Another day, another potentially dubious climate change story in the Guardian. According to the headline, “The Roman forts near Hadrian’s Wall are full of historical riches – and the climate crisis is destroying them”. The sub-heading is almost as sombre: “It isn’t just our planet’s future that’s at risk: soon the artefacts buried deep in our soil may be lost for ever”.

So what’s the story? According to Richard Hobbs, the senior curator of the Romano-British and late Roman collections at the British Museum:

To the long list of destructions wreaked by the climate crisis, we now have to come to terms with the loss of our own shared heritage within the untold archaeological riches beneath our feet.

The claim, basically, is that the anaerobic soil at Vindolanda, near Hadrian’s Wall, which has served wonderfully to preserve leather, including shoes, textiles, and fragments of wood, is changing irreversibly. The wood fragments include wooden leaf-tablets, which have opened a window on life at Vindolanda during the Roman occupation. Over 1,500 have been discovered so far, mostly dating to around 100AD. But now, apparently:

…the climate crisis is irreversibly altering these [anaerobic] conditions, destroying Vindolanda’s buried treasures faster than archaeologists can get to them…

…much of the archaeology that makes Vindolanda so unique will be gone long before then. During the drought of 2022, it became clear that the site was drying out at an alarming rate. The damage being caused had already been indicated by the diminishing number of tablets being recovered: only a handful in recent seasons and about a dozen this year, whereas in those early days it was not uncommon to find hundreds in a single excavation season. Textiles have fared even worse. About 700 pieces have been recovered since digging began, but only a single piece in the past decade.

What is happening? Probes providing live data on conditions deep below ground have detected something troubling: oxygen in the previously anaerobic layers. Oxygen allows bacteria that break down organics to thrive. It is believed that extremes of weather characteristic of the changing climate are causing the problem. During dry periods the topsoil dries and cracks, allowing rainwater during wet periods to penetrate deeply, carrying oxygen and bacteria with it.

The claim is made so repeatedly and so earnestly that one can’t help feeling that it is categorically true. Climate change is wrecking the archaeology of Vindolanda. This is a very worrying claim. I have lived within reasonable driving distance of Vindolanda for most of my life and have visited it – and its excellent museum – on many occasions. The thought that the treasures waiting to be discovered may be lost before they can be unearthed is a deeply troubling one.

The thought does occur to me that the recent shortage of finds might be because the low-hanging fruit has already been picked, so to speak, and that oxygenation of the soil might be explained in other ways than simply “it was climate change wot dun it”. After all, as anyone knows who has visited Hadrian’s Wall, most of it and its hinterland, including locations such as Vindolanda, is in a wild and wind-swept location, where it is often cold and damp. Certainly my recollections of many visits to the site are of being well wrapped-up against the weather, and often wearing waterproofs, even when visiting during the summer. It does seem odd that artefacts that have survived burial in the ground for almost 2,000 years, many of them during the Roman Climate Optimum and the Mediaeval Warm Period (times which may have been warmer and drier than today) are now falling foul of “climate change”.

To discover more, I thought the best thing I could do would be to visit the website of the Vindolanda Charitable Trust, and specifically to read the section dealing with steps taken to monitor the buried treasures, to see what they have to say about these worrying claims.

Thankfully the Vindolanda Trust website is rather more circumspect than is the Guardian article, basically saying that if the waterlogged soil is damaged by rapid climate change, then the artefacts within it could be lost – the claim is not made that this is happening, rather that due to the possibility of it happening, the situation is being monitored. Specifically:

Those deposits are preserved in waterlogged or reduced oxygen environments but these are sensitive to environmental changes and could be lost forever if they become affected by rapid changes to the climate. To help the Vindolanda Trust preserve and manage the buried remains its archaeological team, working with world leading ground monitoring specialists at Van Walt have installed a series of deep probes into the ground to measure environmental conditions.

The buried probes monitor several different variables including water level, water quality, soil moisture and pH. An important parameter is how much water is in the soil at different depths, with potentially sensitive archaeology known to lie between about 0.5 and 4 metres. If the soil dries out completely, or is subjected to natural drying and re-wetting cycles, the sensitive buried environments can rapidly change, leading to decay and destruction of artefacts. In this scenario organic materials – writing tablets, leather, wood and textiles – would rot away before archaeologists can rescue them and even the generally more robust inorganic remains – bone, pottery and metals – would also be badly affected.

All the monitoring probes are linked to a Vindolanda weather station. This meteo station gives us live data on wind, temperature, rain and atmospheric pressure at the site, providing accurate updates every 15 minutes. As the seasons change and the months roll into years, this ground monitoring system will silently and diligently report back to our scientists and archaeologists and provide an unparalleled picture on what is happening below the ground at Vindolanda.

The monitoring probes will allow us to see how much climate change can impact our buried past as well as our present and future.

Concern from the specialists is evident from reading those paragraphs. Nevertheless, they are subject to several caveats – “ifs” and “could”, rather than “is”, “are” or “will”. As an amusing aside, the team from Van Walt has written a blog about their adventures at Vindolanda while installing the sensors. My takeaway quote from it (which is so reminiscent of my own memories of visits to Vindolanda) is this:

Field work in a humid and cold climate is not the ideal therapy for dodgy limbs.

It sounds as though there may well be hope for the Vindolanda artefacts after all. Fingers crossed.

Postscript. The Guardian isn’t really reporting news; rather it’s regurgitating a claim made almost two years ago – see, for instance this report on the BBC website back in January 2022.