SCI207 GREENHOUSES LAB WEEK 4
In Chapter 7, we learned how the build-up of heat-trapping pollution caused by human activities is destabilizing Earth’s climate. This phenomenon – referred to interchangeably as “global warming” and “climate change” – has more recently been called “climate disruption” and even (by sustainable business guru, Hunter Lovins) “global weirding”. Primary human causes of heat-trapping or “greenhouse gas” pollution include the burning of fossil fuels (e.g., coal, oil, natural gas), detailed in Chapter 6. They also include land use changes such as the conversion of forest ecosystems to industrial agriculture, as detailed in chapters 3 and 4.
In this lab you will use a computer model to explore how human activities are creating a blanket of heat-trapping pollution in Earth’s atmosphere. The model illustrates sources of top heat-trapping pollutants and their general impacts on Earth’s temperature. In the lab questions, you will reflect upon how destabilizing Earth’s climate not only impacts ecosystems and biodiversity, but also critical elements of human well-being such as fresh water supplies and agricultural production.
Earth’s climate is becoming increasingly unstable, resulting in more frequent and intense storms (hurricanes and tornados alike), droughts that fuel catastrophic wildfires, deplete water supplies and devastate agriculture, and wars over increasingly scarce natural resources. Still, given that greenhouse gases are invisible and that the slow-moving nature of climate change makes the problem difficult for people to “see”, many people remain unconvinced that global warming is an urgent issue.
As an environmental scientist in training, you know why and how this situation needs to change. You attend a workshop of the National Academy of Sciences – the All-Star Team of U.S. Scientists. This organization recently joined with the National Academies of 12 other leading industrial nations to call on world leaders to take bold action to solve climate change. You are part of a new generation of environmental scientists learning to understand and effectively communicate the seriousness of climate change.
Your training includes use of the latest technologies for “seeing” how heat-trapping pollution is affecting Earth’s climate. The first technology you use is a computer model that allows you to see how a “blanket” of heat-trapping pollution has built up in our atmosphere since 1750 and is now affecting Earth’s temperature.
The second technology you use is a new space electron microscope that allows people to visualize the action of three heat-trapping molecules. These include:
1. Carbon Dioxide (CO2) is by far the most abundant anthropogenic (caused by humans) heat-trapping pollutant – about 220 times more abundant than methane in the atmosphere, according to the U.S. EPA. However, on a per-molecule basis, it is not as powerful of a heat trapper as methane or nitrous oxide. Its chief sources are the burning of fossil fuels (particularly coal and oil) and deforestation.
2. Methane (CH4 ) is about 21 times more powerful a heat trapping gas than CO2, but has a relatively short lifetime in the atmosphere. Its main sources are landfills and livestock. Melting of permafrost and warming of deep-sea methane hydrates may be leading to positive feedbacks that are increasing methane (as well as CO2) emissions, further increasing temperatures.
3. Nitrous Oxide (N2O): Due to its long atmospheric lifetime, N2O is 310 times more powerful a heat-trapping gas than CO2 on a per-molecule basis. Its main sources are agriculture, sewage and fossil fuels.
• To learn how to visualize, understand and effectively communicate the basic environmental science underlying climate change.
• To learn how to identify science-based solutions to climate change and consider how they will benefit ecosystems, biodiversity and human well-being.
Review the following material from your readings:
• Chapter 7 - Climate change
• Chapter 6 - Fossil fuel pollution
• Chapter 4 - The contribution of land use change to climate change
o Climate change fact sheet
o Article about effectively communicating climate change. More resources here.
o The problem with “global warming”
View the following computer model simulation that illustrates how human activities are causing the build-up of a blanket of heat-trapping pollution in Earth’s atmosphere. Follow the steps below to achieve your objectives.
First, view the effects of heat-trapping pollution on Earth’s temperature in 1750, the current year, and 2050. Your goal is to help decision-makers see how as the blanket of pollution becomes thicker, more heat is trapped, which causes the average global temperature to rise. In the simulation yellow photons (sunlight) are entering the atmosphere. Red photons (heat) are being released from the Earth’s surface. Some red photons escape Earth’s atmosphere, but others are trapped by the blanket of greenhouse gases.
Complete the following steps:
1. Look for sources of greenhouse gases shown in the simulation in 1750. Then look for sources visible in the present and in 2050, noting how they change and what happens to the thickness of the blanket of heat-trapping gases.
2. Note the impacts of heat-trapping pollution on Earth’s temperature in each year. Note how many red photons are visible on the screen, the speed of temperature increase, and the final temperature.
Click on the microscope icon (on the right), which allows you to “zoom into” the blanket and view the action of the top three heat-trapping pollutants. Complete the following steps:
1. Select CO2. Observe how it responds to the sun’s heat (red photons). What percent of red photons is it affected by (does it trap)? Repeat this exercise for CH4 and N2O.
2. Note of which molecules seem to be most and least frequently affected by infrared photons. The more powerful a greenhouse gas is, the more frequently it is affected.
Once you have completed the above steps, use your findings and the course’s readings to complete the lab questions below.
1. Identify natural and human-made causes of climate change visible in the computer simulation. According to the computer model, how have sources of heat-trapping pollution changed from 1750 to today? How does the simulation predict they will change by 2050?
2. According to the computer model and your readings, which source(s) of heat-trapping pollution contribute the most to climate change? Explain.
3. Recalling your observations from the three time periods, how has the thickening blanket of heat-trapping pollution affected Earth’s temperature between 1750 and today? How will the blanket and Earth’s temperature look in 2050? Does the simulation predict that positive feedbacks will kick in by 2050 (e.g., does the temperature increase appear to be accelerating)? According to your readings, what might explain positive feedbacks?
4. Briefly describe three impacts of climate change on ecosystems and biodiversity. Cite examples from course readings.
5. Briefly describe three impacts of climate change on people – e.g., economic, health, safety, national security. Cite examples from course readings.