Richard Betts/Met Office warming Indicator

The Met Office are proposing to use a 10 year average temperature indicator to define when and if the 1.5 degree since industrial periods will be exceeded. The pre-industrial period is defined as 1850-1900 which is different from  the 1961- 1990 baseline that are used for calculating station anomalies because this maximises the available station count. The offset for the preindustrial period is consequentially based on  these anomaly values  before 1900. 

A comparison of the latest HadCRUT5 with my Spherical triangulation results shows an  almost perfect agreement between the two methods.  This then results in a joint pre-industrial baseline (1850-1900) of -0.4C.  Thus the Paris agreement to limit total warming to 1.5C equates to limiting these measured (baseline) temperature anomalies to less that 1.1C.

It is clearly evident that the year to year variability is large, for example due to El Nino and other transient effects which makes estimating the effect due to CO2 alone difficult. However there is another way to calculate global temperatures which allows for far longer integration periods avoiding this problem. This is based on Icosahedral 3D binning as I described here. This method allows for  the integration period in each cell to be extended up to a decade. These are the results that I get using the latest complete 2010s decade measurements.

Views of the 3D equal size Icosahedral bins for 2011-2020

Temperature anomalies calculated on a regular icosahedron Click here to view in 3D

Now we compare the decadal temperature values with the normal annual calculated values by spherical triangulation.

Annual temperature trends updated for October 2023 compared to the underlying decadal trends.

This result proves that the decadal temperatures describe very well the underlying temperature trends in the data,  unaffected by annual variability. As a consequence of this we can simply extrapolate the observed linear decadal trend forward in time to determine when the Paris agreement limit of 1.5 degrees will likely be exceeded.

The observed stable decadal trend shows that the Paris Agreement to limit warming to 1.5C since the preindustrial level will very likely be exceeded in 2032

The conclusion is that a net warming of 1.5C since preindustrial times exceeding the Paris Agreement will most likely occur in 2032. This figure of 1.5C, if I remember well, was anyway a compromise resolution made at the end of the conference.

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Temperature update for Oct 2023 is 1.1C

A little late but here is my update on the global temperatures for October 2023, The method used is always by spherical triangulation. Temperature fell from the peak in September of 1.49 to 1.29 in October.

Temperatures for November showing a cool area off Chile below a continuing El Nino

These are the monthly temperature trends

Monthly temperatures 2010 – Nov 2023

The annual average temperature for 2023 with just 2 months to go is 1.09C for 2023

Annual temperature trends updated for October 2023 compared to the underlying decadal trends.

I am convinced the decadal trends are calculated on an Icosahedral Grid are the most accurate description of “climate change”.

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Direct evidence that CO2 forcing alone determines Global Temperatures

The well known result that CO2 radiative forcing is approximately 5.3 Ln (C/CO) [1] is confirmed here by comparing decadal global temperature anomalies with CO2 concentrations. Positive feedbacks are not needed to explain the observed warming. A value of Transient Climate Response of 1.6C is observed to confirm this. The Moana Loa CO2 measurements when combined with earlier estimates of emissions show that CO2 concentrations have essentially been increasing monotonically since before 1955.  As a result we would expect resultant temperatures to  increase linearly with time [see here], unless there are any positive feedbacks present to increase this rate.

A new method based on a fixed Icosahedral binning  over the surface of the earth allows us  to calculate the decadal averages for each bin and then integrate these to derive the global average temperature for each decade from the 1880s to the 2020s. The big advantage of using decadal temperatures rather than annual temperatures is that natural variability (ENSA, AMO, etc) is simply averaged out.

Figure 1 below shows the result using a 1961-1990 baseline.

The red data-points are the decadal temperatures (left hand scale) while the blue dotted line are the Maona Loa CO2 data combined with NOAA CO2 values before 1955. The data after 2020 extends the linear temperature trend and the exponential CO2 increase to 2050

The linear increase in temperature after 1970 shows that a doubling of CO2 by 2050 if this increasing CO2 emissions trend continues ( blue arrows ) would results in a temperature rise of 1.6C. This is almost identical to the value calculated from directly from radiative forcing from CO2 alone. This proves that proposed feedbacks such as changes in cloud cover or increased water vapour have had no measurable effect so far.

Essentially this implies we have at least 40 years left to develop a reliable low carbon energy source (nuclear).


[1] Myhre et al. New estimates of radiative forcing due to well mixed greenhouse gasses Phys.Rev.Lett., 25, 2715-2718,1998

[2] View the 2000s temperature grid by clicking here 2001-2010 (2000s) Click and spin the globe !

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