Climate and environmental risks
Climate change poses significant risks and challenges to churches and other buildings.
Church officers, architects and Quinquennial Inspectors, and other construction professionals working for parishes and churches, all need to understand these risks and how to mitigate them.
Climate change and the weather
So far in the UK, climate change has mainly shown itself in higher temperatures, rainfall and river flooding.
More recently there has also been an incidence of wild fires.
On average, UK temperatures have risen more or less in line with global warming, from the early 20th to the early 21st c.
Since 2014, global average temperatures have been shooting up alarmingly. The warmest year in the record was 2016, with 2019 close behind.
The UK is on the fringe of a relatively cool spot in the north Atlantic, possibly associated with a weakening of the Atlantic Meridional Overturning Circulation (AMOC, or the ‘Gulf Stream’). ‘The jury is out’ on whether that will in time cause net cooling in the UK, or merely slow down the warming slightly.
Average increases from the 1910s to the 2010s are about 1½% of the total diurnal range in the UK from about -18C to +38C. That is not negligible, but buildings do not feel it the way human beings do or wildlife does.
Rain and drought
There is about 4% more moisture in the clouds over the UK than the historic average, due to increased evaporation from the oceans. Rainfall has increased significantly towards the north-west of the UK mainland, relative to the 1961-1990 mean; on average it has decreased slightly towards the south-east, including in London.
Drought has been more prevalent in the south-east, though there have been major rainfall events as well. When rain comes, it seems to be getting more concentrated in sudden downpours. Time will tell how the pattern is shifting in the long-run. But the consensus is there will be major changes, with more rain on and flooding on average.
Weather extremes are already beginning to occur with greater frequency and the seasons are becoming more chaotic, especially Spring and Autumn. There are also periods where the pattern of weather becomes locked in by the position of the jet stream.
Some severe winters may still occur in the UK, in spite of the general warming; though they are expected to become less common worldwide. It is notable how temperature highs, lows and averages are all slowly rising, on a range of timescales. Even the cold winters of 2008/9, 2009/10 and 2010/11 were much less severe than those of 1946/7 and 1962/3.
Climate risks to churches and their buildings in London over the next few years may include the following:
- Extreme heat; this affects comfort conditions, and can cause ventilation and cooling systems to malfunction or under-perform outside their design range;
- Heat damage to fabric, leading to melting eg of an asphalt roof, and to stress on the structure, metalwork, glazing etc;
- Occasional (though less frequent) severe frosts, which obviously can still damage buildings when they occur;
- Drought, leading to subsidence on shrinkable clay soils. Worldwide, alternating droughts and rains are becoming the norm; we aren’t exempt in the UK. This causes subsidence followed by heave;
- Fires caused by drought in combination with heat – including wild fires which can spread to adjoining settlements and buildings (this has happened every recent summer in many countries, including the UK);
- Heavy rain leading to flooding from rivers or sewers. It may not matter to a building necessarily whether rain falls in January or July, so long as rainwater collection and drainage can cope. Major flooding occurred several years in succession during the 2000s, especially in 2007, 2009, 2010, 2012, 2013, 2014, 2016, 2019 and 2020 (though this has not been so serious in London as in other places);
- Flash flooding in a storm, including run-off from roofs and gutters, where they are blocked or of insufficient capacity; more and more churches are finding it necessary to enlarge their gutters and downpipes;
- Excess humidity causing mould, moss and lichen growth;
- Wind damage; in the long run, it remains uncertain whether climate change will lead to more storms, and/or more severe storms. The balance is tilting towards ‘yes’ to one or both of these questions.
Poor air quality is thought responsible for several thousands of excess deaths each year.
Although the London smogs caused by soot are a thing of the past since the Clean Air Acts, air pollution has become more notorious in recent years due to tailpipe emissions from vehicles, including oxides of nitrogen and particulates, being only partly controlled by the London Low Emissions Zones.
Lead has of course been eliminated from petrol, but there remains a degree of acidification in the rain.
Metal including iron, steel and bronze are at increasing risk of corrosion due to poor air quality.
Increasing adverse effects are expected from growth of bacteria, mosses, lichens, fungi and ivy on buildings of all kinds due to a warmer wetter climate.
Also we are seeing the introduction of new species (and the recession of others) as their habitats generally shift northwards.
Abatement, mitigation, adaptation
Different kinds of action in response to climate and environmental threats can be divided into three categories:
- Abatement – action to reduce the causes, including greenhouse gas (GHG) emissions and other causes of environmental damage;
- Mitigation – measures to lessen the consequences, to the extent they can’t be avoided;
- Adaptation – changing how we live including how we build, to better cope with the consequences to the extent they can’t be prevented or even reduced.
All three kinds of action are needed. Buildings we build now must remain habitable in the event of extreme flooding and also high temperatures.
Historic or ‘traditional’ buildings
In some respects historic buildings, having survived a process of natural selection, are those best adapted to the range of climates they have so far encountered, so long as they remain well maintained. But now extreme weather is become more frequent and severe, and may soon move into no-analogue situations.
An assessment of any ancient building is advisable, for its capacity to withstand high wind loads and to handle high volumes of rainfall without overflow of gutters, hoppers and pipes. This may indicate upgrades that are necessary in individual cases. Some building elements may also require more frequent replacement even if on a like-for-like basis.
Traditional buildings need to move and need to breathe. Inappropriate imposition of insulation or over-rigorous draught exclusion can lead to heat stresses on the structure and/or condensation and mould growth.
Potential impacts on particular buildings should be assessed through quinquennial inspections (QIs).
Owing to successive PCCs, QIs and architects, over the last 30 years an immense volume of stone repairs has been completed in the Diocese. Steeples were rebuilt after being scraped of their soot – e.g. St Mary-le-Strand, St Clement Danes. Others had rusting iron ties replaced, e.g. St Mary Aldermary in the City.
However the job is not done. There is a catalogues of repairs needed now to churches. Some of these present greater risk in an extreme weather event.
Has your PCC prioritised remaining essential repairs – especially to steeples, spires and finials? Sandstone and soft limestone or brick are the most vulnerable materials.
Where resources are tight, at least get a steeplejack’s survey and report. A photogrammatic survey may be considered, making any reconstruction easier.
Some more points for thought and action:
- Make sure your lightning conductors are tested, to current standards and in tip-top condition;
- External/uninsulated plumbing should be given a nice warm jacket before winter;
- Tall brick chimneys often bend towards (not away from) the wind, as their pointing is scoured out – make sure brick pointing is renewed in due time (and if they blow down it could be the other way!)
- Consider any hazard to the public – contact your Archdeacon if unsure what to do.
University College London
A report of 2003, ‘Climate Change and the Historic Environment’, May Cassar and Robyn Pender, University College London, advocates amongst its recommendations:
- Effortless measures – adapting to impacts of floods, rainfall, high winds and drought;
- Local response – disaster preparedness, responses, cooperation between disciplines and agencies;
- Preventive maintenance – eg gutter cleaning;
- Emergency preparedness – immediate damage protection pending repairs;
- Realism – not everything can be protected forever;
- Assessment and planning – forewarned is fore-armed;
- Adaptation – modifying drainage and rainwater goods, irrigation and water storage in parks and gardens.
The EU’s project, with several UK universities including UCL, ‘Climate Change Impact on Built Heritage’, set out to map the likely impacts of climate change on heritage sites in different European regions, including the UK.
Intermediate results were presented in a conference in 2006. Qualitative conclusions included:
- Heavy rain and drought will present increasing problems;
- A three-fold increase in salt weathering to sandstone and soft limestone is expected;
- Redistribution of bacteria, moss and lichen is expected between N and S Europe;
- Acid corrosion of glass is predicted, including in the UK;
- Fungal damage to external woodwork and limewood is expected to double.
Data on insurance claims is among the evidence that climate change is real.
Always keep your insurers informed of significant events and action taken. Consult or at least inform them of impending works or other measures.
Parish Property Support Team
Head of Environment and Sustainability.
Flooding in churches
Generic Building Solutions
Climate Action Projects
Resources on the environment.
Sustainable Traditional Buildings Alliance.
Environment and Sustainability, front page.