So, sunlight in the visible spectrum (and IR) hits the earth.\u00a0 Some of that visible light energy is reduced in wavelength to infrared energy and radiated away from the Earth’s surface.\u00a0 Carbon dioxide in the atmosphere absorbs some of that energy and starts vibrating.\u00a0 In turn, that energetic carbon dioxide molecules hits other molecules (nitrogen, for example) and transfers some of that energy to the other molecule.<\/p>\n
What is ‘temperature’?\u00a0 In the most basic form, temperature is the measure of the kinetic energy of a group of molecules.\u00a0 It’s like a big microwave oven, except instead of microwaves, the energy comes from infrared.\u00a0 That’s how carbon dioxide (and other gases like methane and water) act as a ‘greenhouse’ and trap heat energy on the Earth.<\/p>\n
Anyone who disagrees with this simple fact has some major problems.\u00a0 They are basically disagreeing with all of established chemistry and physics and should not be taken seriously.<\/p>\n
Second, this brings up a fairly common complaint from global warming deniers.\u00a0 The complaint is (and I may not have it exactly right), “the amount of carbon dioxide added by man can only account for 5% of the temperature of the Earth”.<\/p>\n
That’s an interesting statement because it’s true.\u00a0 If there were no carbon dioxide or other greenhouse gases in the atmosphere, the average temperature of the Earth would be very, very cold.\u00a0 The 20th century average global temperature was approximately 15.5\u00b0C (59.9\u00b0F)<\/a>.\u00a0 If there were no greenhouse gases, then the average temperature of the Earth would be close to zero degree Fahrenheit<\/a>.<\/p>\n So, the Earth is livable because of carbon dioxide (and other greenhouse gases) in the atmosphere.\u00a0 But let’s look at what people are actually doing…<\/p>\n So, yes, the Earth goes through massive changes in the CO2 levels.\u00a0 Compare that chart of the last 400,000 years to this chart of the last 50.<\/p>\n In the last 50 years, the CO2 level in the atmosphere has gone from near the maximum reached four times in the 400,000 years (310ppm) to well over 380 ppm.<\/p>\n Now, we know that carbon dioxide increases the temperature of the planet.\u00a0 No doubts about that.\u00a0 We also see, that the average amount of CO2 in the atmosphere is nearly 25% higher than at any point in the last 400,000 years.\u00a0 Where is all that extra carbon dioxide coming from?<\/p>\n Well… it’s coming from us.\u00a0 This isn’t speculation or even a guess based on the number of cars on the road.\u00a0 It’s a very detailed scientific explanation<\/a>.<\/p>\n To understand why, we need to look at the carbon cycle.<\/p>\n The numbers indicate the amount of carbon either stored in a system (reservoir) or flowing between two systems (i.e. burning of fossil fuels).\u00a0 The numbers are in Gigatons of carbon per year… yes…\u00a0billions of tons<\/strong> of carbon\u00a0per year<\/strong>.<\/p>\n If you look closely, you’ll see that most of the flows between the atmosphere and ground\/water\/etc are fairly close to the same value. For example, respiration (organisms breathing out carbon dioxide) results in 119.6 gigatons of carbon going into the atmosphere every year.\u00a0 But gross primary productivity (i.e. photosynthesis) takes about 120 gigatons of carbon out of the atmosphere each year.<\/p>\n The entire system is delicately balanced… except for that one value over on the right.\u00a0 Fossil fuels don’t have any system in place for taking carbon out of the atmosphere.<\/p>\n We all know that carbon in fossil fuels comes from deep under the ground.\u00a0 Oil, coal, and natural gas formed tens to hundreds of millions of years ago from peat bogs, forests, and swamps.\u00a0 That carbon was removed from the Earth’s carbon cycle millions of years ago.\u00a0 It was buried deep.<\/p>\n And humans, for the last 100 years, have been sucking up all that carbon and converting it into atmospheric carbon dioxide.\u00a0 In just 10 years, we have burned enough fossil fuels to be responsible for\u00a0 full 10% of the entire atmospheric reservoir.<\/p>\n Here’s some slightly more detailed data<\/p>\n![\"File:Carbon](\"http:\/\/upload.wikimedia.org\/wikipedia\/commons\/1\/1c\/Carbon_Dioxide_400kyr.png\")
<\/a>![\"File:Mauna](\"http:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/51\/Mauna_Loa_Carbon_Dioxide-en.svg\/800px-Mauna_Loa_Carbon_Dioxide-en.svg.png\")
<\/a>![\"Anthropogenic](\"http:\/\/www.gfdl.noaa.gov\/pix\/research\/climate_ecosystems\/AnthropogenicCarbonCycleBox2.png\")
![\"http:\/\/www1.ncdc.noaa.gov\/pub\/data\/cmb\/images\/indicators\/global-temp-and-co2-1880-2009.gif\"](\"http:\/\/www1.ncdc.noaa.gov\/pub\/data\/cmb\/images\/indicators\/global-temp-and-co2-1880-2009.gif\")
<\/p>\n