An excerpt from Patagonia’s republished version of A Forest Journey, about what the loss of trees has meant for past life on our planet.
By John Perlin
The headline read
“Deforestation, Wildfires and Flooding.” Yesterday’s news? No, it was the
subtitle of an academic paper regarding the end-Permian Extinction, when life
on Earth almost came to an end: more than 90 percent of the animals in the sea
and almost an equal number on land went extinct. It is ranked as the most
severe of all the biological catastrophes over the last 540 million years since
life has flourished on Earth. Many blame mass volcanic eruptions as the killer;
others claim the resultant lava cooked adjacent petroleum-bearing rock and the
consequent vapors poisoned the seas and land. (The latter resembles the
processing of tar sands today.) Or perhaps it was a one-two punch.
Most agree that whatever
the cause, greatly increased carbon dioxide levels in the atmosphere had
significantly raised the temperature at sea and on land.
“The rise of forests and their near demise clearly foretell
what to expect in a future forested or deforested world.”
The Permian successors
of Archaeopteris (the earliest form of
tree)—gymnosperms—could not properly photosynthesize due to the crippling heat
and the dearth of sunlight brought on by a sky choked with smoke. Just as their
predecessors had turned Earth’s landmass into an Eden for the living, the death
of most of the world’s trees contributed to an inferno that consumed most
everything alive. As the forests perished, so did herbivorous animals of
varying sizes from tiny insects to huge reptiles and protomammals, leaving
giant insectivore lizards and ferocious carnivores without meat to eat and
therefore to starve and die.
Wildfires added to the
carnage. With no leaves to protect the soil from the harsh sun, the pelting of
raindrops, and blasting winds, and with no roots to tame raging torrents into well-ordered
riverbeds, the land gave up its water and soil chock-full of algae to the
oceans. Massive erosion not only polluted the seas; it furthered the
destruction of life by enhancing the theft of oxygen from them. As scientists
concluded, “The drop in O2 concentration
across the Permian-Triassic boundary … [is] believed to have been due mainly to
a substantial reduction in the geographic extent of lowland forests …” A coal
gap throughout Gondwana [an ancient supercontinent] for over five million years
attests to just how long the loss of closed forests (forests in which the
canopy touches) on Earth persisted. No forests of sufficient size meant no
coal. The consequence: little, if any, carbon sequestration, resulting in a
great increase in atmospheric CO2 over this
period.
As cartographer Tim Robinson waxed poetically, “The axe evolves from stone to bronze to iron to steel. Great woods with all their sighs and cries go down into silence …”
The story of Archaeopteris and its arboreal successors and their subsequent decline by humanity puts, according to Dr. William Stein, a prominent paleobotanist, “a sobering lens on the climatic shifts our planet is undergoing now. Around the world, forests are being cut away, and the ancient carbon left by prehistoric trees—our main source of coal—is being dug up and burned. What’s happening today is the opposite of what happened in the Devonian [Period]. Once again, sweeping change begins and perhaps, ends with trees.”
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