This blog is an essay / analysis that follows from comments on both this blog and my blog on Wunderground.com .
The predictions of climate change provide us knowledge of the future. These predictions are not like those from a crystal ball; they are not magic. Neither are the predictions speculation nor are they opinion. The predictions are based on scientific investigation of the physics of the Earth’s atmosphere, ocean, land, and ice. The predictions include the role of chemistry and biology. There are uncertainties in the predictions, but the core of the predictions, that the Earth will warm, that sea level will rise, and that the weather will change is of little doubt.
The predictions are grounded, ultimately, in observations. The quest to explain the behavior of the observations and their relation to each other leads to the development of scientific hypotheses that are formed into theory. These hypotheses and theories are testable; they change with time; they are not speculation nor are they opinion. The theory can be expressed as mathematical expressions, and the mathematical expressions are solved to provide predictions. The collection of mathematical expressions which represent the theory are called models.
As representations of theory, models are both founded in observations and testable. The tests sometimes reveal that the models are fundamentally correct; sometimes they reveal that the models are incorrect. When a part of the model is incorrect, then attention is focused on observations, the further development of theory, the improvement of models, and the generation of new predictions. If the observations, predictions, and validation of the predictions form a coherent and convergent body of evidence, then the confidence is increased that the predictions are of sufficient accuracy to be actionable.
The models used to describe and predict the Earth’s climate have been evaluated and validated in many ways by many people. Of specific relevance, the models have been used to reproduce the variability of the observations of the past. The models are repeatedly tested with the modern set of observations that have evolved with the availability of satellites. Predictive experiments are carried out, and the predictions are evaluated with new observations. There have been useful predictions of the Earth’s climate for at least three decades. As we see the core of these predictions come true, the Earth is warming and sea level is rising, we substantiate the quality of the predictions.
The models can assist in the attribution of cause and effect. That is, if we observe a change in, for example atmospheric temperature, can we determine what caused that change? In many instances the convincing answer to that question is yes. In some cases it is difficult to attribute cause and effect. The observations, the theory, and the models lead to the conclusion that the Earth is warming and that a major cause of that warming is the increasing concentration of greenhouse gases in the Earth’s atmosphere. This increase is directly related to the activities of humans, and in particular, the combustion of fossil fuels: coal, oil, and natural gas.
If the warming does not directly follow from our combustion of fossil fuels, then we are left with a vast gap in our knowledge. If the warming is not a consequence of our changing the atmosphere, then we require the identification of missing mechanisms that are of a nature that defy our ability to observe. The existence of an unobserved or alternative explanation of the warming of the Earth is unlikely.
The existence of an explanation other than, primarily, human-made changes to the composition of the atmosphere is unlikely because the underlying physical principles are simple. At the foundation of the quantitative description of the climate is the conservation of energy. Specifically, the energy that exits the Earth to space balances the energy received by the Earth from the Sun. Otherwise, the climate of the Earth would not be stable. Humans do not change the principle of energy conservation; humans change how long the energy is held near the surface of the Earth. The physical principles that govern the climate of the Earth are simple. How energy flows through the atmosphere, the ocean, the biological creatures, and the chemical reactions is complex. This complexity challenges our ability to observe and the precision of our predictions, but it does not challenge the fundamental, simple physical principles that describe the Earth’s climate.
Scientific-based prediction of the climate produces knowledge of two types. There is a prediction of environmental parameters such as temperature and wind and moisture. There is also an estimate of the uncertainty of that prediction. To the scientist the estimate of the uncertainty is a measure of how probable it is that the prediction is accurate. Scientists often pursue the quest to reduce uncertainty, to make the predictions more accurate, and hence, more useful.
The science of climate change and the use of science-based predictions has, however, extended far from realm of science. If the predictions of climate change are fundamentally correct, then the change in the climate will impact every continent, every region, every nation, every person on Earth. If the attribution of climate change to the combustion of fossil fuels is correct, our use of energy and our economic success contribute directly to a changing climate. Therefore every component of human endeavor has a vested interest in the climate change problem. Therefore, every component of human endeavor has a vested interest in the predictions of environmental parameters and the uncertainties of those predictions.
Uncertainty will always exist in scientific investigation. It is part of the process. Investigation of complex systems will often lead to new sources of uncertainty. Challenging and re-challenging models and theory with observations will not uniformly lead to reduction or simplification of uncertainty. When the uncertainty is used in the development of arguments or policy that lie outside of the realm of science, the uncertainty can always be used to keep the argument or policy from converging. Always.
We have knowledge of how the climate will change. We know that this change will offer opportunity. We must evaluate that opportunity in context with our self interest and with regard to the risk. We know that this change will prove to be one of risk for many people. We have the responsibility, therefore, to act to reduce this risk.
Figure 1. This is a picture of a cypress knee on the shore of the Neuse River in eastern North Carolina. This picture was taken shortly after Hurricane Floyd in 1999. Hurricane Floyd stalled, and there was so much rain in North Carolina, that the mouths of the Neuse and Pamlico Rivers and Pamlico Sound were completely fresh water. I put the picture here because I recently came across it in my album and I thought it was pretty.