12 January 2011
Though some experimentation is an important part of the geological sciences, the historical geological record is written in nature. Experiments are any exercises we do where we control the variables and we watch how a system responds to our tweaks (e.g., rock deformation experiments, metamorphic reaction experiments under elevated P/T conditions, sedimentation rates in controlled chambers).
Experiments inform our understanding of nature, but nature comes first. Parts of our understanding may be decoded in a lab setting (e.g., isotopic dating, strain ellipse analysis, or groundwater chemistry), but the data are collected outside and must then be processed indoors. In geology, the big experiment has been run: its result is the planet we see before us. As archaeologists, cosmologists, and crime scene investigators must do, geologists use subtle clues to interpret the past.
Historical sciences have a different fundamental logic than experimental sciences, but they cannot be considered lesser merely because we cannot run experiments on the size and scale of the planet Earth’s 4.5 billion year history. Fixed laws are one thing, a sequence of events with contingency is another. Paul Hoffman has argued that a scientific approach to unraveling past events is geology’s greatest contribution to human thought.
Now that we have (maybe) entered the Anthropocene, we can run experiments of sufficient magnitude to be justly considered “experimentation on the Earth system,” where perturbations of planetary scale have been induced by agriculture, industrialization, and a human population rapidly approaching 7 billion. These are, empirically speaking, experiments on nature “her”self, experiments on the planet Earth. However, these experiments are hardly ideal, as (a) the variables are insufficiently controlled, (b) there is no control planet for comparison, and (c) we live in the “test tube” which hosts the experiment. This means that if the experiment produces civilization-destabilizing results, we have screwed ourselves over big time.
Human civilization is an independent variable in the Earth experiment, in that it has demonstrably altered the natural Earth system with novel conditions of quantifiable extent. Geoscientists may then watch to see how the Earth system responds (the “dependent variables”). What happens to the Earth system when we double CO2 in the atmosphere? NO2? CH4? What happens when we deplete the stratospheric O3 layer? Denude the soil? Chop down a third of all forests? Lower the oceanic pH by 0.7 units?
These are all interesting questions, and I’m sure interested in the answers. I fact, I’d go so far as to say that it’s the most interesting set of experiments that humans have ever run, insofar as their unprecedented scale is concerned…
…But I also have a wee bit of trepidation living in the “test tube” which until now has been so homey and comfortable, …so homeostatic…
Anyhow, what’s my point? Historical and experimental sciences… we need both. As for the Big Experiment, I find it both fascinating and sketchy.
I’m not about to claim that the planet is in danger of being imminently rendered unfit for science, but maybe in addition to experimental science and physical science, we could also use a sense of empathy for the residents of our planet’s coastal plains, for the aragonitic-shell secreting organisms of the world ocean, and for the altitude-limited organisms who have reached the top of their local hill and can climb no further. Do these empathetic considerations deserve higher weight than the knowledge we stand to gain by letting the experiment run?
How do we balance this fascination with finally getting to run an (albeit imperfect) experiment with the fact we must live among the results?