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Global warming explained in under a minute

The views expressed are those of the author and are not necessarily those of Scientific American.


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Pop quiz, hot shot: how does global warming work?

Harder than it sounds. Credit: Twentieth Century Fox

OK, but do you really know why? That’s the idea behind this video by the folks at howglobalwarmingworks.org.  Tania Lombrozo has the backstory at NPR’s 13.7:

The researchers wanted to know how well the average American understands the basic processes responsible for global warming, and whether there’s a relationship between this basic understanding and the belief that global warming is actually occurring.

The results were sobering. While a majority of volunteers believed that global warming is a reality (80 percent) and that human activities are a significant contributing factor (77 percent), only a slim minority was able to explain even rudimentary aspects of the mechanism. Twelve percent referenced gases in the atmosphere that trap heat (such as pollution or carbon dioxide), and of these, none addressed a puzzle that this partial answer seems to raise: why gases that trap heat in the earth’s atmosphere don’t similarly block heat from entering the atmosphere in the first place.

So why don’t greenhouse gases like water vapor, carbon dioxide, trap the heat as it comes from the Sun? That’s because greenhouse gases let visible light pass on through (like what we see from the Sun) so that it can do things like help plants grow and warm the surface of the planet. When that energy leaves our planet, it does so slowly as infrared energy, which greenhouse gases are more than happy to slow down. The more greenhouse gases there are, the warmer things get. And so on.

So there you have it. Or you could just watching this video:

There are also longer videos that include more detail, if you’re interested: howglobalwarmingworks.org.

UPDATE: Dr. Michael Ranney, one of the leads behind the research into how people understand global warming, was kind enough to reach out to me and share some additional info. First, there is a short paper (less than six pages) on their study and the results. I encourage you to read it (PDF here). Second is a longer (400-word) explanation of the global warming mechanism/greenhouse effect. As many of you pointed out, distilling something as large and complex as global warming down to a minute-long video or several sentences is bound to leave out some important info. Although, I think the distilled version gets at the core mechanism. So here is a longer explanation that Dr. Ranney passed along (from UC Berkeley):

Scientists tell us that human activities are changing Earth’s atmosphere and increasing Earth’s average temperature. What causes these climate changes?

First, let’s understand Earth’s “normal” temperature: When Earth absorbs sunlight, which is mostly visible light, it heats up. Like the sun, Earth emits energy – but because it is cooler than the sun, Earth emits lower-energy infrared wavelengths. Greenhouse gases in the atmosphere (methane, carbon dioxide, etc.) let visible light pass through, but absorb infrared light – causing the atmosphere to heat up. The warmer atmosphere emits more infrared light, which tends to be re-absorbed – perhaps many times – before the energy eventually returns to space. The extra time this energy hangs around has helped keep Earth warm enough to support life as we know it. (In contrast, the moon has no atmosphere, and it is colder than Earth, on average.)

Since the industrial age began around the year 1750, atmospheric carbon dioxide has increased by 40% and methane has increased by 150%. Such increases cause extra infrared light absorption, further heating Earth above its typical temperature range (even as energy from the sun stays basically the same). In other words, energy that gets to Earth has an even harder time leaving it, causing Earth’s average temperature to increase – producing global climate change.

[In molecular detail, greenhouse gases absorb infrared light because their molecules can vibrate to produce asymmetric distributions of electric charge, which match the energy levels of various infrared wavelengths. In contrast, non-greenhouse gases (such as oxygen and nitrogen – that is, O2 and N2) don't absorb infrared light, because they have symmetric charge distributions even when vibrating.]

Summary: (a) Earth absorbs most of the sunlight it receives; (b) Earth then emits the absorbed light’s energy as infrared light; (c) greenhouse gases absorb a lot of the infrared light before it can leave our atmosphere; (d) being absorbed slows the rate at which energy escapes to space; and (e) the slower passage of energy heats up the atmosphere, water, and ground. By increasing the amount of greenhouse gases in the atmosphere, humans are increasing the atmosphere’s absorption of infrared light, thereby warming Earth and disrupting global climate patterns.

Shorter summary: Earth transforms sunlight’s visible light energy into infrared light energy, which leaves Earth slowly because it is absorbed by greenhouse gases. When people produce greenhouse gases, energy leaves Earth even more slowly – raising Earth’s temperature.

David Wogan About the Author: An engineer and policy researcher who writes about energy, technology, and policy - and everything in between. Based in Austin, Texas. Comments? david.m.wogan@gmail.com Follow on Twitter @davidwogan.

The views expressed are those of the author and are not necessarily those of Scientific American.





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Comments 22 Comments

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  1. 1. sault 4:40 pm 12/17/2013

    Wow, it’s no surprise how easily it is for fossil fuel companies to confuse people about how the greenhouse effect and climate change work! I wonder if the fact that about 25% of Americans cannot even identify the USA on a globe plays into the sad state of scientific awareness seen in the poll…

    Link to this
  2. 2. tuned 4:46 pm 12/17/2013

    Ha!
    You think that’s bad.
    I can’t even identify compassion in a Fossil Fuel lobbyist.
    To boot, when they say “CO2 is okeedokee” and I say, “how long can you breathe it?” they get disturbia.

    Link to this
  3. 3. Jim Steele 6:12 pm 12/17/2013

    It is pure foolishness to suggest that a dynamic complex climate can be reduced to a single variable. As climate expert Dr. Richard Lindzen from Massachusetts Institute of Technology said “That climate should be the function of a single parameter (like CO2) has always seemed implausible. Yet an obsessive focus on such an obvious oversimplification has likely set back progress by decades.” This video’s oversimplification does a disservice to science education.

    If CO2 was causing recent warming then we should see a rise in maximum temperatures. However in many places as exemplified in US Historical Climate Network for Yosemite, maximum temperatures have gone down since the 30s and 40s. Minimums have risen and minimum temperatures are often driven by landscape changes. If the heat was truly being trapped maximums should show the same trend, but they don’t as seen here for USHCN data for Yosemite http://landscapesandcycles.net/image/73289385_scaled_390x294.pngaaand here for GHCN-D data for the USA http://landscapesandcycles.net/image/75158484_scaled_590x444.png

    Link to this
  4. 4. Marc Lévesque 6:16 pm 12/17/2013

    Nice !

    Link to this
  5. 5. Jim Steele 6:21 pm 12/17/2013

    The links did not work correctly so lets try again

    here for Yosemite

    http://landscapesandcycles.net/image/73289385_scaled_390x294.png

    and here for USA

    http://landscapesandcycles.net/image/75158484_scaled_590x444.png

    Link to this
  6. 6. squidboy66 10:18 pm 12/17/2013

    Climate Misinformer: Richard Lindzen

    http://www.skepticalscience.com/skeptic_Richard_Lindzen.htm

    Link to this
  7. 7. jackdale 12:23 am 12/18/2013

    Jim Steele

    The IPCC does and always has considered natural variability and other factors in its reports.

    http://www.ipcc.ch/ipccreports/tar/wg1/042.htm

    Link to this
  8. 8. Devonshire 9:11 am 12/18/2013

    “Whatever happens, don’t give up and don’t despair. Results may not be immediately apparent, but you may have touched a receptive chord without knowing it. Even the most unsympathetic and unenlightened politician, industrialist or bureaucrat begins to take notice when a lot of people write about the same subject.”

    Prince Philip, Duke of Edinburgh, husband of Queen Elizabeth and environmental activist

    Link to this
  9. 9. jayjacobus 11:15 am 12/18/2013

    If many people believe in global warming and the link to CO2, it isn’t because these people are good scientists. It is because global warming is being hyped.

    Few people will independently confirm the hype.

    The majority may be right but the beliefs of the majority is not proof of the theory. Moreover, the common believer does not have the data or the knowledge to confirm or refute the specific forecast.

    Is it a fact that hype can replace accurate methodology? Probably, otherwise why is the data and forecast hidden but hype is rampant?

    Link to this
  10. 10. sault 12:13 pm 12/18/2013

    “If many people believe in global warming and the link to CO2, it isn’t because these people are good scientists. It is because global warming is being hyped.”

    This isn’t a logical statement and it doesn’t mean anything. All you’re doing is regurgitating from your denialistic creed that you willingly accept from the fossil fuel companies.

    Link to this
  11. 11. sault 12:17 pm 12/18/2013

    Jim Steele,

    It is pure foolishness to think we can dump billions of tonnes of fossilized carbon into the atmosphere and expect NOTHING to happen. Sorry, but the science is settled on this one: CO2 traps heat, we’ve increased its concentration in the atmosphere by 40% and all that extra heat is throwing our climate system out of whack.

    Trying desperately to prove a point about GLOBAL warming by cherry-picking a SINGLE location on the Earth’s surface is the oldest long-debunked canard in the climate denier’s book. Come on, I thought the fossil fuel companies were churning out better misinformation and propaganda than that!

    Link to this
  12. 12. Sisko 1:43 pm 12/18/2013

    David Wogan

    What prompted you to again allow comments to your articles????

    In regards to this article most people do not understand the basic warming impact is quite small (about 1 degree). It is the theoretical additional impacts (forcing) that some believe magnify the base CO2 impact into one that will result in much faster warming. They then further their or expand their belief with a fear that whatever warming does occur will result in a net change in conditions that will result in net harms for humanity overall (or in the particular nation of their residence) over the long term.

    Most people do not fully realize that the foundation of many of these beliefs are general circulation models (GCM’s or Global Climate Models) that forecasted changes based upon changes in atmospheric CO2 concentrations. The truth is that these GCMs have now been shown to be largely inaccurate beyond what was thought when they were programmed. Scientists who wrote papers based on these models–well wrote garbage.

    Link to this
  13. 13. kehvan 3:08 pm 12/18/2013

    To me, the irony is, the majority of the people who support the notion of dramatic regulatory action to “stop” global warming readily admit that it won’t stop it at all.

    Link to this
  14. 14. jayjacobus 4:58 pm 12/18/2013

    Does snake oil fix your ills? If only you believe the sales pitch, you’ll be none the wiser.

    But don’t ask for proof. There is no proof.

    If you ask for proof, you will be attacked for no other reason then you asked for proof.

    Link to this
  15. 15. sault 5:04 pm 12/18/2013

    Sisko,

    What time horizon / CO2 concentration are you basing this assertion upon?

    “the basic warming impact is quite small (about 1 degree)”

    Is that 1 degree (C or F?) already, 1 “degree” for a doubling of CO2 or 1 “degree” by 2100 or some other date? Or do you not even try to sound like you know what you’re talking about anymore?

    “It is the theoretical additional impacts (forcing) that some believe magnify the base CO2 impact into one that will result in much faster warming.”

    There’s NOTHING theoretical about it. We’ve seen that the Earth’s climate MUST be very sensitive (about 2 – 3 times more sensitive than I THINK you’re trying to say) based on the swings in climate of the past. Saying that these hard observations are only theoretical smacks of scientific ignorance and disrespect for the experts devoting their life’s work towards investigating climate science.

    “They then further their or expand their belief with a fear that whatever warming does occur will result in a net change in conditions that will result in net harms for humanity overall (or in the particular nation of their residence) over the long term.”

    I guess I’ll have to trot this out AGAIN just so your silly denier tactics won’t manage to fool anybody this time:

    http://skepticalscience.com/global-warming-positives-negatives-intermediate.htm

    You’ll see very few limited benefits outweighed by many more and much more severe drawbacks on that page with EVERY point backed up by a peer-reviewed paper. And while the high northern latitude countries stand to see the most benefits, it is the developing countries in tropical and subtropical regions that stand to see the worst effects of climate change. These are also the countries least able to afford mitigation and adaptation measures, amplifying any impacts.

    And what part of

    “Warming of the climate system is unequivocal, as evidenced by increases in global average air and ocean temperatures, the widespread melting of snow and ice, and rising global average sea level.[5]

    Most of the global warming since the mid-20th century is very likely due to human activities.[6]

    “Benefits and costs of climate change for [human] society will vary widely by location and scale.[7] Some of the effects in temperate and polar regions will be positive and others elsewhere will be negative.[7] Overall, net effects are more likely to be strongly negative with larger or more rapid warming.”[7]

    “[...] the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time”[8]

    “The resilience of many ecosystems is likely to be exceeded this century by an unprecedented combination of climate change, associated disturbances (e.g. flooding, drought, wildfire, insects, ocean acidification) and other global change drivers (e.g. land-use change, pollution, fragmentation of natural systems, over-exploitation of resources)”[9]

    No scientific body of national or international standing maintains a formal opinion dissenting from any of these main points”

    do you not understand?

    And you are hilariously wrong when you try to claim that the evidence for climate change rests on models or that these models have been proven wrong in any way! You spout off this nonsense CONSTANTLY yet you have provided ZERO proof to back it up. Meanwhile, 98% of the world’s climate scientists and over 99% of peer-reviewed papers over the last 20 years disagree with you. Maybe you should find some friends in the Flat Earth Society and spew your unscientific nonsense onto them instead of wasting our time with it…

    Link to this
  16. 16. sault 5:14 pm 12/18/2013

    “To me, the irony is, the majority of the people who support the notion of dramatic regulatory action to “stop” global warming readily admit that it won’t stop it at all.”

    To me, I can’t fathom how some people can’t even conceptualize RATE OF CHANGE or the PEAK VALUE of a certain factor given the forces at play. Sure, when you take your foot off the gas pedal, your car isn’t going to stop right away, but you’re still going to start slowing down. And depending on WHEN you took your foot off the gas pedal, you MAY stand a shot of not hitting a brick wall that is clearly in front of you. (And you don’t have any brakes because geoengineering and carbon capture & storage are non-starters).

    We already have a lot of warming baked into the cake, but we don’t need to make matters even worse by sitting on our hands and loading the atmosphere with CO2 while future generations get a worsening hand dealt to them.

    Link to this
  17. 17. jayjacobus 6:16 pm 12/18/2013

    You must be a nut case because only a nut case would turn an interested party against your cause without reason.

    Jerk.

    Link to this
  18. 18. copernicuscousin 8:44 pm 12/18/2013

    Nice little video presentation but you seem to have trimmed off a little too much with Occam’s razor. Nothing EVER happens for just one reason (greenhouse gasses). Bare-footing in the summertime might give you a few ideas for a sequel.

    Link to this
  19. 19. WarmNeutron 10:30 am 12/19/2013

    Anyone who is trying to make precise predictions regarding the impact of global warming is indulging in false delusions of rigor; anyone who believes that one can calculate accurate numbers for systems as complex as the climate and the biosphere is indulging at best in wishful thinking. I reject as speculative at best all the studies which demonstrate the catastrophic effects of warming, in the same way that I dismiss the studies demonstrating beneficial effects. The best strategy right now is to dig in and plan for both the good and the bad consequences.

    Link to this
  20. 20. davidwogan 2:04 pm 12/19/2013

    @Sisko Merry Chistmas ;-)

    Link to this
  21. 21. Eliot 2:41 pm 12/19/2013

    It seem that most people do not understand the physics of why some chemicals react to infrared (IR) wavelengths more then others. If asked “Why CO2 reacts to IR and CO not so much” or “Why H2O and not O2,” I just get a, “Don’t know,” and no curiosity of why or what is the effect of such.
    I wanted to know what was the most likely change in climate for my state, so I learned about climate science from the quantum physics to macro-sociology. (It’s not hard to learn. No math or science prerequisites needed. Just a willing mind.)

    Link to this
  22. 22. BBHY 9:05 pm 12/19/2013

    So, one commenter (Jim Steele) seemed to think that CO2 does not cause warming because we are not seeing maximum temperatures going up.

    Here is a list of countries that have recorded their all time highest ever temperatures since 1990:
    Greenland,Algeria,Chad,Gambia,Libya,Morocco,Mozambique,
    Namibia,Niger,Nigeria,Sudan,Zambia,China,Indonesia,
    Iraq,Japan,Malaysia,Myanmar,Pakistan,Qatar,Russia,
    Saudi Arabia,Singapore,Taiwan,Turkey,Solomon Islands,
    Bolivia,Brazil,Colombia,Paraguay,Cuba,Austria,Belarus,
    Croatia,Cyprus,Czech Republic,Estonia,Finland,France,
    Germany,Hungary,Italy,Lithuania,Macedonia,Malta,Moldova,
    Montenegro,Portugal,Serbia,Slovakia,Slovenia,Spain,
    Switzerland,Ukraine,United Kingdom

    Wow, that is a whole lot of maximum temperatures, so by his logic this proves conclusively that CO2 is causing the Earth to warm up.

    I can easily predict his response. After claiming that the data supports his argument, and after it has been pointed out that the data does just the opposite, he will now claim that the data is somehow faulty. I have observed this pattern over and over and over.

    Link to this

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