Has Global Warming Stalled?

Guest Post By Werner Brozek, Edited By Just The Facts

In order to answer the question in the title, we need to know what time period is a reasonable period to take into consideration. As well, we need to know exactly what we mean by “stalled”. For example, do we mean that the slope of the temperature-time graph must be 0 in order to be able to claim that global warming has stalled? Or do we mean that we have to be at least 95% certain that there indeed has been warming over a given period?

With regards to what a suitable time period is, NOAA says the following:

”The simulations rule out (at the 95% level) zero trends for intervals of 15 yr or more, suggesting that an observed absence of warming of this duration is needed to create a discrepancy with the expected present-day warming rate.”

To verify this for yourself, see page 23 of this NOAA Climate Assessment.

Below we present you with just the facts and then you can assess whether or not global warming has stalled in a significant manner. The information will be presented in three sections and an appendix. The first section will show for how long there has been no warming on several data sets. The second section will show for how long there has been no significant warming on several data sets. The third section will show how 2012 ended up in comparison to other years. The appendix will illustrate sections 1 and 2 in a different way. Graphs and tables will be used to illustrate the data.

Section 1

This analysis uses the latest month for which data is available on WoodForTrees.org (WFT). (If any data is updated after this report is sent off, I will do so in the comments for this post.) 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 8 years and 3 months to 16 years and 1 month:

1. For GISS, the slope is flat since May 2001 or 11 years, 7 months. (goes to November)

2. For Hadcrut3, the slope is flat since May 1997 or 15 years, 7 months. (goes to November)

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

4. For Hadcrut4, the slope is flat since November 2000 or 12 years, 2 months. (goes to December.)

5. For Hadsst2, the slope is flat since March 1997 or 15 years, 10 months. (goes to December)

6. For UAH, the slope is flat since October 2004 or 8 years, 3 months. (goes to December)

7. For RSS, the slope is flat since January 1997 or 16 years and 1 month. (goes to January) RSS is 193/204 or 94.6% of the way to Ben Santer’s 17 years.

The following graph, also used as the header for this article, shows just the lines to illustrate the above. 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:

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 WoodForTrees.org and the ironically named SkepticalScience.com. This analysis indicates how long there has not been significant warming at the 95% level on various data sets. The first number in each case was sourced from WFT. However the second +/- number was taken from SkepticalScience.com

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

For RSS: +0.127 +/-0.136 C/decade at the two sigma level from 1990

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

For UAH: 0.143 +/- 0.173 C/decade at the two sigma level from 1994

For Hacrut3, the warming is not significant for over 19 years.

For Hadcrut3: 0.098 +/- 0.113 C/decade at the two sigma level from 1994

For Hacrut4, the warming is not significant for over 18 years.

For Hadcrut4: 0.095 +/- 0.111 C/decade at the two sigma level from 1995

For GISS, the warming is not significant for over 17 years.

For GISS: 0.116 +/- 0.122 C/decade at the two sigma level from 1996

If you want to know the times to the nearest month that the warming is not significant for each set, they are as follows: RSS since September 1989; UAH since April 1993; Hadcrut3 since September 1993; Hadcrut4 since August 1994; GISS since October 1995 and NOAA since June 1994.

Section 3

This section shows data about 2012 in the form of tables. Each table shows the six data sources along the left, namely UAH, RSS, Hadcrut4, Hadcrut3, Hadsst2, and GISS. Along the top, are the following:

1. 2012. Below this, I indicate the present rank for 2012 on each data set.

2. Anom 1. Here I give the average anomaly for 2012.

3. Warm. 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. Anom 2. This is the average anomaly of the warmest year just to its left.

5. Month. 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. Anom 3. This is the anomaly of the month immediately to the left.

7. 11ano. This is the average anomaly for the year 2011. (GISS and UAH were 10th warmest in 2011. All others were 13th warmest for 2011.)

Anomalies for different years:

If you wish to verify all rankings, go to the following:

For UAH, see here, for RSS see here and for Hadcrut4, see here. Note the number opposite the 2012 at the bottom. Then going up to 1998, you will find that there are 9 numbers above this number. That confirms that 2012 is in 10th place. (By the way, 2001 came in at 0.433 or only 0.001 less than 0.434 for 2012, so statistically, you could say these two years are tied.)

For Hadcrut3, see here. You have to do something similar to Hadcrut4, but look at the numbers at the far right. One has to back to the 1940s to find the previous time that a Hadcrut3 record was not beaten in 10 years or less.

For Hadsst2, see here. View as for Hadcrut3. It came in 8th place with an average anomaly of 0.342, narrowly beating 2006 by 2/1000 of a degree as that came in at 0.340. In my ranking, I did not consider error bars, however 2006 and 2012 would statistically be a tie for all intents and purposes.

For GISS, see here. Check the J-D (January to December) average and then check to see how often that number is exceeded back to 1998.

For the next two tables, we again have the same six data sets, but this time the anomaly for each month is shown. [The table is split in half to fit, if you know how to compress it to fit the year, please let us know in comments The last column has the average of all points to the left.]

To see the above in the form of a graph, see the WFT graph below.:

Appendix

In this part, we are summarizing data for each set separately.

RSS

The slope is flat since January 1997 or 16 years and 1 month. (goes to January) RSS is 193/204 or 94.6% of the way to Ben Santer’s 17 years.

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

For RSS: +0.127 +/-0.136 C/decade at the two sigma level from 1990.

For RSS, the average anomaly for 2012 is 0.192. This would rank 11th. 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 2011 was 0.147 and it will come in 13th.

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 significant at the 95% confidence level. 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 for the 95% confidence limits. Note that the lower line is almost horizontal but slopes slightly downward. This indicates that there is a slightly larger than a 5% chance that cooling has occurred since 1990 according to RSS per graph 1 and graph 2.

UAH

The slope is flat since October 2004 or 8 years, 3 months. (goes to December)

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

For UAH: 0.143 +/- 0.173 C/decade at the two sigma level from 1994

For UAH the average anomaly for 2012 is 0.161. This would rank 9th. 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 2011 was 0.130 and it will come in 10th.

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, 2 months. (goes to December.)

For Hacrut4, the warming is not significant for over 18 years.

For Hadcrut4: 0.095 +/- 0.111 C/decade at the two sigma level from 1995

With Hadcrut4, the anomaly for 2012 is 0.436. This would rank 10th. 2010 was the warmest at 0.54. The highest ever monthly anomaly was in January of 2007 when it reached 0.818. The anomaly in 2011 was 0.399 and it will come in 13th.

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 May 1997 or 15 years, 7 months (goes to November)

For Hacrut3, the warming is not significant for over 19 years.

For Hadcrut3: 0.098 +/- 0.113 C/decade at the two sigma level from 1994

With Hadcrut3, the anomaly for 2012 is 0.403. This would rank 10th. 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 back to the 1940s to find the previous time that a Hadcrut3 record was not beaten in 10 years or less. The anomaly in 2011 was 0.340 and it will come in 13th.

Following are two graphs via WFT. Everything is identical as with RSS except the lines apply to Hadcrut3. Graph 1 and graph 2.

Hadsst2

The slope is flat since March 1997 or 15 years, 10 months. (goes to December)

The Hadsst2 anomaly for 2012 is 0.342. This would rank in 8th. 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 2011 was 0.273 and it will come in 13th.

Sorry! The only graph available for Hadsst2 is this.

GISS

The slope is flat since May 2001 or 11 years, 7 months. (goes to November)

For GISS, the warming is not significant for over 17 years.

For GISS: 0.116 +/- 0.122 C/decade at the two sigma level from 1996

The GISS anomaly for 2012 is 0.56. This would rank 9th. 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 2011 was 0.54 and it will come in 10th.

Following are two graphs via WFT. Everything is identical as with RSS except the lines apply to GISS. Graph 1 and graph 2.

Conclusion

Above, various facts have been presented along with sources from where all facts were obtained. Keep in mind that no one is entitled to their own facts. It is only in the interpretation of the facts for which legitimate discussions can take place. After looking at the above facts, do you think that we should spend billions to prevent catastrophic warming? Or do you think that we should take a “wait and see” attitude for a few years to be sure that future warming will be as catastrophic as some claim it will be? Keep in mind that even the MET office felt the need to revise its forecasts. Look at the following and keep in mind that the MET office believes that the 1998 mark will be beaten by 2017. Do you agree?