In Summary
To summarize, Earth’s climate is amazingly, mind-blowingly complex and science has only just begun to figure out how it works. While our theoretical knowledge improves and our data become more accurate with each passing year, it is safe to say that there is still more we don’t know about climate change than things we think we understand. Here are some fundamental questions about the state of Earth’s climate:
- Is Earth’s climate warming? Yes, by around 1¬∞C (1.8¬∞F) during the 150 years leading up to the present.
- Do human activities impact the climate? Yes, all numerous and widespread species do to some extent (see the concluding remarks of “What Killed The Mastodons?“).
- Do atmospheric CO2 levels rise and fall with temperature? Yes, according to historical data.
- Are atmospheric CO2 levels rising because of people? Yes, it would appear so.
- Does this mean that the theory of anthropogenic global warming is correct? Absolutely not.
For the reasons given in the article above, and those described in greater detail in The Resilient Earth, I have concluded that science does not understand the climate system well enough to make the predictions that climate change alarmists keep making. Scientists continue to argue about fundamental mechanisms and the accuracy of historical data. In the absence of better theoretical knowledge and sufficient accurate data, climate scientists have filled the void in understanding with output from computer models, which are the most fickle and fallible of tools.
Consider the following main points:
- Climate is a nonlinear system.
- Not all feedback relationships are known or well characterized.
- Based on known empirical evidence a doubling of atmospheric CO2 levels will only cause a further increase of 0.2 to 0.5°C in global temperature.
- In order to achieve the temperature levels predicted by the IPCC requires amplifying positive feedback from the climate system.
- There is no compelling proof that Earth’s climate system acts as a temperature change amplifier.
- Not all known factors are included in climate models.
- Models cannot predict nonlinear responses not built into them.
- Baseline data used to calibrate the models are uncertain and possibly erroneous.
- Different climate models predict different future outcomes because they make different assumption or use different values for model parameters.
- All climate models contain errors that are fundamental to their construction.
In the wake of Climategate and Glaciergate it is tempting to dismiss the theory of anthropogenic global warming as bogus science foisted off on a gullible public by a number of bad scientists. The reasons for this climate science chicanery are not clear: the torrent of grant money, the novelty of fame or simply error amplified by ego. As entertaining as the news accounts of unfolding scandal have been, it is important to remember that many serious scientists believe in human caused global warming to one degree or another. But science is a human endeavor and as prone to mistakes as any other. This will not be the first time that a majority of the scientific community believed in an erroneous theory, and it certainly will not be the last. Eventually, science will decide the fate of AGW based on empirical evidence—nature itself will provide the proof, one way or the other.
To date, climate science has not produced any incontrovertible proof that rising CO2 levels will, in fact, cause the temperature increases predicted by GCM models. The information presented above reinforces the observations I made in my earlier post, “The Crumbling Pillars of Climate Change.” The theoretical understanding is incomplete, the historic data are spotty and uncertain, and the models are not an accurate representation of the climate system. Further, models have been used inappropriately to bolster the IPCC’s case—models are not scientific evidence and should not be used to predict long-term real world behavior.
The truth is, climate science uses computer models like a drunk uses a lamppost, not for illumination but for support. Even AGW supporters agree that if the only evidence for global warming were computer models, then skepticism would be entirely justified. But, while models are most definitely a sore point in the global warming debate, they are not the central point. It is the science itself that is uncompelling. Neither current scientific knowledge nor historical data prove the theory of anthropogenic global warming as put forth by the IPCC. If anything, new data and new studies reveal that current climate change dogma has got it very wrong. That is why I remain a global warming skeptic.
Be safe, enjoy the interglacial and stay skeptical.