Neil deGrasse Tyson is an astrophysicist, and science communicator par excellence. He’s also the host of Cosmos: A Spacetime Odyssey, a reprise (or rather, update) of the original Cosmos: A Personal Voyage hosted by Carl Sagan.
He is the most worthy choice to step into the very large shoes left behind by Sagan. The new series is also, in proper tribute to Sagan’s inspiring original, produced and written by Ann Druyan, who was a co-writer of the original Cosmos series (and soon after married Sagan). Tyson’s enthusiasm, his clarity, his love of science, leap off the screen; it’s hard to imagine not being inspired by his presentation. It’s inconceivable that one could be bored by it. If anyone can inspire a new generation of kids, sparking their interest in science, it’s him. Neil deGrasse Tyson.
As was made clear in early episodes, and as I had heard in interviews of him that I’ve seen on TV, Tyson was also inspired and assisted by Carl Sagan himself when he was a young student embarking on his higher education. You can almost feel the reverence with which he regards his former mentor. It’s a poignant tribute to the universe, that the student becomes the master.
Germaine to this blog, the latest episode of Cosmos deals with climate change. Man-made climate change. And the danger it poses. It should really piss off the deniers.
It’s not too hard to view it online, if you haven’t seen it already. It’s on Hulu, and I think you can find it elsewhere too. I strongly urge everyone who hasn’t seen the latest Cosmos, to take the time to view. I think you’ll enjoy it.
Open Mind 
I really enjoyed the episode,and thought it was well crafted for an audience that might not be up to speed on climate change. It wasn’t a hit-you-over-the-head approach but it still didn’t pull any punches either.
I hope it inspires people to learn more from (hopefully) reliable sources what the facts are,and who has been stringing them along for the last couple of decades.
Its also available on the web here: http://www.cosmosontv.com/watch/270803523723
Not available outside North America, it seems. What is the title of the video? Maybe I can find an internationally accessible version.
Season 1, episode 12, “The world Set Free”
I’ve had no luck so far.
Here over in Ireland I’m having to bit torrent the series onto my PC. It does make for compelling viewing, and I love how they got Fox to carry the series instead of the more likely PBS, where it wouldn’t have found as large or as young (and dare I say – as politically to the right) a potential audience. If we can’t get the republicans to listen to the voice of reason, maybe their kids will.
Aside from the last episode that tamino is talking about, #12 of 13, which deals almost exclusively with AGW, I found the most interesting one so far to be episode #7. It turns out that the person who discovered the true age of the earth (no mean task) is also the person who, collaterally, discovered a great environmental harm that was being inflicted on us. Fascinating stuff.
Fox (broadcast) TV doesn’t have the same political tilt that Fox Cable News does; their local news shows are pretty much like CBS, NBC or ABC, as is their produced content.
But yes, they are more prominent than PBS.
Can’t wait to hear Uncle Willard explain away this one.
Indeed there is at least one substantive (and unfortunately valid) criticism of this episode which will detract from this most important message. To wit: H2O (water) is the most important greenhouse gas, not CO2, for maintaining Earth’s greenhouse. Water, which has the major vibrational (and rotational bands) bounding the 10-micron radiative region (peak thermal emission wavelength of the Earth), provides the underlying basis for and largely controls the greenhouse process because of its short residence time, condensable and evaporative properties near the triple point (sufficiently near the average temperature of the Earth’s atmosphere) and great energy transport properties (latent heats). The variable nature of H2O concentration as a function of temperature (latitude and altitude) and pressure (altitude) make the water-driven greenhouse system much more complicated than this simple picture. CO2 (primarily and in concert with CH4, etc.) has major vibrational bands in the same spectral regions and so provides the concentration-driven destabilization of the radiative transfer process, the issue of concern. It is this destabilization of the much larger H2O-driven greenhouse system that is so dangerous. A little (or too rapid a) push on the system may send it to a new (and catastrophic to us) equilibrium. No matter what the new equilibrium is, the time scale for the transition, driven by the current incredibly rapid infusion of CO2, is of immediate threat to much of Earth’s life and especially human economies.
So it is unfortunate the statement is made that CO2 is the most important greenhouse gas without the caveat that it is important (at current concentrations) because just a little bit of change can tip over the bigger system. Especially since it opens up valid criticism. Can the lesson be salvaged? Who knows. The denial arguments are largely ideologically driven and giving deniers the ability to grasp onto and pound a factual error will cause endless distraction.
Disclaimer: I had the pleasure of being a research colleague with Carl Sagan at Cornell and had the pleasure of teaching several of his classes while he was in LA preparing Cosmos. Neil deGrasse Tyson provides a wonderful and most valuable update and extension of that original series and this episode is right in keeping with that theme. Perhaps Neil will continue in Carl’s footsteps and become the honest broker for science in our times. God knows we need one now.
[Response: No, the criticism is not right.
The thing about water vapor is that if we change the atmospheric load, the change won’t persist. In a brief time (climatically) it either precipitates out or evaporates in to restore the equilibrium value determined by other factors (mainly temperature).
CO2 is the most important greenhouse gas which regulates the global thermostat. Tyson was right, you are wrong.]
Its always a balance between just how much depth you want to go into, and what details you want to leave out. We tend to worry about being exactly right, because the fake skeptics will jump on anything at all.
However, I think it best to get the message across clearly without every bit of detail.
John, in this particular case, Tyson is right, and the commenter here is wrong. H2O can’t maintain Earth’s greenhouse by itself; it needs the CO2. H2O is an amplifying feedback. That’s why, contrary to the comment, CO2 is “more important” than H2O even though H2O has a larger effect.
Or to put it another way, CO2 is a forcing but H2O is a feedback. We can’t alter the latter directly but we have been altering the former ever since we started using fossil fuels.
At the margin, CO2 is a more significant GHG than H2O.
I agree completely with Tamino’s comment that Tyson was right and you (Jonathon) are wrong about CO2 being the most important greenhouse gas. The importance of something isn’t based on how much of it there is or on what it does day to day, but on its ability to change what happens day to day. True, water vapor in the atmosphere has the strongest overall effect as a greenhouse gas as far as trapping energy that would otherwise be lost back to space. But it’s in constant flux with a residence time that can sometimes be measured only in hours. Its overall concentration depends on the average air temperature (concentration goes up non-linearly with temperature as long as there’s a ready supply from the oceans and vice versa). Meanwhile, CO2 is an extremely stable molecule that has a residence time measured in centuries once it gets into the atmosphere above the immediate surface layer and away from the clutches of photosynthesizing organisms and absorption by bodies of water (also dependent on temperature; warmer, less absorption and vice versa).
It is true that methane and nitrous oxide among natural greenhouse gases are also much more effective absorbers of infrared energy. But their concentrations are only a tiny fraction (at least at present!) of that of CO2 and so not as important in the big picture. But because of CO2’s stability and longevity in the atmosphere, it makes an ideal thermostat and that’s what makes it so important. As someone else has stated on this thread, it is a significant driver, such as are the concentration of aerosols, the distribution of the continents and ocean currents, orbital variations, and minute changes in solar output, while H2O acts principally as a feedback.
Of course, CO2 also acts as a feedback to orbital variations and changes in solar output (anything that causes minute changes in energy retention by Earth’s climate system and so causes the oceans to either absorb or emit CO2). But that just shows how complex and interconnected everything in the climate system is. But on the scales and effects that we’re talking about, CO2 is definitely the most important greenhouse gas!!
Perhaps those who find fault with Tyson’s comment would be happier if he had added the qualifier that CO2 concentration is the climate system’s thermostat and in that sense becomes the most important greenhouse gas. But after watching the entire series, I came away wishing the producers and FOX had allowed Tyson 10 times as much time to really get into some explanations. But just the fact that FOX carried such a fine series at all was outstanding, as was the series itself. One can’t have everything, especially on as flawed a medium as modern television.
I just finished watching that episode again, and Tyson specifically mentioned that CO2 concentration is in fact the climate system’s thermostat. So, even that caveat was in there and that makes it “unanimous” that Tyson was right.
To wit: H2O (water) is the most important greenhouse gas, not CO2, for maintaining Earth’s greenhouse. Water, which has the major vibrational (and rotational bands) bounding the 10-micron radiative region (peak thermal emission wavelength of the Earth),
A fundamental mistake here, consider the plot vs wavenumber, because the peak of that curve represents the peak energy which the plot vs wavelength does not. You’ll see that it is the CO2 absorption which is near the peak thermal emission energy not H2O. Also water is not a gas it is a liquid in equilibrium with its vapor which makes a fundamental difference in the ability of water to drive temperature change.
“There are no scientific or technological obstacles to protecting our world and the precious life it supports. It all depends on what we truly value, and if we can summon the will to act.”
Assuming that this “precious life” is what we truly value, then it all depends on summoning the will to completely re-design our global economic system to protect our world, and not destroy it.
Perhaps this realisation will dawn upon us in the end, but will it be too late?
“Pale Blue Dot”
(my versification of Carl Sagan)
The Earth is where we make our stand,
Against each other, or hand in hand.
This pale blue dot is all we know.
There is no other place to go.
Or, as Dave Carter and Tracy Grammer put it
“This is my home
This is my only home
This is the only sacred ground that I have ever known
And should I stray
In the dark night alone
Rock me Goddess in the gentle arms of Eden”
Well.. I’d disagree to some extent.
We have to redesign our energy infrastructure to eliminate fossil fuel use, which is perfectly achievable with current or near-current technology. This would be hard, but certainly not WWII-mobilization hard. And quite frankly the economy needs such a Keynesian boost right now, it would be a lot more effective than printing cash and handing it to very large banks.
Indeed, I regard this as the single fact the the denialist crowd don’t want out in the open. If the general public knew that the problem was fixable without major lifestyle changes, then the denialists would be revealed as what they are, desperate shills for a relatively small part of the economy.
I love how they got Fox to carry the series instead of the more likely PBS
Seth MacFarlane, one of the producers, has a ton of clout at Fox, because he created and produces a couple of very popular animated series for them. My imagined version of the pitch has MacFarlane saying, “You want more ‘Family Guy’? Sign here, here, and here.”
And good for him.
Some might be surprised by who put up the money for this.
In the UK you can watch Cosmos on the National Geographic channel (Sky and Virgin but not Freeview).
What the deuce?
Here is a link that works for viewing in Europe, but I don’t know if it is legal. http://www.watch-series-online.li/Watch/Cosmos-A-Space-Time-Odyssey-3539.html#!episodes_tab
Legal or not, it works here in Australia. Thanks.
In Canada, you can watch it here.
http://www.globaltv.com/cosmos/
No commercials either, but is only available for a week. Haven’t watched this one myself yet, but will do so this morning.
I thought it was an excellent presentation, making fine graphic choices to visualize the explanations, with just the right touch of idealism and enthusiasm to make the subject inspiring as well as accessible.
A mental passenger along for the ride was the little homunculus contrarian, or the most honest climate change skeptic I could ideate. I wondered how they’d view it. I guess he’d lay a quibble on the notion of nights warming faster than days. That seems to be the case since the mid-20th century, but not so clear for the satellite period. My devil’s advocate would be saying that the diurnal range trend has not descended in the period when antrhopogenic global warming had supposedly taken off. Wasn’t sure what to say to him.
But it’s a nit for the die-hards. This episode gets the message right, backs it up with reasonable generalizations from science, and tells a rather unique story all in all. The bit about early 20th century solar power being killed off by oil and WWI was a news, and leaving the thematic implications to the viewer was an intelligent, effective choice. Very well done.
Neil’s series has reminded me several times what I love about science, but it also reminded me what an incredible scientist and communicator Carl Sagan was. I’m rereading portions of Ray Pierrehumbert’s “Principles of Planetary Climate” and there’s some of Carl’s groundbreaking work in Ray’s text!
In the spirit of the Cosmos episode, here is a thing that should go not just viral, but be a plague on social media. Solar roadways, a real thing.
http://trendinghot.net/invention-will-change-world-just-watch/
Any other day this could be classed as spam, but maybe you’ll allow it, Tamino. If not, enjoy watching it, and maybe you’ll promote it in other ways.
Uhg. I’m getting tired of seeing that. I WORK in the solar industry, and typically relish the opportunity to jump up and down and shout “Look! Look at what we’re doing, people!”.
It’s not that I don’t think it won’t work. Almost anything can be made to work if it’s based on proven technology. I just don’t think it’ll be cost-effective. Ever. I’ve got experience with building integrated photovoltaics (BIPV). They’re neat, good-looking, and at face value would seem to make a lot of sense. But dive into the nuts and bolts of actually making and installing something that works, is safe, and serviceable… and the wheels start to fall off. Better to just cover the roof/carport/open field with a PV array made from standard format PV modules and be done with it.
And that’s the problem with this solar road stuff. I’d bet my savings that the cost of this type of road will always be much greater than the combined cost of a ‘regular’ roadway and a ‘regular’ PV array sited somewhere else. That’s why there is the emphasis on the ancillary benefits like the LED lighting and sensors. But to me it’s still a tough sell.
Don’t get me wrong. I think it’s clever. The LED and sensor stuff IS neat, and co-locating power production and transportation infrastructure has some merit. I’m glad to see they’re building a prototype, and I’m even glad that the DOT is throwing some money their way. Maybe they’ll prove me wrong. I hope they do! But I’m pretty sure they won’t.
In the meanwhile I’m baffled by how much play this is getting on social media. I’d prefer to see less attention lavished on “Look what we might be able to do in the future!” and more on “Look what we are doing right NOW, and need to be doing more of, right NOW!”
Sorry to come down on you like that. But seeing that link here… was just the last straw for me. Rant terminated :)
No worries about the rant. I read a few negative posts on solar roadways and took them in. A common argument was the cost – gonna take a few trillion to replace every road in the US. Well, sure. Who is proposing to replace every roadway tomorrow? It’s expensive. But why not lay a few k here and there, where the sun shines brightest and the traffic is light, or where there are traffic lights, to supplement power to them? Add slowly over time, and cost will reduce. Doesn’t need to displace other efforts at renewable energy. Keeping the hexes clean was another good point, as was the sound they’d make against the tyres at 100 kph. Wasn’t convinced that concerns about load-bearing was an issue.
Roy Spencer had a good lash at them on his blog, but in making his argument he pointed out that regular photovoltaics are becoming cost-effective. Taking a potshot at what he figures is outlandish seemed to move him closer to supporting regular renewables.
Yes, once we’ve got solar panels on every rooftop, then we can look at the roads.. my instinct says that the combination of weathering and physical stress makes this a very hard problem.
Yes. It’s a ‘sexy’ idea, so it’s a shame to have to take a ‘show me’ kind of stance. I think another problem that may turn out to be worse than expected could be fouling of the surface by dust, various automotive fluids and what have you–especially in the parking lot scenario.
Click to access BR_SE_Solar_005.pdf
In response to your criticism: Perhaps my perspective on the issue is weighted too much by my (pre-climate change debate) planetary atmosphere perspective of radiative transfer and changes in terminology. My alarm bell went off when I heard Tyson say (11:29), ”The CO2 in the atmosphere absorbs most of the outgoing heat radiation, sending much of it right back to the surface. That’s all there is to the greenhouse effect. Just basic physics.”
My point is simply this: Ignoring (not mentioning) the importance of the H2O system in the radiative transfer process in the terrestrial greenhouse system and the role of CO2 concentration as the destabilizing factor opens the debate up to arguments (by deniers) that detract from the real issues. I think it would it have been better if Tyson had said, “”The CO2 and the H2O in the atmosphere absorb most of the outgoing heat radiation, sending much of it right back to the surface reaching a delicate balance of incoming light to outgoing heat. That’s all there is to the greenhouse effect. Just basic physics. But changing the concentration of CO2 just a bit can upset this delicate balance.”
Some other points: The integral of the energy absorbed from the thermal emission from a ~300 K BB (ground) is dominated by the 8 um and 18 um H2O bands (for the moist lower atmosphere, but not for the dry stratosphere): the 5-8 um H2O bands absorbs the higher energy photons and the 16-20 um H2O ragged absorption absorbs quite a bit, too, and at least in the lower atmosphere that is more than what the (opaque) 14-16 um CO2 band absorbs. Add to this condensability (clouds) and you get another important H2O-driven radiative transfer factor on the solar energy input side. I thought this implied the process termed amplification, but apparently did not.
I also pointed out that the CO2-concentration-driven radiative transfer process causes destabilization of the complex H2O system on which life and economies depend directly. Perhaps this is less precise terminology than “regulating the global thermostat”.
Is the disagreement whether the boiler is more important than the thermostat or vice versa? Life depends on the boiler, the boiler listens to the thermostat.
[Response: Our disagreement is whether or not a program to inform the public about the very real danger of CO2 increase should have to satisfy your standard of a scientifically complete explanation at the expense of drowning the message. I think the Cosmos episode did it right.]
The moment one mentions things like “integrals”, “residence time”, “absorption bands” (vibrational, rotational, ragged, kempt or otherwise), “CO2-concentration-driven radiative transfer” and (especially) “condensable and evaporative properties near the triple point”, most TV watchers are going to feel an overwhelming urge to change the channel to “America’s Got Talent” [though not for science]
Tyson understands this very well, as did Sagan before him, which is precisely why they have been able to connect with the general populace on science.
I think the details you note are highly valuable in a medium for climate nerds (like this blog), but perhaps less so in a medium for the layperson. Your comments bring up a question: Is it true that the “importance” of CO2 is greater in the upper atmosphere, where water vapour is scarce?
It would be hard to guess at the effect on the average viewer of your suggested change to a couple of sentences in the narration. Probably it would be minor, and the benefit to accuracy may be worth it. But the proposed problem, in which regular folks start questioning and learning about the relative roles and functions of greenhouse gases, is likely a winning situation given that a large fraction of people still don’t think about it at all.
I have to admit that when Tyson said that about CO2 absorbing most of the heat radiation and then re-radiating it back to the surface I knew it wasn’t technically correct since H2O is in fact the prime absorber. But I put it in the same category as when he said in a previous episode that it would be another 50 thousand years before we would have gotten into the next ice age since technically we would be starting the long erratic decline into the next ice age soon, if we hadn’t started significantly warming the atmosphere with our global industrialization fed by fossil fuels (there has been some speculation that the Little Ice Age might have been the first stirrings of that decline and the real end of the Holocene interglacial).
But this is television after all, and the general American public is quite illiterate when it comes to science and more affected by general statements that have a lot of emotional impact than by scientific minutiae, even if it is as significant as which greenhouse gas does the most absorbing. So, in this regard, Tyson’s wording probably had the more emotional impact, and therefore was more valuable in getting the message across that CO2 increase is the problem that everyone has to accept and be willing to do something about. In my opinion, this Cosmos episode did more in its hour time slot to put the message out there that human civilization is in trouble because of what we’ve been doing to the climate system that anything else I’ve seen over the last 10 years. Neil deGrasse Tyson and the entire Cosmos team are to be commended for doing an outstanding job in a very difficult medium relating an extremely difficult and potentially catastrophic and existential problem to a public which very scientifically challenged.
On the relative importance of H20 v. CO2 as greenhouse gases, it all depends on context. But the H20 greenhouse effect wouldn’t exist if there were no CO2 to warm the atmosphere sufficiently to allow H2O to become/remain a vapor. See Lacis et al, “Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature”, http://pubs.giss.nasa.gov/docs/2010/2010_Lacis_etal_1.pdf , in which the authors zeroed out non-condensable GHGs (and aerosols) in a GCM whose initial state represented current conditions. Result: snowball earth (GAT ~ -21 degrees C) within 50 years.
Jonathan’s points are well-taken. However, neglecting the issue of forcing vs. feedback for a moment, the fractional contribution of H2O:CO2 to the modern greenhouse effect is about 5:2. This means H2O is responsible for a greater amount of our atmosphere’s thermal opacity, but in no way dwarfs what CO2 is doing…the ratio is not 100:1 or even 10:1, so the boiler/thermostat analogy is not really correct. CO2 remains competitive with water vapor over a range of climates in which CO2 is successively decreasing/increasing (dragging the water vapor greenhouse to change with it). See e.g., Table 2 of our paper http://pubs.giss.nasa.gov/abs/ru00200g.html . This competitiveness would only break down on a planet devoid of much CO2 or in a runaway greenhouse regime in which the atmosphere became almost pure steam.
In addition, CO2 is by far the most important non-condensing greenhouse gas in Earth’s atmosphere. All of the other non-H2O, non-CO2 absorbers only constitute ~5% of the modern greenhouse effect, and that number must be split up between methane, N2O, ozone, etc. Even the prevailing N2/O2 atmosphere doesn’t exert a completely zero greenhouse effect, and can even compete with methane in a very dry region. Thus, to first-order the terrestrial greenhouse effect can be understood as one dry component (CO2) with H2O as the wet component, in both the gas (water vapor) and cloud form.
As others have already noted, the H2O-greenhouse on the modern planet would nearly collapse if the skeleton provided by the non-condensing greenhouse gases were removed. In the Lacis et al. and other experiments, only about 10% of the modern H2O greenhouse persists on such a world, which inevitably drives global temperatures well beyond the point of total ice cover.
At this point, the argument becomes one of deciding what we mean by a “thermostat” or “most important.” And I think Neil gets it right. Because of water vapor’s condensable nature, its concentration in the atmosphere averaged over a sufficiently long period of time must be slaved to long-term external climate drivers, whether it be the Sun or CO2. The Sun itself doesn’t vary too much except over geologic time, and albedo fluctuations are typically small (or themselves driven by feedback processes), or are short-lived (as with volcanic eruptions). Furthermore, since CO2 is the principle long-lived, non-condensable longwave agent, it follows that it is essentially the sole candidate for driving Earth’s climatic changes. The fact that CO2 exerts such a strong greenhouse effect and is so long lived in the atmosphere (not chemically reactive, not broken down photochemically, and is governed by long-term sources and sinks) makes it a much more intuitive “knob.”
Even on geologic timescales, silicate weathering drives CO2 concentration against the prevailing climate trend, thus regulating its surface temperature on the longest of time horizons, making it a rather elegant thermostat. All of this allows us to make past climate changes intelligible, whether it be fairly rapid changes like the PETM, glacial-interglacial cycles, etc or the slower changes associated with long-term Cenozoic cooling (and inception of the Antarctic or Greenland ice sheets). This framework allows us to make the escape of Snowball Earth understandable, or when the weathering thermostat breaks down, provides a predictive framework for understanding the evolution of other planets (as on Venus). Thus, CO2 is really the most important greenhouse gas in the inner solar system and perhaps many planets at analogous orbits to their host star.
It should be noted however, that there is very little evidence that CO2 can itself drive a Venus-like runaway greenhouse as one may have guessed from the Cosmos episode (not that anything short of a runaway isn’t worth worrying about, of course!). Runaway greenhouse effects, however, are driven by having too much stellar radiation incident on a planet with a sizable ocean. CO2 doesn’t need to be in the picture at all, but it enters into the post-runaway story of Venus’ evolution since the geologic removal processes for carbon that are present on Earth become absent on a water-devoid Venus.
After going through the comments above, I agree with Jonathan. If Tyson did indeed say
”The CO2 in the atmosphere absorbs most of the outgoing heat radiation,…”
this is an unforced error. I think he could have done better.