Author Topic: Cave Related Climate Change discussion  (Read 13884 times)

Offline Peter Burgess

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Cave Related Climate Change discussion
« on: February 01, 2007, 12:43:23 pm »
It seems like climate change is a popular topic at the moment here. But just how relevant is it to caves?

Are more violent storms, hotter summers, rising seas, or indeed other significant weather-related factors going to affect caves for better or worse?

Unlike skiiing, is caving going to be affected significantly by the climate changing?

It seems to me that most of the discussion on the forum is of little relevance to caves and caving, so I thought I'd redress the balance.

Offline whitelackington

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Re: Cave Related Climate Change discussion
« Reply #1 on: February 01, 2007, 01:06:29 pm »
Well, there may be a slight connection between increases of CO2 in our atmosphere
and increasing problems of bad air in caves. :(
« Last Edit: February 01, 2007, 01:14:34 pm by whitelackington »

Offline gus horsley

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Re: Cave Related Climate Change discussion
« Reply #2 on: February 01, 2007, 01:09:29 pm »
Good topic Peter.

I think there are some obvious affects, especially if we experience wetter and drier seasons.  Some caves may well become inaccessible for months on end and, when they are enterable again, there may be debris chokes which will need to be cleared.  Other caves could become much drier, which will be ok for those of us who don't like free-diving, but could cause serious problems with water supplies.

In Cornwall we could have a problem with mine shafts.  Many were "capped" at the end of the nineteenth century by simply lobbing timbers down the hole until they jammed and then chucking rubble on top.  Normally these timbers are kept wet by seepage but if they are subjected to prolonged periods of drying they lose their strength and crumble.  There's at least 20,000 mine shafts in Cornwall, the majority of which still can't be located because they are located beneath houses, inductrial estates, car parks, etc.

Offline Peter Burgess

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Re: Cave Related Climate Change discussion
« Reply #3 on: February 01, 2007, 01:19:10 pm »
Would a rising concentration of carbon dioxide in the air result in higher saturation levels in water entering caves? As I recall, the amount of gas that can dissolve in water is partly related to the partial pressure of that gas in the air. Conversely, solubility of the gas decreases as temperature increases, so if the water temperature is higher, doesn't the carbon dioxide content go down? What effect might this have on a) corrosive effect of water on limestone, b) the corrosion or creation of stal, c) the carbon dioxide levels in the air in the cave. Any thoughts? Might this explain high carbon dixode levels in caves in summer months - as the cave temperature rises more than it has in previous summers, the gas comes out of solution and accumulates underground?


Offline ditzy

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Re: Cave Related Climate Change discussion
« Reply #4 on: February 01, 2007, 02:36:01 pm »
well with the climate change and global warming it could actually affect caves in a few ways
the main one being climate change could cause more rain effecting the flow of water within caves and may flood some out.

Offline Peter Burgess

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Re: Cave Related Climate Change discussion
« Reply #5 on: February 01, 2007, 02:37:28 pm »
Indeed - more rain might cause sumps to form where there are none now.

Offline ditzy

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Re: Cave Related Climate Change discussion
« Reply #6 on: February 01, 2007, 02:42:58 pm »
yes and also with the fain fall some caves that are normally pretty dry may beciome wet caves and as a result change the format of the caves slightly

Offline Peter Burgess

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Re: Cave Related Climate Change discussion
« Reply #7 on: February 01, 2007, 02:45:20 pm »
I wonder if there is a correlation between size of cave and whether it is more prone to carbon dioxide build-up?

This is how I am thinking - the water in a cave - dampness in walls, static pools, water in mud and sand deposits - contains a certain amount of carbon dioxide, in equilibrium with the natural carbon dioxide content of the air. Something causes the cave environment to warm up or cool down - it might be air flowing from the outside, or heat brought in as warm water. The cave warms up a bit, and some of the carbon dioxide is released from the water into the cave, because the solubility of the gas in water drops as temperature rises.

Small caves I would imagine are more prone to temperature change than large ones, except where they contain strong streams in which case size might not matter. So a small cave might warm up more than a large one in a hot spell. More carbon dioxide would be therefore be released.

Offline ditzy

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Re: Cave Related Climate Change discussion
« Reply #8 on: February 01, 2007, 02:49:03 pm »
would this mean that if this happens in the futuer with a lot of climate chang causing a lot of heat thatsome small caves may be prone to a lot of bad air?

Offline gus horsley

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Re: Cave Related Climate Change discussion
« Reply #9 on: February 01, 2007, 02:54:10 pm »
One of the crawls in Pant-y-llyn is subject to build-ups of CO2 in the summer.  It acts like a u-tube.  The increase is presumed to be due to CO2 released when the crawl dries out combined with decaying organic material falling in from the entrance.

Offline ditzy

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Re: Cave Related Climate Change discussion
« Reply #10 on: February 01, 2007, 02:57:07 pm »
in relation to global warming and the weather instead of heat if it was to have a downpour could this effect a cave in outher ways apart from flooding for example could it end up with  parts of a small cave collapsing under water pressure?

Offline Peter Burgess

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Re: Cave Related Climate Change discussion
« Reply #11 on: February 01, 2007, 03:00:14 pm »
Only if the differential between the cave temperature and the outside temperature increases. If the basic cave temperature stays as it is now, but the summer warming of it causes a higher differential from the norm, then it would happen regularly. Its a question of what determines the 'normal' cave temperature ie the temperature of the rocks and the caves 'static' water content. This is all just a Peter Burgess theory, waiting to be shot down in flames by some learned type (currently in France, I believe.) Cave temperatures in the tropics are higher than in the UK. This must be due to the climate being warmer there. The only other things to affect ground temperature are geothermal affects, and we don't got a lot of that in this country. Deep mines are obviously an exception to this.

I'm beginning to think I am just talking a load of rubbish.  :-[

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Re: Cave Related Climate Change discussion
« Reply #12 on: February 01, 2007, 04:52:50 pm »
Aren't cave temperatures the average annual temperature of a region?

Offline gus horsley

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Re: Cave Related Climate Change discussion
« Reply #13 on: February 02, 2007, 09:15:01 am »
Aren't cave temperatures the average annual temperature of a region?

Yes, more or less.  Or at least that's what I was told.

Offline Cap'n Chris

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Re: Cave Related Climate Change discussion
« Reply #14 on: February 02, 2007, 10:30:57 am »
Since the weather and caving are fundamentally linked topics, understanding the likely results of an increase in the vigour of weather systems is highly relevant to decisions caving team leaders make.

For instance, it appears as though we are experiencing more frequent very heavy, but brief, downpours - on Mendip such events could result in fatal flood levels for cavers negotiating sections of Stoke Lane Slocker, Thrupe Lane Swallet and Longwood August - and there may be other caves which become similarly dangerous as a result. The small catchments of Mendip caves pale into insignificance by comparison with Yorkshire where hard-baked ground capturing heavy thunderstorm precipitation could result in catastrophic and unexpected flood pulses in popular systems: especially likely to catch out visiting caving groups who lack local knowledge of the cave and its characteristics in flood conditions.

Rapid thawing of surface snow/ice, in sufficient quantity to result in icy-cold run-off which results in hypothermic cavers is another major consideration; it doesn't take much water to be dangerous, when the water's that cold. At the other end of the scale there's the problem of dehydration caused (esp. in Yorkshire) in extremely hot summers on long/steep approach walks, compounded by dehydration resulting from underground endeavour and subsequently triply compounded by further dehydration on the return walk - people suffering from a hangover before the day has begun would be at increased risk from this - again this is potentially fatal IIRC: failing to carry sufficient* water (due, principally to its weight and the distance to be covered) is an easy oversight in such scenarios.


* For a whole day out on the moors, this would probably conservatively be in the region of 5-7 litres per person (1 litre = 1 kilo): it's easy to see why a decision could be made which resulted in water being left behind.

 
« Last Edit: February 02, 2007, 10:42:35 am by cap 'n chris »

Offline Peter Burgess

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Re: Cave Related Climate Change discussion
« Reply #15 on: February 02, 2007, 10:41:40 am »
Oops! See below....... :chair:
« Last Edit: February 02, 2007, 11:10:12 am by Peter Burgess »

Offline gus horsley

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Re: Cave Related Climate Change discussion
« Reply #16 on: February 02, 2007, 10:43:14 am »
If we are going to be experiencing heavier downpours then we will also see an increase in sinks not being able to take the full amount of water, leading to serious flood risks when they back up and overflow.  This has happened before - believe it or not, Hull Pot once overflowed (in the 1940's I think) - the resulting flood poured down the dry valley below, taking walls with it, and roared through Horton, taking out two bridges and several houses.

Offline Cap'n Chris

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Re: Cave Related Climate Change discussion
« Reply #17 on: February 02, 2007, 10:49:00 am »
Oops! Sorry Peter! - You'll need to do that again.  :-[

The wetsuit being worn on the approach to Bar Pot tale; seems the wrong button got pressed by mistake. Muchos apologias!  :kiss2:

Offline Peter Burgess

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Re: Cave Related Climate Change discussion
« Reply #18 on: February 02, 2007, 11:08:59 am »
Quote
At the other end of the scale there's the problem of dehydration caused (esp. in Yorkshire) in extremely hot summers on long/steep approach walks

This isn't new, but probably something to be increasingly aware of. In about 1980, I went on my first trip to Yorkshire, camping at Clapham on a warm August Bank Holiday weekend. It was also the first opportunity I had to wear my 'made to measure' Caving Supplies wetsuit. We walked up to Bar Pot in the blazing sun, and suffered. With the cave already rigged, at least we didn't have to carry much kit. This was, I think, before the days of widely available caving oversuits.

I have saved the text of this message on my hard drive, so no matter how many times cap'n chris deletes it, I can put it back.  :tease:


Offline whitelackington

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Re: Cave Related Climate Change discussion
« Reply #19 on: February 02, 2007, 05:16:39 pm »
Only if the differential between the cave temperature and the outside temperature increases. If the basic cave temperature stays as it is now, but the summer warming of it causes a higher differential from the norm, then it would happen regularly. Its a question of what determines the 'normal' cave temperature ie the temperature of the rocks and the caves 'static' water content. This is all just a Peter Burgess theory, waiting to be shot down in flames by some learned type (currently in France, I believe.) Cave temperatures in the tropics are higher than in the UK. This must be due to the climate being warmer there. The only other things to affect ground temperature are geothermal affects, and we don't got a lot of that in this country. Deep mines are obviously an exception to this.

I'm beginning to think I am just talking a load of rubbish.  :-[

I belive as you go deeper in Lec, it gets warmer :'(

Offline ditzy

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Re: Cave Related Climate Change discussion
« Reply #20 on: February 04, 2007, 11:26:19 am »
i thought that the cave tempreture is the same throughout a cave apart from the entrence were there is normally a breeze?

Offline Cap'n Chris

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Re: Cave Related Climate Change discussion
« Reply #21 on: February 04, 2007, 02:43:01 pm »
By comparison with the major temperature swings experienced on the surface of our planet, cave temperatures are relatively constant but this does not mean they do not vary - it's just that the variations aren't particularly major.

There are many things which will affect temperature underground; the most obvious being whether or not there is an active stream and the surface temperatures affecting that stream's water temperature. Windchill caused by breezes either resulting from atmospheric changes, through drafting or waterfalls etc. can also have very localised and major effects. The usually quoted average "constant" temperature is 10-11C; however, some Mendip caves measure as high as 13C - and Gough's is even hotter but I don't have a figure for that (Gough's temperature is increased by the presence of electric lights for the showcaves which generate "thermals" rising to the higher parts of its up-slope chambers). In winter, the streamway in Swildon's Hole will have localised windchill (e.g. at the Twenty and again at the Old Forty) of around -9C.

« Last Edit: February 04, 2007, 02:54:13 pm by cap 'n chris »

Offline Peter Burgess

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Re: Cave Related Climate Change discussion
« Reply #22 on: February 04, 2007, 03:53:40 pm »
I suppose the point I was trying to make was that there might be more temporary fluctuations from the norm in localised parts of caves due to extreme weather. And that during those temporary fluctuations, the equilibrium between carbon dioxide content of water and air might be upset, resulting in some of it coming out of solution and collecting in stagnant parts of the cave. Like you see air bubbles coming out of tap water if you leave it to stand in a glass for a few minutes.

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Re: Cave Related Climate Change discussion
« Reply #23 on: February 04, 2007, 06:44:16 pm »
I suppose the point I was trying to make was that there might be more temporary fluctuations from the norm in localised parts of caves due to extreme weather. And that during those temporary fluctuations, the equilibrium between carbon dioxide content of water and air might be upset, resulting in some of it coming out of solution and collecting in stagnant parts of the cave. Like you see air bubbles coming out of tap water if you leave it to stand in a glass for a few minutes.

But that's chlorine not CO2.

Offline Peter Burgess

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Re: Cave Related Climate Change discussion
« Reply #24 on: February 04, 2007, 06:57:42 pm »
I think you will find it is air. Actually, oxygen-enriched, as oxygen is more soluble in water than nitrogen. Despite the smell you get from tap water, there is virtually no chlorine in tap water - the smell is from some harmless complex chlorine compound I seem to recall, that forms when water is chlorinated.


 

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