I'm a professor at U Michigan and lead a course on climate change problem solving. These articles often come from and contribute to the course.
By: Dr. Ricky Rood , 06:39 AM GMT on aprilie 25, 2012
Rhetoric Again - Cycles:
A few entries ago I wrote about the form of argument and the rhetoric used by those who advocate that the science of climate change is flawed in some fundamental and philosophical way (also here). In that piece I made reference to long-reaching metaphors and isolated facts that are used to create doubt about climate science. These metaphors and facts, for example that there was a lot of carbon dioxide when there were dinosaurs, create a stop or a pause in the conversation and pose as seeming contradictions and serve as distractions to make logically flawed points. For those who want to hone up on your arguments, I find the Marshall Institute’s Cocktail Party Guide to Global Warming some of the better coaching of anti-climate-science rhetoric.
I have been thinking about one of the common statements that is made, and that is the one about their being a lot of carbon dioxide when there were dinosaurs and, more generally, that there is a long record of cycles between times of high and low carbon dioxide in the Earth’s atmosphere. This has been presented to me many times, and I often wonder, what exactly is the point that is being made?
At first, when I heard statements that there was very high carbon dioxide in the past, it seemed to be with the implication that this was one, a natural occurrence and two, a fact that was being hidden by climate scientists. True, it is a natural occurrence. Any comprehensive text book on climate change will discuss the past variations in carbon dioxide and that there have been times when carbon dioxide was much higher, and the Earth was much warmer. It is not hidden, rather it is used to inform our future.
Following from the introduction into the argument that the high values of carbon dioxide in the past were a natural occurrence, there seemed to be two points. First, was that very high values of carbon dioxide were possible in the absence of human-responsible emissions and second, that changes in carbon dioxide amounts were beyond our control and hence there was little sensibility in reducing our emissions. There is the further implication that since this is natural then it is OK.
Our real concern about climate change is that climate change impacts humans. If it were not for the impact on humans, climate change would be a curious problem of natural science. When there was a lot of carbon dioxide and dinosaurs, there were no humans. That does not mean that with high carbon dioxide that humans can’t survive and that dinosaurs will return. However, getting from the stable temperate climate in which our civilizations evolved to a climate where the temperatures are several degrees warmer will be a disruptive path. There will be less land as sea level rises, and since there is a huge concentration along the coasts of the world, there will be huge relocation of people, disruption to nations, and loss of infrastructure. There will be enormous changes in ecosystems and domestic plants and animals.
So yes, there are cycles and there has been a lot more carbon dioxide in the air, but that has been in the absence of billions of humans, our built environment, and our fragile balances of nations and economies. It is the disruption of the fragile balances of human enterprise where the risk lies – so how does the fact that carbon dioxide was high when there were dinosaurs bear on the current concerns about increasing carbon dioxide and global warming?
Carbon dioxide was high in the distant path – does this suggest that carbon dioxide amounts in the atmosphere are beyond our control? Why was carbon dioxide high? Is that simply an unknowable mystery?
The composition of our atmosphere is determined by many factors. In the long term, my geologist friends always remind me that the composition of the atmosphere is determined by geology and the cycling of gases between the atmosphere and ocean and the solid Earth. This long time frame, millions or billions of years, is not exactly relevant to our human experience. On a shorter amount of time, like the ice age cycles, or the large amounts of carbon dioxide when the dinosaurs were present, biological processes are important for determining the composition of the atmosphere. We have benefitted from many millions of years when carbon dioxide and oxygen existed in a balance that support plants and animals. Those cycles, those extended periods of high carbon dioxide, are characterized by changes in balance of plant and animal life. They are characterized by the ocean taking up and giving back large amounts of carbon dioxide to the atmosphere through both chemical and biological processes.
So are we destined to simply be at the fate of these major shifts? Are these shifts beyond our control? Aren’t they natural?
Let’s get back to humans. There is little doubt that humans are the dominant life form on the planet today. We shape every ecosystem. We consume all forms of energy. Like the balances between plants and animals in the past we change the atmosphere and the ocean. Not only are we a dominant life form, we have this amazing ability to extract rocks and liquids and gas from the Earth and burn it. We have the ability to push around land, to make concrete, to remove mountains, and build islands. We are, therefore, not only biological, we are geological.
We are part of the cycle. We don’t simply exist at the mercy of the cycle.
So what is the point of a far reaching reference to the time of the dinosaurs and high amounts of carbon dioxide? Perhaps the point is to take us out of the equation, to absolve us of our responsibility to the planet, to allow us to do that which we want to do.
In the end this takes us to some very basic questions about humans and knowledge. I recently saw an idea attributed to Tim Flannery (also here), that humans are a species prone to destroying their future by destroying ecosystems. As I understand the argument, because of our intellect, we can continue to extract from the Earth resources beyond which a less creative species would be limited by brutal, natural barriers. We can rapidly cause extinctions. So far we can find and perhaps nurture new resources as we destroy the old.
We have this unique capacity of knowledge. We can place ourselves into our environment and see ourselves as shaping our environment, and have responsibility for maintaining our environment. We are not, entirely, at the fate of nature, or cycles, but we are part of nature, of cycles. And as such we might not be able to determine our future, but we are able to influence our future. We don’t have to be destined to destroy our future.
Scientifically, the statement of facts about cycles and high carbon dioxide millions of years ago has little bearing on whether or not we are burning fossil fuels, increasing carbon dioxide and warming the planet. Such presented facts are a diversionary part of a belief-based and politically based argument. Some advocates of the politically based arguments are trying to stop a societal response to carbon dioxide emissions. Other advocates are making a basic belief based argument that humans are somehow outside of biology and geology of the planet as a whole; that we are not just another age of some dominant life form. To me, what makes humans different is we have this ability to accumulate science-based knowledge, which is actionable, which imbues responsibility, which allows us to be different, and to sustain our future.
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