It's Time For Potatoes To Shine
According to Guy Singh-Watson of Riverford Organic Farmers British summers are getting hotter whilst autumns are getting wetter, forcing growers to juggle varieties, but is this true?
As I write our turkey carcass is being transformed into bone broth and a tray of leftover veggies is being transmuted into bubble and squeak, so I fancied analysing something germane to climate and carcass.
As it stands the Dee family have placed 445 orders with Riverford Organic Farmers since we joined their box scheme back in 2014. I love my veggies, I love tasty veggies, and I love tasty organic veggies, so to have a big box of them arrive 7am every Friday morning seems like magic.
When it comes to potatoes – surely the king of all veggies! - Riverford do something rather annoying. They advertise a variety then send something else. Normally this isn’t a problem but when it comes to perfecting your roast potatoes for the Christmas dinner-of-all-dinners then variety is everything!
Just prior to Christmas I sent them a diplomatically-worded email explaining that we’d be getting our spuds (King Edwards) from Waitrose since we couldn’t trust Riverford to deliver what they say they’re going to deliver. A few days later all customers received an email entitled It's Time For Potatoes To Shine; herewith an extract:
A Christmas favourite we cannot do without is roast potatoes. We've been delivering Sorrento potatoes for Christmas since 2020, when our growers Neil and Gary Farley found that this variety grew better in our changing climate, through hotter summers and wetter autumns.
These slow-grown spuds are perfect for your Christmas dinner. Their floury texture makes for the best roasties: golden on the outside, fluffy in the middle. Sorrento potatoes also don't need to be parboiled for long, and have smooth, clean skin – great news for your veg peeler.
Now I don’t know about you but those words looked rather promising to me, so we ordered two large bags of Sorrento to have a variety called Carousel arrive. Doh! Fortunately Carousel turned out to be rather nice – not as splendid as Sorrento, admittedly – but yummy nevertheless.
Given we cannot trust Riverford to deliver what they say they’ll deliver, even when they explicitly promise via email, my thoughts turned to that claim of “hotter summers and wetter autumns” – is this also a load of hot air or does it have a golden biscuit base?
With each weekly box comes a newsletter and Guy Singh-Watson uses the opportunity to point out the many issues within farming: economics, legislation, pollution, supermarkets, pesticides and whatnot, whenever he can. All good stuff but at the same time he’s a climate change alarmist and influencer: little does he realise he’s sawing away at the very branch he’s sitting on.
So how about those hotter summers and wetter autumns? Let’s cut another slice of Christmas cake and go see what we can see…
Defining Britland
Whilst there’s an enormous amount of UK meteorological data to be had online getting hold of it isn’t easy unless you happen to be a dab-hand at programming software to sift through tens of thousands of files on MIDAS servers. NOAA’s Global Historical Climatology Network (GHCN) Daily Database is also a fabulous online resource if you have the time and/or skill to trawl through thousands of files, but since I have neither I have to resort to cunning.
Cunning, in this instance, comes in the form of KNMI’s Climate Explorer, and if you haven’t familiarised yourself with this extraordinary resource I recommend you add this to you list of New Year resolutions! To get this tool to work we have to define what we mean by Britland.
Britland is essentially the UK’s most fertile potato growing region and I have crudely defined this according to this bounding box:
With the bounding box coordinates entered in Climate Explorer we can pull down all manner of data and restrict daily observations to those GHCN stations with at least 30 years worth. All we need after this is to determine what we mean by ‘hotter’ and ‘wetter’, and I guess we ought to try and figure what Guy Singh-Watson actually means by ‘hotter’ and ‘wetter’.
He’s bound to be keen on mean daily temperature and mean daily rainfall (since this is what we’re all fed) so we better look at these. However, he is also a farmer, so he’s going to physically experience maximum temperature and total rainfall. I presume he’s going to keep a mental tally on the number of really hot days and really wet days, so we better derive a measure for these also.
As regards the tally for really hot days I’m going to set a threshold of 25°C for the mean maximum temperature attained across all stations in the sample, this being close to the 97.5 percentile of 24.4°C. As regards the threshold for really wet days I have set this at 10mm for mean daily rainfall, this also being close to the 97.5 percentile of 10.2mm. We can easily fiddle with these values if anybody raises any objections but IMHO such fiddling makes little difference: a scone is never going to become a lardy cake.
NOTE: What constantly amuses me is that nobody can physically experience average temperature or average rainfall since these are abstract mathematical constructs, yet they are the very abstractions upon which our illustrious leaders and their cheque book expertistas are erecting our collective future. As a statistician I can experience these constructs through my stats package but as a human I can only stand outside my office and get hot and/or wet.
Summary Statistics
KNMI Climate Explorer found 46 GHCN stations with +30 years of data for daily temperature and rainfall within Britland, this being plenty for a preliminary consideration of potato growing conditions.
From 1 January 1900 to 30 November 2023 there are no less than 45,259 daily records to consider and here’s the grand overall summary statistics for the five main time series under study: