When it comes to carbon dioxide, just a little goes a long way to warming the planet. Unfortunately, we’ve been dumping vast amounts into the atmosphere, recently passing 400 parts per million. Let’s look at the science of the greenhouse effect, and how it’s impacting our global climate.
Fraser: Astronomy Cast episode 308 for Monday, May 27, 2013 – Climate Change
Welcome to Astronomy Cast, our weekly facts based journey through the cosmos. Where we help you understand not only what we know, but how we know what we know.
My name is Fraser Cain, I’m the publisher of Universe Today. With me is Dr. Pamela Gay, a professor at Southern Illinois University Edwardsville, and the director of CosmoQuest.
Hi Pamela, how are you doing?
Pamela: I’m doing well, how are you doing Fraser?
Fraser: Doing great. So we are now recording this after the hangout-a-thon and it was awesome. 32 hours of us hanging out with tons of special guests and lots of fund raising for CosmoQuest and Astronomy Cast.
Pamela: Yeah we presented what was originally 24 hours of guests and content and science art, science fact, science everything but so many people wanted to take part that we ended up stretching it out to 32 hours and now I’m suffering from the fact that sleep is actually cumulative. The fact that I slept 12 hours last night, my body doesn’t care, it’s still sleep deprived.
Fraser: So if you missed the Hangout-a-Thon itself we can still take and still really would love your donations for CosmoQuest. You can just go to CosmoQuest.org/donate and donate whatever you can to help put word out. As you may not know, the new sequestration that is happening in the United States is having a big impact on education funding. A lot of our funding for CosmoQuest is getting pulled away.
Pamela: So anything you can do helps. Honestly what we really need is help identifying corporations and grants that we can apply for funding from. We want your brains, we want your science, we need your dollars right now but we don’t want to have to keep asking.
Fraser: I think that’s really the key is that our long term goal here is for the thing to be self-financing through the services we provide to you through educations, through classes, through really cool trips, gear, thing that we can do that will provide you value and then will make the whole thing self-funding. It’s kind of been on the wall for a while now that you can’t depend on these kinds of grants for too long. That’ll be the future. Okay, well lets get rolling then.
Fraser: When it comes to carbon dioxide, just a little goes a long way to warming the planet. Unfortunately, we’ve been dumping vast amounts into the atmosphere, recently passing 400 parts per million. Let’s look at the science of the greenhouse effect, and how it’s impacting our global climate. I think the most important thing here is to understand the greenhouse effect. What is the process? What is the chemistry and the physics going on here.
Pamela: I don’t know the chemistry well, that is not my forte.
Fraser: What is the biology of this? What is the numerology of this?
Pamela: (Laughs) Let’s start with the physics of this, the physics of this I can get to. The basic idea of this is that you have sunlight in all of its different colors coming through our atmosphere. Our atmosphere quite successfully blocks the x-rays, the gamma rays, the ever decreasing amount of the ultraviolet, segments of the infrared and segments of the radio. The reason we see in what is called the visible part of the spectrum is because that part of the sunlight gets straight down to earth, no big deal. The sunlight that comes through warms our air, warms our soil, warms our buildings and warms us but under less greenhousey conditions, a lot of that heat that gets built up from heating us up and heating the ground up is able to re-radiate and escape the earth’s atmosphere and go back out into space. The problem is when you have greenhouse gasses in the atmosphere, those gasses block that infrared light. When the warm soil and the warm oceans try to radiate away their heat, that heat bounces off the atmosphere, comes back and just builds up the heat on the planet. Greenhouse gasses are simply like adding an extra layer of insulation that prevents the earth’s heat from escaping.
Fraser: Can we see some analogies? We love your analogies. Where are some other places where we see this effect happening?
Pamela: Well on Venus. (Laughs)
Fraser: Well I was thinking a little closer to home like cars or greenhouses, things like that. Absolutely, we’ll go to Venus if that’s where you want to go.
Pamela: (Laughs) This type of chemical greenhouse effect is certainly on Venus. Here on Earth, people use the analogy of a greenhouse effect in a hot house all the time. The way these work is the sunlight comes through, warms the air then the gas acts like insulation and that is slightly different.
Fraser: But the infrared light can’t get through the glass, right?
Pamela: It doesn’t thermally conduct the same way so it’s a slightly different circumstance. You transmit heat in a variety of different ways. You can have the kinetic energy between the gas particles escape and interchange with the outer atmosphere. This is what happens when you have poor walls on your house is the warm air in your house is able to escape and interact with the air outside. The air outside is able to come in and interact with the air inside and the gas particles interactions cause the overall motion to… if you’re hot inside and cold outside, having that cold air come in, it slows down the reactions of your hot air by exchanging energy. In this case the warm energy, the high motion, goes to the lower energy. There are several different ways that you can lose heat. You can lose it through infrared radiation which is what we’re failing to do here on the planet earth. You can also lose it just by slowing down the particles which is what happens when your house is poorly insulated. When we talk about greenhouses, what is often happening is you simply aren’t allowing that exchange of the particles inside getting heated up by the solar energy coming in and exciting the particles into moving faster. The outside ones are moving slower and the exchange of those energies isn’t allowed.
Fraser: That’s why if you crack a window that’s why it cools down so quickly.
Pamela: This is physics and this is where saying it’s a “greenhouse effect” just bothers me.
Fraser: Really? Okay.
Pamela: The greenhouse effect here on the earth is due to a failure to be able to radiate away infrared radiation effectively. It’s not due to the earth’s atmosphere failing to allow hot particles to interact with cold particles that don’t actually exist in outer space. It’s a pet peeve.
Fraser: It’s a radiation problem not a convection problem.
Fraser: You wanted to jump straight to Venus so I will permit it. Let’s talk about Venus and how it’s a process gone mad.
Pamela: It’s the end process in a lot of ways. We think once upon a time that Venus had water on its surface and it was probably cooler but as it’s temperature increased you ended with this two-fold problem. First as the temperatures increase you end up with more and more humidity being able to be supported in the air and water vapor is a greenhouse gas. It does more to help trap in that infrared radiation and as you trap more infrared radiation more water evaporates and eventually you end up evaporating away your entire ocean and that continues to lead to the run away build up of heat on the surface of the world. With Venus you have the carbon dioxide and carbon monoxide water vapor and all of these different gasses so when we talk about greenhouse gasses the one that is most notorious is the carbon dioxide that we have here on earth. It’s not the only one though, it’s just one of many.
Fraser: With Venus you have this situation where the atmospheric pressure of the surface of Venus is nine times the pressure of Earth. The temperature there is 735 kelvin. It’s a hot place. How much of that heating is happening from the fact that it’s carbon dioxide and how much of that is the weight and pressure of all that atmosphere? Is that having an impact as well?
Pamela: Well the weight and pressure of the atmosphere in this case will have some effect on the temperature, that’s the standard gas law. The higher the pressure of the gas the higher the temperature of the gas but it’s not going to account for 900 degrees Fahrenheit of the gas. Yes, that plays a roll but a major roll is played by the trapping of solar radiation which allows the planet to warm up and allows the atmosphere to stay warm because the radiation can not escape effectively.
Fraser: If I recall correctly, way back when we did our episode on Venus and plate tectonics that it’s possible that the high temperatures on Venus have actually shut down the whole plate tectonic cycle on the planet preventing the sequestration of the carbon, right?
Pamela: Well it’s not that simple. You also have the fact that Venus isn’t rotating as fast as other worlds and without that rotation of the inner core it’s harder to have plate tectonics… but yes, having the atmosphere that it has, the carbon dioxide does stay in the atmosphere instead of getting rejuvenated through life and through tectonic processes to go back under the surface.
Fraser: So back here on earth we know that the amount of carbon in our atmosphere rises and falls naturally over long periods of time. We know that the temperatures rise and fall naturally over long periods of time. There is this natural cycle going on but what are we doing to unbalance it?
Pamela: There’s a whole series of cycles that go on in any given time. There are cycles due to the slight changes in the elipticity of the earth’s orbit that vary how far or how close we get to the sun over the course of our orbit. Because of the way that orbits work you move slower the further away from the sun you are. That can have global impact. It has to do with slow changes in the tilt of planet, don’t worry we’re not going to flip on our side the way some crazy people think. The planet’s tilt does ever so gradually change small amounts, it has to do with the procession of the pull of the planet. All of these are gradual long-term processes with known cycles. There are other cycles on top of that that are harder to predict, the sun misbehaves. There was a period called the maunder minimum where there weren’t the same number of sunspots that had been seen at other points throughout the hundreds of years that we’ve been studying sunspots. During that maunder minimum, that period of lack of solar activity, the earth experienced a mini ice age especially in Europe. This was tied in part to what caused the dark ages, famine, and many other issues that were experienced in Europe. On top of that right now we see the measurements of the solar radiation but it’s not sufficient enough to explain the increase in temperatures on average across our planet. We’re seeing drastic melting of glaciers. We’ve seen that in the past on earth in various records but the rate at which it’s occurring and the timing at which it’s occurring are unusual and hard to explain. When we start looking at the levels of carbon dioxide in the atmosphere, it’s increasing at a rate that hasn’t really been seen in the past. It’s this sudden sharp increase and the way it’s behaving just doesn’t look like anything we’ve seen in the tens of thousands of years data that we’ve been able to retrieve from ice cores, from ground cores, from looking at trees (that doesn’t give you the tens of thousands but still). This seems to indicate that our planet is sick in a way that we’ve never seen before. When we start to look at how long-term colonies of life that are highly sensitive to their environment are starting to die off indicates that this is something that is new within the period of industrialization. When we look at coral reef which are sensitive to temperature and pH. When we look at fresh water lakes which are sensitive to temperature and ultra violet light. When we look at where animals are currently migrating compared to all oral and written histories of various places. All of these things are changing.
Fraser: That’s one of the most stark graphs that I’ve ever seen. Every year during the summer for the northern hemisphere all of the plant life grows and absorbs carbon out of the atmosphere and then stops happening in the winter time. You see this cycle, this rise and fall of atmospheric carbon, but instead of it being this ongoing sine wave it’s actually this stepping up and keeps going up and up by a precise amount every year. We’re really seeing this amount of carbon dioxide in the atmosphere going up in this very set amount. As I mentioned in the intro, we’ve crossed the 400 ppm mark this year right?
Pamela: There are other concerning gasses. There are people that are concerned, and the research is out on this one, I recognize that this is an open question at this point but one of the open questions that is being looked at right now is that we know that methane is a greenhouse gas. We see its effects on Titan. We see in our own geologic history how methane in the earth’s atmosphere allowed us to be a warm world when the sun gave off 70% of its current energy in the distant past when it was 30% cooler. We are now releasing methane into the atmosphere at a new rate that hasn’t been seen in the past due to things like fracking. Methane is generally collected and used in things like our dryer which runs off of methane for instance; it’s a natural gas. We can use it for things but the amount that is escaping into the atmosphere is another form of greenhouse gas. The question is being asked “Is fracking leading to a precipitous release of methane that is also of concern as we look at the global warming effects.
Fraser: Yeah, global warming is the way that most people describe it but I think that the new name that we use “climate change” is a lot more accurate. Let’s talk about the warming first. So far, since people have been keeping track of this, about how much has the planet warmed?
Pamela: So in just the past 100 years and the temperatures have been much colder in the past. In just the last 100 years the folks at UCAR have measured the temperatures 1.3 degrees Fahrenheit That doesn’t sound like a lot but it’s enough that we can start seeing major changes in glaciation, it’s enough that we are starting to see the northern passage through the north pole essentially becoming sail-able, perhaps even year around in the next couple of years but the idea that you could ever sail through that is nothing we ever really imagined would be possible.
Fraser: I don’t know what 1.3 degrees Fahrenheit is in Celsius.
Pamela: 0.74 Celsius
Fraser: Okay I’m sorry… I’m bilingual in weight and distances but I only speak metric in terms of temperature.
Pamela: No, it’s all good.
Fraser: So as you said, we’re already seeing the implications being the hottest years on record have happened within the last decade, the polar ice cap is now free of big chunks of ice every year and glaciers are melting at a larger rate. I think as I mentioned a little bit ago that it’s this transition from global warming to climate change that makes it a lot more accurate because it’s not necessarily going to be global warming for everybody right?
Pamela: No, no, and that’s actually one of the harder to stomach parts of this when you start looking at the planet models. We live on a planet that is in many ways a very fine tuned machine. We have the mid-ocean conveyor belts that transport the warm waters from the equatorial regions north to the colder regions near the north pole and south to the colder regions near the south pole. These mid-ocean conveyor belts are, in part, driven by salinity and temperature but the salinity of the ocean is what allows them to stay in balance the way they are. If you change the salinity of the ocean you can shut down cold… that wasn’t meant to be a pun… but you can shut down cold turkey the mid-ocean conveyor belts. This would have the effect of temperate climates like England suddenly becoming significantly cooler because they are not getting that warm water circulating up toward them. There are those in the scientific community that are looking to try and understand if the recent snow fall that has been measured in England and the significant cold snaps that happen in northern Europe this year are an early sign that this is starting to happen.
Fraser: Yeah but of course part of the problem is if you look at the last year, 2012 in the United States, was just a disaster across the whole country. You had horrible droughts, terrible flooding, terrible wild fires and tornadoes.
Pamela: Yeah a tornado two blocks from my house.
Fraser: Yeah well that was 2013… and hurricanes and so on and so forth. So you have all of this increased weather, storms and all of these problems so it’s very much unpredictable but at the same time it’s also very difficult and essentially impossible to connect any one of those events to global warming.
Pamela: What you have to do is look at it globally. You have to look at what the models are of how the temperature build up at various places is allowed to occur. Where are the hot spots? Where are the cold spots? How is this effecting moisture transport in the atmosphere? How is this effecting the thermal gradients? Massive storms are driven by the thermal gradients of hot and cold in different places. If the equatorial regions are able to build up higher and higher temperatures, it’s going to lead to increased thermal gradients and increased storm power. One concern is that this could end up leading to more category five earthquakes and typhoons so what we have to do is track long term. Do we see an increase in not just in the global temperature but do we see an increase in the temperature gradient between the poles and the equator?
Fraser: The terrible irony is that where I live we’re expected to do quite well from climate change. It’s kind of cold and kind of wet but is expected to get colder and dryer.
Pamela: Well yeah you live in the northern rainforests.
Fraser: Yeah and for a lot of creatures it won’t be as much rainfall as they would appreciate but it will become more Mediterranean-like, more northern California-like For the mass majority of people it’s going to be worse because you’re going to end up with all of the resources that you rely upon are going to change and shift. Then you’ve got natural disasters on top of that. So right now if the carbon continues to be let out into the atmosphere…
Pamela: …And methane and other greenhouse gasses
Fraser: Yeah and methane and water vapor and other nasty greenhouse gasses, what kind of temperature rises can we expect in the future?
Pamela: Looking at different studies, pretty much everyone says between three to seven degrees increase.
Fraser: That doesn’t sound like the end of the world. A three degrees rise, a seven degrees rise, that’s not that bad.
Pamela: That’s in the next 100 years and the issue is when that happens you end up with loss of glaciers that which leads to the end of salinity in the ocean … not the end of but a significant change which leads to the loss of this mid-ocean conveyor belt which leads to massive changes in weather patterns and temperatures in various areas which leads to greater extinctions which leads to… do I need to keep going?
Fraser: No, no, that’s fine, I think we understand. There is also a potential for more unforeseen things like the vast reserves of methane that locked in the permafrost of Canada and all that heats up it could all just seep out into the atmosphere.
Pamela: Right and you end up with a collapse of different logical niches like loss of all sorts of different water creatures. That’s the one that is most disturbing because this leads to a change to the pH of the water and also leads to a change in temperature of closed bodies of water and of bodies of water where the animals don’ have the ability to necessarily migrate. Critters living on a coral reef can’t just hop to a slightly more northern coral reef and keep hopping north because eventually reach waters that don’t currently have coral reefs. This is vast food stores here in the United States and Canada. We don’t live off of local fish but for all of the different nations of the world where are they are still living quite well but less and less well off the oceans, it’s going to become harder to survive.
Fraser: So what strategies have been proposed to actually deal with this and actually try and get the carbon levels back down to some reasonable level?
Pamela: There have been a lot of things that vary from behavior changes to drastic changes to our planet using technology. There are those that have suggested everything from needing to deploy a bunch of little tiny umbrella satellites that shade our planet to a certain extent thus preventing significant portions of the sun’s light from getting to the planet. There are those that propose that we need to produce massive algae blooms in the ocean so that they absorb carbon dioxide out of the atmosphere and then there are those that instead of trying to manufacture change are suggesting that we simply change our behavior so that mother nature can take care of itself while we start adding new. So there is the movement to eat less meat. Not because meat is immoral or at least immoral on the animal side of things but because it’s irresponsible because of the amount of carbon emission tied into the whole raising up cattle, chicken or pig process. There are those that argue that we need to never use things like Amazon Prime two day shipping that leads to packages getting shipped air all over the world instead of using the more efficient of trains and barges. There are those that argue that we need to eat local and eat in-season so you shouldn’t be eating tomatoes in January unless they happen to come from a local greenhouse. We don’t need those Fuji apples in… any time if you live in the north. All of these solutions have significant economic question marks. We actually find in general that it’s more cost efficient to decrease and be more efficient and eat locally but the transition period is always hard and I think people live in fear of that change.
Fraser: The good news is that carbon dioxide is a very volatile substance in our atmosphere and it doesn’t really want to stick around. I think that if you let the planet do its own thing and we’re not adding to the carbon footprint it will decrease naturally on it’s own right?
Pamela: And methane is even worse because it breaks down into ultra-violet light. So yeah, if we can find a way to stop releasing significant amounts of carbon dioxide through combination of moving to greener energies, greener transportation methods, greener ways of eating and are able to swallow the inconvenience that we seem to think is too much and swallow that and change our behaviors, I think we can heal our planet. Well we can’t but I think our planets natural ability to return to equilibrium will hopefully prevent too much further damage from coming. Some damage is done and some species are gone. We may reach the point where they don’t have the genetic diversity to return.
Fraser: So we think about the long-term here on Astronomy Cast. Sometimes a 1 followed by a hundred zeros if necessary. I think it’s really important to understand that the planet will be fine over the long-term and there will be times when it won’t like when a massive asteroid will crash into it and kills 99% of the life on earth as it has in the past. In 5 billion years up the sun will load up and blast it with radiation. We’re talking about ourselves here, we’re talking about the species that are here with us right now and what it’s going to be like for human beings. This is kind of a moral imperitave for all of our fellow human beings, not like we need to save the earth, the earth is going to be just fine. The earth didn’t care about us before. It’s the current ecology that includes us that we depend on so much and that’s what’s really at risk are human beings.
Pamela: I won’t say it’s just human beings. I have to admit I’m one of those people that can not get over emotional about the penguins and the polar bears if you just pick your pole of concern. Both of those species are struggling. The fact that polar bears are starting to get discovered cross breeding with Grisly bears because for the first time in record-keeping, there territories are starting to significantly over-lap. That’s a really weirdo side effect of climate change. I don’t know what you call an offspring of a polar bear and a grisly other than not something to get near.
Fraser: So now maybe you should use standard shipping with Amazon from here on out and other stuff.
Pamela: Or just buy local. I’m lucky enough to live in a small town where for the most part I can get anything I need from a family owned store that is a lot of time getting from local manufacturers.
Fraser: I work from home which is great except for the fact that I never leave my cul-de-sac but other than that it’s good that I don’t have to commute to work everyday. Technology is going to make a big impact we just need to embrace it as it’s coming down the road: these new kinds of energies, these new kinds of devices, these new cars and everything else. Well thank you very much Pamela.
Pamela: Thank you, it’s been my pleasure.
This transcript is not an exact match to the audio file. It has been edited for clarity.