Comments on: Medieval Treeline in Finland

By: The Finnish "Supra-Long" Chronology #1 « Climate Audit

The Finnish "Supra-Long" Chronology #1 « Climate Audit — Wed, 18 Jul 2012 14:59:32 +0000

[...] discussed one such study (Kultti et al 2006) at CA here (which estimated MWP temperatures as 0.55 deg C higher than at present) in passing in 2006, but, [...]

By: The fight to get the temperature data that Global Warming Hysterics don't want you to see « UD/RK Samhälls Debatt

Sat, 10 Jan 2009 13:42:32 +0000

[...] discussed one such study (Kultti et al 2006) at CA here (which estimated MWP temperatures as 0.55 deg C higher than at present) in passing in 2006, but, [...]

By: bender

bender — Sat, 05 Aug 2006 00:23:50 +0000

Interesting. Did you hear they found a hybrid polar/grizzly this spring? Story here

By: beng

beng — Fri, 04 Aug 2006 23:15:28 +0000

This has been posted before, bender — still worth repeating regarding arctic treelines. Nichols is a real biologist, seemingly in the Lamb fashion.

http://pielkeclimatesci.wordpress.com/2006/07/12/open-arctic-ocean-commentary-by-harvey-nichols-professor-of-biology/

By: TCO

TCO — Fri, 04 Aug 2006 14:30:32 +0000

A specific case study would be a good start. Trying to understand your point about “the fastest moving tree lines” do so from this effect.

By: bender

bender — Fri, 04 Aug 2006 13:30:23 +0000

Re #33 I doubt it, because that would require a set of spatially replicated studies. The process I’m referring to would be relevant only in the northern Rockies where the sub-polar storm track generates alot of lightning caused fires. I will dig for an authoritative reference for you on that – however this alone will not answer the “extent” question.

By: Mark H.

Mark H. — Fri, 04 Aug 2006 03:50:03 +0000

I’m just hoping this message will push that long web link OFF the sidebar so my search results stop getting truncated.

By: TCO

TCO — Fri, 04 Aug 2006 03:42:02 +0000

Is there a good study describing the extent of this confounding factor?

By: bender

bender — Fri, 04 Aug 2006 03:40:11 +0000

Where treeline is rising fastest in the northern Rockies it is, ironically, DESPITE warming. In these areas it is fire frequency that is the slow-changing variable modulating treeline. When lightning caused fires are frequent and burn large, mountain-tops stay tree-free longer (colonization rates are slower at harsher elevations). In the 20th century, however, human-caused fire suppression is allowing these natural tree-free grassy meadows to fill in with trees. Not knowing any better, one might ignore the intermediate controlling process (fire occurrence) and conclude that the treeline is creeping up because of the direct effect of temperature rise. But of course, human populations are rising at the same time, and these humans don’t like fires, so fire frequency and size have dropped tremendously in alpine areas. If fire suppression were suspended, the tree line might actually drop under a climate warming scenario!

This may have no relevance for pre 20th century changes in treeline. But it does show (1) how treeline is controlled by more than one variable, and (2) how spurious correlations can arise very easily with low-frequency processes where you don’t have all the facts about what the rate-limiting processes are.

By: TCO

TCO — Fri, 04 Aug 2006 03:00:13 +0000

Ok.