Winter Climbing

I’d like to tap the collective wisdom about the special issues involved with winter climbing. We have LLLOOONNNGGG winters here, and having to stay out of trees the whole time would be a serious bummer. Here is my current take on this, based on living in “the north” (Wisconsin, Sweden, Minnesota) most of my life, and a teeny bit of winter climbing.

The climber
Dress It’s that old balance between too cold (with all the fun mental judgement issues that go along with hypothermia being amplified by being far above the ground), and too hot (getting sweaty, which makes you more vulnerable to chilling later on). The usual advice for physical activity in the cold is “wear layers”. This is all well and good, but adding or shedding a layer in a harness is easier said than done. Seems like the best move is breathable synthetics with the option to add a windbreaker as you get to the top of the tree (where the wind is usually brisker) and/or the climber slows down. Or, dress as well as possible for the temperature and climb slow…
Toes Any ideas on how to keep 'em warm?!?
Manual dexterity Gloves most of the time, but able to shed them for a bit when extra dexterity is needed. Warming up hands against the neck works pretty well when not wearing gloves.
Slipping and sliding Keeping tied in seems to be even more important than usual.
Hot drinks Dick Flowers speaks highly of hot coffee while up a tree in the winter. Sounds wonderful. Don’t spill.

The gear
Temperature Rope and metal don’t seem to be too affected by the sort of temperatures anyone is actually likely to climb in (I’m figuring minus -20 degrees F will put off even pretty macho climbers…). If anyone knows otherwise, we’d like to hear about it. Anything with lubricant could get a bit stiff – has anyone had trouble with an old carabiner not self-locking in the cold?
Snow and ice Either of these could interfere with the operation of knots and mechanical ascenders/descenders, not to mention affecting one’s grip. Anyone have any experience with this?
Throwline issues I was worried about throwline getting stiff in the cold (and carrying stiff little loops of line up into the tree to tangle on everything), but this was not a problem in my last climb at 15 deg F.

The tree
Snow and ice loading Probably the biggest issue regarding the mechanical integrity of the tree. Evergreen conifers are particularly vulnerable, since they have all that needle area to carry ice and snow (we’re in the middle of an ice/snow storm up here as I write, and the white pines are looking pretty unhappy). However, most conifers have a “monopodial” growth form (one big central stem with side branches coming off at right angles), and that seems to help with snow and ice loading. Deciduous trees don’t usually have the problem with leaf area holding ice/snow (except in freak early or late storms), but that more typically spreading growth form makes them a bit less stable when loaded. Combine ice, wet snow, & wind and I suppose that’s not the best time to go tree surfing.
Wood strength and temperature It’s possible that a really hard freeze could form expanding ice crystals and make cracks in wood. From what I’ve been able to glean (from reading bits from Alex Shigo and others, and what I’ve seen), this doesn’t seem to happen much in sound wood, but freezing can easily widen an opening from some other kind of injury and propagate a crack along the grain. According to USDA Forest Products Lab, dry wood is actually a bit stronger when cold, but that is not especially relevant to what’s happening in a living tree. Most of the literature in forest ecology deals with what temperature extremes do to the vulnerable living tissues like leaves, buds, and inner bark; this is more of a long-term issue than anything you worry about during a climb. The short version: inspect the tree carefully – but we already do that don’t we?

So, if you made it this far: What’s missing from this list? Anything wrong? What can you add from your own experience?

Cheers,
MarkF

I've climbed at 28 degree f recently but mostly it's been warmer. Yesterday we had balmy mid-60's with southern air being sucked up by an incoming front. It made for a nice evening climb, almost felt like summer.

Layering up
If your layers have zip up fronts or necks you can wear all your layers and open up as much as you need above your saddle to cool down in the tree.

I nearly maxed out the waist on my NT saddle during my last cool weather climb, If I want to add more layers for a real winter climb I'll have to go one saddle size larger.

Gloves
I have a pair of glove liners with grip dots on them: Manzell Thermax Grip Gloves . They grip well enough to hold the rope and I can tie knots even in 2.2 mm throwline. I wear them under mountaineering mittens and pull them off when I need fine dexterity without exposing skin to very cold air. Bare hands don't grip the rope as well when it gets very cold.

Head
I wear a thin head cap under my climbing helmet (I think it's bicycling gear) for cool weather (high 20.s f) and a balaklava for colder (depends how much wind there is).

Footwear
I haven't tried this but a boot with a felt liner like a Sorel's or something similar should keep your feet warm for more extreme cold. You can't do fine ballet moves in them but they should do the trick.

Climbing caution
Body-thrust technique can result in a face plant on the trunk in slippery conditions.
-moss

Re: the face-plant when body thrusting. Ouch! I hope that's not from direct experience...

I've also just about maxed out my NT saddle dressing for the cold, but I might be able to layer more efficiently to get around that. And yes, zippers help a lot.

Thanks for the other observations. We midwesterners are sending lots of cold air your way, so you should have plenty of opportunity to gain more experience.

Cheers,
MF

Here are a few selected web references on winter tree injuries; not overly technical, but generally the sort of things that tree climbers might want to know about.

General References

There are lots of ways that winter weather can be hard on trees; most of them are described in these pages.


- Winter Injury Fact Sheet -- Cornell University
http://plantclinic.cornell.edu/FactSheets/winterinjury/winterinjury.htm
General discussion of winter tree injuries, the conditions under which they occur, and how to manage to avoid them.
- Protecting Trees and Shrubs Against Winter Damage -- U. of Minnesota Extension
http://www.extension.umn.edu/distribution/horticulture/DG1411.html
More of a focus on injury prevention in landscape trees.
- Managing Winter Injury to Trees and Shrubs -- Virginia Tech
http://www.ext.vt.edu/pubs/envirohort/426-500/426-500.html
Like the Cornell site, gives a pretty good explanation of the mechanisms of injury.


Frost cracks in particular

Frost cracks are cracks parallel to the grain in tree trunks that seem to be primarily caused by cold weather; since they involve major mechanical injury during the winter, tree climbers should probably be aware of them. A trunk with a frost crack is not necessarily dangerous to climb (depending on where the crack is, and how large it is), but you'd want to have a pretty close look at the whole tree for signs of rot or other mechanical damage. Most of the sites mention rapid temperature change (especially rapidly falling temperatures) as a key factor, but there are dissenting opinions about that. Shigo (in the book Modern Arboriculture) emphasizes that most frost cracks start from the enlargement of previous injuries and flaws, like included-bark joints and uneven growth.

- How to Identify and Control Noninfectious Diseases of Trees -- USDA, St. Paul, MN
http://www.na.fs.fed.us/spfo/pubs/howtos/ht_non/non_all.htm
Includes a pretty good discussion of frost cracks with nice pictures.
- Cracks and Splits in Tree Trunks -- Missouri Botanical Garden
http://www.mobot.org/gardeninghelp/hortline/messages/3360.shtml
More discussion of how frost cracks happen and what trees do about it. Winter Injury Fact Sheet

The best things I've found for cold feet are those small chemical heating packets. They can usually fit right under my toes and most do a really good job. Every now and then I get a dud, but most of them are fine.

Re: layers, while I haven't had to try this yet in tree climbing, I know that the rule for hiking or skiing is to be just a bit cold when moving, then just a bit warm when stopped. I found that when hunting I could put my warm (down or Polarguard) jacket on over my webbing. The tree stand I used was basically a climbing harness - in fact that's what I use for tree climbing. If needed I can zip the jacket, leaving the bottom 1/3rd open for the ropes, etc. Of course I wouldn't do this while climbing - it's just for when resting and drinking some of Flower's coffee.

Also for legs, fleece or flannel lined pants
work great. I've gotten a pair of trail hiker flannel lined pants from Cabelas that are really nice. They're tough, warm, roomy and have plenty of pockets, some of which are held closed with velcro also.