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It seems to be the case that 1C of global heating caused the whole global temperature bell curve to shift two standard deviations to the right. (see below)

To anyone knowing much about statistics and bell curves this would seem to make the 80 years BAU 5C temperature anomaly have the drastically lethal consequence of much more frequent heat waves greatly exceeding the 44C maximum human survival limit.

My own projections of the current trend are a little more pessimistic than IPCC RCP8.5 projections. They simply extrapolate the current exponential increase of atmospheric CO2 and project 877 PPM by 2100 then apply the current IPCC equilibrium CO2 sensitivity formula

3C ± 1.5C for every doubling of atmospheric CO2
log2(877/280) * 1.5 = 2.47
log2(877/280) * 3.0 = 4.94 // Business as usual for 80 more years
log2(877/280) * 4.5 = 7.41

​​​​https://www.giss.nasa.gov/research/briefs/hansen_17/
When we examine this graph we see that a single degree of temperature anomaly is associated with a shift of the whole temperature bell curve two standard deviations to the right.

enter image description here

If we hypothesize that a single degree of temperature anomaly directly caused the entire bell curve to shift the right two standard deviations then the consequences of a 5C would seem to be quite lethal.

Once we numerically quantify the relationship between temperature anomaly and shifts of the bell curve then we would be able to apply this to historical geographical temperature extremes and predict the frequency, geographic and temporal extent of heat waves that would kill everything within their boundaries.

This relationship seems to predict that the 5C temperature anomaly projected from "business as usual" for 80 more years could reasonably result in 60C (140F) killer heat waves. A 60C heat wave will kill everything in its path very quickly. Apparently humans cannot survive 44C for very long.

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  • $\begingroup$ Idk what a killer heat wave is, but on a statistical level there definitely is a connection between heat waves and mortality. Several publications exist on the matter, attributing many hundreds of deaths per country for the past heat waves. Humans can survive high temperatures when they drink a lot and don't work hard. $\endgroup$
    – user18411
    Dec 17, 2019 at 0:09
  • $\begingroup$ @ebv The key question that I am asking is does the fact that a 1C temperature anomaly seemed to have moved the whole temperature anomaly bell curve to the right by two standard deviations indicate that a 5C temperature anomaly may cause temperature extremes greater than 50C? (no possible human survival at 50C). $\endgroup$
    – polcott
    Dec 17, 2019 at 0:16
  • $\begingroup$ The assumption here is not including any other cycle to get involved to 'remove' or balance heat effects that increase to the extreme. For instance, increased cloud cover from the heat would increase cloud cover and rainfall as an 'air conditioning' event much like what is experienced in tropical regions. Also, if less cloud cover is not happening, then in the evening, much of this heat would escape to space and temperatures would drop below 60F in the evening as they do in the desert. Having living in both types of climates, daytime heat often balances by what happens in the evening. $\endgroup$
    – J. Kaciulis
    Dec 17, 2019 at 3:02
  • $\begingroup$ @J.Kaciulis All that I am focusing on it that when a 1C temperature anomaly causes 3 sigma events to occur 10% of the time instead of 0.13% of the time. I don't know how this extrapolates to a 5C anomaly, I only know its not good, it is probably very bad. bbc.com/news/world-australia-46859000 $\endgroup$
    – polcott
    Dec 17, 2019 at 3:49
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    $\begingroup$ @Fred I already have good numbers on human survivability from NASA. In very low humidity a human can survive for an hour @ 60C very high humidity a human can survive less than 10 minutes at 50C. nib.com.au/the-checkup/healthy-living/… $\endgroup$
    – polcott
    Dec 19, 2019 at 4:36

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Neither an answer, just common sense.

Not sure if anybody can give exact numbers for temperatures of future heat waves in their projections. Predictions are difficult, especially those regarding the future. But there is consensus and now observation that heatwaves become more frequent and hotter not only on land. One could perform a search for publications that deal with the impact of land heatwaves, e.g. on agriculture (wheat for example), desertification, loss of habitable space, flooding, loss of resources like potable water, etc. There is a lot of published work around.

We went past the 1°C warming compared to pre industrial levels in 2015, after [https://www.ncdc.noaa.gov/cag/global/time-series] and many publications. Current estimations range between 0.9 and 1.6°C for 2019. Several islands have been devastated in the past years, damage still not totally repaired. Jakarta is drowning, catastrophic fires in California, Australia and elsewhere, fed by drought, heat and mismanagement, cost lives and property.

The effect of past and current heatwaves on the health of the population is pretty well visible, western European countrie's and the US health departments have published their estimations of fatalities attributed to heat.

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  • $\begingroup$ I am trying to provide the best information available on the worst possible adverse consequence on global heating. Prior to Greta I only was aware of sea level rise and really didn't care if some cities would be under water within a thousand years. On the other hand if we start having 100 square mile heat waves that kill everything in sight in less than five minutes and this will happen by simply continuing "business as usual" for 80 years, then I am sufficiently alarmed that we must fix this now, no matter how much it costs. $\endgroup$
    – polcott
    Dec 18, 2019 at 18:30
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    $\begingroup$ Maybe you find some relevant information: duckduckgo.com/…. Skip over the tabloid style stuff. It always good not to concentrate on a single work (that's from 2012 anyway). $\endgroup$
    – user18411
    Dec 18, 2019 at 20:13

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