To get things started, here is my post to the KYGeologist listserve 11/12/08...
The topic of global warming suggests three main lines of questioning:
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What is global mean surface temperature? How is it determined (especially over geologic time)? Is it increasing?
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What factors contribute to climate change?
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Can we humans do anything about climate change?
It seems the question receiving the most attention concerns climate stressors and whether human activity, carbon emissions and the like, is a significant contributor to the changes observed in the last few centuries. Rather than scientific, the answer has become a political battleground between conservative right Republican ideologues who tend to favor business as usual solutions (don’t do anything that is "bad for business") and oppose the claim of climate forcing by human activity and the liberal left Democratic “tree huggers” (summary dismissal implied).
To address the global warming issue, the factors that contribute to climate change should be clearly identified. Those factors of which I am aware include:
- External
- Milankovitch Cycles (effects the amount and distribution of the available solar energy across the surface of the Earth)
- Orbital eccentricity (change in the shape of the orbit between more elliptical and more circular configurations)
- Precession of the equinox (the major axis of the elliptical orbit changes orientation about the Sun with respect to the background stars)
- Axial tilt (the “wobble” of the Earth’s rotational axis)
- Solar cycles (sunspot cycles, effects overall luminance of the Sun and therefore the amount of radiant energy emitted)
- Impact events (comets and asteroids, effects particulate and aerosols in the atmosphere, their volume, Earth’s albedo, cloud cover, integrity of the ozone layer, and others)
- Internal
- Plate tectonics
- Number and distribution of continental land masses (ocean and wind circulation patterns)
- Number, distribution, and activity of volcanoes (heat transfer from mantle to surface and atmospheric effects: particulates, aerosols, natural emissions of H2O, H2S, CO2, etc.)
- Natural emissions of green house gases (primarily CO2 and CH4)
- Swamps and wetlands (biomass decay)
- Biomass (respiration, transpiration, flatulence)
- Volatile organic carbon seeps (oil and gas springs)
- Human activity
- Fossil fuel extraction and combustion
- Agricultural practices
- Clear cutting, slash and burn
- Large-scale animal husbandry for food production (feed lots, CH4)
- Urbanization (large concentrations of concrete storing and radiating heat and the accumulation of aerosols and particulates [smog] are creating climate islands that can change weather patterns locally and in the surrounding terrains)
“Confirmation bias” can often cloud thinking. It is a common bias whereby persons tend to seek and accept those data and positions that confirm the notions they already hold, effectively an ideological inertia. With that in mind, intellectual honesty impels me to state clearly that I favor the data and arguments that support anthropogenic forcing of global climate change.
At the forum, I was surprised that several lines of evidence concerning the natural climate variations through geologic time were not addressed. Dr. Patterson presented an effective argument for solar cycles but didn’t show how those cycles affected temperature changes over geologic time. I thought his argument would have been stronger had he included the Milankovitch cycles and other external factors. He built his argument in support of solar cycles and as his best example presented a figure showing the global temperature curve in lock step with the solar cycle data.
Dr. Cuffey presented a case that followed the main climate model-based lines of reasoning documented by the IPCC. The main weakness of this argument is that the predictive climate models are relatively opaque. With only the output of the models presented in graphs and charts, the underlying assumptions and math are not generally accessible. For persons not directly involved in the modeling and climate science, the whole thing kind of has to be accepted on the faith that the experts know what they are doing. The most effective point he made was to show the exact same graph that Dr. Patterson presented earlier (showing the correspondence between solar cycle and temperature). Dr. Cuffey showed the caption published with the figure, however. That caption indicated the correlation illustrated in the figure worked because the current “linear” global warming trend had been subtracted from temperature data.
The important point is that the mean global temperature is increasing at a rate that appears inconsistent with predictions based on solar cycle data (and the solar cycle data were not demonstrated to match the paleoclimate record over a significant span of geologic time). Looking at the factors that influence climate change, I have to assess both the significance of particular factors and whether their effect has changed recently in measurable ways. My conclusion is that human activity is a significant contributor to the observed warming trend. I’m not saying it is the only factor, but, as difficult as changing human behaviors might be, that kind of change is at least possible. Renewable energy, fuel switching, nuclear and the like are doable strategies. So, while my position could be attributed solely to a confirmation bias, I believe, given the evidence presented by the panel, the anthropogenic cause of warming argument was strongest (based on the mistake of a single slide).
The elephant in the room of all debates about the problem and potential solutions is the human population. This elephant must be both invisible and a mime as no one seems seriously to consider the question.
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