Facing the facts of climate change
This page contains a transcript of a talk by the Head of Environmental Challenge to a Diocesan Advisory Committee study day for Quinquennial Inspectors on Thursday 12 January 2012.
(Just a few small changes have been made, to reflect scientific research and events since.)
Two PowerPoint presentations can be downloaded from this page:
- Climate change briefing
- Hope in God’s future.
I’m going to kick off with some reflections on climate change and its consequences.
Global warming and natural variation
I am speaking, of course, of global warming – its climate consequences, and all that entails.
There is plenty of natural variation in the climate, obviously. Superimposed on that, however, we have this much more rapid and extreme, and potentially very dangerous, warming trend. This is human induced.
By and large, in an interglacial period as we are now, the natural trend is for slow cooling towards the next ice age. It’s a very slow trend compared to human lifetimes – about 8-9 degrees Celsius, spread over perhaps 25K years – that’s about 1/30th of 1 deg C per century.
And even that is varied by the sun’s cycles, and volcanoes, and other factors – so it’s pretty effectively masked.
The notorious prediction in the 1960s, that we were suddenly heading for a new ice age, has become a hoary old urban myth – much hyped by the media even at the time, though with very flimsy foundations.
Actually, from the 1940s to the 1970s, there was probably a small fall of one to a few tenths of 1 deg C average worldwide. But it is thought to have been caused by a rise in sulphate aerosols from coal burning during post-WWII reconstruction – not from interglacial cooling.
However the warming trend we now see – taking the 20th and early 21st centuries as a whole – arguably runs counter to all natural trends combined.
And, indeed, it is already causing the polar ice caps to melt, not re-freeze. There is even talk of the next ice age being cancelled due to our influence!
Furthermore, the warming we are causing is very steady, very sustained – but fast, at up to about 0.2 deg C per decade:
- More than 300 consecutive months, worldwide, have been warmer than the average for that month over the 30 year period 1961 to 1990 (up to end of 2010)!
- Every year since 1997 has been warmer than any recorded year before that, with the exception of 2000 which was slightly cooler than 1995).
- Climate sceptics like to say ‘global warming has stopped’. That is a myth. Warming of the surface and lower atmosphere may have slowed from 1999-2013. But around 90% of the new heat goes straight into the ocean. Anyway, temperatures started warming sharply again from 2014.
How sure are we?
It might seem like we’re unsure about all this. But if there is one message I can communicate today, it is that the jury is NOT still out! The scientific consensus that global warming is happening is much more than just consensus. It is a certainty.
We are less sure about some of the details – which I’ll come to – but we are certain that the climate is warming.
A very small handful of ‘reputable’ scientists still question this – but one has to call into question the reputation of any scientist who holds out against such strong evidence.
So, what can we say that we know for sure?
There are basically three parameters to watch out for – temperature rises, increases in greenhouse gas concentrations in the atmosphere (especially CO2), and the connection between the two.
Note that in the present case, the greenhouse gases cause the temperature rises, whereas before and after ice-ages they are locked together in a repeating cycle – the mechanism is not the same.
Anyway, for now we know that:
- Sustained increases in the heat content of the earth’s surface, ocean and lower atmosphere are occurring; these manifest in temperature rises;
- A sustained increase is also occurring in the atmospheric concentration of greenhouse gases.
- Temperature increases due to the greenhouse effect have been predicted since the early 19th c (by Fourier), and especially since Arrhenius over the turn of the 19th – 20th c;
- The greenhouse effect has been tested in the laboratory.
- Our belief that the temperature rises actually recorded are, in fact, due to the greenhouse effect is an inference not a fact. But it is an exceedingly strong inference, in which a high level of confidence is justified. There is indeed no other mechanism to account for the temperature rises we are seeing.
Now there are other things which we are much less certain about.
For a start we must acknowledge, the climate is a very complex matter. It may well be indeterminate – incapable in principle of exact prediction.
To point out the obvious, the weather varies from year to year and place to place.
We can have cold spells in winter in the UK, like December 2010 and March 2013 – even though 2010 was one of the warmest year worldwide.
How much has the climate warmed so far? Well it’s at least about 0.8 deg C so far, since the 1910s. Of that, about 0.5-0.6 deg C has occurred since the 1970s, and is unequivocally attributable to human influences.
Some people point out that these increases are small – in fact, they are only about 1/100th of the range of temperatures experienced seasonally just in the UK – from about -18C up to about +38C.
It is now widely expected that by the end of this century, average temperatures may have risen by as much as 4 deg C, from the pre-industrial average in the 18th c. That’s about half the temperature rise from the depth of the last ice-age up to the present.
However, it is the total energy in the global climate system which is the issue.
How the additional energy is distributed at any time is another matter.
Most of it goes into temperature rises, some may be vested in wind energy and ocean currents – though such transactions may be adiabatic, by and large – leaving no net change in heat energy. (But that is very uncertain, as are the quantities of energy involved, especially in ocean eddies.)
Moreover, it is not possible to say for sure that a particular weather event – a storm or a flood – is attributable to anthropogenic causes.
This question is often wrongly stated as: was this or that flood ‘caused by climate change’? Strictly speaking, no weather event is caused by climate change – though it may be ’associated with’ it.
There are always proximate causes – a shift in the jet stream, blocking over the Atlantic, a cold wind from the Arctic – which are reported by the weather forecasters.
Whereas, the climate just is the sum total of all the weather that happens, and its long term pattern. Climate change denotes a family of systematic changes in patterns that have been consistent over a previous period.
So yes, the climate is too complex for a brief talk like this to do justice to it. Yet it is increasingly well understood. The work that is going on among scientists in all continents is enormously broad and deep.
Human beings as the cause
We as human beings are deeply, deeply, implicated in all this.
We are the primary cause of the problem (even though we can’t be sure in relation to particular events), and we will suffer its consequences (as will other species).
Almost everything we do affects the climate directly or indirectly – mainly through:
- Burning fossil fuels – gas or oil in buildings and vehicles
- Electricity generation from coal or gas
- Land use change especially deforestation
- Livestock farming and fertiliser
- Water and waste treatment
- Cement manufacture, plastics and metallurgy.
Let me cite one piece of smoking gun evidence, if ever there was. Carbon released from burning fossil fuels bears a different isotopic signature – it is all carbon 12. Whereas a small proportion of carbon naturally occurring in the atmosphere and the biosphere is radioactive carbon 14. This underlies the principle of carbon dating.
The proportions of these two isotopes are altering due to fossil fuel burning, releasing pure C12 into the atmosphere.
In principle one should be able to estimate the proportion of carbon in our own bodies which comes from the coal and gas and oil we ourselves have burnt.
However I have yet to find such a calculation, which is pretty complex and dependent on other factors such as diet. Nevertheless you are what you burn as well as what you eat!
How far and how fast is climate change going to progress?
How can we make predictions to guide the action we take?
The answers to these questions are shrouded in doubt I’m afraid.
Nevertheless, we have to have a go. Computer models do attempt to make predictions, to increasingly finer levels of detail.
Few would stake their reputations on such exact predictions.
However what is possible is to assign probabilities, levels of risk – the percentage chances of a particular temperature increase, or sea level rise, for example.
That can be done, although different researchers will come up with widely varying numbers.
Note though, that even the most conservative of predictions, at the lower end of the range, are looking catastrophic. Increasingly as time goes by, the outlook for climate change lies somewhere between dangerous and apocalyptic.
It’s interesting as well as disturbing to see how far the impacts of climate change have progressed worldwide already.
Of all the consequences of global warming, four stand out as the most tangible so far:
- Temperature increases almost everywhere (just a few places have stayed the same, even fewer have got a little cooler – the central mid-Atlantic, and a handful of counties in the southern USA);
- An increase in precipitation. This rain and snow too – paradoxically – is very unevenly distributed. This is the principal cause of flooding – eg in Pakistan or Queensland – but the UK is not exempt;
- As a result, greater land instability, leading to more frequent land slips and slides;
- Disruption of the seasons, such as we are experiencing right now;
- Partial melting of the cryosphere (the ice caps, tundra etc).
Munich Re is the world’s largest re-insurer. In 2010, they published a study showing that in the previous three decades since 1980, climate related insured events doubled in their combined frequency and severity. Floods trebled over that period.
Of course there are more people suffering these effects, infrastructure costs have increased – more events may be insured against – all raising the level of claims.
However Munich Re found an interesting way of correcting for these factors, and their headline result is nett of that correction.
But what practical action can we take to limit the risks?
- Abatement of the causes
- Mitigation of predicted consequences
- Adaptation to actual consequences, to the extent that they have not been mitigated.
These three kinds of responses are all essential. However it is the second and third – dealing with consequences rather than causes – which we are focussing on today.
Especially in regard to our buildings, and churches in particular.
Issues which affect our buildings include:
- Freezing cold and frost;
- Flooding even more than that;
- Subsidence and heave, and even land slips on slopes and coasts;
- Wind damage – severe wind storms are getting more likely.
Temperatures and even sea level rises are not the thing to worry about most so far as our buildings are concerned, at least not over the next few decades; though major impacts such as these may well come to the fore within the lifetimes of some of us here.
In the shorter term, the cause of any weather damage may not matter to you necessarily – when the steeple blows down, you won’t spend time worrying who’s to blame (unless it’s you).
The last time before 2012 we had exceptional storms was in the late 1980s and early 90s – the famous ‘hurricane’ (so-called), and the Burns Day storm. I would be prepared to expect events at least comparable to that episode, within the next few years. (This turned out to be right – in the storms of late 2013 and early 2014.)
A few months ago I undertook a risk assessment of buildings most vulnerable to wind in the diocese. Has this filtered through to any of you? Have essential repairs been done to towers and steeples and finials?
So please take this as your cue to risk assess the buildings you’re appointed to, and advise your clients accordingly.
There’s an old Chinese proverb:
“If you treat the disease after the symptoms have appeared – isn’t that like digging a well when you feel thirsty? Is it not too late?”
Let’s hope not – but let’s still act now. I hope you enjoy today’s programme, and find it interesting and inspiring. Please act on it afterwards, for benefit of the churches and parishes in your care.
To read more
See Resources on the environment.
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