Comments on: The Weekly Carboholic: boreal forest moves north, reducing Arctic albedo

By: Scholars and Rogues » The Weekly Carboholic: U.S. consumer choices control U.S. carbon emissions

Wed, 08 Oct 2008 12:30:45 +0000

[...] can it absorb enough to offset human CO2 emissions and slow the rate of global heating? Or will the reduced albedo change dominate, warming the Arctic to the point that methane hydrates undergo massive melting? I suspect some of [...]

By: Scholars and Rogues » The Weekly Carboholic: good-bye Holocene, hello Anthropocene?

Wed, 23 Jul 2008 12:30:47 +0000

[...] this year. And in general, the revision shows that hardiness zones have moved up in elevation and north toward higher latitudes, both expected results of global heating and both of which have been [...]

By: Dr. Denny

Dr. Denny — Wed, 21 May 2008 16:48:10 +0000

I’ve got Sam in my trunk. He really influences my mileage.

By: Brian Angliss

Brian Angliss — Wed, 21 May 2008 15:50:13 +0000

Russ – Yeah, and it’s a great example of the problem of positive feedback vs. negative feedback. As the earth heats up, the boreal forest can expand and thus can store more carbon. But at the same time, a hotter Arctic means more carbon emissions from permafrost, peat bogs, and submarine methane hydrates. In addition, green trees absorb more energy than tundra plants and mosses do. So which force dominates, the positive feedback of more carbon emissions plus a falling albedo, or the negative feedback of more carbon storage in the trunks of growing boreal trees? It’s a complex exercise, and I don’t know the answer personally, but I suspect that scientists with experience in this area (how much carbon a tree can store, how fast boreal forest is expanding, how many trees that is per acre or sq. kilometer, etc.) can make an estimate and attach error bars to it.

The “good” thing is that, in realty, every positive feedback mechanism has a limiting factor that constrains the instability. In electrical engineering, if I design a circuit that is unstable, it’ll go crazy until it hits the limit of the circuit, usually the power supply. In the Arctic, melting sea ice is a positive feedback element because open water absorbs more sunlight than floating ice does – until there’s no more ice to melt. At that point, the positive feedback term in the Arctic climate equation is negated and other terms take over again.

Of course, just because there’s a limit doesn’t mean that limit is a good thing. In an electrical circuit, the limit could be a capacitor that overheats, pops, and dumps foul-smelling black carcinogenic smoke into the air. In climate feedbacks, just because the limiting factor of sea ice would be no sea ice doesn’t mean that homo sapiens en toto would like the global climate at that point.

By: www.buzzflash.net

www.buzzflash.net — Wed, 21 May 2008 15:26:36 +0000

The Weekly Carboholic: boreal forest moves north, reducing Arctic albedo…

This week: boreal forest expansion may make Arctic warming worse; ice core pushes CO2 data back from 650k to 800k years; study links 29,500 changes since 1970 to hotter climate; hybrid car emission claims suffer from marketing "adjustments"…

By: Russ Wellen

Russ Wellen — Wed, 21 May 2008 15:20:21 +0000

Forests taking over the tundra exacerbating global warming? That’s wild.

Damned if you do; damned if you don’t.