Atmospheric Residency & Oomph (part 1)

A quick look at the HADCRUT5 global mean annual temperature anomaly and human emissions over the last 170 years

So far I’ve been focusing on my home-spun UK34 data series obtained from a handy Met Office resource, which may be found here. In the previous article we noted how well just 34 UK stations tracked the CRUTEM5 state-of-the-art northern hemisphere land surface temperature anomaly, revealing that the crew at CRU have somehow artificially cooled the period 1932 – 1961 (presumably to make the rate of post-WWII warming look big and beefy). Today I fancied going really big and globally bold and pulling down the HADCRUT5 global land and sea surface temperature anomaly and plotting this against global human CO2 emissions:

The scatterplot yields a lovely red snake of data points that indicate the global temperature has been rising along with human CO2 emission. Whether temperature has been rising as a result of CO2 emissions or something else is a rather controversial matter, and one in which viable alternative theories and voices have been crushed, humiliated or silenced. This alone should make anybody suspicious because the truth never needs to hide behind censorship masquerading as public safety, especially when the perpetrators admit that they “own the science”.

Let us ignore causality for the moment and look at the blue line (linear regression) and the green line (LOESS regression). Apart from a wonky start both are effectively telling the same story and that is a near linear rise in the global anomaly as human emissions rise. If we assume 100% bone fide causality then climate sensitivity fetches-up at 0.028°C per Gt of human emission (p<0.001). This is a handy figure because it appears to give us a rate estimate for any modelling work we may care to undertake; that is to say, if we go ahead as a species and emit 45Gt of CO2 next year instead of 35Gt we may expect the HADCRUT5 mean global anomaly to rise a further 10 x 0.028°C = +0.28°C.

Except there’s a dirty great fly buzzing in the ointment called atmospheric residency.

A Matter Of Residency

Something we need to get to grips with is the issue of atmospheric residency. That is, humans chucked out 35Gt of CO2 during 2020, and whilst this is still floating in the atmosphere it can contribute to the greenhouse effect. Once it comes back down to Earth as part of the carbon cycle it can no longer do the greenhouse gas thing. A really big question, then, is how long does human CO2 stay up there? Another question is whether this is a sensible question to ask ‘coz stuff is perpetually in a state of flux.

With thus see that residency of human emissions is incredibly tricky to nail with estimates in the range 5 year - 200 years or thereabouts. The IPCC favour long residencies in their modelling because this allows human emissions to dominate. In a future article I’ll reveal a statistical method I used in an attempt to settle the matter of human emissions residency but for now I just want to present the same slide again but with an assumed net atmospheric residency of 100 years for human emissions:

We are looking at exactly the same pattern of data points but note the values on the x-axis (horizontal). These are now substantial because we are looking at the cumulative total of 100 years’ worth of human emission. If we once again assume 100% bone fide causality and reach for linear regression (OLSR) then the warming rate fetches-up at 0.008°C per Gt of human emission (p<0.001) – a rate that is 3.5x lower than our initial estimate of 0.028°C per Gt! Thus, by assuming a 100-year residency for net fluxes, we’ve had to rope-in a fair bit more human emission for the same anomaly rise, thus making our estimate of climate sensitivity far less.

Whilst waiting for my coffee to brew to a pleasing strength I rustled up this plot of climate sensitivity (degree rise in HADCRUT5 global anomaly per Gt of human emission) against a range of assumed residencies so you can see just how critical these assumptions are, especially for residencies below 100 years:

The upshot is that if residency is really up at +200 years like IPCC and other alarmists claim then crude climate sensitivity works out at 0.007°C per Gt of human emission. Thus, if our fossil fuel output rose from 35Gt in 2020 to 45Gt in 2021 then we may expect the HADCRUT5 global mean anomaly to rise 10 x 0.007°C = +0.07°C, but I’m not sure we can measure the global temperature to that precision!

Bizarrely, then, even if the highly politicised theory of the anthropogenic climate was bang on the money in all assumptions then nothing much is going to change if we continue to use fossil fuels as we do. Equally, nothing much is going to change even if we return to pre-WWII levels overnight owing to +200 year’s worth of emissions that need to play out. We are being conned left, right and centre, as well as up and down.

Kettle On!