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ing gases emitted by the algae, such as carbonyl sulphide, COS, and carbonyl disulph-
ide,CS 2 ) seed clouds, some of which deposit sulphurous rain on the sulphur-hungry
mosses sitting atop the peat bogs. In fact rain brings the mosses much more than sulphur,
for they are perched so far above the nutrient-rich bedrock by the thick intervening layer
of peat, that their root-like rhizoids have no hope of tapping into nutrients weathered out
far below them, at the interface of rock and peat. The mosses thus have no option but
to be almost totally dependent on rainfall for all of their essential minerals. If Klinger
is right, the peat bogs and the oceanic algae feed each other the scarce nutrients each
one needs, an unexpected case of cooperation between two great ecological communit-
ies. But this coupling doesn't only affect algae and moss; it also has major effects on the
Earth's climate.
Peat bogs and marine algae cool the planet in similar ways. Both produce dense white
clouds, and both absorb carbon dioxide directly from the atmosphere through photosyn-
thesis. We've already seen how a rain of dead oceanic algal bodies settling on the sedi-
ments carry carbon sucked out of the air; this is the biological pump, but peat bogs also
remove carbon dioxide from the air, fixing it as peat where it resides in dark, moist en-
tombment for many centuries. Peat bogs also cool the planet by killing off dark, snow-
shedding coniferous forest. Snow settling on the treeless bog creates a high albedo sur-
face which cools the Earth about 80% more effectively than the snow-free moss of sum-
mer.
The bog-alga coupling is a positive feedback that could potentially plunge the Earth
into a permanent snowball state if it moves in the direction of cooling. What prevents
this from happening? Klinger proposes that as the world cools, advancing ice scrapes
away the peat, reuniting it with oxygen in the air, giving off warming carbon dioxide
gas. Even before the glaciers destroy them, the peat bogs could fix so much carbon that
there is too little carbon dioxide left for photosynthesis, a negative feedback that would
limit the growth of the mosses.
Biomes and Climate
Relationships between different biomes—Gaia's major ecological communities—also
have a huge impact on climate. Up in the far northern latitudes, below the tundra regions
where most of the peat bogs grow, lies the great boreal forest composed of dark ever-
green pine trees which shed snow because of their triangular shapes. The trees' dark
green foliage warmed the whole boreal region and the entirety of the northern hemi-
sphere by a staggering 2.5 0 C during the period 1965-1995. This simple fact has a
massive impact on the Earth's climate, for in the absence of trees the surface would be
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