Homogenisation of temperature data

How accurate is the pair-wise homogenisation algorithm applied to GHCN land temperature measurements and the instrumentation corrections made to sea surface temperatures?

Long term station measurements are affected  by a station’s physical relocation, by environmental changes (urban development)  and by instrumentation changes. Station relocations are usually recorded in metadata but not in a consistent way. Therefore an automated algorithm called the pairwise homogenisation has been developed which compares nearby stations to then identify “break-points” for a given station relative to its neighbours. A statistically significant and persistent violation of relative homogeneity is presumed to be artificial. The GHCN data is updated daily and the full pairwise algorithm is then also run daily.

Sea Surface temperatures have been measured since 1850 using different methods from bucket temperature, engine inlet temperatures, through to buoys and satellite data. Methods to correct instrumentation changes have been developed. The latest HadSST4 data incorporating satellite corrections to recent buoy data.

The overall result of both these updates has been to increase the apparent recent warming. This can be seen by comparing the uncorrected global temperature data with the corrected data each calculated in exactly the same way by spherical triangulation.

Global temperatures calculated both on the raw and corrected temperature data

We see that the net effect is to increase the apparent warming since ~2000 by about 0.15C.  How sure are we that these automated algorithmic corrections are correct? A recent paper has looked in detail at the effects of the pairwise algorithm on GHCN-V4 and the results are surprising. They downloaded all daily versions of GHCN-V4  over a period of  10 years providing a consistency check over time of the corrections as applied. They studied European stations and found that an average of 100 different pairwise corrections were applied during that time while only 3% of these  actually corresponded to documented  metadata events e.g. station relocations.

This implies that the algorithm is far too sensitive. You can see below how consistent these adjustments were by seeing how many times each was repeated. This results in a consistency rate of just 16%. The rest are most likely wrong.

Just 19% of the adjustments made in V4 correspond to documented events in the associated metadata. There could be station moves or instrumentation changes that are not documented but if so then we would expect consistency after some particular date. This is not observed and most changes occur very inconsistently or intermittently.

Proximity of PHA adjustments to a documented event in the station’s metadata.


Another consideration is that a comparison of the temperature of one station with its near neighbours should occasionally identify those reading too hot and reduce the recorded temperature accordingly. Yet the trend  always seems to be towards a warmer trend than  that in the raw measurement data.

Here is one example. Click on image to see animation.


Posted in AGW, Hadley, NOAA, Uncategorized | Tagged | 19 Comments

Steven Koonin v Andrew Desler

I have just read the book “Unsettled” by Steven Koonin a Caltech Physicist who has a long academic, industrial and political career. Of course he agrees that CO2 emissions have a warming effect, but he argues that many of the more extreme claims of climate change are unproven and potentially dangerous.  The policy to reach net Zero emissions by 2050 based on renewables alone  could well destroy western economies. As a result of his criticism, mainstream climate scientists have ganged up on him to call him a “denier”, especially as he once worked as Chief Scientist for BP.  His main point is that the basic physics of greenhouse warming as described say in AR5 is correct, but the implication  that this means we  must close all fossil fuels immediately is mainly political. Furthermore he criticises those Climate scientists that push scare stories of increasing severity of Hurricanes, droughts, and accelerating sea level rise, to imply that time is short.  On the contrary the data do not support  such  alarmist statements. Extreme weather events are not increasing in frequency and sea level has been rising for hundreds of years.  Instead we probably have about 50 years to finally solve the energy/climate dichotomy.  Pushing current wind and solar right now will not work, partly because we will need new nuclear. I am pretty much aligned with his thinking.

Joe Rogan has managed to achieve the impossible – an actual long distance debate between Steven Koonin and Andrew Desler. First up was Steve Koonin.

Some sound bites:

“I hate the term CO2 pollution.”

“Nobody has put together a sensible decarbonisation plan. The plans that you see are put out by a bunch of academics , but noone will implement them unless they can make money.”

“You need to change the energy system not by tooth extraction but by orthodenture !” i.e. carefully!

Decarbonisation must be done in a graceful way.

6 billion people in the third world need energy to improve their life and who are we to tell them they can’t do that. So yes maybe we can cut our carbon emissions but who are we to restrict their development?

US emissions are 16% of global emissions so reducing by global emissions by 30% will have a modest effect on climate change.

Plans  are put out by a bunch of academics e.g. 2075 carbonisation. The daily weather that gets referenced to climate change drives me crazy! There is no evidence that the frequency of extreme weather is increasing. No wonder kids are getting scared all the time for the future.

Climate Models typically use 3D tube boxes 60 miles in dimension size so they can’t effectively  simulate the details of weather, because the weather acts on much smaller sizes for example clouds, onshore and offshore winds etc.

That’s why climate models  only give you a hazy picture of the future

We only have one chance at decarbonising the energy system We’ve  got the time to get this right.

“Minimum temperatures are going up faster than maximum temperatures” I agree with this statement see Nights warm faster than Days

Joe Rogan then gave  the right of reply a week later to Andrew Dessler.

Andrew Dessler does not address any of Koonin’s criticisms of climate science itself, but focuses instead on the Energy debate.

He starts up by comparing Kronin  to the old Tobacco lobby, the fluorocarbon ban, etc. which is kind of silly since I am sure he agrees too that those were easily solvable problems. Andrew’s argument is that Koonin is no different to the tobacco scientists of the 1960s. The slur is implied because  Kroonin was once chief scientists at BP, so somehow he is still in the pay of the oil industry.

Climate change though is fundamentally different to the tobacco or fluorocarbon debate, because  there are no obvious simple alternatives to fossil fuels. The real problem with the proposed solution is that renewables are intermittent,  even if  prices for solar and wind power “capacity” are now competitive, because they still need an equivalent amount of dispatchable backup.

He keeps repeating the ugly slur  that “Dr Koonin rejects anything which doesn’t support his client (fossil fuels) because quote “He is trying to create doubt”

During the two hour interview he  doesn’t really discuss climate science at all, or address Koonin’s criticisms.

1/4 of emissions go into the biosphere and 1/4 got into the oceans (Greening and Acidifying) and 1/2 remains in the atmosphere. If there were an easy way to drag more out eg. planting forests then we would be doing it.

If you could reach $50 a ton to suck out CO2 then it would be worth it.

In Europe natural gas is very expensive. He likes geothermal because drilling has got so good thanks to fracking.

Plastic depends on oil and he agrees we need that we need them long term. Similarly oil is used to make tar for road surfaces and even wind turbine blades.

We might be able to solve the energy system but farming and agriculture will be tougher to decarbonise. Ethanol blending in petrol is really for the farmers. Fertilizers etc. Factory farming is awful.

“We really should be phasing out fossil fuels as fast as possible”

When invited at the end to have a debate with Steve Koonin, he declines because he says it is all in the peer reviewed  papers. The other reason he gave was that he once had a debate with Richard Lindzen which clearly didn’t go so well. I think this may be this one (see footnote).

This is the first time I have ever heard a Jo Rogan’s podcast. I was really impressed by the way he handled things and had prepared himself by reading the book first. He has come n for a lot of stick recently but on these podcasts he came out of it really well and with open mind.


Footnote: Debate between Andrew Dessler and Richard Lindzen.

Posted in Climate Change, climate science, nuclear, renewables, wind farms | 27 Comments

2021 finishes as 4th Warmest year

The Average temperature anomaly for 2021 was O.80 C above the 1961-1990 average. This is cooler than recent years probably due to La Nina. The warmest year overall was 2020 reaching 0.90 C. These calculations (spherical triangulation) are now based on the latest GHCN V4 for the station data and HadSST4 for the SST data. Upgrading  from HadSST3 to HadSST4 has also increased slightly the net warming trend (see previous post).

The final month December saw a further drop in temperature from November of 0.10 C.You can see below that a strong La Ninja redeveloped in December after nearly disappearing in October/November.  Also notice the very cold December temperatures across Western  Canada and Siberia.

Spatial temperatures for December.

The monthly and annual data can be downloaded at these links

I  suspect these results will be very similar to those of HadCRUT5

Posted in climate science, Hadley, NOAA | Tagged | 8 Comments