How Good Are Met Office Predictions? (Now Includes at Least May Data)

Image Credit: WoodForTrees.org

Guest Post By Werner Brozek, Edited By Just The Facts

“We are now using the system to predict changes out to 2014. By the end of this period, the global average temperature is expected to have risen by around 0.3 °C compared to 2004, and half of the years after 2009 are predicted to be hotter than the current record hot year, 1998.” Met Office Hadley Centre 2007

“The Met Office Hadley Centre has the highest concentration of absolutely outstanding people who do absolutely outstanding work, spanning the breadth of modelling, attribution, and data analysis, of anywhere in the world.” Dr Susan Solomon, Co Chair IPCC AR4 WGI

So let us see how “absolutely outstanding” the Met Office Hadley Centre’s 2007 prediction is turning out.

As of 2012, the 1998 record has not been beaten on HadCRUT3. The 1998 anomaly for 1998 on HadCRUT3 was 0.548. For the years 2010, 2011, and 2012, the anomalies were 0.478, 0.340 and 0.405 respectively. The ranks were 3rd, 13th and 10th respectively. To the end of May, the average on Hadcrut3 is 0.414 and this would rank 9th if it stayed this way. Simple arithmetic allows us to calculate what the average anomaly has to be for the rest of year to tie 1998. If we let x be the required anomaly, then 0.414(5) + 7x = 0.548(12). Calculating for x gives 0.644. Naturally this is above the 1998 average, but it is lower than the all time record for HadCRUT3 of 0.756 set in February of 1998. One must keep in mind that for every month that 0.644 is not reached, the later months have to be higher to set a new record.

Here are some relevant facts today: The sun is extremely quiet and ENSO has been neutral since the start of the year. Even if a 1998 type El Nino started to set in tomorrow, it would be at least 4 or 5 months for the maximum ENSO reading to be reached. Then it would take at least 3 more months for the high ENSO to be reflected in Earth’s temperature. If a 1998 type El Nino does not start within a few months, then it is doubtful that even 2014 would set a new record. CO2 passing the 400 ppm mark certainly cannot do it alone.

(Note: If you read my prior article Are We in a Pause or a Decline? and just wish to know what is new with the May and June data, you will find the most important new measurements from lines 7 to the end of the table.)

In the sections below, we will present you with the latest facts. The information will be presented in three sections and an appendix. The first section will show the period that there has been no warming for various data sets. The second section will show the period that there has been no statistically significant warming on several data sets. The third section will show how 2013 to date compares with 2012 and the warmest years and months on record so far. The appendix will illustrate sections 1 and 2 in a different way. Graphs and a table will be used to illustrate the data.

Section 1

This analysis uses the latest month for which data is available on WoodForTrees.com (WFT). All of the data on WFT is also available at the specific sources as outlined below. We start with the present date and go to the furthest month in the past where the slope is a least slightly negative. So if the slope from September is 4 x 10^-4 but it is – 4 x 10^-4 from October, we give the time from October so no one can accuse us of being less than honest if we say the slope is flat from a certain month.

On all data sets below, the different times for a slope that is at least very slightly negative ranges from 5 years and 0 months to 16 years and 7 months.

1. For GISS, the slope is flat since February 2001 or 12 years, 5 months. (goes to June)

2. For Hadcrut3, the slope is flat since April 1, 1997 or 16 years, 2 months. (goes to May 31, 2013)

3. For a combination of GISS, Hadcrut3, UAH and RSS, the slope is flat since November 2000 or 12 years, 7 months. (goes to May)

4. For Hadcrut4, the slope is flat since November 2000 or 12 years, 7 months. (goes to May)

5. For Hadsst2, the slope is flat from March 1, 1997 to April 30, 2013, or 16 years, 2 months. (As of July 12, the May anomaly was not up.)

6. For UAH, the slope is flat since July 2008 or 5 years, 0 months. (goes to June)

7. For RSS, the slope is flat since December 1996 or 16 years and 7 months. (goes to June) RSS is 199/204 or 97.5% of the way to Ben Santer’s 17 years.

The next graph shows just the lines to illustrate the above for what can be shown. Think of it as a sideways bar graph where the lengths of the lines indicate the relative times where the slope is 0. In addition, the sloped wiggly line shows how CO2 has increased over this period.

When two things are plotted as I have done, the left only shows a temperature anomaly. It goes from 0.1 C to 0.6 C. A change of 0.5 C over 16 years is about 3.0 C over 100 years. And 3.0 C is about the average of what the IPCC says may be the temperature increase by 2100.

The next graph shows the above, but this time, the actual plotted points are shown along with the slope lines and the CO2 is omitted.

Section 2

For this analysis, data was retrieved from SkepticalScience.com. This analysis indicates for how long there has not been statistically significant warming according to their criteria. The numbers below start from January of the year indicated. Data go to their latest update for each set. In every case, note that the magnitude of the second number is larger than the first number so a slope of 0 cannot be ruled out. (To the best of my knowledge, SkS uses the same criteria that Phil Jones uses to determine statistical significance.)

The situation with GISS, which used to have no statistically significant warming for 17 years, has now been changed with new data. GISS now has over 18 years of no statistically significant warming. As a result, we can now say the following: On six different data sets, there has been no statistically significant warming for between 18 and 23 years.

The details are below and are based on the SkS Temperature Trend Calculator:

For RSS the warming is not statistically significant for over 23 years.

For RSS: +0.122 +/-0.131 C/decade at the two sigma level from 1990

For UAH the warming is not statistically significant for over 19 years.

For UAH: 0.139 +/- 0.165 C/decade at the two sigma level from 1994

For Hadcrut3 the warming is not statistically significant for over 19 years.

For Hadcrut3: 0.091 +/- 0.110 C/decade at the two sigma level from 1994

For Hadcrut4 the warming is not statistically significant for over 18 years.

For Hadcrut4: 0.093 +/- 0.107 C/decade at the two sigma level from 1995

For GISS the warming is not statistically significant for over 18 years.

For GISS: 0.105 +/- 0.110 C/decade at the two sigma level from 1995

For NOAA the warming is not statistically significant for over 18 years.

For NOAA: 0.086 +/- 0.103 C/decade at the two sigma level from 1995

If you want to know the times to the nearest month that the warming is not statistically significant for each set to their latest update, they are as follows:

RSS since July 1989;

UAH since May 1993;

Hadcrut3 since August 1993;

Hadcrut4 since July 1994;

GISS since October 1994 and

NOAA since May 1994.

Section 3

This section shows data about 2013 and other information in the form of a table. The table shows the six data sources along the top and bottom, namely UAH, RSS, Hadcrut4, Hadcrut3, Hadsst2, and GISS. Down the column, are the following:

1. 12ra: This is the final ranking for 2012 on each data set.

2. 12an: Here I give the average anomaly for 2012.

3. year: This indicates the warmest year on record so far for that particular data set. Note that two of the data sets have 2010 as the warmest year and four have 1998 as the warmest year.

4. ano: This is the average of the monthly anomalies of the warmest year just above.

5. mon: This is the month where that particular data set showed the highest anomaly. The months are identified by the first two letters of the month and the last two numbers of the year.

6. ano: This is the anomaly of the month just above.

7. y/m: This is the longest period of time where the slope is not positive given in years/months. So 16/2 means that for 16 years and 2 months the slope is essentially 0.

8. sig: This is the whole number of years for which warming is not statistically significant according to the SkS criteria. The additional months are not added here, however for more details, see Section 2.

9. Jan: This is the January, 2013, anomaly for that particular data set.

10. Feb: This is the February, 2013, anomaly for that particular data set, etc.

21. ave: This is the average anomaly of all months to date taken by adding all numbers and dividing by the number of months. However if the data set itself gives that average, I use their number. Sometimes the number in the third decimal place differs by one, presumably due to all months not having the same number of days.

22. rnk: This is the rank that each particular data set would have if the anomaly above were to remain that way for the rest of the year. Of course it won’t, but think of it as an update 25 or 30 minutes into a game. Expect swings from month to month at the start of the year. As well, expect more variations between data sets at the start. Due to different base periods, the rank may be more meaningful than the average anomaly.

If you wish to verify all of the latest anomalies, go to the following links, For UAH, version 5.5 was used since that is what WFT used,, RSS, Hadcrut4, Hadcrut3, Hadsst2,and GISS.

To see all points since January 2012 in the form of a graph, see the WFT graph below.

Appendix

In this section, we summarize the data for each set separately.

RSS

The slope is flat since December 1996 or 16 years and 7 months. (goes to June) RSS is 199/204 or 97.5% of the way to Ben Santer’s 17 years.

For RSS the warming is not statistically significant for over 23 years.

For RSS: +0.122 +/-0.131 C/decade at the two sigma level from 1990.

The RSS average anomaly so far for 2013 is 0.248. This would rank 7th if it stayed this way. 1998 was the warmest at 0.55. The highest ever monthly anomaly was in April of 1998 when it reached 0.857. The anomaly in 2012 was 0.192 and it came in 11th.

Following are two graphs via WFT. Both show all plotted points for RSS since 1990. Then two lines are shown on the first graph. The first upward sloping line is the line from where warming is not statistically significant according to the SkS site criteria. The second straight line shows the point from where the slope is flat.

The second graph shows the above, but in addition, there are two extra lines. These show the upper and lower lines using the SkS site criteria. Note that the lower line is almost horizontal but slopes slightly downward. This indicates that there is a slight chance that cooling has occurred since 1990 according to RSS.

graph 1 and graph 2.

UAH

The slope is flat since July 2008 or 5 years, 0 months. (goes to June)

For UAH, the warming is not statistically significant for over 19 years.

For UAH: 0.139 +/- 0.165 C/decade at the two sigma level from 1994

The UAH average anomaly so far for 2013 is 0.219. This would rank 4th if it stayed this way. 1998 was the warmest at 0.419. The highest ever monthly anomaly was in April of 1998 when it reached 0.66. The anomaly in 2012 was 0.161 and it came in 9th.

Following are two graphs via WFT. Everything is identical as with RSS except the lines apply to UAH.

Graph 1 and graph 2.

Hadcrut4

The slope is flat since November 2000 or 12 years, 7 months. (goes to May.)

For Hadcrut4, the warming is not statistically significant for over 18 years.

For Hadcrut4: 0.093 +/- 0.107 C/decade at the two sigma level from 1995

The Hadcrut4 average anomaly so far for 2013 is 0.450. This would rank 9th if it stayed this way. 2010 was the warmest at 0.547. The highest ever monthly anomaly was in January of 2007 when it reached 0.829. The anomaly in 2012 was 0.448 and it came in 9th.

Following are two graphs via WFT. Everything is identical as with RSS except the lines apply to Hadcrut4.

Graph 1 and graph 2.

Hadcrut3

The slope is flat since April 1997 or 16 years, 2 months (goes to May, 2013)

For Hadcrut3, the warming is not statistically significant for over 19 years.

For Hadcrut3: 0.091 +/- 0.110 C/decade at the two sigma level from 1994

The Hadcrut3 average anomaly so far for 2013 is 0.414. This would rank 9th if it stayed this way. 1998 was the warmest at 0.548. The highest ever monthly anomaly was in February of 1998 when it reached 0.756. One has to go back to the 1940s to find the previous time that a Hadcrut3 record was not beaten in 10 years or less. The anomaly in 2012 was 0.405 and it came in 10th.

Following are two graphs via WFT. Everything is identical as with RSS except the lines apply to Hadcrut3.

Graph 1 and graph 2

Hadsst2

For Hadsst2, the slope is flat since March 1, 1997 or 16 years, 2 months. (goes to April 30, 2013).

The Hadsst2 average anomaly for the first four months for 2013 is 0.306. This would rank 11th if it stayed this way. 1998 was the warmest at 0.451. The highest ever monthly anomaly was in August of 1998 when it reached 0.555. The anomaly in 2012 was 0.342 and it came in 8th.

Sorry! The only graph available for Hadsst2 is this

GISS

The slope is flat since February 2001 or 12 years, 5 months. (goes to June)

For GISS, the warming is not statistically significant for over 18 years.

For GISS: 0.105 +/- 0.110 C/decade at the two sigma level from 1995

The GISS average anomaly so far for 2013 is 0.57. This would rank 9th if it stayed this way. 2010 was the warmest at 0.66. The highest ever monthly anomaly was in January of 2007 when it reached 0.93. The anomaly in 2012 was 0.56 and it came in 9th.

Following are two graphs via WFT. Everything is identical as with RSS except the lines apply to GISS.

Graph 1 and graph 2

Conclusion

You saw how an earlier prediction by the MET office ended. The MET office felt the need to revise its forecasts. Look at the following and keep in mind that the MET office now believes that the 1998 mark will be beaten by 2017. Do you agree?