Sci207 - Greenhouse Gases

Lab: Greenhouse gases

PURPOSE

Overview

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.

Scenario

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.

OBJECTIVES

* 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