Was the Slowdown caused by 1998?

Agree to Disagree

Debate in a non-hostile environment

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Was the Slowdown caused by 1998?


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Al Bundy (on RealClimate.org), made this statement:

~ ~ ~ start of quote ~ ~ ~

Sheldon Walker,
You want a dataset to test the “slowdown”? OK, take GISS and replace 1998 with a placeholder that’s spot on the trend line.

What you’ll find is that your “slowdown” completely disappears once an extreme outlier is removed. As I’ve said before, my take is that it’s a spike followed by a reversion to the trend as opposed to a slowdown. What’s your take on your results?

~ ~ ~ end of quote ~ ~ ~


After I questioned his original statement, Al Bundy (on RealClimate.org), added this to his statement:

~ ~ ~ start of quote ~ ~ ~

So, take the Gistemp meteorological station data from 1966 to present (I chose 1966 because it looks like a good start for the current trend; if you wanna use a different start date, tell me why). Replace 1998 with your guess for the appropriate value to match the trend. Do a trend. Is 1998 spot on the trend? If so, you’re done. If not, select another value for 1998 based on how far off you were in your first attempt. Repeat until 1998 is on the trend. Post a link to the results here.

Kind of a DUH! thing, eh?

~ ~ ~ end of quote ~ ~ ~


The 2 statements that Al Bundy made, define a fairly precise test of:

1) whether there was a slowdown, and

2) whether the slowdown was caused by the super El Nino in 1998.

I am happy to perform this simple test, because most Alarmists don’t seem to have the skills or ability to do it for themselves.

I have tried to follow Al Bundy’s “rules” exactly. So don’t bother asking me why I “took the Gistemp meteorological station data from 1966 to present”. I did it because Al Bundy suggested it.

One additional rule that I used, which Al Bundy did not mention, was to ignore all date ranges which are less than 10 years. Warming rates for short periods are too variable, and just confuse the situation.

Note that slowdowns have more than 1 dimension. The main 2 dimensions are length (how long the slowdown lasted), and strength (how much the warming rate slowed by). The strength can be measured in “warming rate” units (e.g. degrees Celsius per century), or as a percentage decrease of a “standard” warming rate (e.g. the warming rate decreased by -27% or -54% or -92% of the warming rate from 1966 to 2017).

In this article, I am concentrating on the strength of slowdowns. I am only looking at slowdowns which are 10 years long, or longer. I am using the convention that the percentage slowdown is negative for a slowdown (e.g. -60% means a slowdown which is 60% less than the “standard” warming rate. +60% means a speedup which is 60% greater than the “standard” warming rate).

An example should help to make this clear. If the “standard” warming rate was +2.0 degrees Celsius per century, and the slowdown warming rate was +0.5 degrees Celsius per century, then the percentage slowdown = (+0.5 – +2.0) * 100 / +2.0 = -75%.

Using this convention:

  • The more negative that the percentage slowdown is, the stronger the slowdown is.
  • a percentage slowdown of 0% means that it didn’t slow down.
  • a percentage slowdown of -10% means that it only slowed down a little bit.
  • a percentage slowdown of -40% means that it slowed down by a reasonable amount.
  • a percentage slowdown of -50% means that it slowed down to half the “standard” warming rate.
  • a percentage slowdown of -65% means that it slowed down by a lot.
  • a percentage slowdown of -90% means that it almost stopped warming completely.
  • a percentage slowdown of -100% means that it was a true “Pause”. There was NO warming.

To make it perfectly clear what temperature anomalies I have used, and what value I changed the 1998 anomaly to, see the following graph and table.

I downloaded the temperature anomalies from this web address:
https://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.csv

I downloaded the file on 10 July 2018, and the file contained anomalies up to and including May 2018. Please note that anomalies may be slightly different in other versions of this file. The file is updated every month, and adjustments may be made to the anomalies.

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GISTEMP Graph True and False

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GISTEMP Data True and False

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I have presented the results in 2 pairs of tables.

The 1st pair of tables show the calculated warming rates (in degrees Celsius per century). The first of these 2 tables shows the “True 1998” data, and the second of these 2 tables shows the “False 1998” data.

The 2nd pair of tables show exactly the same data, but converted into percent slowdown, compared to the average warming rate from 1966 to 2017 (1.7524 degrees Celsius per century). The first of these 2 tables shows the “True 1998” data, and the second of these 2 tables shows the “False 1998” data.

Please note that percentages are rounded to the nearest whole number. This makes it much easier to understand the tables.

Because the 2 pairs of tables show the same data, but presented in different ways, you can choose which pair of tables you look at. If you like actual warming rates, then look at the first pair of tables. If you like percentages, then look at the second pair of tables. If you like looking at both warming rates and percentages, then look at both pairs of tables. Both pairs of tables show the same thing, so it doesn’t really matter which pair of tables you look at.

To summarise:

The 1st table shows the calculated warming rates for the “True 1998” data.

The 2nd table shows the calculated warming rates for the “False 1998” data.

The 3rd table shows the percent slowdown of the “True 1998” data, compared to the average warming rate from 1966 to 2017.

The 4th table shows the percent slowdown of the “False 1998” data, compared to the average warming rate from 1966 to 2017.


It should be obvious, that changing the temperature anomaly for 1998, can not affect the warming rate of any date range which starts after 1998. For example, changing the temperature anomaly for 1998, does not affect the warming rate from 2002 to 2012. So when you compare the “True 1998” tables with the “False 1998” tables, you will find that all of the rows with a first year of 1999 and greater, are identical in both tables.

To help you understand these tables, I have highlighted some of the cells, to save you having to search for the lowest values.

All tables are highlighted using the exact same set of rules, so that you can easily compare different tables.

The lowest warming rate (or strongest slowdown), of each table, is highlighted in blue.

The next nine lowest warming rates (or strongest slowdowns), of each table, are highlighted in green.

The lowest warming rate (or strongest slowdown), of each table, THAT INCLUDES 1998 IN THE DATE RANGE, is highlighted in red.

The next nine lowest warming rates (or strongest slowdowns), of each table, THAT INCLUDES 1998 IN THE DATE RANGE, are highlighted in orange.

Remember that percentages are rounded to the nearest whole number. This makes it much easier to understand the tables.

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True 1998 warming rates b

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False 1998 warming rates

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True 1998 percent slowdown

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False 1998 percent slowdown

 

I will summarise the results using the 2nd pair of tables, which show the percent slowdown, compared to the average warming rate from 1966 to 2017 (1.7524 degrees Celsius per century).

Points to note:

1)  The strongest slowdown that includes 1998 in the date range, is not even in the strongest 10 slowdowns. This applies to both the “True 1998” data and the “False 1998” data.

2)  There were slowdowns for date ranges that include 1998.
For the “True 1998” data, the strongest slowdown was [1998 to 2013], 15 years with a percent slowdown of -45%.
For the “False 1998” data, the strongest slowdown was [1997 to 2013], 16 years with a percent slowdown of -27%.

3)  It was expected (by Al Bundy and me), that lowering the temperature anomaly for 1998 would weaken slowdowns which had 1998 in the date range. This is what happened. But the slowdown didn’t completely disappear as Al Bundy thought, it just weakened the slowdown from -45% to -27%.

4)  The strongest 10 slowdowns all started on or after 2001. THEY HAD NOTHING TO DO WITH 1998. I had previously explained this to Al Bundy, but he claimed that everything that I said was “stupid goop”.

5)  The strongest slowdown was from [2002 to 2012] 10 years with a percent slowdown of -92%. This is almost a total Pause of warming, which lasted for 10 years. Imagine driving your car at 100 km/h, and having to slow down to 8 km/h, FOR 10 YEARS.

6)  Even the weakest of the 10 strongest slowdowns, [2004 to 2014], 10 years with a percent slowdown of -49%, was about half the strength of the standard warming rate from 1966 to 2017 (1.7524 degrees Celsius per century).

7)  Note how all of the strongest slowdowns occur in a small group, from 2001 to 2014. There are no random single slowdowns, which might happen if the slowdowns were weak, random, events. These slowdowns form a clear, definite, event, which everybody should accept.

8)  Alarmists have been denying the slowdown for many years. They insult skeptics (like me), who claim that there was a slowdown.

9)  Some Alarmists, like Al Bundy, grudgingly admit that there was a slowdown, but claim that it only exists because of the super El Nino in 1998. It was this claim, that caused me to write this article.

10)  I hope that all Alarmists will now accept the following:

  • that there was a slowdown, which started in or after the year 2001
  • that the slowdown lasted for about 13 years
  • that the slowdown did NOT depend on the super El Nino of 1998
  • and that the slowdown was strong (almost a total Pause)

If Alarmists persist with their stupidity, then I will be forced to show you the “monthly” data, which has a date range of over 10 years, which is actually cooling. You have been warned.

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