Monkeying With the World
Look at the world. A brilliant, shifting blue and white orb spinning through the star speckled darkness. As the eons tick by, watch the brown continents slide around the oceanic globe, pieces in an animated, spherical puzzle. The white polar caps grow and shrink as the Earth wobbles in its orbit. The day side glints in the brightening light of the sun. The night is a deep black. For billions of years, the dark is only broken by a quick flash of lightning, or splash of aurora. And then, after 2 billion years, a wash of green crawls over the dayside continents, bringing flickers of forest fire to the night. Otherwise, for four billion years, the shadowed side of the planet is as dark as the starry space surrounding it.
But then, what is this?
Suddenly, new lights start dotting the night side along the coastal areas, connecting along tiny threads, and spreading in brightening webs. On the dayside, a loose mesh of dark lines is now visible, winding between these dots, each swiftly surrounded by a geometric patterning of verdant vegetation. The oceans are now crossed by regular movements of small wave-generating objects. New, linear clouds streak through the skies. And then, little insect-like constructions of refined metal start jumping off of the planet, visiting the neighboring worlds and sending radio pulses toward home, signaling the arrival on Earth of curiosity and technology. This planet is looking for answers.
When we compare Earth’s unique story with that of our sister planets we gain new perspective on global change. Venus and Mars each once enjoyed an environment quite like Earth, but Venus has become a desiccated oven and Mars a stale freezer. Comparative planetology teaches us that Earth is balanced between these fates. It also teaches us that global climate systems are frighteningly complex, and that all our detailed predictions are surely wrong at some level. However, based on well known physics we can make some secure predictions about long term climate evolution.
As a star ages, it also slowly heats up, as hydrogen is fused into helium, increasing overall density, and thus requiring a higher core temperature to balance the inward gravitational force. This results in gradually increasing solar heating of all the planets. Earth has been protected from the runaway greenhouse fate of Venus, so far, by a nifty negative feedback which regulates the amount of CO2 in our atmosphere through the supply of volcanism and the demand of chemical weathering making carbonate rocks. If we don’t muck it up, this system will work for another billion or two years. (Our best way to refine the prediction is to explore Venus more thoroughly.) Eventually, as the sun keeps heating up, dangerous global warming will be inevitable.
Will the green recede again from the land, and the night lights go dim?
Earth has endured radical global change many times before. The climate has varied between greenhouse and icehouse conditions. As Earth becomes more populated with humans, coastal areas become densely inhabited and food consumption approaches the planetary carrying capacity. Under such circumstances, climate change becomes a more dangerous prospect. Earth’s past pattern of climate oscillations, projected into the future, becomes a recipe for future disasters even in the absence of global warming. Eventually we’ll have to intervene in climate evolution.
We are not the first species to cause global change. The atmosphere has been altered more than once, in ways that were fatal for many creatures, by the collective actions of bacteria. We proudly call ourselves Homo Sapiens, which translates roughly as “wise monkeys”. But in our inadvertent tinkering with our planet, are we really that different from bacteria?
When we contemplate taking collective action to guard against global warming, to detect and deflect damaging asteroids heading our way, and even when we model the terraforming of Mars we are starting to imagine ourselves as wise monkeys in the role of planetary engineers.
The evolutionary transition to active planetary management is one that will be necessary for long term survival on any planet. In a universe full of evolving worlds, could we be the first to confront these challenges? If we learn to take the long view, with the planetary perspective born of this new interplanetary age, we are much more likely to find out.