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.
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.
There’s no doubt that global surface temperatures have been on the rise. There may have been a slight pause while it caught its breath in 2011 & 2012, but with the help of a record ENSO event in 2015, the linear trend for the last 10 years is almost +0.4°C per decade in the CRUTEM4 series (fig 2).
The American GISS data shows a slightly higher linear trend for the last 10 years of +0.429°C (fig 3).
So Nigel Lawson was wrong big time about global data for the last ten years, he thought the pause had been continuing, and refused to look at the latest temperature data. But was Nigel wrong about temperatures closer to home in the UK during the last 10 years?
Not a great deal of solace for Nigel from the 1910 UKMO gridded data series, the linear trend for the last 10 years is not that dissimilar to the CRUTEM4 of GISS showing warming at the rate of +0.34°C per decade (fig 4). What about the Central England Temperature series.
Even worst than ever with the CET I’m afraid Nigel, the decadal linear trend on the 12 monthly moving mean CET for the last 10 years is above 0.5°C per decade (fig 5). So the simple answer to the question I posed in the title of “did Nigel just get muddled up?” is no, he’s just an idiot, and how he ever got to be the Chancellor of the Exchequer beggars belief. To be fair to him, he should have picked a longer time period than 10 years, because even with long-term temperature series like these there are natural background fluctuations.
*There are a couple of things wrong in the titles of charts that I used for figures 2 & 3, I’ll award special bonus points to those that can spot where I ballsed up.
Matt McGrath, an environment correspondent at the BBC, has written an article that clarifies that any increase in frequency or intensity of tropical cyclones, is not directly linked to increases in the sea temperature in the oceans in which they form. This corrects the misleading, and rather strange 30 second news video that David Shukman made on the 19th of September who said that higher sea temperatures meant more tropical cyclones. Although SST is a key ingredient, there are a lot more factors that have to be just so before a tropical cyclone is formed.
Here’s a chart of the number of hurricanes each year since 1851.
And here’s a chart of the combined ACE score for each year since 1851.
You may wonder why the linear trend is upward in both charts, that’s because of the increased scrutiny that each tropical cyclone has been under since the start of the satellite era (~1960), has meant that we are now in a position to watch each subtle move and deviation that a tropical cyclone now makes which was never possible before. There must have been many lesser tropical cyclones, especially in the 19th century that escaped detection and don’t even appear in the HURDAT2 dataset, which must skew the trend down to the left.
At least this article is more balanced in what is a says about what we do know about tropical cyclone formation, and not just using adding it to the list of what increased CO2 is doing to the planet, as David Shukman seems to think.
Increased global temperature ✔
Reduction in sea ice ✔
Shrinking of glaciers ✔
Increase in intensity of heavy rainfall events ✔
Increase in the number and severity of tropical cyclones 🗙
Apologies for the scribblings on the news item like I have, I was just interested in the number of clichés Matt McGrath had used in his article – and why is it that tropical cyclones always seem to ‘barrel’ across the ocean?
I was listening to a 30 second science-bite about hurricanes from David Shukman on the BBC News website yesterday. David was presenting a ‘idiots guide’ to just how hurricanes are formed, and for once the explanation didn’t involve that ‘fast moving ribbon of air high in the atmosphere that the experts call the jet stream’. The basic premise of his explanation was that when a thunderstorm forms over the ocean in the tropics, if derives its energy from the warm seas, and if the temperature of that sea was 26°C or higher, and you added a little bit of rotation, then before you know it you would have yourself a tropical cyclone. Of course this was a thinly disguised bit of propaganda to implant in the viewer’s mind the undisputed fact that: higher sea surface temperatures mean more hurricanes, and of course it must logically follow that’s why they’ve been so many this year.
That got me to thinking about El Niño and La Niña events and how they might influence tropical cyclone development in the eastern Pacific. If you apply the same ‘Shukman’ type logic, the extra warmth of the Pacific during El Niño years, should be apparent in the accumulated cyclone energy. So I have produced a couple of graphs that plot ACE for the eastern Pacific from 1950 for both total ACE and ACE anomalies (fig 2). The pale pink and blue stripes in the lower graph are the ENSO events during that time.
I could do further statistical analysis on the results, but I think I wouldn’t find a strong correlation between SST and the ACE index. Active years do occur in El Niño years that’s true, but they also seem to occur just in La Niña or neutral years. I personally think that the BBC should be explaining that although the warmth of the oceans is a key part in tropical cyclone development, any perceived increase in their number and ferocity is a little more complicated, rather than this glib thirty-second news item with its fancy graphics implies.
I did find an analysis concerning El Niño and intense tropical cyclones in the Journal Nature but was unable to download it without getting a second mortgage on the house. I did find this online debate about the conclusion that the report came up with which might be of interest.
The Guardian must have known they were onto a winner with this article from the great Michael Mann about Hurricane Harvey, who states categorically in the article that Hurricane Harvey was made more deadly due to climate change (fig 1). I wonder just how many comments this article will attract?
Michael Mann states that one of the main factors why it was more deadly was due to higher than average SST in the Gulf of Mexico. So I thought that I’d have a quick look and see what the latest anomalies were across the North Atlantic, Caribbean and Gulf of Mexico to see if what he was saying was correct. Courtesy of NCOF, here are the SST (fig 2), on which I’ve drawn a very approximate track for the path of tropical cyclone Harvey, which as far as I can see from the NHC records, sprang into life as a cyclone at around 54° west on Thursday the 17th of August. Harvey has had a very fitful life, it ‘died’ as a tropical storm as it entered the Caribbean late on Saturday the 19th, before being reborn again as a tropical depression on Wednesday the 23rd as a tropical depression in the Bay of Campeche, the rest as they say is history.
All that you can say about the SST anomalies along the path of Harvey was that they were generally in the slightly warm category +0.5 to +1.0°C for much of its life. Interestingly these ‘higher’ than average SST in the Caribbean didn’t seem to stop it from dying for four days though, and it wasn’t till it entered the Bay of Campeche that it was reinvigorated. Because the SST anomalies in the above chart (fig 2) are in a bit of a turmoil after the passage of what was a category four hurricane, I have included an extra chart (fig 3) from the 23rd and before the waters got churned up. The SST anomalies in that chart show anomalies between +0.5°C and 1.5°C, generally across coastal regions of Texas extending eastward to Florida, with negative anomalies of the coast of the Yucatan peninsula.
So what caused Harvey to reform and quickly turn nasty as she entered the Gulf of Mexico? I personally don’t think it was ‘more deadly’ because the waters of the Gulf of Mexico were slightly warmer than average, I think it was more to do with the atmospheric mechanics that were driving Hurricane Harvey, of which the SST, although important are just one factor. Anyway now that I have provided one piece of the evidence you can make your own minds up.
The Independent today has an article entitled ‘Scientists find what they think is largest volcanic region on Earth hidden in Antarctica after student’s idea’ (fig 1). I can’t believe for one moment that this work hasn’t been previously done before by the Americans or the Russians, but apparently it was all the idea of a third-year student at the University of Edinburgh, Max Van Wyk de Vries, that would be a great collective name for the 91 volcanoes that they discovered – the Van Wyk de Vries volcanoes. They found 91 volcanoes which range in height from 100 m to 3,850 m in a massive region known as the West Antarctic Rift System.
I had to take exception with the bit that Paul Ward has written, because with a story like this there just has to be a link to AGW no matter how weak:
Previous studies have suggested that volcanic activity may have occurred in the region during warmer periods and could increase if Antarctica’s ice thins in a warming climate.
I don’t know about the reference to a previous study he carelessly throws into the article, but what it (or he) is suggesting is that if the ice cap begins to thin a little, this could encourage the dormant volcanoes to reawaken. I am no geologist, or volcanologist come to that, but I find it hard to believe that these volcanoes were effectively plugged by an icecap that formed on top of them, and that they’ll suddenly spring back into life if ever the icecap starts to thin. Surely it’s got more to do with what’s going on under the mantle, and the tectonic forces that are at play, rather than waiting for the icecap to thin? I imagine that volcanoes would have no problem finding the ir way to the surface, despite being sat under an icecap which is 4 km thick in places, isn’t that what recently happened in Iceland with the Vatnajökull volcano.
That just leaves one important question as far as I’m concerned, and that is, what are all the scientists in the many Antarctic ice stations that the nations who have staked a claim to their piece of Antarctica actually doing with their time?
First off I will admit I haven’t fully read the study “Changing climate shifts timing of European floods” by Günter Blöschl and numerous other contributors from across Europe. The study has been picked up on by the BBC in this news article (fig 1), because they obviously see that it’s just another byproduct of AGW, rather than just climate change, and yes I do think there is subtle distinction. As far as I can see, none of the many contributors are employed by the UKMO, which I find unusual.
I have highlighted in yellow the areas in the news article that I have misgivings about, the first one is from Matt McGrath
The scientists believe this is due to changes in the North Atlantic Oscillation (NAO), the weather phenomenon that pushes storms across the ocean into Europe.
The North Atlantic Oscillation is simply an index of the pressure difference between the Azores and Iceland, as far as I know this index doesn’t push anything across any ocean, you might say that the Azores high or Icelandic Low are weather phenomena, but surely the difference between the pressure at two points is just a number?
Günter is the quoted as saying:
In southern England, it has been raining more, longer and more intensely than in the past. This has created a rising groundwater table and higher soil moisture than usual and combined with intense rainfall this produces earlier river floods
I refute that, unless the changes that the study is talking about have suddenly started to occur in the last five years. Cue some evocative pictures of rivers in southern England that have dried up in recent years that I’ve found on the Internet (figs 2 & 3). (N.B. to the BBC, two can play at that game!). Yes, I know these images are from 2012, but what about the River Derwent in the Lake District in May 2017 (fig 4). So it’s a well-known fact that river levels and groundwater tables do fluctuate, and can do so very quickly, that’s what they naturally do.
I can’t get any daily rainfall climate data for anywhere in the UK without paying loads of money to the Met Office, so I am stuck with the free 1910 monthly rainfall gridded data that they produce, I wonder if they used this kind of data or if the Met Office felt pity on their research and gave them the ‘real’ rainfall station data that they guard so jealously on our behalf? From that data here are some graphs with a simple linear trend for the southeast and central southern England region for winter, spring and summer (figs 5-7). I can’t see any discernible upward trend in rainfall in any of those three seasons, although I will admit that the 10 year moving average for summer is on the rise, and won’t be any lower after this wet summer.
Günter goes on further to say:
Half the stations recorded floods at least 15 days earlier than previously. A quarter of the stations saw flooding more than 36 days earlier than in 1960.
This one is a hard one to counter, especially without daily rainfall climate data and the dates of all fluvial flooding incidents since 1960, which I simply don’t have. But I don’t see that there is some kind of flood or monsoon season across the UK that starts at any precise date that you can readily identify, and if you can’t identify it, then how can you then go on to say that it’s starting 15 days earlier than it did in 1960? I do know from my interest in CET, that the spring is probably around 15 days earlier and it was in 1960, and that temperature is linked to increased convection and heavier rainfall, but I see little sign of it from the rainfall climate data that I can access.
Finally, here’s the last 12 months rainfall over southeast England (fig 8). It’s been a funny last 12 months as far as rainfall goes, up until mid May there was talk of an impending drought later in the year across southern and eastern areas, but the wet summer has put paid to that. There have definitely been some wet days in the last 12 months across the southeast of England, but they can occur in any month as far as I can see, and the accumulated rainfall is still only 84.7% of the annual average at the end of July 2017. What I really need is now is data from the environment agency, some kind of daily count on the number of alerts that they issue for rivers across the UK, a bit like the NAO, but not a phenomena, just a daily count.
PS I’ve just download the report to read – for a change it’s free to do so – and better still it’s only four pages long.