TeacherTECH - January 24, 2006
Notes to accompany the presentation. Please note that some of the information and comments within these notes are not necessarily the views of experts, but are limited to my own general observations about the subject.
Topic Summary and Key Concepts
Global warming and how it relates to life
Global climate is warming overall because of the great amount of greenhouse gases (GHGs) that people have added to the atmosphere. When people first harnessed fire and began burning carbon-based fuels like wood and oil, they must have intended to improve the quality of their lives rather than to intentionally cause harmful climate change. As this activity continues in a big way, it is now causing climate to change in undesirable ways that run counter to our intentions to make our lives better. Some GHG is normal in the atmosphere, but it is now significantly elevated by the cumulative activity of a great number of people. GHGs include carbon dioxide, methane, water vapor, nitrous oxide and chlorofluorocarbons, among other gases.
- is a warming of the Earth's surface and lower atmosphere by certain gases in the atmosphere that absorb infrared radiation and slow its escape from the Earth's surface into outer space.
Expectation - The more greenhouse gases in the atmosphere, the greater the warming.
- are gases in the atmosphere that absorb infrared radiation (heat), causing the greenhouse effect and global warming. GHGs include the following gases:
Note that most of these gases contain carbon and are organic in origin (produced by living things).
Average temperatures are expected to rise between 2-10 degrees F by the end of the next century. Although predictions cannot be tested except in hindsight, the predicted range of elevated temperature is a concern because it is enough to generate negative impacts on people and other living things. One example of a significant negative impact includes water shortages that threaten the lives of large numbers of people. As time passes, the range of predicted temperatures may change.
Knowing this, people are now trying to make plans that require some difficult decisions- 1) How much should we try to lessen these effects of global warming by minimizing future GHG emissions?, 2) If we do that, who should be allowed to use more energy and who less? - who decides? - how would a ration be enforced?, and 3) What kinds of alternative fuels should be developed? These decisions are difficult because the prosperity, stability and infrastructure of societies depends on a delicate balance between social, economic, environmental and energy considerations, and relationships between global neighbors. These things ultimately impact everyone's life at home. The particular technologies that exist at a particular time make some choices of action possible or not.
The decisions made to positively impact the lives of individuals requires some level of global agreement about what to do. Air quickly moves and mixes around the globe so its quality is set globally. Even though GHGs pose threats to the quality of people's lives around the world, lack of access to sufficient energy resources is also a threat. At current levels of energy usage, even the basic needs of many people are not being met in many places. In other places, people are concerned about meeting very human needs beyond just staying alive. Different groups of people have varying capabilities to reduce energy usage at varying rates. Discussions surrounding international agreements such as the Kyoto Protocol are just the beginning. What will we agree upon?
The primary forms of industrial energy available to humankind today come in the form of GHG-emitting carbon-based fuels which include wood, peat, oil, gas and coal. Of these, oil, natural gas and coal are fossil fuels which are nonrewable in our lifetime. Technologies to manufacture gas from agricultural products is under development. Alternative fuels that do not release GHGs and their infrastructures of distribution and utilization are not yet significant. Alternative fuels include nuclear material, solar radiation, wind, moving water, and hydrogen among others. Energy sources such as electricity that appear safe, because they do not produce GHGs directly, can consume large quantities of fossil fuels indirectly during production. Although not directly related to global warming, reduction of selected fuels has the added benefit of alleviating other problems such as smog.
Fossil fuels contain the energy in sunlight that arrived at the surface of the Earth very long ago, as long as millions of year ago. Oil, gas and coal are the preserved energy-rich organic chemical remains of what was once living matter, mostly derived from marine life. Fossil fuels occur as buried deposits. Coal occurs as a rock, and oil and gas occur as fluids that saturate porous rock and sediment.
Choices of mitigation cause hardships to individuals, groups, businesses and nations in different ways. Thus agreements about mitigation are difficult. Some consider the effects of global warming too uncertain to invest in some kinds of mitigating action. Others think that the risks are so high that they should be avoided at all costs, even if the worst-case scenario might not happen. People living today will get to decide what to do. Those living over the next century will get to live with the consequences.
What could happen as a result of rising GHG release into the atmosphere? - A chain reaction of too many things to describe, from very small to large effects. When the Earth's surface temperature warms, it in turn causes many other changes. Energy is to natural systems what money is to humans - it is the currency that fuels the capacity for things to happen. Imagine all the things that you might end up doing if a large sum of money fell into your lap? That same range of results is expected from a slug of energy delivered to the Earth's surface when GHGs increase. The change will affect weather and climate, water supplies, and living things including humans.
Some of these subsequent changes will circle back and change the amount ot GHGs in the atmosphere that triggered change in the first place, forming a complex circle of feedback between cause and effect. Consider the effect of a warmer climate on polar ice. Increasing warmth will melt polar ice and reduce the area of ice, making the ground less reflective to sunlight and leading to even greater warming. This is like adding insult to injury, or presented in a more positive light, like thinking that with money, you can make even more. This kind of impact, one that amplifies climate change in the same direction as the initial disturbance is called a positive feedback.
On the other hand, a warmer climate may lead to increased glacial meltwater in the Arctic, preventing the ocean from delivering energy to the North Atlantic as it normally does, causing cooling in the region (an effect exaggerated in the movie "The Day After Tomorrow.") This kind of impact, one that causes climate to change in the opposite direction is called a negative feedback. It is like going one step back for every two steps forward. Negative feedbacks help to offset our GHG emissions.
An accurate summation of all that will happen is important in achieving the greatest degree of climate regulation with the least investment of effort and disruption. We need to know the bottom line net effect after all positive and negative impacts are added up.
Our decisions and actions now, can make a positive difference in the future, even though it will be hard to achieve. Even if we don't understand all of the complex interactions that result in overall climate, they can affect us. In our example, whether the North Alantic will actually warm, cool or stay the same is very important to people in Europe. Cooling, warming and staying the same are mutually exclusive, so even though each forecast may sound good in principle, only one scenario will be accurate. Identifying the accurate scenario is important so that we can be on the right track to finding a solution to a real problem. It is a little bit like someone saving your life, it's not just the thought that counts but the capability and action to make it so. Results count. In the absence of enough knowledge to make an accurate prediction, what's the best course of action? It depends on the degree of risk people want to take.
Scientists provide expertise about the details of how things work. Everyone needs to know enough about these subjects to make good decisions about how to use scientific knowledge to their benefit, and to check up on the general thinking of scientists. How do we tackle problems that require long term action beyond a single person's lifetime, particularly for those problems that seem less pressing early on and easily put on the back burner. Those problems may be easy to solve early on, but very difficult to deal with later.
What do scientists contribute? Scientists do the critical work of:
Individuals have great access to understand and participate in solving challenges posed by global change. It is an exciting time to be living in a world where the average person can access the same materials available to scientists, and discuss and participate in matters related to global climate. The internet allows unprecedented communication opportunities and access to information. Accessible information includes not just everyone's opinions, but direct access to the body of work produced by scientists, and governmental, and nongovernmental agencies around the world. That body of work and data can be used for your own purposes. Access to information illuminates the concerns and conditions of people everywhere.
©2006 by Earthguide at Scripps Institution of Oceanography.