ANTHROPOGENIC GLOBAL WARMING AND CLIMATE CHANGE

AGW 101

The first seven paragraphs are derived from a blog post by Dr Roy Spencer, Climate Scientist, University of Alabama, Huntsville  [LINK TO SOURCE DOCUMENT]

1. The temperature change in the climate system is the result of an imbalance between the rate of energy gain and the rate of energy loss. The current warming since the Little Ice Age is thought to be due to the small (~1%) imbalance between absorbed sunlight and infrared energy lost to outer space averaged over the whole of Earth’s surface. 
2. AGW theory attributes this imbalance to increasing atmospheric CO2 from fossil fuel burning. This attribution is arbitrary because it has not been shown that the climate system, without fossil fuel emissions, is in a natural state of energy balance.
3. The energy imbalance is too small to be directly measured. We cannot measure the amounts of absorbed sunlight and emitted infrared energy across the Earth’s surface with sufficient precision to determine that the current warming is unnatural and therefore artificial. Therefore the objective and rational conclusion is that we do not know whether the post LIA warming is natural or artificial. 
4. Current best estimates of this energy balance is 239 to 240 Watts/m2 for these energy flows coming in and going out. In early climate models these global-average energy flows in and out of the climate system did not balance requiring the model programmer to adjust the uncertain processes such as cloud effects until a balance was achieved. 
5. In later models, the infrared radiative effect of increasing CO2 was added; and that did create an energy imbalance in the model and therefore global warming. This refinement of the model that could explain the observed warming was then taken as evidence of artificial cause now stated as anthropogenic global warming or AGW. 
6. This attribution is form of circular reasoning and the so called Texas Sharpshooter Fallacy because a theory derived from the data cannot be tested with the same data. The attempt to overcome this weakness in AGW theory with the “fingerprint” argument has no scientific basis. It is not possible for the the current warming to have a fingerprint of human cause because warming looks exactly the same regardless of cause. If a natural decrease in marine cloudiness, or a decrease in ocean overturning were driving the observed warming, it would still be larger over land than ocean, greater in the upper ocean than deep ocean, and greatest at high northern latitudes and least at high southern latitudes. These properties of warming are not a fingerprint of human cause.
7. The causation sequence from emissions to rising atmospheric CO2 and from rising atmospheric CO2 to energy imbalance, and from energy imbalance to warming are plausible but their plausibility establishes only possibility and not proof.
8. Proof, if any, in this circular reasoning logic, requires, as a minimum, that certain relationships must be shown to exist in the data. For example, it must be shown in the observational data outside of climate models that (a) atmospheric CO2 concentration is responsive to emissions and (b) that global mean surface temperature is responsive to atmospheric CO2 in consistent relationships that are statistically significant.
9. The relationship between emissions and atmospheric CO2 is tested in a related post at this site [LINK] . No evidence is found that atmospheric CO2 is responsive to the rate of emissions. An investigation of the mass balance for this relationship is presented in another related post at this site [LINK] .
10. The proposed relationship between atmospheric CO2 and surface temperature is tested in related posts at this site. These tests show instability and uncertainty in the data [LINK] [LINK] . An uncertainty problem in this theoretical relationship in observational data is acknowledged by climate science [New, Mark, and Mike Hulme. “Representing uncertainty in climate change scenarios: a Monte-Carlo approach.” Integrated assessment 1.3 (2000): 203-213], [Stainforth, David A., et al. “Uncertainty in predictions of the climate response to rising levels of greenhouse gases.” Nature 433.7024 (2005): 403], [Anderson, Barry, et al. “Uncertainty in climate change modeling: can global sensitivity analysis be of help?.” Risk analysis 34.2 (2014): 271-293]. These uncertainties imply a failure of the equilibrium climate sensitivity model of the energy imbalance.
11. Evidence for the failure of the climate sensitivity model is also seen in the post hoc and arbitrary attempt to explain climate sensitivity mis-match in the data in terms of ocean heat content [LINK] and the need to move from climate sensitivity to the Transient Climate Response to Cumulative Emissions (TCRE)  [2017: Knutti, Reto, Maria AA Rugenstein, and Gabriele C. Hegerl. “Beyond equilibrium climate sensitivity.” Nature Geoscience10.10 (2017): 727] .
12. Yet the move to the TCRE and the use of the TCRE to construct cumulative emissions carbon budgets for climate action reveals even greater weaknesses in climate science as it has been shown in a related posts at this site that the TCRE is illusory because it is based on a spurious correlation [LINK] [LINK] [LINK] .