NOVA: Decoding the Weather Machine is a two-hour episode that documents the history of the study of climate change and its current status. The video identifies the causes of climate change and links it to our use of fossil fuels. Evidence for present and past climate change is found in ice, ocean sediments, fossil coral reefs, and even in New York’s Central Park! The documentary details the work of numerous climate scientists as they study earth’s changing climate and its possible effects such as rising sea levels, the death of coral reefs, extreme weather events, and the overall rise in world temperatures. It also stresses the well-understood science behind climate change, and the ability of human ingenuity and will to solve the problem.
The Google Forms self-grading quiz consists of 113 multiple-choice questions. This may sound like a lot to do, but I have found that this format enables the students to pay attention to the video while quickly recording their answers. I try to avoid situations where the students are bogged down by writing long responses during a video. You will need to obtain a DVD of the video or locate an internet site for streaming.
A printable, PDF version of the video worksheet is available here.
NOVA: Decoding the Weather Machine Overview
Meteorologist Paul Douglas, once a climate change skeptic, became convinced of its reality after a number of extreme Midwestern storms occurred. He began to notice a change in the weather, which led to his acceptance of climate change science. In recent years, an abundance of wild fires, the shrinking of Arctic sea ice, more frequent “1000-year” floods, rising sea levels, heat waves, changes in plant and tree flowering, changes in bird migrations, and strong hurricanes have been attributed to earth’s changing climate. As scientist, and evangelical Christian, Katherine Hayhoe states in the video, over 26,500 independent lines of evidence support the theory of climate change.
Climate change has occurred all throughout earth’s history, and evidence for past changes in earth’s climate can be seen today in New York City’s Central Park, and in Alaska. Large boulders named erratics are found in the park, and they were dropped in their locations by melting glacial ice, which implies that New York had an Arctic climate a few thousand years ago. In Alaska, paleontologists have unearthed the fossils of palm trees, evidence of an ancient time when parts of Alaska were located near the equator. While acknowledging past climate change, today’s scientists have amassed evidence that human activity is likely exacerbating natural trends towards a warming earth.
During the late 18th and 19th centuries, scientists began to make fundamental discoveries concerning the earth and its climate. French mathematician Joseph Fourier used a simple demonstration to model what we now call the greenhouse effect. The demo consists of a black box with one clear side. A thermometer inserted into the box will register a higher temperature when the clear window is pointed towards the sun. Fourier reasoned that energy from the sun was able to penetrate the glass but then became trapped inside. He also thought that the earth’s atmosphere confined heat in a similar manner.
In 1859, using an experimental apparatus, British physicist John Tyndall was able to determine which gases in the atmosphere were most effective at trapping heat. Tyndall presented his results in a triumphant public demonstration at London’s Royal Institution. His device, which consisted of a heat-measuring device called a thermopile, was exposed to two similar yet opposing heat sources. When one side was filled with oxygen or nitrogen—the two gases which make up most of earth’s atmosphere—virtually no heat was trapped, and the device read the same heat from both directions. With carbon dioxide, methane, and water vapor, heat was prevented from travelling through the apparatus and was confined by the gases. Tyndall also realized that the burning of coal and oil released carbon dioxide into the atmosphere, and that this might become a cause for concern in later years.
The video moves to the 1960s, where American chemist Dave Keeling began his historic measurements of atmospheric carbon dioxide from Mauna Loa Observatory in Hawaii. When first beginning the measurements, Keeling noted a rise and fall of carbon dioxide within a single year. At first he was concerned about instrument failure, and then realized that he had made a discovery; the level of atmospheric carbon dioxide rises and falls each year due to the annual growth and decline of vegetation. This is analogous to the earth “breathing”. After a few years of observing, Keeling also determined that the level of atmospheric carbon dioxide was rising each year. His curve was trending upward. Corroboration of the rising “Keeling curve” was obtained by the analysis of Antarctic ice. When snow falls, it traps bubbles of air in layers of ice. These bubbles of ancient air provide samples of earth’s past atmosphere extending back 800,000 years (see my lab Carbon Dioxide & Global Warming). The air samples can be studied to determine their carbon content, and a comparison of the amount of oxygen-16 and oxygen-18 isotopes can be used to determine the prevailing earth temperature. Comparison of Keeling’s measurements and the record trapped in recent Antarctic ice display a close match, providing external support for Keeling’s discoveries. Past abundances of oxygen isotopes can also be measured using seashells and ancient coral to further support the Antarctic ice core results.
Dave’s son Ralph Keeling is also a climate scientists and has maintained his father’s research. In the video, Ralph discussed how the carbon content of modern air reflects its “ancient” source. Carbon derived from coal and oil burning displays a unique isotopic signature that can be measured in today’s atmosphere. This isotopic signature (ratios of carbon-13 and carbon-12) began to decline in the mid 19th century, precisely the time when fossil fuels began to be utilized as a source of energy for the industrial revolution. In this way and others, the case for a man-made cause for the increase in atmospheric carbon dioxide has been proven beyond a reasonable doubt.
Confusion over the conflicting definitions of weather and climate can lead to climate change denial or skepticism. An infamous example is Oklahoma Senator James Inhofe’s inane demonstration of bringing a snowball to congress in February 2015 in order to disprove global warming. “Weather” represents the daily properties of the atmosphere, and “climate” is the long-term recording of past weather. In the video, meteorologist Paul Douglas compared climate to the “History Channel” and weather to “CNN Headline News”. Earth’s climate is also linked to four segments of the climate machine: Land, water, ice, and air.
Vegetation and soil acts as a carbon sink, and the decline of either would contribute to an increase in global atmospheric carbon dioxide and warming. Scientist Greg Asner’s work documenting the extent of earth’s forested areas is shown in the video. Using laser remote sensing, Asner is able to create a computer map of forests, which display amounts of vegetation and their carbon content. Time studies can reveal changes in forests and their effects on atmospheric carbon.
The oceans have been so far experienced the greatest amount of climatic warming, and have also absorbed about 25% of the excess carbon dioxide that humans have released into the atmosphere. Unfortunately, this combination of heat and carbon has been linked to the dying of world coral reefs, which have experienced a 50% decline in the last 30-40 years. Warm, carbon rich waters likely contribute to coral bleaching events, where the algae that sustains coral evacuates leaving a dead husk behind. Climate scientists have been using a network of 3,000 “Argo floats” to measure the chemistry and temperature of the oceans. The floats reveal that the ocean has warmed by ½° F in the past 30 years. This may sound insignificant, but the same amount of energy would correspond to an atmospheric temperature increase of 20° F! In this manner, the oceans have borne the brunt of manmade climate change. It is estimated that the oceans have absorbed 93% of the excess heat that we have caused to be added to the atmosphere. The Argo floats have also revealed characteristics of ocean currents, and that the oceans experience a deep cycle of hundreds of years in duration. Deep cold water (or “old water”) from before the time of atmospheric warming rises in the Southern Ocean near Antarctica, where it is then able to absorb immense amounts of heat.
The Greenland ice cap represents a potential source of sea level rise. Measurements of glaciers reveal that significant ice loss has been occurring (also see my NOVA: Extreme Ice Video Questions). The video documents the efforts of scientists to study the motion of Greenland glacier Jakobshavn, where helicopters are used to place sensors directly on the ice. Satellite images reveal that the glacier has retreated by 10 miles in the past decade. In the video, climate scientist Waleed Abdaladi likens the motion of Greenland ice to “uncorking a bottle of wine”. If all of Greenland’s ice were to melt (an unlikely event), it would correspond to a 23 ft. rise in sea level. 200 ft. of sea level rise is also locked up in Antarctica’s ice.
Along with the measurement of oxygen isotopes in ancient shells mentioned above, Andrea Dutton investigates the placement of ancient coral reefs corresponding to an earlier period millions of years in the past when the earth had the same temperature as today. The video documents ancient reefs in Australia that indicate a sea level height of 9 ft. in excess of today. Since one-third of the human population lives near ocean coasts, a similar rise in sea level now would represent a significant problem.
The video documents two areas that are experiencing rising sea levels. The Marshall Islands may represent one of the first places with rising sea levels that will be abandoned to produce “climate refugees”. Marshall Islands poet Kathy Jetnil-Kijiner was highlighted in the video, and she also addressed the United Nations in order to bring attention to the plight of the islanders.
Residents of Norfolk, Virginia are also dealing with rising sea levels. A couple in Norfolk that spoke in the video decided to raise their home on concrete blocks to avoid flooding. Walkways near the ocean were shown to be underwater. Norfolk is also the home of the world’s largest naval base, and retired Admiral Anne C. Phillips described climate change as a “national security issue”. The Army Corps of Engineers has proposed a $1.5 billion plan to build sea walls and flood retention ponds, but this is considered a temporary measure.
In 2017, three massive hurricanes were active near the Americas at the same time. Hurricane Harvey flooded Houston, Texas, Hurricane Irma damaged Barbuda and Florida, and Hurricane Maria caused widespread destruction and loss of life in Puerto Rico. Hurricanes are fueled by warm ocean water, and it is hypothesized that warmer oceans may result in larger, more powerful hurricanes.
Computer climate models are being used to predict the effects of climate change. In these models, the earth is broken up into a grid with overlying layers. Each cube calculates the properties of the air, land, oceans, and ice using well-established mathematical relationships. The models are able to adequately model the earth’s past climate, giving scientists confidence that the models are able to predict future conditions. Computer models forecast that the number of +90° F days in New York City will triple by 2100, and that city will also experience a 1.5-4 ft. sea level rise.
Many of the scientists interviewed in the video remain optimistic about solutions for global warming. The problem is well understood, and human ingenuity will likely provide solutions far into the future.
The main source of greenhouse carbon dioxide is the burning of fossil fuels, which are currently used to generate 80% of the world’s power. Wind and solar power are two alternative sources that come to mind, as well as nuclear power. Although not addressed in the video, nuclear power remains the most viable non-carbon polluting energy source that we have. Problems with nuclear power in the past have led to much improvement in safety and reactor design, but the main hurdle lies in public acceptance.
Wind power is being utilized in many parts of the world. In the United States, “wind technician” is a fast growing profession. The video documents the use of wind power at a Whirlpool washing machine plant in Findlay, Ohio. The plant has installed wind turbines on site, and these devices generate 15% of the power used by the factory.
Solar energy is another exciting area of growth for non-fossil fuel derived energy. Current technology is expensive, but costs will most likely come down. At the National Renewable Energy Laboratory, scientists are developing solar cells made from perovskites, which are made of cheap, easily obtainable ingredients. Perovskite is made into a “paint on” solar material that can be prepared as flexible material, even clothing.
Engineers and scientists are also working on ways to sequester the carbon generated by fossil fuel use. At SaskPower in Canada, a coal burning power plant is being used in an experiment where the carbon-enriched emissions are pumped into the ground and stored in an inert fashion in layers of rock. The main impediment to such technology is the cost, and the current energy market has not made such installations viable. The introduction of emissions trading, or a type of market friendly carbon tax would help push industry in the direction of carbon sequestration. Also shown in the video is Lisa Dyson’s company Kiverdi, which is working on ways to take carbon emissions and convert them into useful products such as food, oil, and plastics. She claims that the technology can be workable in a market economy and that it can be attractive to carbon emitting businesses.
Some scientists claim that just leveling off carbon emissions is not enough, and that we need to create “negative emissions” and remove more carbon from the atmosphere than we generate. Nature itself provides a carbon-capturing process in the form of plant photosynthesis. The goal is to use farmland and home gardens as carbon sinks through the use of no-till agricultural techniques.
Although well understood by scientists, the most unpredictable aspect of climate change is human behavior and the willingness of societies to step up and solve the problem. Climate change, global warming, and human culpability are scientific facts that are beyond dispute. Politically conservative, and originally a skeptic of global warming, meteorologist Paul Douglas now agrees with the scientific consensus on climate change. He was brought to this position by observing the weather for thirty years as a forecaster. Katherine Hayhoe of Texas Tech is a climate scientist, and evangelical Christian, who is also trying to convince conservative and religious climate change deniers that global warming is a real phenomenon, and that it represents a threat to our civilization. If we don’t act soon, today’s 2 billion children will likely grow up into a different world, a world transformed by once preventable climate change.