Warming of the climate system in the recent decades is unequivocal; nevertheless, there is no scientific proof to show that the greenhouse gases and human activity are the main causes of global warming and the debate is not over. Some relevant topics/criticisms about global warming, causes, consequences, the UN’s Intergovernmental Panel on Climate Change (IPCC), etc are putting up for discussion and debate:

1) All the greenhouse gases (carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFCs), hydro-fluorocarbons, including HCFCs and HFCs, and ozone) account for about a tenth of one percent of the atmosphere. Based on Stefan–Boltzmann law in basic physics, if you consider the earth with the earth's albedo (a measure of the reflectivity of a surface) in a thermal balance, that is: the power radiated from the earth in terms of its temperature = Solar flux at the earth's cross section, you get Te =(1-albedo)^0.25*Ts.*sqrt(Rs/(2*Rse)), where Te (Ts) is temperature at the surface of the earth (Sun), Rs: radius of the Sun, Rse: radius of the earth's orbit around the Sun. This simplified equation shows that Te depends on these four variables: albedo, Ts, Rs, Rse. Just 1% variation in the Sun's activity lead to variation of the earth's surface temperature by about half a degree.

1.1) Is the Sun's surface (photosphere layer) temperature (Ts) constant?

1.2) How much is the uncertainty in measuring the Sun's photosphere layer temperature?

1.3) Is solar irradiance spectrum universal?

1.4) Is the earth's orbit around the sun (Rse) constant?

1.5) Is the radius of the Sun (Rs) constant?

1.6) Is the largeness of albedo mostly because of clouds or the man-made greenhouse gases?

So the sensitivity of global mean temperature to variation of tracer gases is one of the main questions.

2) A favorable climate model essentially is a coupled non-linear chaotic system; that is, it is not appropriate for the long term future prediction of climate states. So which type of models are appropriate?

3) Dramatic temperature oscillations were possible within a human lifetime in the past. So there is nothing to worry about. What is wrong with the scientific method applied to extract temperature oscillations in the past from Greenland ice cores or shifts in types of pollen in lake beds?

4) IPCC Assessment Reports,

4.1) "What is Wrong With the IPCC? Proposals for a Radical Reform" (Ross McKitrick):

https://www.thegwpf.org/images/stories/gwpf-reports/mckitrick-ipcc_reforms.pdf

IPCC has provided a few climate-change Assessment Reports during last decades. A few glaring errors have already occurred in their comprehensive reports, like melting Himalayan glaciers by 2035. Is a radical reform of IPCC necessary?

4.2) The sort of problems typical of IPCC reports:

- The summary reports focus on those findings that support the human interference theory.

- Some arguments are based on this assumption that the models account for all sources of variation in the global mean temperature anomaly.

- "Correlation does not imply causation", in some Assessment Reports, results gained from correlation method instead of investigating the downstream effects of interventions or a double-blind controlled trial.

4.3) Nongovernmental International Panel on Climate Change (NIPCC) also has produced some massive reports to date.

4.4) Is the N/IPCC a scientific or a politically biased panel? Can N/IPCC climate reports be trusted?

4.5) What is wrong with their scientific methodology?

5) Changes in the earth's surface temperature cause changes in upper level cirrus and consequently radiative balance. So the climate system can increase its cooling processes by these types of feedbacks and adjust to imbalances.

6) What is your opinion about political intervention and its effect upon direction of research budget?

Here are some Al Gore's comments about climate change as the former US Vice President:

- Humanity may have only 10 years left to save the planet from turning into a total frying pan (2006)."

- The Arctic would be ice-free by summer of 2014.

- The flow of the Gulf Stream would be slow down leading to climate catastrophe.

- Polar bears are in danger of extinction.

- Sea levels would rise by as much as 20 feet in the near future.

I really appreciate all the researchers who have had active participation with their constructive remarks in these discussion series.

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Link to the discussions of Global Warming (Part 1):

https://www.researchgate.net/post/Global_Warming_Part_1_Causes_and_consequences_of_global_warming_a_natural_phenomenon_a_political_issue_or_a_scientific_debate

Link to the discussions of Global Warming (Part 3):

https://www.researchgate.net/post/Global_Warming_Part_3_A_growing_threat_or_nothing_to_worry_about_An_effect_of_greenhouse_gases_or_a_natural_climate_change

Link to the discussions of Global Warming (Part 4):

https://www.researchgate.net/post/Global_Warming_Part_4_Causes_and_consequences_of_global_warming_a_natural_phenomenon_a_political_issue_or_a_scientific_debate