Wednesday, May 9, 2012

Why belief in CAGW (Catastrophic Anthropogenic Global Warming) is not currently justified by the standards of the scientific method

A post today at the Paths to Knowledge blog notes that belief in CAGW is not justified under the scientific method because no peer-reviewed study as ever falsified the null hypothesis that global warming is substantially natural. But, the reverse is not true. A recent peer-reviewed study has shown that the null hypothesis [warming is substantially natural] has a statistically significant higher probability of being true than the CAGW hypothesis. Therefore, belief in CAGW is not currently justified by the standards of the scientific method. The IPCC attempts and fails to falsify the null hypothesis using circular reasoning, as noted by Dr. Tim Ball:
Computer models are key to the IPCC circular argument. They’re programmed to the assumptions of the [CAGW] hypothesis, and therefore produce results that confirm the hypothesis. The problem is, nature hasn’t cooperated.
reblogged from Paths to Knowledge:

Posted by strategesis on May 9, 2012
Science does not deal in absolute proofs. The scientific method depends upon falsification of alternative hypotheses until only one remains.
But “falsification” in science is not absolute. Instead, it is a matter of relative probabilities. Such “proof” by falsification of all alternatives is never final: All scientific laws, theories and hypotheses forever remain subject to falsification at any time–at least in principle, even if the odds of that ever happening are infinitesimally small.
All that is required to falsify an hypothesis, or to falsify the currently-accepted theory, is for an alternative hypothesis to be shown–by empirical evidence and quantitative analysis of the relative probabilities–to have a statistically-significant higher probability of being correct.
The CAGW hypothesis is that a) The Earth’s climate is warming, b) The warming is substantially a result of human emissions of CO2 and, c) The magnitude of the warming will be enough to have significant effects, and d) The net effects of the warming will be harmful, and e) The harm caused by the warming will be great enough to be worth the net costs of politically-coerced mitigation.
The alternative hypothesis–which is also the null hypothesis (<= click the link for more info)–is that a) The warming is substantially due to natural causes for which humans are not substantially responsible, and/or b) The magnitude of any human-caused warming will not be not be great enough to have significant effects by itself (regardless of the effects of any warming not caused by man,) and/or c) The net effects of warming will not be harmfull–or if they are, then not by enough to be worth the cost of politically-coerced mitigation.
The null hypothesis has never been falsified. There have been no peer-reviewed studies published that quantitatively analyze both p(CAGW | Historical-Temperature-Data) [the probability that CAGW hypothesis is true, given the historical temperature data] and p(NullHypothesis | Historical-Temperature-Data) [the probability that the Null Hypothesis is true, given the historical temperature data], showing that the former (CAGW) has a statistically significant higher probability of being true than the latter (the null hypothesis–that warming is substantially natural.)Not one.
But the reverse is not true:
We evaluate to what extent the temperature rise in the past 100 years was a trend or a natural fluctuation and analyze 2249 worldwide monthly temperature records from GISS (NASA) with the 100-year period covering 1906–2005 and the two 50-year periods from 1906 to 1955 and 1956 to 2005. No global records are applied. The data document a strong urban heat island effect (UHI) and a warming with increasing station elevation. For the period 1906–2005, we evaluate a global warming of 0.58°C as the mean for all records. This decreases to 0.41°C if restricted to stations with a population of less than 1000 and below 800 meter above sea level. About a quarter of all the records for the 100-year period show a fall in temperatures. Our hypothesis for the analysis is, as generally in the papers concerned with long-term persistence of temperature records, that the observed temperature records are a combination of long-term correlated records with an additional trend, which is caused for instance by anthropogenic CO2, the UHI or other forcings. We apply the detrended fluctuation analysis (DFA) and evaluate Hurst exponents between 0.6 and 0.65 for the majority of stations, which is in excellent agreement with the literature and use a method only recently published, which is based on DFA, synthetic records and Monte Carlo simulation. As a result, the probabilities that the observed temperature series are natural have values roughly between 40% and 90%, depending on the stations characteristics and the periods considered. “Natural” means that we do not have within a defined confidence interval a definitely positive anthropogenic contribution and, therefore, only a marginal anthropogenic contribution cannot be excluded.

In other words, this study finds that the probability that the observed climate change is some combination of natural variability and urban heat island effect to be as high as 90%. That’s a very strong case in favor of the null hypothesis, and makes it extremely unlikely that there could be a 3-sigma difference in favor of the AGW hypothesis.

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