Diabolical carbon dioxide base catches much of the blame for global warming
Among the earliest hard evidence linking rising global temperatures and the emissions spewed out by modern industrial societies has been collected about 30 miles west of Boulder on Niwot Ridge.
There, on a windswept ridge sweeping up to the Continental Divide, air samples have been taken weekly since 1968. The flasks are taken to a laboratory in Boulder, where the concentrations of methane, nitrous oxide and other gases usually found in small quantities in the atmosphere are determined.
All are what we call greenhouse gases. Unlike pure oxygen, the greenhouse gases trap a portion of the solar energy that hits the Earth every day, similar to the way your windows trap heat in your car. Too little of these greenhouse gases, and the Earth becomes a snowball. Too much, and our planet becomes an oven. It’s the difference between Venus and Mars.
Carbon dioxide is also collected at Niwot Ridge. Because it is the most common greenhouse, C02 most concerns scientists and some policy makers. Each year concentrations of CO2 rise, not only at Niwot Ridge but across the globe ” 11 percent in just four decades. If the current pace continues, atmospheric concentrations will have doubled by the middle of this century compared to when the Industrial Age began.
So what? Well, consider that the atmosphere has never had such high concentrations of CO2 in at least the past 400,000 years. If the greenhouse effect works as scientists predict, Mother Earth could be renamed the Hot Tamale.
Scientists have been piercing together this understanding of greenhouse gases for nearly 200 years. The basic idea is credited to a French mathematician, Jean-Baptist-Joseph Fourier, who in the 1820s likened the atmosphere to a glass vessel.
That idea was refined in the 1860s by a scientist and mountaineer from Ireland, James Tyndall, after whom a glacier in Rocky Mountain National Park is named. Tyndall observed that not all gases are equal in retaining heat. While he speculated about the possibility that reduced greenhouse gases could trigger another ice age, he seems not to have considered the idea of increased greenhouse gases warming the globe.
The essential idea underlying the theory of global warming is attributed to Svante August Arrhenius. A Noble Prize-winning chemist from Sweden, he set out to understand any connection between the temperature of the ground with the presence of heat-absorbing gases in the atmosphere. In his 1896 paper he used the term “hothouse” ” what we now call the “greenhouse effect.”
Arrhenius understood that the Industrial Revolution, from 1750 to 1850, was sending massive amounts of carbon dioxide into the atmosphere. He predicted that doubling of carbon dioxide levels would lead to an average temperature increase of 9 to 11 degrees Fahrenheit. Such heat did not trouble him. It wouldn’t happen for 300 years, he said. Besides, living in Sweden, he thought more heat would be a blessed change.
Several decades later, a British meteorologist, Guy S. Callendar, confirmed that what Arrhenius had predicted was happening.
Studying records from 200 weather stations around the world, Callendar in 1935 revealed that the Earth’s temperature had risen nearly 1 degree Fahrenheit in the previous half-century. Like Arrhenius, he saw this as a positive, producing more prosperous farms and delaying the return of glaciers.
Then, beginning about 1940, the Earth’s climate began cooling. When baby boomers tell you it was colder when they were growing up, they’re not merely being nostalgic. Despite increasing concentrations of carbon dioxide, temperatures stayed cooler until the mid-1970s. Some climatologists think the cooling was caused by an abnormally high amount of volcanic ash in the atmosphere.
This cooling trend had some scientists speculating about the imminent arrival of another ice age. In fact, if the past 740,000 years reliably predict the future, we are already overdue. The warm interludes between ice times have been lasting 10,000 years, and we’re already at 12,000 years. Never have times been so propitious for the species called homo sapiens.
But even as the planet cooled, other scientists continued to argue that the cooling was a blip and warmer temperatures would return. They were right. In 1980, temperatures began rising. Now, five of the hottest temperatures during the past 200 years have occurred in just the past decade.
Meanwhile, even in the 1950s, scientists had turned to computers in hopes of projecting what would happen in the future. Computer models at first did a poor job of accounting for the many vagaries of the global climates. Still, by 1968, a U.S. government agency research team had created a three-dimensional computer model that predicted that a doubling of carbon dioxide would be accompanied by a rise of 5.4 degrees Fahrenheit.
The problem with such predictions is that you can’t wait to see if they’re accurate. If they’re accurate, your goose could be cooked. Greenhouse gases can’t be withdrawn from the atmosphere like an offer on a house. That’s what a panel informed President Jimmy Carter in 1976.
A similar case of atmospheric pollution illustrates this lag time between cause and effect. Scientists beginning in 1974 had predicted that release of chlorfluorocarbons and other chemicals into the atmosphere would result in holes in the ozone layer, which is sometimes called the Earth’s sunscreen. By 1985, holes had been detected above Antarctica.
A multi-national agreement was hastily assembled in Montreal in 1987 that quickly took action to minimize further emission of CFCs and the other chemicals. Still. the ozone hole has continued to widen, and only now are scientists seeing evidence the breaches will fill ” but not heal for decades.
Similarly, with climate change, the proof is not evident until long after the damage has been done. Without that sure-fire evidence of long-term temperature increases, the issue of greenhouse gases remained a low-level issue. That changed in 1988 when climate scientist James Hansen, of the Goddard Institute of Space Studies, told a U.S. Senate committee that “global warming is now large enough that we can ascribe with a high degree of confidence a cause and effect relationship to the greenhouse effect.”
For good measure, Hansen offered to bet anyone that one of the first three years of the 1990s would be the warmest on record. He won his bet in the first year. He also predicted that the 1990s would be the warmest decade on record. He was right again.
A series of reports issued by panels of scientists from around the world reached the same conclusion as Hansen, if more slowly. The 1990 report by the Intergovernmental Panel on Climate Change said that the “unequivocal detection of the enhanced greenhouse effect from observations is not likely for a decade or more.”
By 2001, the scientists had reached that agreement. There is, they reported cautiously but with new cohesion, “new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.”
Doing something about the greenhouse effect, say most scientists, means curbing our burning of hydrocarbons. Burning of fossil fuels causes 75 to 80 percent of the carbon dioxide that goes into the atmosphere, with the balance explained mostly by deforestation and other land-use changes.
Ice cores taken from glaciers in Greenland and elsewhere show that before industrialization there were 280 parts per million of carbon dioxide. Readings were at 385 parts as of several years ago. By mid-century, they are expected to hit 550 parts per million.
These collections are taken in remote locations well away from localized pollutants. The oldest continuous record comes from the 11,300-foot level of the Mauna Loa volcano, in Hawaii. Another tropical collection site is in American Samoa. Other key sites are at the South Pole and at Barrow, Alaska.
There also are dozens of volunteer collectors around the world. Among these volunteers is a retired teacher who lives in a remote outpost in the Gobi Desert of Mongolia. Twice a week, Mrs. Bamuuu Dorjnorov fills two flasks of air, then takes a 12-hour train ride to the country’s capital of Ulaan Baatar. From there, the flasks are flown for eventually delivery to the National Oceanic and Atmospheric Administration laboratory in Boulder.
But no matter who collects them or where, the dozens of sample taken each week all show the same thing: rising concentrations of carbon dioxide, as well as other greenhouse gases.
Uncertainties remain, but almost no scientist challenges the strong link between current emissions of greenhouse gases and future warming.
“You have to be a real nut to argue that carbon dioxide doesn’t have an effect on climate change,” says Pieter Tans, an atmospheric scientist at the National Oceanic and Atmospheric Administration in Boulder.
That said, you can find Web sites, as well as articles and even books, that do dispute the greenhouse warming connection or at least argue that the computer models inflate the prospect of heating.
To that criticism, most climate scientists note that long after mainstream scientists had agreed upon the link between tobacco use and disease, the cigarette manufacturers continued to dispute any such link with paid scientists willing to argue that case.
Similarly, the doubts about greenhouse warming come mostly those on the payroll of coal producers and others in the fossil fuels industry.
That said, some uncertainties remain. For example, could the computer models actually understate the heating that is ahead? New evidence suggests that is the case. As greenhouse gases create more warming, they will themselves become warmer. Warmer greenhouse gases are believed to then become more powerful in causing additional warming.
Another large uncertainty, says Jerry Mahlman, a climate scientist at Boulder’s NCAR, is the role of clouds. As the Earth heats, more water vapor is expected, creating more clouds. Will they reduce or amplify the heating?
“But none of that uncertainty makes global warming go away,” says Mahlman. “It is just stuff around the edge, a little less or a little more than what we think.”
Mahlman add, “There is no real controversy about the reality of global warming. We argue about how soon and how much, and we argue about who gets clobbered and how they get clobbered.”
Allen Best is a contributing writer for the Vail Daily.