I think it is a normal significance test, I f the difference between two random variables is less than about two standard deviations, it can be seen as insignificant. For lower differences, the probability of equal values decreases, i.e. the significance of a difference increases (see statistical test theory).

Thanks everybody,

I am confused with statement "standard deviation" and the colours indicating the number like +5% or -5%.

Someone can help me to predict rainfall by 2100 under RCP8.5 if observed rainfall (1986-2010) was about 1,600 mm ?. Say intended regions assume shaded by light blue color (-5%)

Ken

Your 200 years are in reality 50 years

and an increase of 1 degree Celcius (actually 0.8 C) is a huge number for such a short period: in the little ice age the estimated temperature decrease was of that order

Ken

Climate Change is by definition not concerned with "absolute temperatures"

it is change=difference=anomaly with respect to a reference period

I asked you before how an absolute global temperature could be defined

actually not a question. Change is the average of the difference of the temperatures at the global measuring stations. That is the only parameter that can be fully defined

Ken

I just mentioned the pure scientific climatological approach to define a change for the research community

"people" can get a popular idea of the average temperature via the 15 C

question to you is that 15 C corrected to sea-level? mind you; every 100 m in altitude means a decrease in temperature between say 0.8 to 1 C. in between wet and dry lapse rate

The assertion by IPCC that CO2 is a problem is wrong.

CO2 does not now, has never had and will never have a significant effect on climate. Here is why.

 1) Essentially all absorbed outgoing longwave radiation (OLR) energy is thermalized.

2) Thermalized energy carries no identity of the molecule that absorbed it.

3) Emission from a gas is quantized and depends on the energy of individual molecules.

4) This energy is determined probabilistically according to the Maxwell-Boltzmann distribution.

5) The Maxwell-Boltzmann distribution favors lower energy (longer wavelength) photons.

6) Water vapor exhibits many (170+) of these longer wavelength bands.

7) The Maxwell-Boltzmann energy distribution in atmospheric gas molecules effectively shifts the OLR energy absorbed by CO2 molecules to the lower energy absorb/emit bands of water vapor. The ‘notches’ in top-of-atmosphere measurements over temperate zones demonstrate the validity of this assessment.

8) As altitude increases (to about 10 km) the temperature declines, magnifying the effect.

The only thing countering the temperature decline that would otherwise be occurring is the increasing trend in water vapor. (‘Otherwise’ results from declining net effect of ocean cycles since 2005 and declining solar activity which has been declining since 2014  and dropped below 'breakeven' in early 2016). Average global atmospheric water vapor has been measured and reported by NASA/RSS since 1988 and shows an uptrend of 1.5% per decade. WV has increased about 8% since the more rapid increase began in about 1960. This is more than 2.5 times the expected rate from temperature increase alone (feedback).

 Further discussion of this with graphs and links to source data are at http://globalclimatedrivers2.blogspot.com which also identifies the factors which do cause climate change (98% match 1895-2016).

 The warmer temperature is welcome but the added WV increases the risk of flooding. IMO all rainwater retaining systems (dams, dykes, etc.) should be upgraded from 100 yr floods to 10,000 yr floods.