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Earth's Changing Climate

Earth's Changing Climate

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Earth's Changing Climate

Course No. 1219
Professor Richard Wolfson, Ph.D.
Middlebury College
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4.3 out of 5
79 Reviews
73% of reviewers would recommend this series
Course No. 1219
  • Audio or Video?
  • You should buy audio if you would enjoy the convenience of experiencing this course while driving, exercising, etc. While the video does contain visual elements, the professor presents the material in an engaging and clear manner, so the visuals are not necessary to understand the concepts. Additionally, the audio audience may refer to the accompanying course guidebook for names, works, and examples that are cited throughout the course.
  • You should buy video if you prefer learning visually and wish to take advantage of the visual elements featured in this course. The video version is not heavily illustrated, featuring around 100 graphs, diagrams and images. Diagrams featured in this course include those that easily explain fundamental geological processes including the carbon cycle and the greenhouse effect. Graphs include those that explain the average rise in global temperature throughout history and predict future trends. And images help you connect with the numerous aspects of our planet's climate, including hurricanes, volcanoes, and ice ages.
Audio Streaming Included Free

Course Overview

In 2007 the Intergovernmental Panel on Climate Change concluded that "warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level." Representing a consensus of hundreds of scientists, the report went on to note that human activity is "very likely" the cause.

This course of 12 half-hour lectures reviews the most up-to-date research on climate change, explaining the concepts, tools, data, and analysis that have led an overwhelming number of climate scientists to conclude that Earth is warming and that we humans are in great part responsible.

Behind the Consensus

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. In a lucid presentation designed for nonscientists, you will learn about:

  • The difference between climate and weather
  • The concept of energy balance, which governs the natural warming of the planet by the Sun and is the key to a stable climate
  • The greenhouse effect, which makes Earth warmer and more hospitable than it would otherwise be due to naturally occurring gases in the atmosphere, such as carbon dioxide and water vapor
  • The carbon cycle, which controls the rate at which carbon dioxide released by fossil-fuel combustion accumulates in the atmosphere, and how long it remains to enhance the natural greenhouse effect.

Along with these and other concepts, you will investigate the "fingerprints" of global climate change, ranging from borehole temperatures to melting glaciers to the altered behavior of plant and animal species. These and other indicators show that Earth has been warming at an unprecedented rate in recent decades.

You will also explore the physical mechanisms behind these changes and their connections to the increasing concentration of greenhouse gases in the atmosphere since the start of the Industrial Revolution. And you will look at the techniques for projecting future climates, along with the options for switching to alternative energy technologies to avoid the most disruptive scenarios that now seem possible.

Your Personal Scientific Briefing

Earth's Changing Climate addresses only scientific issues and makes no policy recommendations. Instead, this course is 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. In Lectures 1–6 you will focus on the scientific basis of climate; then in Lectures 7–12 you will come to understand the human role in climate change and explore projections of future climate.

Professor Richard Wolfson is no stranger to this subject. A physicist who has written and taught extensively about climate change, in 1996 he taped an earlier course for The Teaching Company titled, Energy and Climate: Science for Citizens in the Age of Global Warming. Professor Wolfson's new course is completely updated and represents the latest research and analysis in this fast-changing field.

A master at making difficult concepts understandable, Dr. Wolfson's other Teaching Company courses are Physics in Your Life, hailed by Library Journal as "a wonderful series of lectures that make learning physics fun and interesting," and Einstein's Relativity and the Quantum Revolution, which one listener said was "as exciting as a suspense thriller!"

In Earth's Changing Climate, Dr. Wolfson brings these educational gifts to bear on a subject that, at times, can be complex and controversial. You will find his presentation clear, objective, engaging, and illustrated with fascinating examples and analogies.

The Evidence Mounts

Like many scientific problems, the gradual assembly of a detailed picture of past, present, and future climates has involved creative detective work. For example, scientists traditionally test their theories by changing different variables, but this has not been possible with theories about climate change on Earth for two reasons: It's unwise to transform the planet just to see what will happen, and there are not multiple Earths to serve as test subjects.

However, researchers have identified cases where nature has done the experiments for us:

  • Mars: Mars's atmosphere has only about 1 percent the density of Earth's and provides a test for the theory of the greenhouse effect—in this case, for a planet with a thin atmosphere. As theory predicts, Mars has negligible greenhouse warming.
  • Venus: Venus's atmosphere has 100 times the density of Earth's and is about 96 percent carbon dioxide. Here, the greenhouse effect has struck with a vengeance—just as theory forecasts—driving temperatures to 500°C, hot enough to melt lead.
  • Mt. Pinatubo: The eruption of the volcano Mt. Pinatubo in 1991 poured massive amounts of dust into the upper atmosphere and allowed scientists to test their climate models. The fall in average global temperature over the following few years was in close agreement with what the models predicted.
  • Ice Cores: Deep ice cores from Greenland and Antarctica preserve a nearly million-year-old record of Earth's past temperature and atmospheric composition, showing a correlation between temperature and carbon dioxide concentration.

Using such clues, scientists are able to connect the 0.65°C rise in average global temperature since the start of the 20th century with the increase in atmospheric carbon dioxide over the same period. Looking ahead, they project a global temperature rise in the range of 1.5°C to 4.5°C during the 21st century, depending on the extent of worldwide economic growth and the rate of fossil fuel consumption.

An increase of a few degrees may not seem serious, but Professor Wolfson stresses that this is a global average. The rise will be more substantial in certain areas—particularly in the polar regions and over almost all land. He further notes that about 6°C separates the present-day climate from the depths of an ice age. Thus, an increase of a few degrees in global temperature is climatologically significant and may lead to many more extreme events, such as heat waves, intense precipitation, droughts, and intense tropical storms. At the same time, the sea level will be rising due to the thermal expansion of the oceans and the melting of land-based glaciers and ice sheets.

Over the longer term, a cause for worry is "surprise" events that could be initiated by as-yet poorly understood processes. These include the sudden slipping of a large land-based ice sheet into the sea with a resulting surge in sea level, or a major upset in patterns of ocean circulation.

As the evidence mounts, scientists will continue to refine their picture of what the climate is doing and where it is heading, and society will continue to grapple with this problem. You can begin to address it yourself—intelligently and prudently—by investing six stimulating and rewarding hours with this course.

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12 lectures
 |  30 minutes each
  • 1
    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? x
  • 2
    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. x
  • 3
    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. x
  • 4
    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. x
  • 5
    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. x
  • 6
    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. x
  • 7
    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. x
  • 8
    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. x
  • 9
    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. x
  • 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. x
  • 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. x
  • 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. x

Lecture Titles

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  • Downloadable PDF of the course guidebook
  • FREE audio streaming of the course from our website and mobile apps
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DVD Includes:
  • 12 lectures on 2 DVDs
  • 88-page printed course guidebook
  • Downloadable PDF of the course guidebook
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CD Includes:
  • 12 lectures on 6 CDs
  • 88-page printed course guidebook
  • Downloadable PDF of the course guidebook
  • FREE audio streaming of the course from our website and mobile apps

What Does The Course Guidebook Include?

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Course Guidebook Details:
  • 88-page printed course guidebook
  • Suggested readings
  • Questions to consider
  • Figures & data sources

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Your professor

Richard Wolfson

About Your Professor

Richard Wolfson, Ph.D.
Middlebury College
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...
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Earth's Changing Climate is rated 4.3 out of 5 by 79.
Rated 5 out of 5 by from Great features A powerful explanation of important information. Every person on Earth should take this course!!
Date published: 2017-10-06
Rated 5 out of 5 by from If you ........., then take this course. If you believe in climate change (e,g, warming), then take this course. If you aren't sure you believe in climate change (e,g, warming), then take this course. If you do not believe in climate change (e,g, warming), then take this course. This is the most coherent, cohesive discussion of the planet earth in situ I have discovered. The professor presents information, data and uncertainty in a logical, well thought out discussion. He doesn't claim to know everything and emphasizes areas of uncertainty. This course helped me to put a better perspective on the ongoing argument/discussion on climate change.
Date published: 2017-10-06
Rated 3 out of 5 by from Good content I enjoyed the course, but would have enjoyed it more if the lecturer didn’t speak so fast. It was hard to keep up.
Date published: 2017-10-04
Rated 5 out of 5 by from Great Explanation of Climate Change I bought this course and have finished 6 of the 12 lessons. It's a very nice introduction to the evidence behind the climate change debate. This is an audio course and I've been listening to it during my commute, so I might not always pay full attention. The course provides a good summary of the evidence that climate change is occuring using a wide variety of data sources ranging from thermometers to observations on other planets. I had heard some complain about adjusting thermometer readings, but the professor explained that when equipment is replaced, the readings are adjusted to provide a continuous series of readings. As an economist, I'm familiar with making similar adjustments in the consumer price index and other data. When I finish this course, I'm going to try to find an equally rigorous explanation of the case against climate change or the human role for climate change.
Date published: 2017-09-25
Rated 2 out of 5 by from Obsolete Upon completion, I sent a note to the professor expressing some concerns with his in-course expression about a lack of understanding of "first principles" in this field, along with my concerns about the data relevance and mathematical modeling. (I don't know much about climate, hence my interest in this course, but have knowledge and practice with research data efficacy and mathematical modeling). His reply was, "Thanks, but that course is hopelessly out of date. Everything we know about climate is a lot more certain today. RW" Professor Wolfson did a good job with this collection of apparently now-obsolete data, "science", and references. Some of that is useful, but definitely "hopelessly obsolete". I was reminded of the famous quote (Wolfgang Pauli as I recall) in which he described such a work as "Not even wrong". I had hoped to develop an understanding of climate change from this course, but clearly, what a reasonably competent and open-minded scientist or engineer would want to know just isn't, by the professor's admission, in there.
Date published: 2017-09-25
Rated 5 out of 5 by from Provides essential information At first I wasn't going to purchase this course, telling myself that I have already read plenty about climate change on the internet, so I probably already knew the material. But I finally decided to buy Earth's Changing Climate, and I am so glad I did! I recommend this course to anyone who finds themselves living in the 21st century. We need to understand climate change in order to make good decisions in our lives. I wish I had bought this course as soon as it came out. I now feel equipped to understand articles I read about climate change. Better yet, I can now engage meaningfully in conversations about this hot topic. Dr. Wolfson artfully manages not to venture into contentious arenas involving political leanings and policy recommendations. Instead, he focuses squarely on factually-grounded technical and scientific explanations relevant to earth's changing climate. He clearly presents facts and processes that we need to grasp, so we can make sense of what we are hearing in news and social media. There is no hype or exaggeration. As a non-science major, I sometimes feel “lost” in Teaching Company lectures in the field of science, but in this course, Wolfson's explanations of concepts (such as earth's carbon cycle, atmospheric composition, computer models, albedo effect and more) are quite understandable and applicable. Thank you for making this course available.
Date published: 2017-08-04
Rated 5 out of 5 by from Solid presentation that explains the science I was concerned that the material was prepared nearly a decade ago. The science hasn't changed that much and the program filled in areas that I was lacking information in. I attended the Climate Reality training in Denver this year (2017) and have a lot of information about the effects of climate change, but I was missing facts on the theoretical/scientific side of the problem. This course is balanced, thoughtful, provides a solid understanding of the science behind climate change, refrains from editorializing and generally proved very helpful to me.
Date published: 2017-07-20
Rated 5 out of 5 by from Is It Hot Enough For You? It’s 2017 and there’s still a lot of hot air over whether the Earth’s average global temperature is rising and whether human burning of fossil fuels is contributing to that rise. Ten years ago Professor Wolfson had the answers: yes and yes. As evidence on the first issue he points (in Lectures 1 through 3) to the shrinkage of most glaciers, to global temperature measurements since 1860, to the width of tree rings, and to the ratios of oxygen isotopes in ice sheet cores going back 400,000 years. In the next three lectures Wolfson explains how greenhouse gases keep the Earth’s atmosphere warmer than it would be in their absence, by about 33 degrees Celsius (+15 instead of -18). The most important are water vapor and carbon dioxide (CO2). While the former continuously cycles from atmosphere to surface to atmosphere in about a week through precipitation and evaporation, carbon takes about five years, through inhalation by plants and their decay, absorption and upwelling in the oceans, and other processes. Much of it remains locked up in ocean deeps and in rocks, especially fossil fuels (10,000 gigatons). Because less than 1% of Earth’s atmosphere consists of CO2, the global climate is currently very comfortable for humans, especially compared to Venus, where the atmosphere is a hundred times denser and 96% of it is CO2. There the surface temperature is 500 degrees Celsius. Unfortunately, we humans are changing the balance in favor of warming by burning fossil fuels and chopping down trees. About half of the CO2 we release remains in the atmosphere rather than being absorbed by oceans or life forms. In 1750 the CO2 level was about 275 parts per million, in 2000 it was 375, and at the time of the course 390. As I write, a National Oceanic and Atmospheric Administration webpage shows it nearing 410 PPM. Wolfson warns that when we reach about 550, we will see serious disruptions to agriculture and marine life, as more CO2 in the ocean makes it more acidic. What is to be done? If we make no changes, the International Panel for Climate Change predicts a CO2 level at 1000 PPM and a 4.5 degree Celsius rise in global average temperature by the year 2100, just 83 years from now (Lectures 9, 12). Even an immediate and aggressive response would not prevent the temperature from rising by 1.5 C. Wolfson argues in Lectures 11 and 12 that nuclear fission is the only major alternative to fossil fuels, though it carries the danger of weapons proliferation, and a nuclear war would be far worse for the planet than even the worst-case climate change scenario. He dismisses massive engineering projects supposed to offset global warming and is skeptical of our ability to capture CO2 emissions. He supports conservation and believes there is plenty of room for increasing the energy efficiency of our transportation. I recommend this course for anyone wanting to better understand the scientific basis for global warming. Wolfson uses plenty of helpful graphs to make his points. My only critique is the time that has gone by since the course came out. In a few more years the Teaching Company should consider issuing a second edition to take account of new research and long-range forecasts. It may also turn out that prospects for solar energy have brightened since Wolfson dismissed them.
Date published: 2017-06-22
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