Global drought, land degradation and desertification - Research by National Research Council of ItalyPadiglione Italia Expo Milano 2015
It’s easy to think of climate change as having its drastic effects somewhere else, somewhere remote where few people live – melting glaciers in Greenland, bleaching coral reefs, desertification in Central Asia.
Flood Damage - Venice by Dmitri KesselLIFE Photo Collection
Yet the damaging impact of global warming is not just a problem for the natural world; it is already affecting cities worldwide, most obviously coastal settlements through rising sea levels. But there has also been an increase in extreme weather events; ‘natural’ disasters that are, most likely, man-made are also having their effect. Our fragile cultural heritage is at particular risk and the international community is hoping to spread understanding that natural and cultural heritage are often interrelated.
The more dramatic events capture the headlines, such as the Louvre evacuating treasures from its basement as the Seine rises, or the more frequent aqua alta inundations that are drowning Venice in its lagoon. In Russia, artefacts from the ancient Scythian culture such as the kurgans, the ‘frozen’ tombs, are threatened by melting permafrost.
Lake Tengiz from space (2017-12-08)NASA
John Hurd from the International Council on Monuments and Sites (ICOMOS) recalls being present at the ancient Silk Road settlement at Otrar in Kazakhstan when the mud structures were destroyed by catastrophic heavy rain. “There was a huge storm and the archaeology disappeared in front of our eyes in a day. I was in tears.”
3-D point cloud scan of the White Tower in London by CyArkCyArk
But it’s not only these dramatic shifts that scientists are tracking with alarm. There are also more subtle points of concern. Even in the geologically temperate British Isles, erosion is threatening coastal abbeys, villages and archaeological sites while centuries-old trees, planted as part of magnificent designed landscapes, are now struggling.
The Thames Barrier was introduced in 1982 to help protect Central London World Heritage Sites, including the Tower of London and Westminster, from catastrophic flooding. It raised its protective booms only four times in the 1980s. By contrast, the booms were raised again about 75 times in the 2000s, and 28 times in a single ten-week period in 2014/5.
Front of Edinburgh Castle (2019-04) by CyArkCyArk
Heritage organisations and think tanks are now responding to the climate emergency with various programmes, getting the basics in place with, for example, periodic monitoring to detect changes.
Heavy rain and saturated ground can also cause problems such as slope instability and landslides. A recent study of 352 heritage sites in Scotland found that, without measures being put in place, 89% are exposed to “very high” or “high” levels of risk. One such site is Edinburgh Castle, within the capital’s WHS – a project case study.
Shait Gumbad Mosque - Sixty domed Mosque (1985) by Historic Mosque City of BagerhatUNESCO World Heritage
At the Mosque City of Bagerhat in Bangladesh, meanwhile, extreme water salinity is among the problems threatening the historic religious structures, along with drinking water supplies and agriculture.
Chan Chan Palacio TschudiCyArk
At Chan Chan in Peru, the world’s largest mud city is being pummelled by storms that are eating away at its fabric.
Rock Art in Rapa Nui (2019-01) by CyArkCyArk
It is not just very visible architectural monuments that are being affected says Will Megarry. “Other sites, like subsurface archaeological deposits, are being lost at an alarming rate, usually before we have a chance to record them. External sites like rock art tend to be at risk from erratic weather patterns where periods of prolonged drought followed by heavy rain is resulting in increased erosion.”
The knock-on effects of changing weather can have less obvious consequences such as increases in burrowing animals at archaeological sites as soils warm; or changing vegetation patterns that affect cultural landscapes and buildings; or creeping damp that pulls decorative plasterwork from a wall.
“One of the most tragic aspects of climate change is the disproportionate way it impacts the developing world,” adds Megarry. “While climate change is predominantly fuelled by large industrialized countries, it is vulnerable communities and heritage which is most impacted. That is one of the reasons why sites were chosen from across the world.”
Ruins of Arches in the Great Mosque in Kilwa Kisiwani (2018-12) by CyArkCyArk
The project will also look at adaptation methods that can be used to mitigate the impact of the climate emergency. At Kilwa Kisiwani, for example, new mangroves are being planted and seawalls built to protect structures. These measures have, for now, reduced the imminent risks. Simple measures such as regular building maintenance can also play a surprisingly important role (although this too can be a big ask in cash-strapped regions).
But while adaptation is vital, it can be seen as a sticking plaster on a global wound that will not be healed except by carbon reduction – a central tenet of which is likely to be adaptive reuse of old buildings rather than tabula rasa demolition and renewal.
Our fragile heritage is the proverbial canary in the coal mine; every collapse a warning of worse to come.
Dr Will Megarry, ICOMOS Ireland and Lecturer in Archaeology at Queen’s University Belfast.
John Hurd, ICOMOS