Although some people say climate change science is a hoax, it dates back almost two centuries and the basics have become very well understood. Joseph Fourier, a French scientist, made a calculation to determine that given the Earth’s distance from the sun, it should be a colder planet, and discovered that the Earth’s atmosphere acted as a kind of blanket with a thermal equilibrium that captured the Sun’s radiation in the greenhouse effect. Later, John Tyndall realized that even a small amount of carbon dioxide and water vapor in the atmosphere could carry out that greenhouse effect. Arhhenius built on this to discover that every doubling of carbon dioxide the atmosphere would lead to a certain step increase of the temperature of the planet. There are many complex details, such as what the feedback mechanisms of the atmosphere are and the function of the ocean in this cycle. Arrhenius underestimated how long it would take to double pre-industrial concentrations because he didn’t anticipate the geometric economic growth of the world economy or the use of fossil fuels at the rate they were used. Professor Sachs shows a well known graph from 800,000 years ago until the present day showing carbon dioxide fluctuations in the atmosphere and the massive human impacts on that concentration in the most recent part of the graph since the Industrial Revolution. In the 1950s, Roger Revelle said that the ocean would not absorb the atmospheric carbon dioxide that humans had produced. Charles Keeling, who created the Keeling Curve, one of the best measurements of human-induced changes of carbon dioxide, gave us a record that humanity is causing a rise in carbon dioxide marked by seasonal changes in concentrations due to photosynthesis. Dr. James Hansen told Congress that climate change is real, but there hasn’t been an adequate response for thirty years. We are in a new geologic epoch, called the Anthropocene, or the human-induced phase of the planet. There is a lot of private action against climate science because it goes against private short-term interests. This video is part of the module Towards a New Climate Change Agreement.
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