Forgot Password?
Written by William Klein   
Share |
Monday, 30 January 2012

Greenhouse Gases

So what are these greenhouse gases we hear about all the time anyway? Lost? I was too! So I set out to look up and understand the basics behind greenhouse gases, and I have shared my recent pursuits with you in this article! It turns out that GHGs (this will be our shorthand for greenhouse gas emissions from here on out) are primarily a story of light energy and scale.

Incoming Solar Radiation 1

If you’re interested, first brush up by revisiting the classic wavelength chart:
  • Ultraviolet (UV) light is what we know as visible light, and is our biggest enemy when it comes to skin cancer. It also is quite necessary for our basic health and well-being, providing lots of vitamin D to keep our positive energy flowing!
  • Infrared (IR) light refers to a longer wavelength on the spectrum, and is responsible for heat radiation. While we and many other animals see only in UV light, some animals such as snakes have adapted to see in IR light.2
Now let’s talk about how light behaves. Light can be absorbed, transmitted, or reflected. In the context of our atmosphere, light has decision points. Within the atmosphere itself, some of the light waves are absorbed by the chemistry of the Earth’s atmosphere, other waves are transmitted through the atmosphere to the Earth’s surface, while other waves are reflected back into space. Temperature drives the specific radiation wavelengths released from an object. The sun releases primarily UV radiation because of its intense temperature, while the Earth releases primarily IR radiation. This difference in wavelength drives the greenhouse effect. It turns out that certain IR wavelengths are just the right length to be absorbed by molecules in our atmosphere, which can then absorb them, increasing its temperature, and then re-radiating them back to the Earth.3

In essence, the amount of energy we receive from the sun is dependent on 3 factors:
  1. Solar energy influx, which is the total amount of energy from the sun that hits the Earth.
  2. Chemistry of the atmosphere—as in, some molecules trap heat better than others, this is quantified as “global warming potentials .” For example, methane is 20 times more powerful than carbon dioxide (CO2).4
  3. Albedo, which is reflected light, mainly off of ice. As a side note, this factor is extremely important and currently sea ice is melting at rapid rates… what will we do as our reflective mechanism dwindles down?
The Three Factors 5

The next step in understanding GHGs involves being mindful of concentrations. You know the old saying, you can have too much of a good thing? Or remember when you ate all your Halloween candy only to regret it the next morning? Well, that’s what’s going on with our GHG emissions. In moderation, they are great, as without them, the earth would be around 0°F.6 However, ever since we made the big leap from whale fat as heating oil to extracting dead plants from the ground to power engines, we have been drastically increasing the levels of GHGs in the atmosphere. And before we know it, we may find ourselves regretting it tomorrow morning.

Science of Greenhouse Gases
GHGs are basically gases in the atmospheres that love doing the shimmy—they absorb infrared radiation which causes them to vibrate. Ultraviolet (UV) radiation, on the other hand, breaks bonds in molecules, severely impacting their ability to do a little dance!7 Water vapor is actually the most abundant GHG8, followed by CO2 (carbon dioxide), N2O (nitrous oxide), CH4 (methane), and other synthetic gases such as CFCs (chlorofluourocarbons), HFCs (hydrofluorocarbons), and PFCs (perfleurocarbons). Do you notice a pattern? All of them are composed of more than one type of atom. Because GHGs have more than 2 atoms (and have different atoms), their vibrations cause a change in their “dipole moment”—essentially they become imbalanced in terms of electrical charges, allowing them to absorb the infrared (IR) radiation.9 This radiation is then released back towards Earth, as opposed to outer space, and we can feel the effects of the heat released.

Our atmosphere is primarily composed of symmetrical paired molecules—Nitrogen (N2) and Oxygen (O2).10 These guys are boring, and can’t do any dancing when IR radiation hits, rendering them useless as far as trapping heat. You often hear people argue that GHGs can’t possible matter that much because they make up just a fraction of the air we breathe. Well, what happens if you just slightly move the tip of an airplane’s wing? It takes a sharp turn.

So, this scientific information is great and all, but why do we care? What does this mean?

Temperature & CO2 Concentration11

Let’s start with a historical perspective on GHGs…
As we can see, GHGs have historically fluctuated, with a corresponding change in global temperature. This is another time when our sense of scale becomes really important. If you look closely at the above graph, it is presented on a 400,000 year timeline that is nearly 40 times longer than modern human history.

Northern Hemisphere 12

This is the famous “hockey stick” model, in which you can clearly see an incrediblely fast increase in global temperatures over the last 100 years, a far shorter timeline than the 400,000 year timeline seen above. Drastic temperature changes disrupt systems. And that is why we care so much, because the changes are so fast and the effects are so unpredictable. The above graph shows just temperature, but we also have strong data from a UCSD research station documenting the rises in CO2 concentrations over the last 40 years. This study, which is well known through the below graph as the Keeling Curve, provides indisputable evidence of rises in CO2 concentrations in the atmosphere. If you look at the graph, you will notice that the latest figures for 2010 are around 380 parts per million, which is the same number as reported in the news media. This study site is one of the primary sources for global CO2 concentrations, and shows that we are well above the 350 ppm that James Hanson and other leading scientists believe is the “magic number.”13

Mauna Loa Record
The Keeling Curve14

The Keeling Curve is incredible documentation because it collects data from high in the sky above Hawaii. Studies have shown that CO2 concentrations at that height in the atmosphere are fairly uniform worldwide, allowing for documentation of global trends.
Pop Quiz: Why does the Keeling Curve fluctuate?
Answer: The fluctuations are seasonal—they correlate with plant growth. Because plants absorb CO2, the global concentrations decrease in the summer, and increase in the winter when plants die-off. Plants are predominantly concentrated in the northern hemisphere.This brings us to the next point…

Where do GHGs Come From?
Greenhouse gases are naturally occurring—they come from breathing animals (this includes us humans), the flatulence (farts) of cows, fermentation of wetlands, and many other carbon sources. We have also created “synthetic sources” such as fluorocarbons, which are used in refrigeration technologies, along with scores of other chemical applications over the last 100 years. The recent uptick in global emissions is the result of humans extracting stored sources of carbon and burning these sources, which releases CO2. Here the issue of scale arises again. We have an ecological system that has systematically balanced itself for billions of years—it has carbon sinks, i.e. forests/plants, to absorb CO2 , and it has carbon sources to release CO2, i.e. animals. It’s a bit more complex, but that’s the basic picture. When this balance is drastically thrown off because we are extracting millions and millions of years worth of accumulated carbon and spewing it out of our planes, trains, and automobiles—along with other gas-guzzling toys—there simply isn’t a place for it to go. So, we see an increase in the atmospheric concentrations of GHGs, which then leads to an increase in the global temperatures. The fun really begins when we start seeing the effects of the rising temperatures —oceans become warmer and take up more space (sea level rise), ice caps melt leading to a reduced albedo effect, and many other environmental disasters.

The national debate gets mixed up around this point. The increase in GHGs is real and documented. The increase in global temperature is real and documented.15 There is an established scientific link between these two trends. What we don’t know are the potential long-term effects. Will we see a great increase in vegetation to absorb the CO2? Will we be able to grow more crops in once cold places? Will we all be flooded away or destroyed by violent storms? No one knows, but there are plenty of good ideas out there. How do we best spend our resources when there are so many other problems facing the world such as poverty, hunger, disease, war, etc.? This is the discussion we need to be having, not a petty debate over established scientific facts.

Browse all Greeniacs Articles Browse all Greeniacs Guides        Browse all Greeniacs Articles


Add your comment
RSS comments

Only registered users can write comments.
Please login or register.

Click here to Register.  Click here to login.

Last Updated ( Wednesday, 01 February 2012 )


Green Facts

  • Recycling for one year at Stanford University saved the equivalent of 33,913 trees and the need for 636 tons of iron ore, coal, and limestone.

  • Washing your clothes in cold or warm instead of hot water saves 500 pounds of carbon dioxide a year, and drying your clothes on a clothesline six months out of the year would save another 700 pounds.

  • Current sea ice levels are at least 47% lower than they were in 1979.

  • Less than 1% of electricity in the United States is generated from solar power.

  • Recycling 100 million cell phones can save enough energy to power 18,500 homes in the U.S. for a year.

  • The World Health Organization estimates that 2 million people die prematurely worldwide every year due to air pollution.

  • A single quart of motor oil, if disposed of improperly, can contaminate up to 2,000,000 gallons of fresh water.

  • A laptop consumes five times less electricity than a desktop computer.

  • Americans throw away more than 120 million cell phones each year, which contribute 60,000 tons of waste to landfills annually.

  • Plastic bags and other plastic garbage thrown into the ocean kill as many as 1,000,000 sea creatures every year.

  • One recycled aluminum can will save enough energy to run a 100-watt bulb for 20 hours, a computer for 3 hours, or a TV for 2 hours.

  • Shaving 10 miles off of your weekly driving pattern can eliminate about 500 pounds of carbon dioxide emissions a year.

  • 82 percent of greenhouse gas emissions in the U.S. come from burning fossil fuels.

  • An aluminum can that is thrown away instead of recycled will still be a can 500 years from now!

  • Americans use 100 million tin and steel cans every day.

  • For every 38,000 bills consumers pay online instead of by mail, 5,058 pounds of greenhouse gases are avoided and two tons of trees are preserved.

  • 77% of people who commute to work by car drive alone.

  • Recycling 1 million laptop computers can save the amount of energy used by 3,657 homes in the U.S. over the course of a year.

  • Americans throw away enough aluminum to rebuild our entire commercial fleet of airplanes every 3 months

  • You’ll save two pounds of carbon for every 20 glass bottles that you recycle.

  • States with bottle deposit laws have 35-40% less litter by volume.

  • Bamboo absorbs 35% more carbon dioxide than equivalent stands of trees.

  • Every week about 20 species of plants and animals become extinct.

  • You will save 100 pounds of carbon for each incandescent bulb that you replace with a compact fluorescent bulb (CFL), over the life of the bulb.

  • You will save 300 pounds of carbon dioxide for every 10,000 miles you drive if you always keep your car’s tires fully inflated.

  • Refrigerators built in 1975 used 4 times more energy than current models.

  • Glass can be recycled over and over again without ever wearing down.

  • A tree that provides a home with shade from the sun can reduce the energy required to run the air conditioner and save an additional 200 to 2,000 pounds of carbon over its lifetime.

  • American workers spend an average of 47 hours per year commuting through rush hour traffic. This adds up to 23 billion gallons of gas wasted in traffic each year.

  • Nudge your thermostat up two degrees in the summer and down two degrees in the winter to prevent 2,000 pounds of carbon dioxide from entering the atmosphere.

  • In the United States, automobiles produce over 20 percent of total carbon emissions. Walk or bike and you'll save one pound of carbon for every mile you travel.

  • Turning off the tap when brushing your teeth can save as much as 10 gallons a day per person.

  • It takes 6,000,000 trees to make 1 year's worth of tissues for the world.

  • Rainforests are being cut down at the rate of 100 acres per minute.

  • Due to tiger poaching, habitat destruction, and other human-tiger conflicts, tigers now number around 3,200—a decrease in population by about 70% from 100 years ago.

  • Recycling aluminum saves 95% of the energy used to make the material from scratch.

  • A steel mill using recycled scrap reduces related water pollution, air pollution, and mining wastes by about 70%.

  • In California homes, about 10% of energy usage is related to TVs, DVRs, cable and satellite boxes, and DVD players.

  • If every U.S. household turned the thermostat down by 10 degrees for seven hours each night during the cold months, and seven hours each weekday, it would prevent nearly gas emissions.