December so far has been characterised by intense media discussions about climate change and its relationship to weather.
Early in the month, the Met Office welcomed the BBC Trust report, which recognised there was a serious breach of their editorial guidelines and that the What’s the Point of the.. Met Office programme, aired in August, had failed to make clear that the Met Office’s underlying views on climate change science were supported by the majority of scientists.
Trustees considered audiences were not given sufficient information about prevailing scientific opinion to allow them to assess the position of the Met Office and the Met Office position on these criticisms was not adequately included in the programme.
In the wake of Storm Desmond, there have been further media comments about the relationship between climate change and weather.
On Monday, in a blog, we were very clear not to link the record-breaking rainfall with climate change. This is what Professor Dame Julia Slingo, Met Office Chief Scientist has said: “It’s too early to say definitively whether climate change has made a contribution to the exceptional rainfall. We anticipated a wet, stormy start to winter in our three-month outlooks, associated with the strong El Niño and other factors.
“However, just as with the stormy winter of two years ago, all the evidence from fundamental physics, and our understanding of our weather systems, suggests there may be a link between climate change and record-breaking winter rainfall. Last month, we published a paper showing that for the same weather pattern, an extended period of extreme UK winter rainfall is now seven times more likely than in a world without human emissions of greenhouse gases.”
So, we have been clear: it’s not easy to link a single weather event to climate change, but last weekend’s record rainfall aligns with the pattern highlighted by our scientists. The Met Office expects an increase in heavy rainfall associated with climate change and this is an active area of research. A recent paper by the Met Office’s Mike Kendon highlights several key findings connected with rainfall records:
- Since 2000 there have been almost 10 times as many wet records as dry records.
- Remarkably, the period since 2010 accounts for more wet records than any other decade – even though this is only a five-year period. It also includes the winter of 2013/14: the wettest on record.
Guided by peer-reviewed science, the Met Office recognises the climate is changing, and with that comes an expectation that more records will be broken.
Official blog of the Met Office news team 
Typo, missing an “is”!
“Remarkably, the period since 2010 accounts for more wet records than any other decade – even though this only a five-year period.”
Thanks Bruce. Corrected now.
Helen
Last month, we published a paper showing that for the same weather pattern, an extended period of extreme UK winter rainfall is now seven times more likely than in a world without human emissions of greenhouse gases.”
The paper you quote could find no anthropogenic influence whatsoever in the record winter rainfall last year (which the study was investigating), and could only find a “not statistically significant shift to wetter conditions for 10-day rainfall”.
Please withdraw your grossly misleading and inaccurate claim, before you become an embarrassment to science.
If you need reminding, your paper is here, in Chapter 10
https://www2.ametsoc.org/ams/index.cfm/publications/bulletin-of-the-american-meteorological-society-bams/explaining-extreme-events-from-a-climate-perspective/
Paul
The study is referring to the winter of 2013/14 not 2014/15.
Helen
Yes, 2013/14, ie last year!
Julia’s phrase was “an extended period of extreme UK winter rainfall”. Clearly, and despite the context of her quoted remarks as cited in THIS news blog post, she meant 10 day long winter periods rather than a whole Dec-Feb winter season. The ORIGINAL context of her remarks was of course not a whole winter’s rainfall but the extreme rainfall in Cumbria in the first few days of this month: https://blog.metoffice.gov.uk/2015/12/07/did-climate-change-have-an-impact-on-storm-desmond/
But perhaps this blog could have been more carefully expressed. I can certainly understand how Paul thought she was accidentally or otherwise misrepresenting the conclusion of that paper in ‘Explaining Extreme Events of 2014 from a Climate Perspective’.
I noticed that too when skimming through the BAMS report. It appears that they can’t even understand their own papers.
Paul
I have skimmed the paper in question. As you suggest its conclusion reads “The prevalent southwesterly flow over the United Kingdom in winter 2013/14 provided favorable conditions for extreme rainfall. Although the atmosphere can hold more water in a warming climate (Allan and Soden 2008), associated rainfall increases are more difficult to detect on small (e.g.,sub-continental, regional) scales. Here, we find some
evidence for a human-induced increase in extreme winter rainfall in the United Kingdom, for events with time scales of 10 days.”
It is also the case that the last paragraph of the results section of the paper states: “Figures 10.2b,d,f illustrate the effect of human influence on extreme rainfall for synoptic conditions similar to 2013/14. The ALL and NAT (high correlation) ensembles are not distinguishable for both DJF and R10x based on Kolmogorov–Smirnov tests (p values greater than 0.2). However, a minor (not statistically significant) shift to wetter conditions due to anthropogenic forcings is identified for R10x,
translating to an increase in the chances of getting an extreme event by a factor of about seven. No change in the likelihood is found for DJF….”
‘djf’ stands for December-February and I believe ‘R10x’ refers to 10 day periods of unusually high rainfall.
Thus it does appear to me that Paul is correct and that Julia Slingo may have slightly misrepresented the paper’s conclusions,
What I don’t understand is why you want to go to such great lengths to try to make a link between extreme weather events and “climate change”? Surely the job of the Met Office is to forecast weather, not to get embroiled in a political controversy. If, as you say, “It’s too early to say definitively whether climate change has made a contribution to the exceptional rainfall”, then you should leave it at that.
OK, but why is it the Met Office’s job to forecast the weather? Well, the answer is that people and society can make better informed decisions about their lives, based on meteorological science.
In that case, surely the implications of extreme weather events (and the record-breaking 340mm of rain in 24 hours certainly counts) are very relevant to the Met’s purpose.
For example, if we could say that the Cumbrian rainfall had a probability of 0.6% of occurring by chance, just 6 years after a similar (slightly lower) catastrophic event, then this has major implications for the lives of the people in the Lake district for at least two, obvious reasons:
Firstly, it implies that this kind of event will happen again and so the current level of flood defences (which cope with century-level events) are going to fail again, unless further mitigation is put into action.
Secondly, if we’re able to say this isn’t ‘just weather’, then we’re able to identify a signal (climate change) from the noise (weather) and we can therefore make a better projection on how often Cumbria is likely to be flooded. And this allows us to determine the best course of action, whether for example, to just buck up and deal with it, or if it’s going to become too expensive or excessively damage the economic viability of parts of Cumbria, make preparations to leave. It’s that serious.
That’s why the Met office can’t just leave it at “It’s too early to say definitively..” We know already that: “Last month, we published a paper showing that for the same weather pattern, an extended period of extreme UK winter rainfall is now seven times more likely than in a world without human emissions of greenhouse gases”
That’s 7 times more likely and that information is of benefit to me, us and you. And the lesson to learn from knowing it’s too early to be certain (though likely) these weather events are caused by global warming is to do more attribution research and keep the public tuned in to these important matters. One way of tuning in would be to change the terms of the conversation. Rather than asking “was this event caused by climate change?” we can ask “How did Climate change most likely affect this weather event – in terms of its frequency or severity?” That makes sense, because in reality all “weather” is affected by the climate and thus affected by how it changes.
“Seven times more likely” my foot.
Have you read the BAMS report that this figure comes from. The kindest thing you could say about it is that it’s statistically inept.
The “Seven times more likely” study says they can only find ” a not statistically significant shift to wetter conditions for 10-day rainfall”
As for your probabilities, there were similar amounts of rainfall in 1897 and 1898
Derek,
Understanding the potential effects of human activity on extreme weather and climate more generally is a scientific question not a ‘political controversy’. I would say that makes its study well within the remit of our national weather service. If they started campaigning on what to do about it, like for example advocating wind power instead of nuclear, then I would agree they had become political. But I have seen nothing to suggest they do that.
Then we will have to disagree about that. Slingo and Stott’s continued attempts to link climate change to weather events, without reliable data, suits the current political agenda. Something Slingo is only too aware of.
Extra brownie points (and funding) are awarded to anyone who can excuse the Governments or Environment Agency’s inadequate response to natural variation in weather.
The problem is that the media, specifically the BBC in your case, continues to selectively quote the Met Office in order to promote doubt.
For example, with respect to your blog on 07/12/2015, the BBC re-represented part of Dame Julia Slingo’s statement in such a way as to make the science appear less certain than it is. So, whereas the Met Office said
“It’s too early to say definitively whether climate change has made a contribution to the exceptional rainfall.. However, just as with the stormy winter of two years ago, all the evidence from fundamental physics, and our understanding of our weather systems, suggests there may be a link between climate change and record-breaking winter rainfall.”
the BBC quoted that as:
“Is it to do with climate change? There can’t yet be a definitive answer but we know that all the evidence from fundamental physics and what we understand about our weather patterns, that there is potentially a role.”
There’s a real difference between the two in that the BBC is basically saying that “there’s no evidence, but it’s theoretically possible”, whereas the Met is saying “we have evidence, and all the evidence we have, along with our scientific knowledge and theoretical models suggests there’s a link, but it’s not yet certain.”
And this is confirmed by the fact the BBC didn’t quote the last of the Met Office’s statements “Last month, we published a paper showing that for the same weather pattern, an extended period of extreme UK winter rainfall is now seven times more likely than in a world without human emissions of greenhouse gases”
And of course, the BBC couldn’t quote that if it had just claimed that the Met said there’s no evidence.
The issue is that the necessity of representing the degree of confidence in the science accurately leaves the Met Office wide open to serious misrepresentation. By contrast, even my crude, amateur deductions allow me to make some claims about attribution. There’s on-line claims that the Cumbria floods in 2009 were a one-in-a-millennium event (at 316mm), so I can fairly claim that the Cumbrian floods in 2015 were also a one-in-a-millennium event (at 341mm). And this would have a probability of 1-(1-1/1000)^(2015-2009) = 0.6%.
Therefore it should be possible to claim that the 2015 floods were 99.4% unlikely to happen by chance 6 years after the 2009 floods. Or, to claim it in another way, that 2009 and 2015 flood events are likely to happen once every 167,000 years.
Of course, this lacks rigour. I can’t claim it’s due to burning fossil fuels (though I can’t think of a convincing alternative); perhaps it’s wrong to directly equate the locations of the floods (the 2015 floods might be in an area with more average rainfall than Cockermouth) and there’s a whole host of other flaws I’m sure I could dig up if I had a supercomputer and a few decades of expertise in the field.
But, at the level of the information available to me, claiming 99.4% certainty that this didn’t happen by chance is a better representation of the science than “there’s no evidence, but it’s theoretically possible.”
And even if I’m wrong about either of the events being one-in-a-millennium events I would be on surer ground (sic) to claim than since the floods breached century-level flood defences that the probability of this is 1-(1-1/100)^(2015-2009) = 6%, a confidence of 94% that it isn’t chance (=1 in 1,670 years).
And I could apply the same reasoning to further flooding events. Let’s say Cumbria experiences another >316mm precipitation event just 2 months after storm Desmond. The probability here would be 1-(1-1/1000)^(2/12) = 0.0167%, in itself 99.98% unlikely to happen by chance or by combining the two events we get a probability of 99.9999%.
The difficulty here is that most of the rainfall records ore very short, some as little as 40 years. We have no accurate empirical records from which we can even begin to determine what the 1/100 event level would actually be, and certainly nothing empirical to determine 1/000 events.
The best we can do is look at the study released last week by the Cambridge University team which tells us that this event was only one of many similar events in this area. Indeed their evidence suggests considerably greater levels of flooding in the past, albeit before much of the present settlements were established.
This is the type of work the Met Office should be doing if they want to have a useful and productive future, unfortunately all their chief scientist appears to be interested in is disseminating CO2 scare story’s.
The way to deal with short records is to look at lots of stations across the UK, Europe and the world to discern the pattern of change. From what I have seen, when the scientists do that a clearer picture emerges from the statistical uncertainty.
That is simply not relevant when you are considering localised flooding events in very specific catchment areas like those in Cumbria.
Of course it is. Climate change is not a local phenomenon it has effects over large geographical scales. You have to look across a range of data to infer its effects.
Then we will have to agree to disagree. I would put more faith in paleo records of the local catchment areas in Cumbria, rather than UK, European or world climate change records to discern whether there was a likelihood of further flooding in Cumbria.
Hello, I am not scientifically qualified and rely on organisations such as NASA and yourselves to keep me informed. I see papers released from NASA saying the Antarctic ice sheet is diminishing and shortly after another NASA paper saying it is increasing. I hear the number of Polar bears are falling then I hear they have increased… Your blogs often mention âshortâ term effects of excess rainfall, higher temperatures, etc., in relation to human activities causing climate change but say very little of longer term effects of say â sun spot activity or hot, cool, wet, dry periods in the more distant past.
This leaves me wondering what caused the cold period in the 17thC when markets were held on the frozen Thames or the warm periods when Vines and other warmer climate crops thrived in the UK, when the Sahara or Greenland were Green. There was little man made activity in those periods that would have caused these changes…
I do believe man is having an effect on our climate but so is nature, what about volcanic activity? for instance and what effect is War having in comparison to commerce? What will world leaders do about the fires in Indonesia or the opencast coal that has burned for 100 years in the Indian sub-continent? Finally what effect is increased world population having and what is being done about that???
I understand the Met. Office cannot take everything into account themselves but to people like myself we do need to hear more of the full facts and, maybe then, people will take action to help prevent a future catastrophe.
Vivienne Kincaid
Unfortunately, a huge stream of information on this subject is continually produced at all levels, from the peer reviewed literature to press releases, newspaper articles and blogs. I am someone who is scientifically trained, albeit in another discipline, but I would admit it hasn’t been easy to fight through this thicket to educate myself. What is clear to me is that there is a lot of misleading information out there. Much of this is plain misunderstanding from ‘recyclers’ like newspapers who don’t get the scientific subtleties. But there are also those who are deliberately out to mislead for their own political ends. It does not help, of course, that much of the original research literature is behind paywalls, although this is beginning to change. That said, the technical literature can be daunting for the average person.
While its easy to be overwhelmed, I’d encourage anyone to stick at it. Your particular point, that climate seems to have always varied so what is different now, is a good one, and one I spent quite a while thinking about myself. I think its been shown that the sort of natural things that influence global average climate, like the sun and volcanoes, should have acted to cool the climate over the last 50 years, not warm it. There is no reason at all why the sort of influences that used to cause the climate to change are the same ones responsible for the observed warming. Its not that the previous forcings have gone away, its just that they are slowly being overtaken by other (man-made) influences.
Explaining what is happening to our climate is not a case of looking for something that is unprecedented in the last thousand, million or billion years, its about having a physical explanation of the changes that have actually been observed in recent decades. The observed growth of greenhouse gases plus their well known physics provides this. In fact it would be more of a mystery, given these facts, if the climate had not warmed over the last 50 years.
I’m not at all sure why you would think that the sun “should have acted to cool the climate over the last 50 years”. You appear to be unaware that the sun was particularly active during the latter half of the twentieth century only reducing around the end of the millennium.
I’m not suggesting that it is the direct cause of the hiatus in temperature increase seen in the satellite data, because I simply don’t know, but it’s clearly the opposite of what you are suggesting.
I am perfectly aware that the sun was in a grand maximum in the mid-20th century and that the recent solar minimum, and subsequent maximum, have been the least active for about a century. Its very simple to calculate the trends. They are downward. Less heat from the sun should make it cool.
The latter half of the twentieth century was not known as the Modern Maximum for nothing.
I’ve had a closer look at the daily rainfall totals for the northwest of England and north Wales and coupled them to the Objective Lamb Weather Type for that day. I’ve found that for specific southwesterly weather types, although the number of days has changed very little since 1931, there has been a 27% increase in rainfall for that type in that area.
This is the same for most of the regional UKP areas, with England & Wales showing an increase of over 43%. Interestingly the only region to buck the trend is the north of Scotland where rainfall has declined by 15%.
It would be great to use ‘real’ daily rainfall totals for Shap or Keswick, rather than the gridded UKP composite data, and live in hope that the Met Office might supply me with some!
https://xmetman.wordpress.com/2015/12/12/seven-times-more-likely-revisited/
It looks likely to me that the variation you have detected, always assuming the data is correct, is more likely to be related to oceanic cycles. There is a marked wave pattern which does not appear to conform to a steady increase in CO2.
BTW – we now find that the “record” 2-day rainfall at Thirlmere comes from an EA gauge which has only been operating since 1995!
Keep sticking new gauges in these extremely wet areas, and is it any surprise you come up with new “records”?