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<\/p>\nThis post is written to describe the basic effects of greenhouse gases, and CO2 in particular, for those who are unfamiliar with how the greenhouse mechanism works.\u00a0 Apologies to any physicists who might be reading this, I\u2019m going for a very gross generalization here, not a paper for Nature<\/i>.<\/p>\n
For starters, let\u2019s define the \u201cgreenhouse effect\u201d.\u00a0 In this context, it is:<\/p>\n
The ability for something to allow energy into a system, but also to prevent or retard its exit.\u00a0 <\/i><\/p>\n
This sounds paradoxical, doesn\u2019t it?\u00a0 How can something let energy in freely, but then prevent it from getting out?\u00a0 I\u2019ll give you an example that probably everyone reading this will have encountered.<\/p>\n
It\u2019s the middle of summer and you walk out into a parking lot to get into your car \u2013 and inside the car it is insanely hot.\u00a0 So hot that it could kill you if you had to stay in there.\u00a0 Yet out in the parking lot, it might be uncomfortably warm, but not lethally so.<\/p>\n
What has happened here is that the inside of your car is subject to a greenhouse effect as a result of the nature of the glass in the windows.\u00a0 Visible and other wavelengths of light can pass through the glass \u2013 they enter the car freely through the windows (which is why you can see through them), and some are absorbed by the interior of the car.\u00a0 Some bounce back out, giving us a view of the interior.<\/p>\n
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(Image from Wikipedia)<\/p>\n
Light, of all sorts, is made of photons.\u00a0 Different photons have different wavelengths, and those wavelengths represent how much energy is contained in that photon.\u00a0 Wavelength changes inversely to energy, so a short-wavelength photon will be higher energy than a long-wavelength one.\u00a0 X-Rays \u2013 very high energy, very short wavelength.\u00a0 Radio \u2013 very low energy, very long wavelength. \u00a0Imagine it this way: if the photon is crammed up into a really small wavelength, it\u2019s going to be very compact and energetic.\u00a0 If it\u2019s stretched out a great deal, it\u2019ll be slow and lethargic.\u00a0 Wavelengths also govern how photons interact with things \u2013 if a thing (like an atom in your steering wheel) is a size that matches the wavelength of the photon, that thing can absorb the photon.\u00a0 If it isn\u2019t the right size, the photon passes it by.\u00a0 So visible light photons pass through glass windows because the glass molecules aren\u2019t the right size to stop them \u2013 but the metal and plastic molecules of the car body are the right size, and absorb or bounce them back.<\/p>\n
Back to your car:\u00a0 it\u2019s the photons that get absorbed that we need to understand \u2013 they end up in the materials inside the car: the seats, the steering wheel, the dashboard, etc.\u00a0 They impart energy into these materials, and then those materials get \u201cenergized.\u201d\u00a0 That\u2019s not a technical term or anything, they just have absorbed the energy of the photon \u2013 the photon is gone, and the atom or molecule is now a little bit jazzed up. After a period of time, the atom or molecule of steering wheel calms down again, by emitting the extra energy it built up when it absorbed the photon.\u00a0 It does this by emitting photons itself \u2013 in this case, on the infrared wavelength, which while we can\u2019t see it, we sense infrared as heat.<\/p>\n
\u201cHot\u201d in our body\u2019s language means we are absorbing infrared photons \u2013 the warmth of your coffee cup, the heat from a fire, all that is infrared.<\/p>\n
Now here\u2019s the catch:\u00a0 glass molecules are the right size to catch infrared.\u00a0 So while your car is sitting in the parking lot, all kinds of visible and other light is getting in through the windows, some bounces back out, but the majority of it gets absorbed inside the car, and then re-released as infrared.\u00a0 That infrared can\u2019t get out directly because the glass won\u2019t let it pass \u2013 so more and more builds up inside, and the interior of the car gets hotter and hotter.<\/p>\n
So how does this relate to carbon dioxide in the atmosphere?<\/i><\/p>\n
CO2 in the atmosphere operates similarly to the glass in your car\u2026ultraviolet, X-Rays, radio, and visible light all pass through it without issue.\u00a0 Infrared gets blocked, however \u2013 much like the glass of your car, CO2 is the right size to catch infrared.\u00a0 It\u2019s this one property that makes things interesting in this context.<\/p>\n
CO2, along with other gases, acts in a similar way to a blanket \u2013 it keeps heat in the atmosphere.\u00a0 It does this similarly to how the glass in your car keeps heat in your car.\u00a0 What happens is that light passes down to earth from space, is absorbed when it comes down here, and is re-emitted as infrared.\u00a0 For example, sunlight comes down, sinks into the pavement of your parking lot, and makes it hot (it is emitting infrared).\u00a0 If there was no atmosphere, the infrared would radiate away into space freely.\u00a0 However, we do have an atmosphere \u2013 and the infrared has to pass through this.\u00a0 CO2 is part of that atmosphere, and catches some of that infrared, gets excited, and then emits infrared again when it calms down.\u00a0 Those emissions from the CO2 molecule will be sent out randomly, half towards space and half back towards the earth.\u00a0 This results in the \u201cblanket\u201d of CO2 keeping some heat in the atmosphere.\u00a0 When you add more CO2, there\u2019s more to catch infrared, and a heavier blanket effect.<\/p>\n
In the 1800s, CO2 existed in the atmosphere to the tune of about 280ppm (parts per million \u2013 for every million molecules of anything in the air, 280 of those were CO2).\u00a0 That amount came from mostly natural sources \u2013 biological respiration, volcanoes, forest fires, etc.\u00a0 Over the last half-million years, that concentration has fluctuated between 180 to 300 ppm, and those fluctuations take place over thousands and thousands of years.\u00a0 As with any concentration of anything, there are ways things enter the system, and things exit it.\u00a0 The system being earth\u2019s atmosphere, and the something being CO2.\u00a0 Respiration by living things being mostly responsible, volcanoes being a dramatic example (their amount of CO2 entering the system is measured to be about 300 million tons per year).\u00a0 Plants remove CO2 from the air, and CO2 also dissolves into the oceans, where plants and animals can take it up and eventually turn it into sodium bicarbonate (a common ingredient in sea shells), and other body parts of plants and animals \u2013 which, when they die, fall to the floor of the oceans and are eventually subducted through tectonic shifts.<\/p>\n
Nature as we experience it today evolved to deal with a pretty steady amount of CO2 in the atmosphere, and had millions of years to adapt to changes.\u00a0 There\u2019s a lot of input and output \u2013 see that chart I put up there, which was current in 2007.\u00a0 As you can see, the total ins and outs are pretty big \u2013 about 750 billion tons or so in, and in 2007, about 735 billion came out.\u00a0 That produced a net gain of 15 billion tons per year.\u00a0 Some of that gain got absorbed by the oceans, but the lion\u2019s share went into the atmosphere.<\/p>\n
Over the last 10,000 years or so, we\u2019ve had a fairly steady concentration of CO2 \u2013 the blanket has stayed about the same.\u00a0 In 1880, the concentration was as I mentioned above, 280ppm.\u00a0 In 2007, it reached 375ppm.<\/p>\n
Just a few months ago in 2013, that concentration reached 400ppm.<\/p>\n
That means the blanket of CO2 in the atmosphere is 43% heavier than it was a little more than a century ago.<\/p>\n
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<\/p>\n <\/p>\n <\/p>\n (Image from the New Scientist)<\/p>\n So where did all that extra CO2 come from?\u00a0 Well, to put it simply, it came from us.\u00a0 The industrial revolution is marked most distinctly by the fact that we discovered vast stores of volatile chemicals in the earth \u2013 hydrocarbons.\u00a0 These became the fuels we know today:\u00a0 gasoline, coal, diesel, jet fuel, etc. We found that these burn very handily, and if we harness the power of burning them, we could drive machines, keep ourselves warm, and so on.<\/p>\n So we burned them.\u00a0 We still do.\u00a0 Do you drive a car?\u00a0 You probably burn them now. \u00a0The Volkswagen Golf 1.6 liter TDI, for example, burns fuel for every km you drive.\u00a0 It\u2019s one of the most efficient vehicles there is.\u00a0 And it still releases 99 grams of carbon for every kilometer you drive.\u00a0 (That\u2019s 5.6 ounces per mile, for my American and British folks.) \u00a0I would take a guess that most readers are driving vehicles that pump out a lot more.\u00a0 Now multiply that weight times the number of miles you drive to work or school.\u00a0 Then x2 because you have to drive home.\u00a0 Now x5 for a work-week.\u00a0 Now x50 for weeks in a year (I\u2019m assuming you take two weeks holiday).<\/p>\n If you drive the TDI above on my commute (9.5km), that means you would be pumping 470.25 kilograms of carbon into the air every year.\u00a0 And that only takes into consideration the driving habits.\u00a0 It does not reflect how much gets burned to keep your lights on, to keep your house heated in the winter and cooled in the summer, how much is used to pump the water that flushes your toilet or runs through your shower.\u00a0 There are hundreds of millions of cars in the United States alone.<\/p>\n Remember how I pointed out that volcanoes, the primary source of carbon dioxide in the atmosphere, that they put out about 300 million tons of CO2 every year?\u00a0 And how this is a naturally balanced value, where geological and biological systems generally absorb this stuff to keep the atmosphere relatively stable?<\/p>\n Humans were not a big contributor to CO2 levels in the 1800s.\u00a0 However, since the beginning of the 1900s, humans have increased their burning of carbon fuels and have exceeded volcanism.\u00a0 By a lot.<\/p>\n We pushed out 31.6 billion tons of CO2 last year (2012).\u00a0 That\u2019s about one hundred times the amount of all the volcanoes on the planet combined.\u00a0 We humans are a force of change exceeding geological scale.<\/i><\/p>\n In addition to the greenhouse effect that CO2 is having on the atmosphere, the CO2 is also being absorbed into the oceans \u2013 and this is having a very serious effect through acidification of the waters.\u00a0 I may post something about that as well.\u00a0 But for now, this post is just on greenhouse effects\u2026something for you to consider.\u00a0 These things I\u2019ve posted up here aren\u2019t opinions.\u00a0 They\u2019re observations<\/span>.\u00a0 So when you see someone arguing about whether humans are causing climate change, point them to this stuff above \u2013 these are facts, not subject to debate or opinion.\u00a0 And sadly, they lead inexorably to the conclusion:<\/p>\n We are causing this.\u00a0 The only option to avoid the overheating of our one and only home, is for us to change how we behave.\u00a0 <\/i><\/p>\n Think about it, every time you climb into the car, every time you use energy.\u00a0 Every time you vote in an election.<\/p>\n Update: to try to add a little scale to the effects this has, I put together a post about annual ice loss and how it equates to the amount of energy our globe absorbs<\/a>.<\/p>\n Update 2: \u00a0corrected biggest source of CO2<\/p>\n Update 3 16.10.2018 – fixed broken link on New Scientist graphic<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" This post is written to describe the basic effects of greenhouse gases, and CO2 in particular, for those who are unfamiliar with how the greenhouse mechanism works.\u00a0 Apologies to any physicists who might be reading this, I\u2019m going for a … Continue reading ![\"\"](\"http:\/\/borkedcode.com\/wp\/wp-content\/uploads\/2013\/09\/dn11638-4_738.jpg\")
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