Monday, April 15, 2013
My wife and I recently returned from a vacation in Patagonia. One thing that struck me were the repeated reminders people in this southern South American region gave us to keep covered and apply sunscreen liberally.
The warnings came because the hole in the atmospheric ozone layer over in the southern hemisphere lets more of the sun’s harmful ultraviolet rays through. The result can be severe sun burns and increased risk of skin cancer.
I was struck by the fact people of Argentina and Chile must take account of a hazard in their everyday lives that humans unwittingly created. For me, it was another example of how the use of our atmosphere as a common waste bin threatens our wellbeing.
It illustrates what economists call the “tragedy of the commons.” No one owns the atmosphere, it is shared by all. So, people have the attitude they can do with it what they want and no one will blame them if they exploit it. “Get yours while you can, then walk away and deny there is a problem or that you are culpable,” the attitude goes.
How do you get people to acknowledge in a timely manner that a problem exist and a cooperative solution can be found to remediate the damage. This is especially difficult when the solution affects people with vested interests who engage in disinformation campaigns to spread doubt about the reality of the problem and where responsibility lies.
Fortunately, the ozone-hole problem was acknowledged and its cause understood. The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer restricted manufacturing such compounds as chlorofluorocarbons (CFC’s) and halons. Nations took the matter seriously and complied.
Now there is direct evidence the growth in the hole has been arrested. It was understood that some of the man-made ozone-depleting compounds the protocol targeted would take decades to dissipate from the atmosphere. But their decline has now been documented by atmospheric- and ground-based measurements.
It is certain humans caused the ozone hole and have the means to reverse the degradation. We must now take the step of acknowledging the reality of global warming. Only then can we begin remedial action.
There is no serious doubt human activities cause or, at the least, contribute heavily to global warming by pumping huge quantities of carbon dioxide into the atmosphere. Will the public face reality and take action as they did by restricting CFCs?
Solutions won’t be as easy as they were with the ozone hole. We could easily find alternatives to Freon and other compounds that were in our spray cans in the 1980s. Finding alternative energy sources to fossil fuels will be daunting, but the consequences if we don’t will be much graver.
Our planet has many natural feedback loops. They make for the relative stability that harbors the Earth’s current diversity of life. The loops are cycles, some occurring over hours while others play out over thousands of years.
There have been times the Earth was much warmer and colder than it is now. It reached those extremes before modern humans came on the scene about 200,000 years ago. Since then, we have had to adapt to a number of nature’s relatively milder cycles. But, since humans last dealt with climatic fluctuations of any consequence, we’ve developed complex civilizations and invested huge resources in making life comfortable.
Our more distant ancestors and other life forms have existed much longer and been subjected to more severe fluctuations. It is a given that every lineage of organism has experienced hardships in adapting. Those that survived did so because they had time to adapt as conditions changed.
This time, though, the pace of global warming is likely to cause massive extinctions. Perhaps it needn’t be so bad. Suppose, as some would argue with little evidence, we are not the sole cause of warming, that what we are experiencing is the warming side of a natural cycle.
But is it wise to do things we know make matters worse?
The culprits are greenhouse gases, principally carbon dioxide and methane. It is well understood how these gases trap radiations that would otherwise harmlessly allow heat from the Earth’s surface to escape into space. It is not unlike how a gardener’s greenhouse functions, hence the moniker, greenhouse gases.
Historic, natural releases of carbon dioxide, such as those accompanying volcanic eruptions, have been instructional in demonstrating the effects of these gases on the atmosphere and resulting climatic changes.
We also know how much carbon dioxide has been released from burning fossil fuels since the beginning of the Industrial Revolution. When comparing natural releases with what humans have released, and have the further potential of releasing, there is no doubt we are the driving force in the elevated concentrations of greenhouse gases.
We are in the process of releasing into the atmosphere carbon (as carbon dioxide) that has been sequestered below ground for hundreds of millions of years. If we find and burn the bulk of the coal, petroleum and natural gas that exists, we will create an atmosphere the Earth has not seen since sediments began burying the marshes, swamps and forests of earlier times.
So, if we know how global warming occurs, is there evidence for its actually happening? Again, the data is overwhelming. You need a large data base. You can’t cherry-pick a few locations and say, “Well look, it was cooler in these places.” You must look at long term planetary patterns.
Furthermore, we know what effects a warmer planet will have on weather patterns – hurricane frequency and strength, droughts, jet stream paths, wild weather fluctuations and the like. Weather pattern data seems to confirm temperatures are rising.
One often hears of a “tipping point” – the point where temperatures have risen to the extent that positive feedback loops initiate or accelerate the release of greenhouse gas stores. The tundra of Canada and Russia, for example, has vast quantities of methane trapped in permafrost. The permafrost is now thawing and release of those gases will ensue.
The oceans are a great reservoir of dissolved carbon dioxide. Their holding capacity is a function of temperature, with higher temperatures causing less carbon dioxide retention. Ocean currents that are the source of moisture for weather patterns are also affected by temperature.
Whether humans are the principle cause of global warming or whether we are accelerating and exacerbating a natural cycle is moot. If we don’t act to arrest warming we will not have a habitable planet for many of the organisms alive today.
If humankind survives, it will be under conditions that are much harsher than those that led the people of Argentina and Chile to be concerned about exposure to the sun’s UV radiation with its enhanced risk of developing skin cancer.
Steve Luckstead is a medical physicist in the radiation oncology department at St. Mary Medical Center. He can be reached at firstname.lastname@example.org.