Christopher Monckton has been showing signs of nervousness in his latest "it hasn't warmed since xyz" article at WUWT (archived here). He has started emphasising statements like this one: "As ever, a warning about the current el Niño. It is becoming ever more likely that the temperature increase that usually accompanies an el Niño will begin to shorten the Pause somewhat, just in time for the Paris climate summit ....". Here are some charts to explain his caution.
What the charts below show are the monthly global temperatures of the lower troposphere (UAH and RSS) and the surface (GISTemp) for the months surrounding the latest strongest El Niños - 1997-1998, 2009-2010 and the year to date 2015. The rectangle on the charts is the period of the El Nino - usually from around April of the first year to March of the second year. I've left the baseline years as reported. It's the shape of the charts that are of interest.
If you are unfamiliar with charts, the lines on each chart are for different periods as indicated by the legend at the bottom of the chart. The charts show the temperature anomaly for each month from January in the first year of the El Nino to December of the second year of that El Nino. What you need to look at is how the temperature anomaly climbed as the El Niño progressed in each period. That is, how the temperature anomaly rose in the later part of the first year of the event (October to December) and early in the second year (January to May). We are still in the relatively early stages of the current El Niño, although it is now considered "mature". The major impact on temperature anomalies is probably yet to come.
The first chart is Christopher's favourite, the lower troposphere temperature, reported by RSS:
|Data source: RSS|
The second chart is again the lower troposphere, this time UAH:
|Data source: UAH v6.0 beta3|
This final chart is the global mean surface temperature as reported by NASA:
|Data source: GISS NASA|
All the charts show that in 1997-98 and 2009-10, the maximum anomaly was reached late in the El Niño or, in the case of the lower troposphere for 1997-98, after the El Niño finished.
If this El Niño has the same effect on the temperatures of the lower troposphere and at the surface, then Christopher will probably have to restart his count going back to zero. He would definitely have to start his count again from zero if the RSS anomaly shoots up enough over that of 1997-98, which it may do. Imagine the WUWT articles then: "It hasn't warmed since 2016", which might last him till 2020 if he (and we) are lucky, though it just as likely won't - if we have entered a warm phase of the PDO (see below).
A La Niña won't bring global temperature back to normal
In his latest "it hasn't warmed since" article, Christopher wrote hopefully if mistakenly: "However, the year or two after an el Niño usually – but not always – brings an offsetting la Niña, cooling first the ocean surface and then the air temperature and restoring global temperature to normal.."
He's wrong. It will be many centuries before global temperatures get back to what is considered "normal" for the Holocene (since civilisation began). Below is a chart showing what has happened with ENSO years over time where the orange/brown is an El Niño year and the blue is a La Niña year. If you considered the temperatures in the middle of last century as "normal", then it's been about forty years since there has been anything approaching a "normal" year. Not since the 1970s. Temperatures now are as high or maybe higher than they've been in the entire Holocene, including the climatic optimum of 5,000 to 8,000 years ago. (In the chart below the most recent column is 2015 year-to-date.)
|Data sources: GISS NASA, BoM, PDO phases|
The chart also shows the phases of the Pacific Decadal Oscillation (PDO). This is a pattern of sea surface temperature in the Pacific Ocean and is described by an index. It shifts from what is called a warm phase to a cool phase over decades. As you can see, when the PDO is in a warm phase, El Niños tend to dominate. In a cool phase, La Niñas dominate. If we have already entered a warm phase, then none of us, including Christopher, are likely to get much relief from the next La Niñas. Even in the cool phase when La Niñas dominate, since around 1999, each one has usually been warmer than the previous.
It's called global warming and we are causing it.
- Global Warming and the Pacific: Kevin Trenberth's Perspective - August 2015
- Much to the dismay of Christopher Monckton and his illiterati fans at WUWT, it's still not cooling - February 2014
- What's happened to global warming since 1996 - August 2014 (from when Christopher Monckton used to claim that global warming stopped in 1996)