Global climate change has become one of the most important issues of our times, vaulting from obscurity to overriding importance in a decade; it is difficult to ignore and harder still to avoid. One hundred thirty-four American cities, including New Orleans, Salt Lake City and Seattle recently voted to adhere to the greenhouse gas emission restraints set by the Kyoto Protocol on global warming – even though the Bush administration refused to ratify the treaty. In July’s G8 meeting, UK Prime Minister Tony Blair will propose an ambitious three-part plan to combat climate change. Last month, the North Carolina state legislature funded a study to determine the effect of global warming on that state’s economy and environment. The issue pops up again and again- in mainstream movies, on online automotive forums, in university classrooms, in the proceedings of international organizations. It holds deep implications for biodiversity, human geopolitics, public health, and the stability of global civilization itself.
However, what understanding the general public has of the issue has been filtered through the spin of corporate politics and an unreliable media. On June 1, 2005, a former government climate change scientist, Rick Piltz, revealed that official reports on climate change had been modified to appear as if research on the phenomenon was fraught with uncertainty. Tellingly, the redactor was ‘White House official’ Phillip A. Cooney, a non-scientist and former lobbyist with the American Petroleum Institute.
Lobbying groups like the Competitive Enterprise Institute, the Cato Institute, the Cooler Heads Coalition, and many others relentlessly misdirect the issue. Capitalizing on the public’s poor understanding of the underlying science, they spread the misconception that global warming is of dubious importance and certainty. In fact, nothing could be further from the truth.
So, what is climate change? How do we effect it, and how will it affect us? How does it work and how do we know it is happening? This article will attempt to cut through the artificial uncertainty propagated by corporations and politicians, and through the opacity of science, to answer those questions.
The Basics
To begin, it’s important to cover the basics. Greenhouse gases are molecules whose structures can absorb lots of heat energy. Methane (natural gas), carbon dioxide, water vapor, and a few other gases are generally responsible for Earth’s global warming. To an extent, this is positive – it keeps energy from the sun in the atmosphere, instead of letting it all reflect back into space. Methane and water vapor are the most efficient greenhouse gases, but CO2 is most worrisome.
Carbon is stored in reservoirs- just like water. It can be in the atmosphere in the form of CO2, or “fixed” into biological material or geological formations like oil. The global carbon cycle consists of carbon shuttling between the biosphere and the atmosphere; plants take in CO2, turn it into carbon compounds like sugars, which are metabolized by many classes of organism and converted back into C02, which is excreted back into the atmosphere. Alternatively, that CO2 can be released when living material dies and decomposes.
Sometimes carbon gets locked up away from that active cycle, when it gets incorporated into minerals, ocean sediment, or in the form of buried organic material which is turned into oil. These reservoirs of inactive carbon are termed “sinks.” Oil is simply biomass converted into energy-rich long-chain hydrocarbons; when they’re oxidized (burned) they release CO2 and energy.
If human beings were not burning oil, that carbon would remain locked up. The climate system is “used to” having a certain amount of carbon dioxide and other greenhouse gases in the mix. It can – and will – adjust to higher or lower concentrations, but this takes time.
The composition of the atmosphere has a direct relationship to the climate – temperatures are dependent in part on the proportion of greenhouse gases in the atmosphere. When we burn lots of fossil fuel over a relatively short period of time, that sudden dump of greenhouse gas into the atmosphere will raise temperatures. The thermodynamics of carbon dioxide leave no doubt that this will happen; greenhouse gas and warming are cause and effect.
Another significant cause of global warming is the conversion of forests and other long-term carbon sinks into farmland for agricultural production. Wide-scale deforestation without an accompanying reforestation releases vast quantities of carbon dioxide into the air – as that biomass is either burned or allowed to decompose (decomposition’s end product is CO2). Deforestation increases with agricultural production and human population; it has been especially severe since the beginning of the Industrial Revolution, although it started with the beginnings of agriculture. Recent research suggests that warming caused by deforestation alone averted an ice age that should have begun roughly 5,000 years ago.
SimAtmosphere
So, to summarize thus far, we know that CO2 absorbs a lot of energy and retains it, and that a mix of gases that contains CO2 retains more heat longer than one that doesn’t. We also know that the more CO2, the more heat your atmosphere can hold. And we know that burning hydrocarbons releases CO2 into the atmosphere, and we even know by how much the CO2 concentration has risen.
Using supercomputers it’s possible to simulate how the atmosphere acts, and to model the effects of increasing greenhouse gas concentrations. The simulations are complex, and incorporate many of factors such as how much heat land and water reflect, the dynamics of air currents and atmosphere cycling, the effects of vegetation, and the like. There’s some leeway in the models, and not everything can be simulated accurately. However, especially now with an extensive body of research informing the modeling of variables, estimates are becoming very reliable – and backed up with real-world evidence.
Hard Core Proof
The simulations give a good idea of what we expect to see. Armed only with a simulation, a researcher has an informed hypothesis. The next step is testing that hypothesis. In the case of climate modeling, the best way to accomplish this is to go to Greenland and drill into the arctic ice to obtain a deep ice core. Polar ice is simply compressed and crystallized snow; each year’s snow forms layer in the core. These layers, like tree rings, can be counted, and it is possible to obtain ages and even seasons for a given core depth.
The cores have bubbles, originally the small spaces between snow crystals. These bubbles entomb a tiny volume of air within them, a pristine sample of the atmospheric composition at the time that snow fell. The proportions of gases in that bubble will tell you exactly what the atmosphere was like in that given year, for every year represented by the core. In this way, researchers have obtained continuous records of what the atmosphere was like for the past 50,000 years or so – including how much CO2 was present.
It is also possible to directly determine the temperatures for that past 50,000 years by analyzing ice cores to determine ratios of oxygen isotopes for a given year. The ratio of oxygen isotopes in the ice is a precise indicator of temperature. Other climate records have been obtained from very old lakes in Colorado and Utah.
The Climate Record
So, what knowledge can be extracted from those CO2 and temperature records? We can tell that temperatures now are higher than they have been at any time in the past 50,000 years. We can tell that concentrations of CO2 match that increase in temperature – high temperatures are accompanied by high CO2 concentrations. It appears that spike of CO2, accompanied by an increase in temperature, began around 150 years ago – matching very well to the beginning of the industrial revolution. Most importantly, the real-life records from the cores match the computer simulations extremely well. The rise in global average temperatures are exactly what the simulation predicted.
Overall global temperature has gained about .6 degrees Celsius, average, since the beginning of the 20th century. (1.1 degree Fahrenheit.) While this may sound insignificant, the height of the last ice age (when there was four miles of ice on top of Seattle) was only 10 degrees C or so colder than it is right now. That was 20,000 years ago, which means that we’ve warmed up about a degree C every 2,000 years – except in the last 100, in which we’ve gained an entire half a degree. Seven of the ten hottest years of the 20th century fell in the 1990’s.
With the simulation results verified experimentally, they can be used to make predictions for the future. It is estimated that Earth will gain at least two or three degrees in the next century, making for an increase of about 4 degrees C worldwide in 200 years. They’ve also been run to figure out what would have happened without greenhouse gases from fossil fuels, revealing that without human influence the climate would have actually cooled, not warmed.
Other triggering factors, such as changes in the amount of solar radiation hitting Earth or volcanic activity, have been ruled out by researcher Dr. Peter Stott, directly contradicting the research of Dr. William Soon and Dr. Sallie Baliunas. His research is generally regarded as definitive.
The Scientific Consensus
There has been a very, very effective disinformation campaign waged to convince the public that global warming is still debatable, that the science is shaky, and that there’s significant discord among climate researchers. Wander onto an average conservative political forum, mention global warming, and this “fact” is brought out faster than one can blink. Is there any grounding to it?
Why not go straight to the source- to climate specialists themselves? Nearly thirty atmospheric scientists, geographers, planetary scientists, and climatologists from the University of Colorado and the University of Denver were interviewed. They were asked whether they personally believed the evidence supported the theory of human-caused global warming, and whether they were aware of valid and significant opposition to the theory in the scientific communuity.
The answers were unanimous. Every researcher approached believed that humans were causing global warming and that the phenomenon was real, and none believed that there was valid opposition to the theory. One name, that of University of Alabama climatologist John Christy, was mentioned as a dissenter; it turns out, however, that he has recanted.
While this survey was hardly scientific or statistically sound, it did not need to be. Nearly twenty climate scientists were approached for their thoughts, and none of them personally doubted global warming or knew of a significant opposition group. The scientific community is interconnected and interactive; researchers communicate through journals and conferences, and as a rule keep firmly abreast of happenings in their field. Significant splits in opinion are accompanied by extended, vigorous debate in journals and conferences. It is inconceivable that twenty specialists, leaders in the field, would be unaware of a strong dissenting movement against global warming. The scientific community is now working on understanding effects and refining understanding, not establishing the theory’s veracity.
The Reality of Anthropogenic Climate Change
By now, it should be obvious that anthropogenic global warming is validated, solid science; furthermore, the theory is generally accepted by the scientific community. Opposition to the theory, and the urgent need for action that it implies, is based not on science but in a desire to maintain the economic status quo. Human activities such as fossil fuel use and deforestation have, and will continue to cause, a massive change in the Earth’s climate. Our species is now the predominant factor affecting our planet’s climate- and, by extension, the entire biosphere.
Charlie Lawton is a student, researcher, compulsive nomad and mountain bum. He holds a Bachelor of Science degree in Ecology and will begin graduate studies in microbial ecology and astrobiology in Fall 2005. He has participated in research into the ecological effects of climate change since 2003.
Thanks to Dr. Don Sullivan and Dr. Michael Kerwin for their information and advice.