Causes of Climate Change
Casey E. Davis Kaufman
AAPB Project Manager WGBH
Throughout this exhibit, scientists and activists, each of whom talk about the various facets of climate change—from a policy perspective to activism to specific research on impacts and solutions—spend a portion of their discussions communicating that climate change is happening and discuss several of the various human-driven causes. Guests, interviewees, program hosts, listeners, and event attendees discuss how greenhouse gases, such as carbon and methane, trap heat in the Earth's atmosphere, making the planet warmer. Scientists report that since the beginning of the Industrial Revolution, human activities have been the main source of greenhouse gas emissions, which has taken place primarily through the burning of fossil fuels.
In a call-in show about climate change and public policy, Stephen Schneider, Professor of Environmental Biology and Global Change at Stanford University, asserts that causes of climate change are global in nature. After discussing how the United States has historically been the primary source of emissions, he contends that with the spread of industrialization, "we need a global process...where we can work with developing countries and say 'you have a right to develop, but don't do it the way we did it, but since we got rich doing it . . . we'll help you with these alternatives.'" If we don't help them, he continues, "we going to end up doubling, tripling, or worse CO2 [concentrations in Earth’s atmosphere]."
Scientists also contend that the process of climate change itself is a cause of further global warming. Once the climate begins to change, argues Dr. Ronald Prinn, Professor of Atmospheric Science in MIT's Department of Earth, Atmospheric, and Planetary science, in a public talk recorded by WGBH in 2010, positive feedback loops begin "and that's bad news." He explains, "if we increase greenhouse gases leading to warming, the warming itself will induce natural emissions of greenhouse gases," which further warm the planet. He discussed the melting of Arctic sea ice as an example of a positive feedback loop. The ice reflects the sun's radiation back into space and reduces the heat added to the atmosphere. When ice melts due to greenhouse gases that have increased global temperature, then it leaves a dark colored surface behind, which absorbs the sun's radiation and leads to more warming.
The three items in this section of the exhibit are unique in their focus on drivers of climate change.
The first, an edited documentary titled After the Warming, originally broadcast in 1990 by Maryland Public Television, looks at the causes of climate change from the perspective of the year 2050.
The second, another program from Maryland Public Television, is a debate about the causes of global warming between Don Boesch, Ph.D., President of the University of Maryland Center for Environmental Science, and Tony Pann, co-host of WCBM radio's Weather Talk and a meteorologist for WUSA-TV. Boesch, who referenced the Intergovernmental Panel on Climate Change (IPCC) which was developed to establish an international scientific consensus, cites the evidence that climate change is happening now. "It's not something that's just in the future." Tony Pann disagreed. He brought a printout of a graph that shows the relationship between temperature and carbon dioxide to prove his point. "If you look really closely, I think it looks like the temperature goes up first, and then the CO2 goes up." "Where do I start?" Dr. Boesch replied, "In terms of the vast majority...95% or more consensus of scientists [sic]...there is virtually no uncertainty that humans are the cause of greenhouse gas concentrations.... Used to be, you had to give both sides. Now, I think, the handful of deniers are in such small numbers that you can ignore them, frankly."
The third item in this section is a public lecture by Anna Lappé, focuses on what she found are often overlooked causes of climate change—our food and agricultural industries.