps it in a state of homeostasis. 

Positive feedback loops on the other hand? Think of a thing like a social media post that goes viral. It initially gets posted, people like, share and comment on it, so it starts to get more views. Even more people like, share and comment and it just keeps on increasing until it goes viral and in not too long, it kind of takes on a life of its own and gets a little hard to control. Even if the original poster were to delete that post, it would still have a life because of all of the shares, and copies and all of that stuff. This is typically a good thing if your desire is to create viral videos, but when talking about things like the environment? Probably not the best thing. 

Like ice melt, for example. A glacier might be losing ice little by little for years, and then, all of a sudden—bam—it hits a point where the ice melt just speeds up dramatically. As the ice thins, the ground below it will begin to reveal itself, and darker colors absorb heat more than do shiny things like ice, right? So the warming ground speeds up the melting even more. And that’s a positive feedback loop. Probably not so positive for us.

That said, these positive feedback loops can take a long time to play out, like that glacier for example. A lot of people imagine tipping points as instant, like a light switch that we can turn on and off. Can’t tell you how many times I’ve heard things like, “Well, they said that oceans would rise 30 feet, and they haven’t!” Well, ya, that level of ocean rise is certainly a very real possibility. It’s not going to happen over night though. Some shifts happen fast, in years or decades and others can stretch out over literally centuries, and we’ll talk about a few of those in a second. Either way, by the time we realize we’ve crossed one of these tipping points, the process is already in motion—we’re already at the top of that log stack and there’s nothing we can do.

How do climate scientists actually figure this stuff out though, where do those numbers come from? 

Three main ways. First, they dig into things like ice cores, ocean sediments, ancient climate records, things like that. Turns out, the planet has seen abrupt climate shifts before, some happening within decades, nothing like we’re seeing now. But there have been some pretty localized climate shifts that have taken place. Second, they use these complex climate models to simulate how different systems interact—oceans, ice, atmosphere, land. These models help pinpoint weak spots. And third, they track real-world changes. They watch for warning signs—things like ice sheets thinning, ocean currents slowing, ecosystems collapsing, you know, death, destruction, all that stuff.

Keep in mind though, that people with a lot of letters after their names, these scientists, they’ve been working on these tipping points since the 1970’s. I’ve met a few people who work on this stuff and, well, suffice to say, they’re not like most of us. These people are scary, scary smart, and they’re into what they do. 

Here’s the tricky part though: these tipping points, they don’t come with a clear temperature label. It’s not like “Hit 2°C, and bam, Greenland’s ice shift is gone.” It’s more about how fast warming happens, how long it lasts, and what other stressors, like pollution, deforestation and more—are piling on top of it.

So let’s look at the first number, the 1.5°C number that we keep hearing about. Why is it special and where does it even come from?

Back in 2015, the Paris Agreement set a goal: keep warming “well below 2°C” and try to stay under 1.5°C. Then, in 2018, the IPCC (that big international climate science group) released a report that made one thing very clear—1.5°C isn’t just a nice target, turns out it’s a critical threshold.  Because even at that level, some major systems begin to break down. Again, this is using science that had been evolving since the 1970’s.

Just to put it in perspective, we’re already at about 1.2°C above pre-industrial levels. And that’s why this urgency is so real—we’re not talking about some far-off future. 2024 took us to that 1.5°C point, hopefully the next few years will be a bit cooler so we don’t stabilize there. 

But, at 1.5°C, if we do stabilize there, coral reefs? Basically, the prediction is that 90-99% of them are gone. Obviously, coral reefs aren’t just pretty underwater scenes that we like to look at—they support about 25% of marine life and feed hundreds of millions of people. Again, these coral reefs disappearing doesn’t happen overnight and, this is pretty well documented, we’ve lost and are continuing to lose a heck of a lot of coral. 

In fact, as of 2021, since 1950, we’ve lost about 50%, that’s half, of the world’s coral reefs. And we’ve no doubt lost more since 2021 and, as the ocean continues to warm, that pace is likely going to speed up pretty significanlty. 

Coral is interesting stuff though. You’ve no doubt heard the term bleaching when it comes to coral? Coral is basically an exoskeleton that has algae living inside of it. Warmer water temperatures are causing that algae that lives in the coral to vacate, leaving just the exoskeleton, which appears white, hence the term, bleaching. It’s basically coral that’s lost its algae.

Now, what you typically don’t hear when talking about coral, is that, as Yale University puts it, there is a “glimmer of hope”. What we’re seeing is that ocean currents are carrying coral to colder waters where that algae can survive, and some reefs are beginning to form in places that have more ideally suited conditions. So some is starting to grow a little bit further south in Australia, and we are gaining a little back of what we’ve lost, but nowhere near the amount that’s being lost, but there is that “glimmer” of hope. You know, we’ll see how this all plays out. 

Enough about coral. 

Arctic sea ice? At 1.5°, Celsius, not Fahrenheit, we start facing ice-free summers. Which means less reflected sunlight, more heat absorption and and even faster warming.

Greenland’s ice sheet, for example? At 1.5°C, parts of it kinda begin to destabilize. Now, if that whole thing melts—again, over centuries, not instantly—we’re looking at about 7 meters of sea level rise. And again, once this process starts, once we get over that log stack, stopping it becomes nearly impossible.=======16:48

As Greenland melts though, it’s impacting something else that, like coral, has been getting a lot of press lately. And this is the Atlantic Meridional Overturning Circulation, better known and more easily pronounced as AMOC, this thing starts to get impacted. 

AMOC carries water from the Atlantic north to the subtropics in the south and all the way back up. As theses Greenland ice sheets melt, fresh water is being dumped into the area where the AMOC lives and dumping a whole bunch of colder and salt free water Into this can have some pretty negative results. Science keeps talking about a complete collapse of this system and, if that happens, some pretty negative impacts are unavoidable. Models predict, and there’s a lot of confidence in these models, that the northern hemisphere would cool down, and the entire southern hemisphere would warm up, and this warming in the southern hemisphere? It will likely flip the seasons in places like the Amazon Basin, meaning the rainy season would become the dry season, and the dry season would become the rainy season. The net effect could be a complete dying out of the Amazon rain forest and in parts of Africa. There’s a lot more to it but I’ll stop there.

Again, this isn’t something that happens over night, we’re looking at a timeframe in the order of 800 years or so, for the impacts of these changing weather patterns to be fully realized. And, we haven’t yet seen that tipping point with AMOC yet. The latest model that I’ve seen though, and this is if I’m interpreting things correctly, says that that tipping point could come around 2075, and we’d start to see evidence of this tipping point little bit after the year 2100. Again, if I’m reading that correctly….there’s a lot of numbers in some of these reports. I did well in math in college, but it’s been a long time and ya, all of that knowledge left me years ago. But the motions on this stuff start at about 1.5° to the best of our knowledge, to the best of these models.

And then there’s mountain glaciers. People don’t always think about those, but they’re a major water source for billions of people, literally. In places like the Andes or Himalayas, glacier melt is a literal lifeline. Lose those, and water security becomes even more of a huge issue.

And here is where it gets especially concerning. Even with current climate pledges, i.e., all of those papers that were submitted by countries in the Paris Agreement. We’re still on track for around 2.5-2.8°C by the end of the century. That’s way past 1.5°C, and firmly in the territory where tipping points start stacking up.

That’s why this matters. We’re not just talking about gradual warming. We’re talking about reaching thresholds where entire systems start changing on their own, where these positive feedback loops just start going crazy, pushing us into places that’s a just, next to impossible to control. Again, 2024 was the hottest year on record, and 2023 was the hottest year on record before 2024. Really hoping that this is just a temporary spike and that we don’t stabilize there. Because, if we did, that would mean that all of these models that scientists have been working on for years, that they’re kinda predicting things more slowly than they’re actually taking place.

And we’ve become really really good at being able to see what temperatures used to be. I was just exposed to a study that took 7 years to complete, and it was released in 2021. Science were able to track temperature data over the last 24,000 years, and they’re fairly confident of their findings. The result? Ya, it’s a lot warmer now. 

And then I come back to people like Bjorn Lumborg, who have this completely casual attitude about climate change, like, “We have plenty of time…” Honestly I do really find some of what he says interesting and valuable, but then that idea that this 1.5° is just an arbitrary number that  kinda sounds good. And he also  says things like, “We can clean up coal, you just need to put a $5 cap on the plants that produce it…” Uhmmm….he’s talking about scrubbers, and they’re pretty complex and, well they cost a lot more than, I’m sure there are $5 parts in them but… I mean we’re talking about basically carbon capture systems. A lot more than $5 and there are a lot of issues with them, not the least of which is that clean coal isn’t exactly clean, no matter what you do with it. He’s a good talker, but some of the numbers are like, where did you get that, kinda thing? 

Where do we go from here though? That is what we’ll dig into next. First though, we’ll look at 2° and beyond and, just thinking about it, I mean this stuff really does, especially when you include AI, have all of the makings of a really good movie series. Like the Terminator meets Mad Max. Who are the actors in that anyway, Zendaya and Dave Franco? Anyway, but I digress…man, I am pretty filled with doom and gloom today, ideally, I want to give some hope. I probably should talk a little bit about some of the positive. You know, China’s actually doing some really cool stuff around climate change right now. In the United States, we love to demonize China. But they’re actually kinda killing it when it comes to climate change so…

I think we’ll wrap up right here and come back next week with what will no doubt be a very hopeful and no doubt inspiring chat about what happens at 2°Celsius and beyond.  

Again, thank you so much for joining me today on Running My Mouth Off about Climate Change. I’m Dave and I hope you have an amazing week.