Climate Risk to Heritage: The Risk Nobody Is Measuring.
Climate change is a material, compounding risk to cultural heritage, yet it rarely reaches the baseline a financed project is built on.
By Neil Fairburn · Director, Cultural Heritage Risk Management Ltd
Ask where climate risk sits on a financed project and you will be shown the carbon accounting, the energy model, perhaps a flood map for the asset itself. Ask where cultural heritage sits in that same climate picture and there is usually nothing. Heritage is assessed for construction impact, then filed. The slow, compounding damage that climate does to it over the life of the asset rarely reaches the baseline at all. That gap is the subject of this piece.
What the climate actually does to heritage
It is not one hazard but a cluster of interacting ones. The recognised reviews map a chain from climate driver to hazard to mechanism to impact: sea level and water table rise, flooding and storm surge, temperature and freeze-thaw, humidity and repeated wetting, wind-driven rain, drought and subsidence, wildfire, biological growth, coastal erosion. A single driver can produce several of these at once, and most sites face three or four together.
The point that is easy to miss is that climate change does not uniformly increase decay. It redistributes it. Biological growth and corrosion tend to rise in the temperate north and fall in the drier south; freeze-thaw decreases across much of Europe while increasing in the far north. More warming does not simply mean more damage everywhere. It means different damage in different places, which is a harder thing to plan for than a single rising line.
And the master variable is usually water. Not the one catastrophic flood, but the repeated wetting and drying, the capillary rise up through old fabric, the salt crystallisation that cycling drives. Mosaics, plasters and the most delicate fabric suffer most from oscillation. In managing conservation planning for a major heritage site, the finding that has stayed with me was exactly this: the quiet, cyclical processes, not the dramatic ones, were doing most of the damage.
The risk nobody is measuring
The sharpest finding in the literature is about the literature itself. The evidence base is thin and skewed. Research overweights the fast-onset, easily measured hazards such as temperature and under-studies the slow-onset ones such as sea-level rise, even though the slow ones threaten more assets over time.
Heritage professionals have been recording flooding, salts, freeze-thaw and biological decay for decades. It has not been directly coded as climate change, as this was not the required measure, so the climate signal in heritage loss may have been systematically underreported, and it is now a reporting consideration. There is no agreed method for quantifying decay and no central inventory of what has been lost. One European assessment found that nine of twenty-eight countries had no legal framework linking heritage and climate at all. The real risk is not only the climate. It is that we are not measuring what it is doing and reporting it.
The adaptation trap
There is a second order risk that should concern anyone financing adaptation: the response can become the hazard. Aggressive energy efficiency retrofits, external insulation, heavy-handed facade work, can destroy the historic fabric they were meant to protect. Adaptation money can damage the very asset it funds. The same literature that calls climate a threat also names heritage as part of the solution, through traditional materials and the embodied energy saved by keeping a building rather than replacing it. Both are true, and a serious assessment has to hold them together rather than choose one slogan.
Where it belongs
The recognised reviews name environmental and social impact assessment as the tool that establishes heritage condition, sensitivity and vulnerability, and they point to the lender cultural heritage standards and the familiar hazard, exposure and vulnerability logic. International policy has caught up: at COP28 a global resilience framework was adopted in which protecting cultural heritage, tangible and intangible, is one of the named targets. The instruments exist. What is missing is the habit of putting climate risk to heritage into the baseline and keeping it there across the life of the asset, not only at construction.
The near term truth is harder than the headline. For most heritage, lack of monitoring, maintenance and timely stabilisation destroys more than climate does. Climate is the accelerant on top of neglect. A financed project that treats heritage as a construction-phase box, assessed once and closed, is leaving a compounding, measurable and badly measured risk on the table, and every year the asset stands, the climate is quietly compounding it.