Let’s set the record straight. The depletion of the atmospheric ozone layer and the climate change often referred to as “global warming” are separate, largely unrelated processes. I remember a comedian maybe 10 years ago making (or should I say attempting) a joke about about discharging aerosol cans during especially cold winter days to hasten the anthropogenic effect on worldwide temperature increases. Far be it from me to step on a punchline, but there are a couple things wrong with that. First, the loss of ozone catalyzed by the chlorine atoms from chlorofluorocarbons (CFC’s), the propellants once used in spray cans, does not accelerate the Earth’s greenhouse effect; it’s the enormous amounts of carbon dioxide gas (and, less directly, methane) we introduce into the environment that pulls off that trick. In fact, man-made ozone can actually act as a greenhouse gas itself when present in the troposphere, the lowest level of our atmosphere, although its impact in that regard is much, much smaller than that of the other offenders. Ozone depletion instead heightens our risk for skin cancer, as the upper atmospheric layer of the compound functions as something of a shield against carcinogenic ultraviolet radiation from the Sun.
Secondly, the widespread use of CFC’s in consumer products ceased in 1994, thanks to the internationally instituted Montreal Protocol. Even their less hazardous temporary replacements, hydrochlorofluorocarbons, will be phased out in much of the world by 2020 and will likely disappear entirely a decade later, to be supplanted by non-destructive hydrofluorocarbons. Due to these burdensome but necessary measures, a study published in February shows that the Antarctic ozone hole has shrunk to its smallest size in 10 years, and some scientists estimate that stratospheric ozone levels should rebound to pre-1970 levels by the year 2050. Now that’s a system workin’! With such an unequivocal environmental success now precedented, could we take similar steps to mitigate that other dilemma, global climate change? Let’s compare and contrast the histories and natures of the two phenomena to find out.
Chlorofluorocarbons are just what they sound like, compounds that contain only chlorine, fluorine, carbon and hydrogen. Belgian chemist Frédéric Swarts pioneered their synthesis in the 1890′s, and some species were used as fire suppressants during World War II. The compounds found greater commercial use in refrigerators and aerosol cans in subsequent decades. University of California at Irvine Scientists Frank Sherwood Rowland and Mario J. Molina first suggested the devastating effects of atmospheric chlorine on ozone in 1974, after James Lovelock had discovered that nearly all the poorly reactive CFC’s ever released into the air were still present. Unsurprisingly DuPont, a heavy producer of the chemicals and creator of the brand name Freon, called their work “utter nonsense.” Rowland and Molina were proved right by laboratory experiments and the direct observation by James G. Anderson of chlorine monoxide, a product of the reaction, in the atmosphere. For their research on the issue, the pair won the Nobel Prize in Chemistry in 1995.
The United States, Canada and Norway banned the use of CFC’s in aerosol cans in 1978, but not much other action was taken until the “holy shit” moment 7 years later. That was when the British Antarctic Survey team announced massive springtime losses of ozone over the South Pole, “holes” that in later years would reduce the stratospheric presence of the compound by up to 70%. The occurrence could have been detected much earlier, but NASA scientists hadn’t noticed the numbers, as values that extreme were automatically eliminated from their data, deemed “impossible.” That’s how bad things had gotten in a short period of time. The international community immediately took notice and the Montreal Protocol was opened for signature just two years later. Atmospheric CFC concentrations continued to rise until the year 2000, due to the continued use of previously produced, non-compliant refrigerators and air conditioners, but as those units have failed over time, we’ve developed the much rosier picture of our future we now see, one that’s been painted by urgent action following smart science.
We fixed one, now let’s work on the other. Images from howstuffworks.com and Scientific American, respectively
The furor surrounding global climate change has been different in many respects. One of the main disparities is the speed at which the problems have become grave. Whereas we’ve been pumping large amounts of carbon dioxide into the atmosphere since the Industrial Revolution began in the late 1700′s, with only a gradual change in temperature, it was just a decade after the mass production of CFC-containing products that their chlorine molecules were shown to pollute the atmosphere, and the titanic damage to the ozone layer was recognized. That made it easier to pin the effect to the cause. Unusual warming was first noticed in the United States and North Atlantic in the 1930′s, but it wasn’t until 1960 that carbon dioxide levels were proved to be rising. But climate is a much more complex monster, and there is more than one factor at play.
Other factors affect global temperature, and we know that climate has changed over geologic history, without our influence. Volcanic eruptions, variations in solar radiation and the Milankovitch Cycles all play roles, but that really just goes to show how delicate the whole system is and how it’s easily nudged. We now know that solar activity has actually decreased over recent years, and ancient ice cores have shown us that the correlation between temperature and the atmospheric concentration of carbon dioxide is very strong. Better and better computer models of the chaotic system have been implemented as technology advances, and now a consensus of 97-98% of climate scientists agrees that global climate change is real, and produced by human beings.
WHAT DOES THIS MEAN?
It took us longer to prove human-induced change to the atmosphere in the case of global warming, and now that we’ve gotten there, the people who stand to lose out if measures are taken to halt it still deny, just like DuPont did into 1987. But even if the oil companies and others were on board, what could be done? The worldwide economy is much more dependent on the burning of fossil fuels, the largest contributor to the problem, than it was the use of fridges and spray cans. And then a less harmful substitute was easily found, whereas the research into alternate energy sources is splintered and slow-moving. Could we use some sort of agreement that forces us to drastically reduce our carbon dioxide emissions, akin to the Montreal Protocol? I mean something actually useful, unlike Kyoto? Would it even help? Some predictions show that even if all carbon emissions stopped today, we couldn’t naturally return to a pre-industrialization climate for a thousand years.
That all seems like a major bummer, but the ozone depletion parable has shown us that as good as we are at wrecking our future, we can also find ways to solve the problems we’ve created. It’s no longer in dispute that puny humans can affect serious changes, and now we also know that taking stringent and serious action can swing the pendulum back. It’ll take brilliantly creative technologies, but it’s not our ingenuity that’s questionable. It’s our commitment. We’ve come together to fix our screw-ups before. We’ll have to do it again. Do we need a “holy shit” moment to get our brains and asses into gear? Don’t brutal heat waves and superstorms fit that bill?
Much of the history of climate change research described here was taken from the wonderful American Institute of Physics resource at this location.