Was England really warmer in medieval times?

thanks to brilliant for sponsoring this video [Music] recently europe has been a little bit on fire i mean that both literally and figuratively in the sense of there being widespread heat waves i've actually already made a video about those these heat waves have understandably sparked a lot of discussion about why this is happening and a particular argument that's come up time and time again on my feeds has been that this isn't actually a problem because england used to be warmer in the medieval period than it is now well if that's the case then this current warming trend is nothing to worry about as it's just within the past variations of european climate but how do we know this is the case where's the evidence for what's called the medieval warm period we don't have temperature records going that far back because thermometers hadn't been invented yet then so scientists use proxy measurements that is an indirect measurement of something by measuring something else i explained how these work in a fair bit more detail in a video about how the man at our hockey stick is the wrong shape so go watch that for more info if you're interested so what are the proxy measurements that tell us england used to be warmer in the medieval warm period firstly vineyards england is known for ale and cider these days not wine but in the doomsday book there are around there's a little bit of uncertainty 50 vineyards listed compare that to the only eight vineyards that apparently existed in this country in the 19th century as winemaking is so highly dependent on climate and we see so many more vineyards in for example much warmer france it stands to reason that england was much warmer at the time of the doomsday secondly however trees a more accurate measure of past climate can be obtained by looking at tree ring data the field known as dendroclimatology love that name measuring the thickness of individual tree rings corresponding to how warm the growing season was in that given year scientists have been able to reconstruct what the average temperature was like in years past and look you can see this helpfully labeled medieval warm period in england remember this graph we'll come back to it so based on these two measurements and others it appears that england was warmer in the medieval period than in surrounding centuries and thus when people talk about current warming it's nothing to worry about it's nothing we haven't already seen in the medieval warm period well two problems with that firstly a paper published in 2009 in the journal science included this figure showing the temperature anomaly during the medieval warm period or as they termed it the medieval climate anomaly so red here means something is warmer than the long-term average while blue means colder than the long-term average as you can see there's a big warm blob in the north atlantic where the uk is but looking at the rest of this map there's a lot of blue on here so while the uk was warmer around the year 1000 than the overall temperature record average for much of the rest of the world around the year 1000 it was actually cooler than that average in other words the warming was regional there was no global temperature trend in fact a decade later scientists writing in the journal nature found that there was no evidence for any temperature changes such as a medieval warm period or little ice age on a global scale before the modern period quote the warmest period of the past two millennia occurred during the 20th century for more than 98 of the globe today we are seeing a rapid global temperature trend unlike anything we've seen in the past few thousand years of the temperature record so while england specifically was warmer around the year 1000 that wasn't the case everywhere else again the warming was regional secondly i don't think i have access to a data set if one even exists that could conclusively quantitatively say that england was warmer during the medieval period than now but you may ask what about that tree ring data well that tree data wasn't actually from england despite being bandied around online as english data for example here it's not english or even british data it's from scandinavia a location the authors of the original paper this figure is from note has experienced relatively little warming this century this is misleading data presentation it's downright deception as professor rob wilson from the university of st andrews notes there are surprisingly few tree ring temperature reconstructions from the british isles and those that do exist are difficult to interpret because there are just so many overlapping factors that determine tree growth in the british isles temperature is just one of them published temperature reconstructions using tree rings instead tend to be representative of the whole northern hemisphere or at least a region of it because using multiple tree sample locations gives you much more confidence in your temperature reconstruction and those reconstructions look more like this with no clearly defined warm or cold periods but a definite uptick in temperatures towards the present day also to briefly return to the other proxy measurement that i mentioned yes in the doom there are more english vineyards than in the 19th century but nowhere near as many vineyards as there are in the 21st century there are over 400 english vineyards operating now and they stretch much further north than they are in the doomsday book so by the logic of this measurement that indicates that the climate is warmer now than it was in the medieval warm period but for the record vineyards are terrible proxies for past temperature there are just too many variables all stacked on top of one another like total precipitation and number of frost-free days in spring that determine if a vineyard is actually feasible at a given location it's not just the temperature based on the data available then medieval england was perhaps modestly warmer than iron age england and renaissance england but not warmer than the england we see today most experts will tell you that the warming we're experiencing today goes beyond any natural climatic variation and that we are currently seeing temperatures that we've not seen in the british isles for the past several thousand years you make me sad the main conclusion here however is that the medieval warm period such as it was was a regional warming certain parts of the planet including england were warmer in the medieval period than in the long-term temperature average and other parts of the planet were cooler than that long-term temperature average but that regional warming was still a lesser magnitude than the global warming we see today he said it he said it if you look at global average tree ring data for the past few thousand years then it's really clear that the medieval warm period is just not detectable and is dwarfed by modern warming this graph really clearly shows that what we're experiencing today is not natural it's not something we've seen before it's absolutely man-made and it's worrying so if you see this argument being made online you're a bit more clued in now and specifically you know that it's complete should you wish to learn more about how scientists talk about climate and specifically some of the terminology like regression and variance then i can highly recommend the course on statistics on brilliant who have kindly sponsored this video brilliant is a website and app designed to supplement traditional education and introduce you to new concepts in maths science and computer science in a fun interactive way they offer expertly written gorgeously illustrated courses from middle school to graduate school level across a huge range of subjects everything from pre-algebra to computational biology and several classes written in collaboration with youtubers you may well know and love such as kuskosak and my mate brian from real engineering if you're in education brilliant takes the concepts you're learning about in school and brings them to interactive life allowing you to have a look at them from a different perspective well if you've left full-time education brilliant in particular the app keeps your scientific skills sharp and allows you to pursue your scientific curiosity i cannot recommend brilliant highly enough i've worked with them for several years now i love their philosophy when it comes to education and i'm constantly impressed by the new courses they honestly keep getting better and better to get started for free so there's really no excuse to not do this visit brilliant.org simon clark or click the link in the description and the first 200 people to do so will get 20 off brilliant annual premium subscription for themselves or for a student in their life with thanks to brilliant for sponsoring this video and for being you know brilliant thank you so much for watching the video i hope that you took something away from this maybe this is a claim you've heard before and hopefully this has cleared things up for you if you did enjoy it please do pop the video a like and let me know what you thought down there in the comments it really does help the channel and if you'd like to watch something next here's the recommended viewing that just leaves me to say thank you again for watching i'll see you in the next one

Channel: Simon Clark

Views: 51,683

Keywords: drsimonclark, dr simon clark, simonoxfphys, simonoxphys

Id: ZFikZnuSahM

Length: 9min 14sec (554 seconds)

Published: Wed Aug 31 2022