Australia has, for a number of years, been something of a natural laboratory for the study of both melanoma and non-melanoma (NMSC) skin cancer. The pertinent facts for this post are:
Australia has the highest rate of skin cancer in the world. Invasive melanoma (as opposed to superficial spreading melanoma ), while the most life threatening, is the least common form of skin cancer. About 68,130 new cases of invasive melanoma are diagnosed in the US each year; around 10,300 new cases of invasive melanoma are discovered in Australia annually.
Australia's population is seven percent the size of the US but they experience fifteen percent as many cases of melanoma annually.
These cancerous growths develop when unrepaired DNA damage to skin cells (most often caused by ultraviolet radiation from sunshine or tanning beds) triggers mutations that lead the skin cells to multiply rapidly and form malignant tumors.
Australians are four times more likely to develop a skin cancer than any other form of cancer.
Approximately two in three Australians will be diagnosed with skin cancer before the age of 70.
The cause of this phenomenon is well known. Australia sets directly below an area of the Earths atmosphere where the ozone layer has been depleted.
By now you might be wondering why I am writing about cancer since my science posts are almost always about climate change. The reason is this; the United States is posed to join Australia as an area receiving significantly higher than normal levels of ultraviolet (UV) radiation and those higher levels will be the result of climate change. For you science fans UV radiation is that portion of the electromagnetic spectrum that falls between x rays and visible light, i.e., between 40 and 400 millimicrons (mm). UV radiation is important to us because, in it's very shortest range (next to X-rays), it is capable of ionizing atoms greatly changing their physical behavior. More importantly, at the middle range of UV radiation it’s rays cannot ionize but can break chemical bonds, causing molecules to be unusually reactive. Sunburn is a good example of damage caused by the disruptive effects of middle range UV radiation on skin cells. UV rays in the middle range can irreparably damage the complex DNA molecules in the cells producing thymine dimers (a pair of abnormally chemically bonded adjacent thymine bases in DNA) resulting from damage by ultraviolet irradiation. The cellular processes that repairs these lesions often creates errors that create genetic anomalies making it a very potent mutagen.
Typically, we are protected from most UV radiation entering our atmosphere by a layer of ozone (O3) in the stratosphere between about 6 and 31 miles above the earth. Somewhat more than ninety-seven percent, of mid-range UV radiation (almost all UV above 280 mm and most above 315 mm) is blocked by the ozone layer. Ozone is additionally important to life since it also extends the absorption of UV by ordinary oxygen (O2) and nitrogen (N) in air (which absorbs all wavelengths less 200 mm) through the lower UV-C (200 mm-280 mm) and the entire UV-B band (280 mm 315 mm). Don’t worry about the -C and –B designations. They are not important to this discussion.
James G. Anderson, the Philip S. Weld Professor of Atmospheric Chemistry at Harvard University and a team of researchers announced in the July 27 issue of Science that a newly discovered connection between climate change and depletion of the ozone layer over the U.S. could allow more damaging UV radiation to reach the Earth's surface, leading to an increased incidence of skin cancer in the United States, an increase possibly as high as that seen in Australia.
To understand Dr Anderson's findings it’s helpful to know a little about the recent history of ozone depletion research in the Arctic and Antarctic regions. Until the late 1980s scientists thought that Antarctic ozone depletion was the result of ice crystals being injected into the ultra cold air of the stratosphere. Then, by using the Lockheed U2 spy plane, an aircraft capable of flying at altitudes of up to a little over 13 miles, scientists discovered that the culprits really were chlorine (Cl) and bromine (Br) fragments caused by a concentration of chlorofluorocarbons (CFC), halons and methyl bromides (MeBr) which, when combined with ice crystals (H2O), created a chemical reaction capable of changing normally non-reactive chlorine atoms into free radicals (an atom, molecule or ion with unpaired electrons or an open shell configuration). These unpaired electrons bond quickly with other atoms causing free radicals to become highly chemically reactive atoms capable of attacking ozone.
They then turned their attention to the Arctic where the air in the lower stratosphere is slightly warmer. They expected to find conditions similar to what they found in Antarctica; they didn’t. Instead, they discovered that ubiquitous, cold sulfate (SO4) water (a naturally occurring compound and a major component of rainwater) was all that was needed to convert non-reactive chlorine into a free radical form. This opened the door to a disturbing realization. It suggested that O3 depletion would happen anywhere on the globe where storms injected sulfate water into the deep stratosphere.
Now, their focus changed from looking almost exclusively at the chemistry involved to considering climate. They started by studying how the convective clouds, updrafts that cause storms to build high into the sky, contributed to the creation of cirrus clouds. "It was in the process of looking at that mechanism that we came to this unexpected observation, that the convective clouds in these storm systems over the U.S. (were) reaching far deeper into the stratosphere than we ever expected," Anderson said in a recent interview. They also learned that the temperature at which the chemical conversion of inorganic, or stable, chlorine into its free radical evil twin could be considerably lower than previously encountered. Essentially, Dr. Anderson and his team found that as you increased the concentration of water vapor in the stratosphere you also increased the “threshold temperature” at which the conversion of chlorine could occur. Stated another way, the more water vapor we force into the stratosphere the warmer the temperature and the lower the altitude at which chlorine conversion and ozone depletion will occur. Since there is a lot more warm air over the Earth than cold, the conclusion to be drawn is we can expect to see more frequent and more extensive ozone destruction. Dr Anderson added that, “If the amount of water vapor and the temperature over the U.S. satisfies the conditions for rapid conversion of inorganic chlorine to its free-radical form, we've got a real problem, because the chemistry is identical to what we previously demonstrated is taking place over the Arctic." It's important to note here that this is not a conclusion based on theory or climate modeling; this is a prediction based on direct observation.
Dr Anderson acknowledged that it was impossible to state with certainty where this process will lead. Simply stated, scientists just don’t have a collection data on the result of water vapor injection into the stratosphere over time. He was willing to say, however that, “If you were to ask me where this fits into the spectrum of things I worry about, right now it's at the top of the list. What this research does is connect, for the first time, climate change with ozone depletion, and ozone loss is directly tied to increases in skin cancer incidence, because more ultraviolet radiation is penetrating the atmosphere." There is, none the less, a hint of where this is headed to be found in the ever strengthening scientific case that adding more and more CO2 to the atmosphere is driving climate change and driving more frequent and stronger storms. "In my mind, this is not just a broad public health issue," Anderson concluded. "This is about actually being able to step out into the sunlight – it's about your children and your children's health. Of course, we don't know how rapidly the frequency and intensity of these storms will increase so we can't place a time scale on this problem but the core issue here is quite straightforward and simple because we understand the chemistry."
Sadly, this story doesn't end here. There is the future issue of potential genetic damage to crops such as corn, wheat, rice and soy. All known living organisms depend on DNA for instructions on replication. If the DNA is damaged mutated crops will develop and we have no idea what form those crops will take. Add that to the devastation we are already seeing from climate change induced droughts and extended abnormally hot temperatures and we have a scene that could be directly out of science fiction but it's not fiction. In Australia, a variety of fish including, fifteen percent of trout living near the Great Barrier Reef, were found to have lesions similar in appearance to human melanoma. Melanoma in dogs and horses is relatively common. Studies on animal melanomas are presently ongoing but research by the National Center for Biotechnology Information suggests that some animal melanomas are more indolent than those found in humans. Why this is could potentially point to new directions for the treatment of human melanomas but much more study needs to be done here.
I've presented a good deal of fairly technical information here but I've done that because it's critical that we see just how complex interactions in nature are, how little we know about them despite our technological advances and the magnitude of damage we do when we mess with forces we don't understand and then deny that what ensues is our fault.. It's also critical that we understand that time is running out. Like it or not, there is a tipping point, a window of opportunity that is closing and once closed we won't be able to open it again. Our children and our grandchildren for generation to come will just have to live with the consequences.
On the other hand, if you are one who believes, as Exxon Mobil CEO Rex Tillerson does, that global warming is just an engineering problem and it has engineering solutions or you are one of the paleoconservative religious righters who believe the problem can be prayed away, then you better look over your shoulder; global disaster is chasing you and it's gaining on you. You'd better start engineering and praying with a vengeance. There isn't a moment to spare.
Resources for this article include:
Researchers find link between climate change, ozone loss and possible increase in skin cancer incidence in Phys.Org at:
Fish with Melanoma - Our Enduring Environmental Legacy in Scientific American at:
Animal-type melanoma: a clinical and histopathological study of 22 cases from a single institution in NCBI at:
Note: In my writing I use the term millimicron (1 metre is equal to 1,000,000,000 millimicrons) because it’s the term that was in use when I first studied this stuff. The currently accepted term is Nanometer (nm)
Historical Note: In the late 1970s, scientists began to realize that chlorofluorocarbons, or CFCs, were making their way into the stratosphere causing a chain reaction that turned UV-blocking ozone into oxygen. By 1987, there was so little protective ozone in the stratosphere over Antarctica that global lawmakers decided CFCs were too dangerous to go unchecked. They established the Montreal Protocol, which set strict limits on the use of CFCs. In the 25 years since, the ozone layer has rebounded some, but it is still 50 to 70 years away (even in the absence of climate change induced, additional damage) from returning to pre-1980s levels.
This may be the only time in modern history when governments recognized a life-threatening problem and, since at that time profits from CFCs were not sufficient to buy those governments, effected truly corrective measures. Thanks to men like Senators Jim Inhofe (R-Big Oil, Chamber of Commerce and Anti EPA Forces), Joe Barton (R-Big Oil, Chamber of Commerce and BP Apologist) and Joe Manchen (D-Big, Coal Chamber of Commerce and Dirty Air Enthusiasts) it's unlikely to happen again
Unfortunately, other substances now beginning to contribute to heat retention are perflurocarbons (PFC) and hydroflurocarbons (HFC), both compounds introduced to replace chlorofluorocarbons, and sulfur hexafluoride (SF6). PFCs and HFCs are warming agents on the order of methane (CH4), about thirty times as potent as CO2, but they exist in much smaller quantities than carbon dioxide or methane, for now.
Not So Historical Note: If you found this article interesting you can see more pf my posts on climate change at my blog, The Last New Dealer at http://rodgzblog.blogspot.com/