Initial Publication Date: January 3, 2016

Living in a Carbon World

Part D: Fossil Fuels, Hydrocarbons and CO2

On April 20, 2010, the Deepwater Horizon oil rig operating in the Gulf of Mexico exploded and sank. Oil and gas moved up the drilling well-bore onto the deck causing a massive fire. The explosion killed 11 platform workers and badly injured 17 others. Following the explosion and sinking of the rig, oil gushed up from the sea floor unabated for 87 days. An estimated 4.9 million barrels of crude oil spilled into the Gulf of Mexico waters inundating the coastlines of Louisiana, Mississippi and Alabama, and damaging coastal ecosystems and fishing industries.

The oil and gas extracted by the DeepWater Horizon rig had been formed and buried in deep sediments millions of years ago. While coal had been used as a fuel resource since 1000 B.C, it wasn't until the arrival of the Industrial Revolution that coal began to replace wood biomass as the primary source of energy. Today, humans are extracting the three primary fossil fuels - coal, oil, and natural gas - to provide energy for a world population that has exceeded 7 billion. Fossil fuels are made of hydrocarbons energy rich organic carbon compounds made of carbon and hydrogen atoms. . In this section of Lab 1, you will investigate how the combustion of fossil fuel hydrocarbons is changing the chemistry of the atmosphere.


Examine the image above of the Deep Horizon oil rig burning in the Gulf of Mexico. With a partner and/or class, talk about the following:

  • What do you already know about fossil fuels?
  • How do you think the carbon cycle is related to this image? Share all ideas.

Burning hydrocarbons releases energy, and CO2 as a by-product

The Deep Horizon rig was drilling for crude oil (petroleum) deep within bottom sediments in the Gulf of Mexico. Crude oil is a mixture of several different chemicals which can be refined into hydrocarbon products such as such as motor oil, gasoline, jet fuel, diesel fuel, and heating oil. If you drive a car, heat your home, turn on a light, or enjoy a good backyard barbecue, the energy you are using most likely comes from burning fossil fuel hydrocarbons, a process called combustion the process of burning something; example is when a substance such as wood, coal, or gas reacts with oxygen to produce carbon dioxide, water vapor, heat, and energy .

To learn some important facts about combustion and hydrocarbons, watch this 7-minute video on combustion. Before you watch the video, make note of the Checking In questions below. You will need to answer these questions when you finish watching the video.

NOTE: If this video does not play, you can also watch it at one of these three sites: YouTube , on Vimeo or at the It's Our Air website.

Hydrocarbon molecules have energy-rich bonds

Consider the combustion reaction of methane below. Combustion produces energy but where does this energy come from?

Methane (CH4) + 2O2 > CO2 + 2H2O (water vapor) + heat energy

Energy is stored in the chemical bonds that hold the carbon and hydrogen atoms together. When the atoms are rearranged in the combustion reaction, bonds are broken and new bonds formed, releasing energy. The chemical energy stored in these bonds originated from solar energy used by plants to power photosynthesis. During photosynthesis, plants transform solar energy to biochemical energy which becomes stored in the bonds of glucose molecules and other carbon compounds made by plants.

Checking In

  1. When a fuel such as coal, oil or gas are burned, what two products are created? Choose all that apply.
  2. Fossil fuels, such as gas, oil and coal, are made of_______atom(s)? Choose all that apply.
  3. When a fossil fuel is burned, where does the carbon dioxide gas immediately go? Choose all that apply.
  4. Which of the following balanced chemical reactions correctly represents the combustion of methane? 

Fossil fuels are made of hydrocarbons produced millions of years ago

We use fossil fuels on a daily basis but do we know their origins? Contrary to what many people believe, fossil fuels do not come from the remains of dead dinosaurs. In fact, fossil fuels were formed 300 million years ago during the Carboniferous period, before the first dinosaurs evolved. Take a view minutes to examine the image pictured on the right and then watch the video on fossil fuel formation below.

If the video does not play, watch here: Fossil Fuel Formation

Checking In

  1.   Read the statements below about fossil fuel formation. Check all those statements that are true.

Humans are extracting and using large amounts of fossil fuel, but how much?

Click here:How much fossil fuel has been used in your lifetime? to enter an interactive created by The Guardian. Click through the interactive until you find out how many barrels of oil, tonnes of coal and cubic meters of gas have been extracted since you were born.


With a peer or with a group, discuss the following:

  • How many barrels of oil, tonnes of coal and cubic meters of gas have been extracted since you were born? What surprises you, if anything?
  • Which of your daily activities connect you to these amounts of fossil fuels that have been extracted and burned since you were born?

Are humans changing the chemistry of the atmosphere? How do we know?

Humans have been burning large amounts of fossil fuel hydrocarbons for energy since the Industrial Revolution. Today, approximately 75% of the world's energy needs are fulfilled by burning fossil fuels. We certainly can't get along without fossil fuels at the present, but are we creating a problem when we burn millions of metric tonnes of fossil fuels every year? 

Watch this NASA video to find out if we are creating a "Gas Problem" when we burn fossil fuels.

If this video does not play, click here NASA's Earth Minute: Gas Problem - YouTube

Laboratory Investigation: Are humans changing the chemistry of the atmosphere?

The video you just watched makes the claim that when humans burn fossil fuels, we release CO2 to the atmosphere causing the atmosphere to become warmer. However, the video provides no data as evidence to support this claim. As a matter of fact, some people on the Internet have claimed that humans have no role in rising CO2and instead blame the rise on natural events such as volcanic outgassing. Providing evidence for a claim is a critical component of science. To that end, you will analyze data from a series of graphs, a NASA animation of CO2 emissions and a video presentation given by geoscientist Dr. Richard Alley. As you analyze the data, you will decide whether the data provides evidence that strongly supports, partially supports, or strongly refutes the claim that humans are changing the carbon chemistry of the atmosphere and that this change is leading to a warmer atmosphere. With a peer or small group:

  1. Create a 5-column table with the following headings:
  • Column A: Title of graph(s) and video
  • Column B: Type of evidence (ex. CO2 data, carbon isotope data, etc. )
  • Column C: Evidence strongly supports the claim.
  • Column D. Evidence only partially supports the claim (i.e., the evidence is incomplete).
  • Column E. Evidence strongly refutes the claim. NOTE: in Columns C-E, make sure you describe the evidence and explain why the evidence strongly supports, partially supports or strongly refutes the claim.


With your class, discuss the evidence you have just analyzed in terms of the following:

  • What evidence, if any, strongly supports the claim that humans are changing the chemistry of the atmosphere? Why?
  • What evidence, if any, strongly refutes the claim that humans are changing the chemistry of the atmosphere? Why?
  • What evidence, if any, partially supports the claim that humans are changing the chemistry of the atmosphere? Why?

Stop and Think

6. Describe how combustion can move carbon atoms from being stored deep in the ground to the atmosphere.
7. Identify and explain at least one piece of evidence supporting or refuting the claim that humans are changing the carbon chemistry of the atmosphere.

Optional Extensions

Want to learn more about fossil fuels and hydrocarbons? Check out these resources!