Truth's Flashlight

A primer for disproving IPCC’s theory of man made global warming using observed temperature data

by Girma Orssengo, MASc, PhD, WUWT

Comparison of the claims by the Intergovernmental Panel on Climate Change (IPCC) of 1) “Most of the observed increase in global average temperatures since the mid-20th century is very likely” man made, and 2) “For the next two decades a warming rate of 0.2 deg C per decade is projected” are shown in this article not to be supported by the observed data, thus disproving IPCC’s theory of man made global warming.

FIRST IPCC CLAIM

In its Fourth Assessment Report of 2007, IPCC’s claim regarding global warming was the following [1]:

Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.

Let us verify this claim using the observed data from the Climate Research Unit (CRU) of the University of East Anglia [2]. In this claim, “mid-20th century” means year 1950. As a result, according to the IPCC, global warming since 1950 is mostly man made.

To verify the claim that global warming since 1950 is mostly man made, we may compare the global warming rate in degree centigrade (deg C) per decade in one period before 1950 to that of a second period after 1950 to determine the effect of the increased human emission of CO2. To be able to do this, we need to identify these two periods, which may be established from the Global Mean Temperature Anomaly (GMTA) data of the CRU shown in Figure 1.

Figure 1. Annual surface Global Mean Temperature Anomaly in degree centigrade from year 1880 to 2009 from the Climate Research Unit of the University of East Anglia [2.”

In Figure 1, the GMTA could be visualized as the sum of a Linear GMTA that has an overall warming rate of 0.6 deg C per century and an Oscillating GMTA that oscillates relative to this overall linear warming trend line. This Oscillating GMTA indicates the relative warming and cooling phases of the globe.

As our objective is to verify the claim that global warming since 1950 is man made, we need to identify two global warming phases before and after 1950. To clearly see the global warming and cooling phases, we plot just the Oscillating GMTA, which is the GMTA relative to the overall linear warming trend line shown in Figure 1. This can be done by using an online software at www.woodfortrees.org by rotating the overall linear warming trend line to become horizontal by using a detrend value of 0.775 so that the Oscillating GMTA has neither overall warming nor cooling trend. The noise from the Oscillating GMTA is then removed by taking five-years averages (compress = 60 months) of the GMTA. The result thus obtained is shown in Figure 2.

“]Figure 2. Oscillating Global Mean Temperature Anomaly that show relative global cooling and warming phases [3.”

Figure 2 shows the following periods for relative global cooling and warming phases:

  1. 30-years of global cooling from 1880 to 1910
  2. 30-years of global warming from 1910 to 1940
  3. 30-years of global cooling from 1940 to 1970
  4. 30-years of global warming from 1970 to 2000

If this pattern that was valid for 120 years is assumed to be valid for the next 20 years, it is reasonable to predict:

  1. 30-years of global cooling from 2000 to 2030

Figure 2 provides the two global warming phases before and after 1950 that we seek to compare. The period before 1950 is the 30-years global warming period from 1910 to 1940, and the period after 1950 is the 30-years global warming period from 1970 to 2000.

Figure 2 also provides the important result that the years 1880, 1910, 1940, 1970, 2000, 2030 etc are GMTA trend turning points, so meaningful GMTA trends can be calculated only between these successive GMTA turning point years, which justifies the calculation of a GMTA trend starting from year 2000 provided latter in this article.

Once the two global warming periods before and after mid-20th century are identified, their rate of global warming can be determined from the GMTA trends for the two periods shown in Figure 3.

Figure 3. Comparison of global warming rates for the periods before and after mid-20th century [4.”

According to the data of the CRU shown in Figure 3, for the 30-years period from 1910 to 1940, the GMTA increased by an average of 0.45 deg C (3 decade x 0.15 deg C per decade). After 60 years of human emission of CO2, for the same 30-years period, from 1970 to 2000, the GMTA increased by an average of nearly the same 0.48 deg C (3 decade x 0.16 deg C per decade). That is, the effect of 60 years of human emission of CO2 on change in global mean temperature was nearly nil, which disproves IPCC’s theory of man made global warming.

SECOND IPCC CLAIM

In its Fourth Assessment Report of 2007, IPCC’s projection of global warming was the following [5]:

For the next two decades, a warming of about 0.2 deg C per decade is projected for a range of SRES emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1 deg C per decade would be expected.

Let us verify this projection using the observed data from the CRU [2]. This may be done by comparing the global warming rate between the last two decades as shown in Figure 4. In this figure, the global warming rate decelerated from 0.25 deg C per decade for the period from 1990 to 2000 to only 0.03 deg C per decade for the period since 2000, which is a reduction by a factor of 8.3, which further disproves IPCC’s theory of man made global warming. If the current global warming trend continues, the GMTA will increase by 0.27 deg C (0.03 x 9) by 2100, not the scary 2.4 to 6.4 deg C of the IPCC.

Note that the projection for the current global warming rate by the IPCC was 0.2 deg C per decade, while the observed value is only 0.03 deg C per decade. As a result, IPCC’s Exaggeration Factor is 6.7.

Figure 4. Deceleration of global warming rate from 0.25 deg C per decade for the period from 1990 to 2000 to only 0.03 deg C per decade for the period since 2000 [6.”

SUMMARY

As shown in Figures 3 and 4, claims by the IPCC of 1) “Most of the observed increase in global average temperatures since the mid-20th century is very likely” man made, and 2) “For the next two decades a warming rate of 0.2 deg C per decade is projected” are not supported by the observed data, thus disproving IPCC’s theory of man made global warming.

According to the CRU data shown in Figure 3, the 30-years global warming from 1970 to 2000, after human emission of CO2 for 60 years, was nearly identical to the 30-years global warming from 1910 to 1940. In the intervening 30-years, there was a slight global cooling from 1940 to 1970. Furthermore, since year 2000, as shown in Figure 4, the global warming rate decelerated by a factor of 8.3 compared to the decade before. This is the story of global mean temperature trends for the last 100 years!

Does not the observed data in Figures 1 and 2 show a cyclic global mean temperature pattern with an overall linear warming rate of 0.6 deg C per century?

Dear citizens of the world, where is the catastrophic man made global warming they are scaring us with?

Or is the scare a humongous version of the “Piltdown man”?

REFERENCES

[1] IPCC: “Most of the observed increase in global average temperatures since the mid-20th century is very likely” man made

http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-understanding-and.html

[2] Global Mean Temperature Anomaly from Climate Research Unit of the University of East Anglia (GRAPH)

http://www.woodfortrees.org/plot/hadcrut3vgl/from:1880/to:2010/compress:12/plot/hadcrut3vgl/from:1880/to:2010/trend

[2] Global Mean Temperature Anomaly from Climate Research Unit of the University of East Anglia (RAW DATA)

http://www.woodfortrees.org/data/hadcrut3vgl/from:1880/to:2010/compress:12/plot/hadcrut3vgl/from:1880/to:2010/trend

[3] Oscillating Global Mean Temperature Anomaly

http://www.woodfortrees.org/plot/hadcrut3vgl/from:1880/to:2010/compress:60/detrend:0.775/offset:0.518/plot/hadcrut3vgl/from:1880/to:2010/trend/detrend:0.775/offset:0.518

[4] Comparison of global warming rates before and after mid-20th century (GRAPH)

http://www.woodfortrees.org/plot/hadcrut3vgl/from:1910/to:1940/compress:12/plot/hadcrut3vgl/from:1910/to:1940/trend/plot/hadcrut3vgl/from:1970/to:2000/compress:12/plot/hadcrut3vgl/from:1970/to:2000/trend

[4] Comparison of global warming rates before and after mid-20th century (RAW DATA)

http://www.woodfortrees.org/data/hadcrut3vgl/from:1910/to:1940/compress:12/plot/hadcrut3vgl/from:1910/to:1940/trend/plot/hadcrut3vgl/from:1970/to:2000/compress:12/plot/hadcrut3vgl/from:1970/to:2000/trend

[5] IPCC: “For the next two decades, a warming of about 0.2 deg C per decade is projected”

http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-projections-of.html

[6] Deceleration of global warming rate in the last two decades

http://www.woodfortrees.org/plot/hadcrut3vgl/from:1990/to:2000/plot/hadcrut3vgl/from:1990/to:2000/trend/plot/hadcrut3vgl/from:2000/to:2010/plot/hadcrut3vgl/from:2000/to:2010/trend

Share