There is no single thermometer measuring the global temperature. Instead, individual thermometer measurements taken every day at several thousand stations over the land areas of the world are combined with thousands more measurements of sea surface temperature taken from ships moving over the oceans to produce an estimate of global average temperature every month.
There’s no doubt that the Earth has been warming since 1970, but the rate of increase in the warming seems to have stalled between +0.16 and +0.18°C per decade since around 1992. I don’t have any particular axe to grind in the AGW debate, and I’m no climate expert, but I can knock out code and generate a good graph from the applications that I develop. Such is the power of modern computers I constructed the top graph (fig 1) by calculating around 1,296 monthly 30 year linear trends since 1910. Using GISS land and sea data the first “y” value is the 30 year linear trend for the period from January 1880 to December 1909, and the last “y” value using data from April 1988 to March 2018, as you can see I didn’t choose to centre the graph but kept it right aligned. I don’t know how valid this technique is statistically, but for all I know it’s a well-known method that’s widely used!
I suppose I decided to publish this particular blog after reading so many snippets of news saying how the latest GISS temperature for March made it “the 6th warmest on record” – so what? Dig just a little deeper into the data series and you’ll find that the 12 month moving average has now been falling now since the start of 2016 which is to be expected at the end of an El Niño event (fig 2), but the pause in the rate of change runs much longer than this, especially as climate experts say that it should accelerating.
I’m not saying global warming has stopped because it’s quite obvious it hasn’t – and if global temperatures continue at this rate they’ll be 1.8°C higher than they are now in 2118 – I’m just saying the rate of change in that warming has flattened out, and seems to be holding steady at the present time.
The slide in 12 month average global temperatures which started 18 months ago now goes on (fig 1). The latest 12 month average is just slightly above the +1°C of warming since pre-industrial levels that the Met Office keep going on about, and is over 0.25°C lower than it was in February 2016. It won’t be long at this rate before there are murmurings of a second pause!
The latest CRUTEM anomaly of global combined land and sea temperature for February 2018 was +0.523°C, making it either the 12th warmest on record, or the coldest since 2014 depending on your religion (fig 2). The continue cooling can no doubt be attributed to the La Niña conditions in the equatorial Pacific over the last year.
Recent global surface temperatures have continued to fall in the two years following the El Niño of 2014-16. January 2018 was the coldest January since 2014 in both the CRUTEM and GISS series (fig 1). The anomalies of 0.553°C and 0.78°C above the long-term average still mean that the global picture is one of various shades of yellow and red rather than blue though (fig 2). There was an interesting cold pool across a large area surrounding the Mediterranean during the month, but apart from this it was the scale of the warmth across eastern north America and northern Asia that were the main talking points.
If you were wondering just how the recent SSW has affected things, and how temperature anomalies ended up in February, here’s a chart that I’ve put together using reanalysis data (fig 3).
In an addendum to yesterdays blog “Is it 1°C higher or not?“, I can now say yes, recent global temperature were 1°C higher than pre-industrial levels for the best part of two years or more, but in the latter part of 2017 monthly temperatures dropped below the magic +1°C, and that’s why the press releases seem to suggest things haven’t changed. In fact they have gone up and crashed back down again in that period.
Perhaps if they had used a more detailed and larger graph of changes in global temperatures in the latest news release that might have helped. And so to clarify what’s actually going on in more detail I decided to create my own graph based on the CRUTEM4 monthly data that you can freely download (fig 1).
I can now also understand why professor Stephen Belcher the Met Office chief scientist is saying that global surface temperature anomalies could reach 1.5°C above pre-industrial levels in the next 5 years. Already monthly values in the last El Niño event in early 2016 got close to 1.5°C (fig 1). He is obviously banking on the current La Niña fizzling out and a return to the strong warming we saw in 2015.
There is a natural seasonality to the monthly values and that’s why I’ve added a 12 month moving average to the graph. That 12 month moving averaged peaked at +1.25°C in early 2016 and by December 2017 it’s fallen back to +1.05°C. The linear trend for the last five years does indicate that there’s been a decadal increase of 0.547°C, which would be enough to take temperatures above 1.5°C, possibly in the next ten years rather than the five suggested by Stephen Belcher.
I’m a bit confused about this weeks press release from the Met Office concerning global warming (fig 1). I was under the impression that global temperature was already 1°C higher than they had been at the start of the industrial age (1850?) from a press release they had made over two years ago in November 2015 (fig 2). I was obviously mistaken, because if you read what professor Stephen Belcher chief scientist at the Met Office says in the latest press release, it appears that this was not the case.
I find it difficult to believe that if the global surface temperature anomaly has hovered around 1°C higher for the last two years, how it could possibly jump to be 1.5°C higher in the next five years.
A massive contrast in temperature anomalies between the exceptionally cold east of North America (-14°C), and a tongue of warm anomalies that extends from northern Russia (+17°C) southwest across Europe to Iberia, during the first six days of the New Year as you can see in this chart (fig 1).
If we do see an easterly anticyclonic spell in the next few weeks the temperatures may not be as cold as usual in the UK, because the source of that cold continental air has been very mild throughout this autumn and early winter. At the moment Moscow isn’t reporting a snow depth, because there isn’t any, which in itself is uncommon at the turn of the year (fig 1), in fact the mean temperature there has been anomalously warm since the start of November. The chart of snow and ice cover for the northern hemisphere (fig 2) illustrates the lack of snow. In the last twenty years a chart similar to this one has become a common feature of many a winter.
Here are the anomalies so far this month for our part of the northern hemisphere, as you can see there is a large positive +5°C anomaly across western Russia, so it’s no wonder there’s not much snow in Moscow (fig 3).
As far as I can see using the daily objective LWT data that I regularly download from the UEA, the 30 percent NW’ly weather types of the last month (7 November – 6 December) are the highest percentage for this period ever seen in the series since it started in 1871 (fig 1). Thirty percent may not seem high but NW’ly types are not a common LWT believe it or not.
Here are the 00 UTC weather charts for the last month (fig 2), and as you can see southerly and southwesterlies have been in short supply.
So the obvious question is with so many NW’ly days during the last month why has the weather been so mild, and not much colder? The last months CET daily mean values (9 November – 8 December) are currently a shade above average at +0.18°C above the long-term 1981-2010 average (fig 3). Even during the first eight days of December, mean temperatures across Central England are currently still +0.75°C above average.
It may have a lot to do with the sea surface temperatures around our part of the northeast Atlantic and they are currently much warmer than average (fig 4).
Here are the 12 UTC temperature anomalies for the start of December for our part of world (fig 5), which show that colder than average temperatures are in short supply even when we are currently in the grips of an Arctic northerly across the British Isles. So the answer to the question why hasn’t the last month been colder, is simply down to the fact that surface temperatures across the world are currently at record high levels, and no matter how many northerly outbreaks we seem to have seen in the last month it seems to have made little difference.
I am surprised that some of the UK climate records used by the Met Office to calculate their global land temperatures for CRUTEM4 with, are from sites where the instrument enclosure, primarily the Stevenson screen, has been compromised over the years by the encroachment of buildings, car parks, and runways and the various ‘climate’ sites around the country, to such an extent that it must in some way be affecting the temperature sensors. Creeping urbanisation has been happening for years, and is not a new problem, it’s a bit like how politicians suddenly realised that life expectancy has been on the rise for the last 100 years.
Before I go any further these concerns have been voiced before, and a review of the observing sites of the UK has been done before, and much more thoroughly than I can do in this short article, most notably in the Surface Stations Survey by Tim Channon on the TallBloke blog.
The Surface Stations Survey work was done a few years ago now, and as far as I see wasn’t directly linked to the ‘raw’ monthly CRUTEM4 temperature data that you can freely download from the Met Office, and which is used to calculate a monthly estimate of global land temperature with. In recent years the Met Office, for some reason known only to themselves, have reduced the number of the UK sites from well over 100 twenty years ago (fig 1), to just 18 sites in 2017 (fig 2).
Here’s a graph (fig 3) of how the total number of UK sites that are currently used in the CRUTEM4 calculations has declined in recent years.
The irony of this 80% or more reduction in UK sites used, is that two of the three sites used to calculate the composite CET series, the longest instrumental record of temperature in the world, are now no longer used – Rothamsted (1872-2012) and Preston Moor Park (aka Stonyhurst 1960-2012).
Poor siting of instrument enclosures
But I digress, what I really wanted to moan about bring to people’s attention was the precarious siting of the Stevenson Screen at some of the 18 sites that we still use to calculate a global temperature with. Generally the siting of the screen didn’t look too bad, but there are a number that are poor, and here are three of the worst sited Stevenson screens that I found using Google Maps. Of course guessing where the screen is an art that has become a bit of an obsession with me. The biggest offenders are all at airports, namely Aberdeen, Valley and the infamous Heathrow (figs 4, 5 & 6).
At this point I would like to say I wouldn’t be able to do this without Google maps, but I have noticed that the generally the quality of the highest zoomed images is inferior to those in the Google map images of the Surface Stations Survey. This might be just a Google maps issue, or it maybe a deliberate restriction on quality and zoom level requested by the MOD for RAF stations. The yellow circle is at a radius of 10 metres and the blue circle at a radius of 30 metres. I won’t go into detail of what I estimate the WMO classification for each site would be as regards temperature, I’ll just leave it your imagination.
What can the Met Office do about it?
When I was an observer every so often at an outstation, someone would come round and inspect the ‘met’ enclosure to see if it was being maintained correctly, I wish now that I had taken a keener interest in what the inspector was looking at other than if the bare patch had been weeded recently! I wonder if there was tick box to confirm that no jet engines were being run up within 30 metres of the screen? I can remember quite clearly being wafted by warm gusts of air from an F3 Lightning at Binbrook en route to the Stevenson screen across the pan to do the 09 UTC observation even in the middle of winter.
They could if they wanted to without much effort do the following with the climate records used from the UK in CRUTEM4:
Reinstate the best of the climate stations that have been lost in recent years, but not the records from RAF Waddington or RAF Brize Norton please!
Immediately reinstate the temperature climate records for Rothamsted and Stonyhurst, at the same time adding the one from Pershore, so that the three stations used for the renown CET series are included in the calculations, which to my mind would be only fitting!
Remove Heathrow until the enclosure has been relocated possibly in the middle of Bushy Park!
This would be very easy for the Met Office to do, they wouldn’t have to go cap in hand to any other meteorological service to ask them to supply the data, as they already have those temperature records.
I know just how sensitive temperature sensors are in AWS these days, I have a Vantage Pro, and over the years I’ve relocated it a number of times in our garden, each location had its different weaknesses, too close to trees or the hedge, or too close to an area of paving, now it’s far too close to the garage. It certainly is a very difficult, if not impossible task to find a location on a modern airfield that’s totally unaffected by external influences on temperature. But in this day and age of advanced wireless communication, I just can’t believe it’s not possible to install AWS as far away as possible from any runway, car park, building or road, at any site, which invariably is at an airport, be it military or civilian. I’ve been doing it with my AWS without a problem for the last 13 years, albeit at a range of less than 10 metres! Inevitably this will have to be done as the demand for green space on airfield sites increases till the whole damn place is paved for a parking lot.