In 2007 the Intergovernmental Panel on Climate Change-representing a global consensus of hundreds of scientists-concluded that "warming of the climate system is unequivocal," citing observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level. And they noted that human activity is "very likely" the cause. Whatever your views on climate change, it's important to understand how the current scientific consensus on global warming evolved out of basic physical principles and a broad range of observations. This lucid series of twelve lectures is designed to do exactly that-reviewing the most up-to-date research and explaining the concepts, tools, data, and analysis that have led an overwhelming number of climate scientists to conclude that Earth is indeed warming and that we humans are in great part responsible. In clear and accessible lectures designed for nonscientists, you'll learn about the "fingerprints" of global climate change-ranging from borehole temperatures to melting glaciers to the altered behavior of plant and animal species and other indicators-that convince scientists that our Earth has been warming at an unprecedented rate in recent decades. The lectures address only scientific issues and make no policy recommendations. Instead, they have been designed to serve as your personal scientific briefing to equip you to engage knowledgeably in one of the most important environmental issues of our time.
Earth's Changing Climate
01: Is Earth Warming?
The course begins with a look at Earth's average temperature over the past century and a half, which shows an overall warming trend. How do scientists take Earth's temperature, and how do they interpret the pattern of variation?
02: Butterflies, Glaciers, and Hurricanes
This lecture looks at more subtle indicators of climate change and shows how statistical analysis reveals clear "fingerprints" of change on a host of natural systems.
03: Ice Ages and Beyond
Thermometer-based temperature records go back only 150 years. This lecture explores techniques that scientists use to push the global temperature record back millions, even billions of years.
04: In the Greenhouse
Stable climate entails a balance between incoming sunlight and outgoing infrared radiation. Infrared-absorbing greenhouse gases in a planet's atmosphere alter the details of this balance, causing the planet's surface to warm.
05: A Tale of Three Planets
How do we know that greenhouse gases such as water vapor and carbon dioxide are associated with the warming of Earth's surface? Nature provides a climate "experiment" on neighbor planets Venus and Mars.
06: Global Recycling
Cycling of materials plays a role in climate, with the most important cycles being those of water and carbon. Carbon added to the system stays for centuries to millennia and adds to the atmospheric carbon content, enhancing the greenhouse effect.
07: The Human Factor
Fossil fuel burning by humans has increased the concentration of carbon dioxide in the atmosphere by nearly 40 percent since the start of the Industrial Revolution—to levels the planet has not seen in at least a million years.
08: Computing the Future
Climate models are mathematical descriptions, exploring how climate behaves in response to human-induced changes and natural factors. Most models project a global temperature rise of several degrees Celsius over the next century.
09: Impacts of Climate Change
A temperature rise of only a few degrees will have significant effects. The rise will be more substantial particularly in the polar regions and over almost all land.
10: Energy and Climate
Energy use is the dominant reason for our increasing influence on Earth's climate. Per capita energy consumption in the United States is more than 100 times our own bodies' energy output, meaning that we have the equivalent of about 100 "energy servants" each.
11: Energy—Resources and Alternatives
The fossil fuels that supply most of the world's energy have many deleterious environmental impacts, one of which is the emission of climate-changing greenhouse gases. This lecture surveys alternative energy resources.
12: Sustainable Futures?
Avoiding disruptive climate change in the future probably means keeping atmospheric carbon dioxide to at most a doubling of its preindustrial level. This final lecture discusses several possible paths to a stable climate.
About
Dr. Richard Wolfson is the Benjamin F. Wissler Professor of Physics at Middlebury College, where he also teaches Climate Change in Middlebury's Environmental Studies Program. He completed his undergraduate work at MIT and Swarthmore College, graduating from Swarthmore with a double major in Physics and Philosophy. He holds a master's degree in Environmental Studies from the University of Michigan and a Ph.D. in Physics from Dartmouth.
Professor Wolfson's published work encompasses diverse fields such as medical physics, plasma physics, solar energy engineering, electronic circuit design, observational astronomy, theoretical astrophysics, nuclear issues, and climate change. His current research involves the eruptive behavior of the sun's outer atmosphere, or corona, as well as terrestrial climate change and the sun-Earth connection.
Professor Wolfson is the author of several books, including the college textbooks Physics for Scientists and Engineers, Essential University Physics,and Energy, Environment, and Climate. He is also an interpreter of science for the nonspecialist, a contributor to Scientific American, and author of the books Nuclear Choices: A Citizen's Guide to Nuclear Technology and Simply Einstein: Relativity Demystified.
