Founding Fathers of the Global Warming Debate

Earth Report goes back over 200 years to learn about the evolving scientific thought that has shaped the global warming debate.

Founding Fathers of the Global Warming Debate Host: For millions of years, forests have absorbed carbon dioxide from the atmosphere, locking it into the earth as oil and coal. With the start of the industrial revolution less than two centuries ago, the widespread burning of fossil fuel began to release the CO2 back into the atmosphere. But just as long climatologists have been preoccupied with the effect this would have. As long ago as 1827, French scientist Jean Baptiste Fourier first suggested the existence of an atmospheric effect that keeps the earth warmer than it would otherwise be. He was the first to use the analogy of a greenhouse, trapping the warmth of the sun to help explain why the earth is not a cold as Mars. In 1863 Irish scientist John Tyndall using instruments he designed such as the spectrophotometer, first showed how gases such as water vapor, carbon dioxide and hydrocarbons are greenhouse gases. Absorbing and reflecting heat. Building on this work, Swedish professor Svante Arrhenius in 1896 published an article putting forward the idea that the amount of carbon dioxide in the atmosphere has a direct relationship to temperature. He predicted that if CO2 levels doubled the temperature of the atmosphere would rise by five degrees. Stephen Schneider: What made him different was (a) he did a calculation and (b) he also said humans through the use of their fossil fuels might affect things. So in essence he deserves the title of being the founding father of the global warming debate because global warming is not about the natural greenhouse effect, it’s about the augmentation of natural gases with human produced kind where we use the atmosphere as a sewer and dump it and he calculated that we might make a difference so but he saw this being pretty far away. Host: Arrhenius realized that burning fossil fuels could lead to global warming. What he did not know was that it had already started. Male: Some of the worst dust storms in the history of the whole world I guess broke loose that was the big middle of the dust bowls. Host: Between 1890 and 1940 the average surface air temperature increased by a quarter of a degree centigrade. It doesn’t sound much but some scientist see the American dust bowl of the 1930’s as an early sign of the greenhouse effect at work. The places have in context, just seven degrees of surface air temperature separates this century from the last ice age. Male: The motorization of our economy, so new, so powerful and so revolutionary as this force that we have hardly been able to appraise its influence. Host: During the next 20 years of rapidly increasing greenhouse gas emissions no one thought much about the climate. Then, in March 1958, a young scientist in San Diego began to search for the first scientific proof that carbon dioxide levels were rising dangerously. Charles Keeling: All these measurements were misleading and I mean all of them. When I first made this pronouncement I was 27 years old and I would just pass getting -- pass my schooling and I was telling this people that the whole field was pretty badly screwed up. Host: Scientist has been measuring CO2 in the atmosphere for decades but Keeling insisted that they're readings had failed to give accurate results. He was convinced he could set the record straight. Charles Keeling: My data were sufficiently compelling and I got to a couple of people you see like the director of the weather service and the director of scripts and persuaded them that these measurements were probably right and all of the others were wrong and they gave me a chance. Host: To record his measurements he went to a new, more reliable place Mauna Kea Observatory in Hawaii. Charles Keeling: If you had to pick a spot anywhere which would have given representation of the whole world with one single site, Mauna Kea Observatory has probably to about the best choice. Host: Into this ideal environment, Keeling introduced the technology that would give him his breakthrough. Readings were taken every 10 seconds for the next 40 years. The results provided dramatic new evidence for global warming. His readings gathered together into the so-called Keeling Curve showed that CO2 levels had risen alarmingly since 1958. Charles Keeling: The increase in carbon dioxide since I started my measurement is twice the total amount of CO2 that was added to the air prior to that. So the 40-year record now is captured enough that we can be pretty sure that we know how to represent the effect of carbon dioxide on the greenhouse effect. Male: Unless we learn otherwise it will be prudent to suppose that the next ice age could begin to bite at any time. Host: However, the mounting evidence that climate change fueled by CO2 emissions would lead to a hotter world will soon to be challenged to buy a new theory. In 1974, after a series of unusually cold winters, scientist claimed the earth was not warming but cooling and that we were on the verge of entering a new ice age. George Kukla: The warm periods are much shorter than we believe originally. They are something go on to 10,000 years long. And I'm sorry to say that the one we are living in now has just passed its 10,000 years bursting. The ice age sure is viewed now anytime. Host: The cooling theory identified a new culprit, not carbon dioxide but dust and smoke in the atmosphere. Reid Bryson: A man made dust poll is spreading over the earth. The use of the soil in a dry country produces dust which the wind blows into the air. This dust all added together spreads around the world, blots out the sun and causes cooling on the worldwide scale. Stephen Schneider: Early calculations under a set of specified assumptions which we admitted were not certain. Nonetheless showed that if the dust were around the world it would win and then it could cool the earth down by several more degrees if the trends for population growth and athlon growth continued into the 21st Century. Several degrees is sufficient according to other theories at the time to trigger an ice age in fact I agree, several degrees would trigger an ice age. And since the world was temporarily, listed in northern hemisphere temporarily in a cooling trend in the 1960’s here this theoretical calculation came along and set all potential ice age possible from human dust and I got that label pinned on me even though I was actually just doing the calculations. Host: And then in the 1980’s had a string of hot summers and all talk of a new ice age melted away. It had all been a big mistake. Stephen Schneider: What happened in the next few years as we studied and found out that the dust is not globally distributed that it’s largely concentrated in industrial areas or an agricultural areas. So therefore not the entire earth is covered by it so the cooling effect was only regional, whereas the greenhouse gas effect was global. The second thing is the early calculation that we did, neglect the stratosphere the high part of the atmosphere where the ozone is. But we didn’t think that would have much to do with CO2 but like all things in science you keep checking your assumptions. So I redid the calculations of the stratosphere and said “woops, we underestimated by more than 50%, how much warming that would be?”