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Climate change is on our minds these days, with increasing wildfires, droughts and floods. What are the variables that play into a planet’s changing climate, and what can this teach us about the search for habitable planets across the Milky Way?
Download MP3 | Show Notes | Transcript
Tobacco manufacturers’ defence against plaintiffs’ claims of cancer causation: throwing mud at the wall and hoping some of it will stick (National Library of Medicine)
Clearing Up the Facts Behind Trump’s ‘Clean Coal’ Catchphrase (FactCheck.org)
COP26: The truth behind the new climate change denial (BBC)
Essential Climate Variables (World Meteorological Organization)
The Sun (NASA)
What Is the Solar Cycle? (NASA)
Chilly Temperatures During the Maunder Minimum (Earth Observatory)
Axis (National Geographic)
Arctic Sea Ice Minimum Extent (NASA)
Absorption / reflection of sunlight (UC Berkeley)
The story of Snowball Earth (Astronomy Magazine)
Atmosphere (National Geographic)
Greenhouse Effect 101 (NRDC)
Importance of Methane (U.S. EPA)
Atmospheric Aerosols: What Are They, and Why Are They So Important? (NASA)
The Environmental Impacts of the New Space Race (Georgetown University)
Drake Equation (SETI Institute)
Carbon Dioxide (NASA)
Giant sinkholes are mysteriously appearing in Siberia, study explores why (The Weather Network)
If you’re not thinking about the climate impacts of thawing permafrost, (here’s why) you should be (United Nations)
More than 99.9% of studies agree: Humans caused climate change (Cornell University)
Climate Change: Ocean Heat Content (NOAA)
How does the ocean affect climate and weather on land? (NOAA)
Warming Seas Are Accelerating Greenland’s Glacier Retreat (NASA)
The Rhine’s low water level adds to Germany’s ongoing economic woes (NPR)
The Colorado River drought across Lake Mead and Lake Powell, as seen in NASA satellite images (Vox)
Transcriptions provided by GMR Transcription Services
Fraser Cain: Astronomy Cast, Episode 653. Climate Change: Looking into the Variables. Welcome to Astronomy Cast, your weekly facts-based journey through the cosmos where we help you understand not only what we know but how we know what we know. I’m Fraser Cain. I’m the publisher of Universe Today. I’ve been a space and astronomy journalist for 20 years. With me, as always, is Dr. Pamela Gay, a senior scientist for the Planetary Science Institute and the director of CosmoQuest. Hey, Pamela, how you doin’?
Dr. Pamela Gay: I am doing well. This is one of those topics that I never look forward to, but I feel has to be discussed. So, dear, audience, please don’t send us hate letters. Listen –
Fraser Cain: Yeah, wait –
Dr. Pamela Gay: – and then send us comments.
Fraser Cain: Well, you know, I don’t care. This isn’t the show for you. If you think the climate change isn’t real, then just go away.
Dr. Pamela Gay: Yeah.
Fraser Cain: Just go talk to your friends who also disbelieve in climate change. It’s not – I’m not gonna get bullied and harassed at talking about the scientific consensus. And it is a little unusual to me that people will just get so boisterous about it. And I think about the political misinformation campaign that has just done such a brilliant job, like the people who helped make people confused about whether or not cigarettes cause cancer and then –
Dr. Pamela Gay: Clean coal.
Fraser Cain: – moved on to clean coal, and then moved on to climate change, and the effect is long-lasting. You know what’s funny? I love my electric car. Like if I had to choose between a gas car – If my electric car destroyed the planet, I would choose it over my gas car, because it’s so much cooler and better and quieter and faster and I just plug it in, and it works better. And I’m genuinely excited at the electrification, the modernization, the self-reliance that we’re moving towards. And, again, it’s so cool. It’s exciting. It’s a technology. It turns everything into a technology that I find real exciting.
Anyway, let’s get into the show. Climate change is on our minds these days with increasing wildfires, droughts, and floods. What are the variables that play into a planet’s changing climate, and what can this teach us about the search for habitable planets in the solar system and across the Milky Way? All right, Pamela, where do you wanna start on this one? How do you wanna crack into this episode?
Dr. Pamela Gay: So, the starting premise is there are variables that determine in part how our atmosphere is able to hold onto heat and release heat, and there are variables that determine how the planet itself is able to retain and reflect heat. Pick a variable.
Fraser Cain: I guess let’s start with the main one, which is the main input: the sun.
Dr. Pamela Gay: Yes.
Fraser Cain: So, let’s start with that one. Energy in.
Dr. Pamela Gay: Yes. So, in general, our sun is a mid-life star. It has changed in brightness very slightly over time and it will continue to get ever-so-slightly brighter over time. These variations are things that are occurring over literally millions and billions of years. And while we can see differences in what was going on in the earliest days of our planet, billions of years ago, over the course of human history’s small fraction of our time on this earth, the sun’s output hasn’t had an overall effect outside of the 11-year solar cycle.
And there was one minor dark patch in the Dark Ages, where the sun was like, “I’m not gonna have sunspots. You do you, I’m gonna do me.” And during that period, we did see some cooling that occurred.
Fraser Cain: But the point being, without the input from the sun, we wouldn’t have a global warming problem. Right? If there was no sun, there would be no global warming.
Dr. Pamela Gay: I can’t contradict that. I also feel though that life as we know it would not exist, so that is really not a concern to me. We have a sun. It’s there.
Fraser Cain: Right, right, right. But the point being that the sun is the input.
Dr. Pamela Gay: Yes.
Fraser Cain: And then how that input gets reflected, changed, absorbed, released, et cetera, all depends on the variables that are happening here on Planet Earth.
Dr. Pamela Gay: Yes.
Fraser Cain: And there are minor variations on the sun. We saw, as you said, we had a time, you know, there’s increased sun activity can change things. Increased solar activity can change things but are not changing things today currently.
Dr. Pamela Gay: No.
Fraser Cain: And in 500 million years from now, the sun will heat up to the point that the earth’s oceans will boil. But that is not tomorrow. And that is not within the next hundred years. That is measured in the amount of time animals have existed on Planet Earth. That’s how long it’s gonna take. All right, so the sun is the input.
Dr. Pamela Gay: Right.
Fraser Cain: So, then what are the variables that define the temperature that we experience here on the planet? I guess, the distance from the sun matters? The shape of our orbit?
Dr. Pamela Gay: The distance from the sun. The shape of our orbit. These things both matter. They aren’t, again, changing over periods of time that matter for humans. We find that the winter in the Southern Hemisphere is slightly worse – ever-so-slightly worse than winter in the Northern Hemisphere simply because the earth is ever so slightly closer to the sun in January, which is northern winter and southern summer, so southern summer doesn’t get quite as much sun. In the grand scheme of things, this is just a constant over the course of human scales.
Fraser Cain: Now what about the tilt – the axial tilt of the planet? Because that changes, not in a human lifetime, but in, I guess, civilization’s lifetime.
Dr. Pamela Gay: What we’re seeing with that though –
Fraser Cain: The wobble.
Dr. Pamela Gay: Yeah, so our planet is a top, and I’m gonna use a coffee stirrer to indicate it. And I am going to use a hairbrush to be the sun. We are high-tech around here, humans. So, as our – disappearing entirely into my background and getting ready to be replaced by a red pen that is easier to see – Okay, so we have our planet, Earth, and it’s going around, and as it’s going around it is constantly pointed towards the same star. But, over time, it’s slowly going to change what star it’s pointed to. But its tilt relative to the sun isn’t really changing.
So, well yes, over the grandest scales of time there is some wobble to that tilt, the big thing that we’re able to see over the course of history is the change of where the North Pole and the South Pole are pointed. But the difference between the location of the sun and the tilt of the earth, that angular distance is fairly constant even though what star the planet is pointed to is varying. So, with the tilt not really changing, it’s not changing how the seasons occur, other than what stars are there.
Fraser Cain: I mean, I guess it’s not changing the total amount of energy that’s falling on the surface of Planet Earth.
Dr. Pamela Gay: Right.
Fraser Cain: It is changing – Like, right now, the cool thing that you discover is that the earth is at the closest point of its orbit during winter in the Northern Hemisphere.
Dr. Pamela Gay: Yes.
Fraser Cain: And it’s at the farthest point of its orbit during summer in the Northern Hemisphere, and that slightly moderates both the winter and the summer. You mentioned earlier that the winter in the Southern Hemisphere is more extreme, partly because there’s more ocean and less land, but also because the earth is at the closest point during its summer and the farthest point during its winter. So, you just get both the tilt and the distance adding up, as opposed to them mildly canceling out as we get in the Northern Hemisphere.
Dr. Pamela Gay: Yeah.
Fraser Cain: All right, so tilt, we can sort of remove that from the system because the total amount of energy is going to hit the earth no matter how the earth is tilted. So, let’s talk about the big, I guess, the variables in terms of how the planet appears to the radiation that’s coming at it.
Dr. Pamela Gay: Right.
Fraser Cain: So, the amount of land versus sea versus ice, et cetera. How does that have an effect?
Dr. Pamela Gay: So, as the sunlight comes down, it hits our planet. And what happens when it hits our planet depends on exactly what it’s hitting. If the sunlight hits ice, it’s going to get reflected upwards. If it hits dirt, it’s going to get absorbed, and over time reradiate that energy but slowly and in the infrared. So, what the sun hits, determines how well we keep or reflect that heat. And over time, what we’re finding is, as we remove forests, that changes how, well, the forests absorb light versus the ground absorbing light.
It changes the colors that the light is reradiated at. As we see the ice melt, that’s causing less reflection to occur. As we see less snowfall occurring, that’s causing less reflection to occur.
Fraser Cain: When you think about the Snowball Earth – back a billion years ago, the earth was completely covered in ice which is highly reflective. And that’s kind of self-reinforcing, it locks in because the sunlight is falling on the earth and then the sunlight is being reflected back out, it doesn’t get a chance to warm, and it stays icy. And, you know, it was thought that you needed to have some amount of volcanism to seriously impact the environment on Earth to kick it out of that Snowball Earth cycle that it was trapped in. Which is kind of interesting. You do wonder, could we get back into a Snowball Earth in the future? What could that take?
All right, so we’ve talked about the surface composition of the planet. We’ve talked about the actual orbital mechanics of it. The sun. Let’s talk about the composition of the atmosphere. This is where the big factors start to come into play.
Dr. Pamela Gay: Yeah, so –
Fraser Cain: Or, I guess, the big factors for variation. I mean, again, back to it, sorry – The sun is the key, but as we change the atmosphere, that’s what will have an impact.
Dr. Pamela Gay: So, as the sunlight comes down through our atmosphere, a whole wide variety of colors of light are able to make it down to the surface of the planet. There are colors that are luckily reflected, like x-rays, they don’t hit us. We’re very grateful because that would cause cancer. Now, all these colors of light coming down through the atmosphere, they get reradiated or reflected depending on if they hit ice or if they’re absorbed by land or water and then released. The reflected light goes back up through the atmosphere. Some of it escapes. Some of it bounces off of molecules and comes back down.
With that infrared radiation, a lot of it hits stuff in the atmosphere and then becomes trapped in our atmosphere. And this is exactly how a greenhouse out in your yard might work. Sunlight comes down through the glass, it warms up the flower beds, it warms up the air. That infrared radiation then hits the glass, and the glass isn’t as transparent, so the heat stays in the greenhouse.
Fraser Cain: So, we have a very real example of this situation in the shop in the studio that I’m in right now. Our original garage doors were gonna have these translucent panes of glass along pretty much the entire wall. We have three garage doors that open up the shop. And we had originally were gonna get these, but then they were back-ordered for six months, and so the garage door installers put in opaque solid doors. And we went through this heat wave, and we were just shocked and amazed at how cool the shop was. We had tons of insulation. The sun would hit the garage doors and keep us cool.
And then finally the doors came in, and we got them installed, and suddenly we were like, “Oh God, we built a greenhouse.” And everything changes. Now, the second the sun comes up, the place just heats up many degrees – five, 10 degrees hotter than it is outside. And it’s been definitely a learning experience to manage the temperature changes, just by having the difference between having a wall and glass and having the heat trapped inside the shop with us. It’s gonna be cool in the winter, but it’s definitely work in the summer to kind of moderate the temperature.
Dr. Pamela Gay: And this is something that any of us who’ve lived in cold climates have experienced in the winter. One of those completely cloudless winter days is going to be so much colder than a completely cloudy day. And this is because those clouds are able to reflect back down – because they’re filled with water vapor, water vapor’s a greenhouse gas – those clouds are able to reflect back down the heat that’s trying to escape. And on those crystal-clear days, you just get frozen ‘cause any heat you might have is escaping.
Fraser Cain: So, which are the components of the atmosphere that are contributing to the variables of the temperature, of the trapped infrared radiation?
Dr. Pamela Gay: So, there’s a variety of different problem children. On one hand, you have specific molecules and atoms. Methane is one that when it gets into the atmosphere, CH4, it will eventually break down in the sunlight, but until then it’s just gonna work to trap infrared radiation. We also have water vapor, a variety of other complex molecules. And then there’s also aerosols and any other large particles that can get lofted up and trapped in the atmosphere can also cause problems.
One of the new forms of research that I hadn’t thought about and now find deeply disturbing is we are regularly dropping things down through the atmosphere, burning them up. The bottom basically storage part of the Dragon capsule and other capsules get dropped through the atmosphere. Trash gets dropped through the atmosphere. Dead spacecraft get dropped through the atmosphere. And researchers are now starting to run models to see if when we add all of the stuff and things that was once a spacecraft to the upper parts of our atmosphere, how does that affect things?
And the answer is some of it scatters light away – yay, cool the world. Some of it traps infrared heat, warming the world. And figuring out the balance of how this occurs is something we don’t entirely know how to do. And this is one of the problems that keeps cropping up with climate change is there are variables that we realize that we never realized before and we know they’re there and we don’t entirely know what to do with them. And it’s not like the Drake Equation where it’s just a fun guessing game to figure out if we’re gonna destroy the planet or not, or if there are aliens or not. Aliens, fun; destroying the planet not so much. So, yeah.
Fraser Cain: So, let’s talk about the carbon-based elephant in the room – carbon dioxide.
Dr. Pamela Gay: Right. So that’s another one of the greenhouse gases, and it’s one of the ones that gets released through myriad different industrial processes, and through forest fires. And we’re finding that along with methane it is getting released in really weird geological events. There have been sinkholes springing up in Siberia releasing large amounts of greenhouse gases as what was once tundra melts.
We are similarly finding, in places like Greenland, Alaska, the tundra that had remained frozen since human beings first made it to this continent is thawing out and all of the organic material that was either put in the tundra by human beings seeking to freeze things or frozen there through minor freeze thaws that allowed some melting, life emerged, and then it got snowed on, got buried, and over time it just built up new layers of that very carefully growing in the few months that it was possible foliage. And as the stuff thaws, microbes are going in, are processing it, and releasing more gasses.
So, we have human-contributed carbon dioxide, which is the thing that sparked all of this in the first place. There’s no denying it when you look at when things started happening.
Fraser Cain: Yeah, I mean, when you think about every variable that could have accounted for the amount of carbon dioxide in the atmosphere, you’ve got the impact from humans, you’ve got volcanoes, you’ve got forest fires, natural occurrence. Scientists have checked this, and it is the human-released carbon dioxide that is the thing that is filling up the – that is contributing the most.
Dr. Pamela Gay: Yes.
Fraser Cain: When you look at the amount of additional carbon dioxide that’s going into the atmosphere, it’s coming from human emissions. We can track it from where it is emitted to where it ends up in the atmosphere. Can watch the seasonal variations.
Dr. Pamela Gay: And the thing that keeps me awake at night is the realization that there were things that we hadn’t thought to account for, like the melting of the tundra. And these things that we hadn’t thought to account for are just making things worse. And so, you always know that in complex systems like this you’re probably going to forget certain factors, and here the factors that we keep discovering just keep accelerating the problem. And it comes down to, okay, so if this melts, how do all of these other things get affected? And it’s, in some cases, as simple as if you melt enough fresh water into the ocean, it changes the thermodynamics of the entire planet.
Fraser Cain: And that kind of leads into the next topic that I wanted to talk about was the feedback effects. The second-order happenings. You mentioned a couple already. You mentioned the fact that with increasing temperatures you’re seeing a rise of gasses that had been trapped released from the Arctic regions. We’re seeing increased forest fires which are releasing particulate and carbon dioxide into the atmosphere. We’re seeing increased amounts of meltwater going into the oceans. Does that change the temperature of the planet or does that just change the local weather patterns for various places?
Dr. Pamela Gay: It changes the energy distribution and the thermal capacity. So, anyone who cooks has probably at some point or another encountered instructions along the lines of boil this in water then add to your soup. And it’s sort of like, “But my soup’s boiling, why can’t I just cook this in my soup?” And I suspect I’m not alone in saying I have attempted to make the dumplings directly in the soup and I have regretted all my life choices for that day and time.
Fraser Cain: Right, every time, yep.
Dr. Pamela Gay: And the issue is that materials that have different compositions are able to share temperatures easier or worse. If you sit on a wooden bench that you are able to measure with your little IR thermometers as being 80 degrees on the surface, it’s not going to feel like you’re burning. If you sit on a piece of metal that’s 80 degrees, it’s gonna feel hot, and the difference is the metal has a greater capacity to transfer its heat. So, changing our oceans’ salinity, it starts doing things like changing freeze point, changing how energy is transferred.
And there’s also the complication of when you add heat to the equatorial regions, you are now triggering bigger storms which create bigger cloud cover which further trap heat.
Fraser Cain: Do clouds trap heat? Or block it?
Dr. Pamela Gay: Yeah, they trap it. I mean, they do both, but if it is a surplus of energy underneath you would like to have radiate away, the failure to radiate away is problematic.
Fraser Cain: Right.
Dr. Pamela Gay: So, the other problem that we have on top of this is when you add fresh water to the ocean, the changing salinity changes how pockets of hot and cold water can rise and sink. And this changes how heat is transferred through the ocean. It actually has the potential to shut down the currents that are what allowed early sailors to get to our continent and what allows England to have palm trees despite being further north than you are in British Columbia.
Fraser Cain: Yeah, it was amazing being in Iceland and being prepared for it being just absolutely – you’re at the Arctic Circle, you’re expecting it to be just so cold –
Dr. Pamela Gay: Yeah, no.
Fraser Cain: – but it kind of felt like Canada. It felt like home. Felt like, yeah, it was chilly, but it wasn’t terrible. And that was the regulating temperature of the ocean currents, which is just absolutely incredible. So, are there any other second-order variables that we would want to throw into this? I guess the loss of ice makes less of the sunlight reflect back out into space.
Dr. Pamela Gay: Yeah, the loss of ice is a major problem. And it also has the added difficulty that once the glaciers are gone, they are currently a major source of drinking water, runoff, just in general keeping major swaths of vast continents well-watered, and, thus, well, not causing deserts.
Fraser Cain: Right.
Dr. Pamela Gay: As the Rhine goes away in Europe, as the Colorado River goes away in North America, entire swaths of land are no longer going to be able to support the current vegetation, which is going to, again, change the retention and reflection of heat. Exposing land that will retain it in completely different ways than the current foliage does.
Fraser Cain: Yeah, I mean, you see you get a forest fire coming through an area like mine and then the vegetation can’t come back because it’s not wet enough anymore. So instead, you get grassland or maybe you get desert, at a certain point, if the rain cuts down. And a lot of these places are driven by flooding which is driven by glaciers.
Dr. Pamela Gay: Yeah.
Fraser Cain: I’ve mentioned this in the past. We have a glacier right over top of my city that we can see most of the time when you’re driving around inside the city. It’s expected it’ll be gone in about probably ten years from now, which sucks, ‘cause the icon of our city is this glacier. And it’ll be gone. And then will the cities have to change their stationery to no longer use the glacier as their icon?
Anyway, I think we’ve reached the end of this week’s episode. No solutions, just a clarification of all of the variables. If you’re gonna write a big math formula, now you have all the pieces to throw in as you solve climate change on your own. Account for all of those. All right, well, thank you, Pamela.
Dr. Pamela Gay: Thank you so much, Fraser. And thank you to all of you out there who support our show on Patreon.com/AstronomyCast.
This week I would like to thank by name: NinjaNick, Don Mundis, Michelle Cullen, Janelle Duncan, Dean McDaniel, Anitusar, Scott Briggs, Benjamin Carryer, J. AlexAnderson, Matt Rucker, Moose and Deer, Frode Tennebø, Father Prax, Peter, Jim McGihon, schercm, Brent Kreinop, Mark Steven Rasnake, Abraham Cottrill, Mark H Widick, Bruce Amazeen, Philip Grand, Dustin A Ruoff, Gfour184, Dwight Illk, Paul L Hayden, Andrew Stephenson, Karthik Venkatraman, Steven Coffey, Glenn McDavid, planetar, Camy Raissian, Cemanski, Tim Gerrish, Benjamin Davies, James Rodger, and The Mysterious Mark. Thank you all so much.
Fraser Cain: Thanks, everyone. We’ll see you next week.
Dr. Pamela Gay: Bye. Astronomy Cast is a joint product of Universe Today and the Planetary Science Institute. Astronomy Cast is released under a Creative Commons Attribution license. So, love it, share it, and remix it, but please credit it to our hosts Fraser Cain and Dr. Pamela Gay. You can get more information on today’s show topic on our website: AstronomyCast.com.
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