Thank you, Dean Mosher. It’s a great pleasure to share the stage with you today; and with Executive Vice-Chancellor Prior; with our colleagues on the faculty; and especially with my dear friend, whom I can proudly claim as a former student, Dr. Chernoff. Thanks to all of you for joining us in this celebration.
First, to the graduates: congratulations, and well done! Perhaps that’s enough said already, but we all know how this goes: commencement addresses are almost always instantly forgettable — a combination of clichés, unneeded advice, platitudes, and lofty sentiments.
What I’m thinking is that if we all agree that we really don’t need to hear another speech like that, we can dispense with those obligations pretty quickly, and move on to other things. So let’s give it a try.
For you graduates, here’s a quick nod to the tradition that this occasion requires:
- First, a cliché: “AIM HIGH.” But I don’t need to tell you that — you know it already. Otherwise you wouldn’t have set your sights on Texas and entered one of the world’s premier geoscience programs.
- A bit of unneeded advice: “WORK HARD.” But I don’t need to tell you that either — you know it already. Otherwise you wouldn’t be set to graduate from one of the world’s premier geoscience programs.
- A platitude: “BE GRATEFUL.” But you know that already, too. Otherwise you wouldn’t be surrounded here by the family and friends and faculty and other supporters who have helped you to come so far.
- How about this, for a lofty sentiment: “YOU HAVE A BRIGHT FUTURE AHEAD, BUT YOU ALSO HAVE A RESPONSIBILITY THAT COMES ALONG WITH A DEGREE FROM ONE OF THE GREAT UNIVERSITIES OF THE WESTERN WORLD.”I’m pretty sure you know and believe this too, but in fact my purpose here today is to ask you to think a bit more about what it really means to have earned a degree — not just any degree, but a degree in geosciences — from the University of Texas.
Your choice to study the earth sciences has set you apart from everyone else on this campus — and not just because it gave you the perfect excuse to take off on fantastic field trips and to get credit for camping out under the stars! Your choice to study the earth sciences has given you an appreciation of the link between Earth and Man that few others can claim, and that everyone on the planet needs very badly just now.
So that’s where I’m headed with this, but let’s back up to the beginning…
How did we all come to be earth scientists? I’ll bet that many of you took a path much like mine. Growing up in Colorado, backpacking in the Rockies, I developed a love of the outdoors and an appreciation of nature that was fed and heightened by family trips to America’s great national parks to see their geological wonders.
But growing up, I never thought about making a career of it. Actually, my plan in college was to study math, and maybe to get involved with a then-brand-new field that we’ve now come to call “computer science.” (Yeah, I know… that was a long time ago…) But one day I came across a poster in the hallway. It was an arresting photograph of a spectacular mountain scene at timberline — lush green below; deep blue sky above; a sparkling lake nestled in a tiny glacial valley; remnant patches of snow clinging to gullies carved in stark gray rocks by the action of ice and water and wind. And at the bottom, all it says is: ” Yes, this will be on the test.” Sign me up!
So that’s how I came to find myself enrolled in an introductory geology course taught by an inspirational professor — some students in the audience may recognize the name “Robert Compton”, the guy who literally wrote the book on field geology. The class met at 8 a.m. every day of the week, but I had no trouble showing up on time to hear Compton’s vivid descriptions of how the earth worked: the astounding ways in which astonishingly slow and gradual processes could build up stunning ranges of mountains, then tear them down again grain-by-grain and dump their detritus into ocean basins, to start the cycle again. I was enraptured to hear how geoscientists could read from the rocks and fossils their origins, and how they could decipher the immensely rich record of Earth’s history that the rocks carry.
So although I was initially drawn to geology just as a backpacker with a keen sense of the majesty of Earth’s natural wonders, Bob Compton made me begin to see, in the study of geoscience, what author Colin Fletcher called “the meaning behind the majesty.”
And so I’d like to invite you to join me for the next few minutes in musing on that theme.
“The meaning behind the majesty”
That lovely phrase comes from a book entitled The Man Who Walked Through Time , which is a narrative description of Colin Fletcher’s 1963 trek through the Grand Canyon. For him, it became a spiritual pilgrimage, as it awakened in him an awareness and appreciation of the unfathomable scale of geologic time.
And it’s that comprehension of what author John McPhee called ‘DEEP TIME’  that sets students of the earth apart from nearly all other scientists.
For those in audience who may not have thought in these terms before: imagine that we took all of the time that has elapsed since the Earth first formed as a planet, and compressed it into one calendar year, starting on the first of January.
- At that scale, the earliest forms of unicellular life — really just a bunch of sticky microbial slimes — would appear sometime in March or April; but not until mid-August would any kind of multi-cellular organisms show up.
- To see anything even faintly resembling a modern animal we’d have to wait until mid-November, and it would be even later before we would encounter those strange aquatic lifeforms like trilobites and echinoderms.
- Not until December 3rd would we find plants and animals on land. The dinosaurs — ancient though they seem — would rule the globe only from about the 16th to the 27th of December.
- And here’s the kicker: Homo sapiens shows up around 7:00 p.m. on December 31st! Our earliest civilizations pop up only 21 seconds before midnight.
- The city-states of ancient Greece and Rome collapse 10 seconds before the year ends, and the Pilgrims celebrate their first Thanksgiving with only 3 seconds to go.
- The Industrial Revolution — and all the immense changes that it brought to our world — would begin less than one second before midnight on December 31st. Less than one second before midnight…
Quite a different perspective, isn’t it? This is deep time, in which Man is the newest of newcomers on the scene. Cast against the immensity of geologic time, all of the activities of humankind shrink into a tiny, flickering instant.
In fact, when you first try to wrap your head around this notion of deep time, it’s hard to escape a sense of insignificance, even futility: Colin Fletcher, The Man Who Walked Through Time , speaks of “the fear that threatens to overwhelm us when we first look back and down into the huge and horrifying vaults of time that ticked away before man existed.”
And yet, in the Earth’s rocks and fossils, geoscientists see — stretching across this mind-bending sweep of deep time — an elusive but entrancing chronicle of change.
The power of deep time inspires even the poets among us: the original Geology Building on this campus — it’s the Hogg Building, just east of the tower — has emblazoned on its most visible façade in three-foot-tall letters the exclamation of Alfred Lord Tennyson :
“O Earth, what changes hast thou seen!”
Earth’s history does reflect massive secular change over time — but why? For about the first half of Earth’s history (let’s say, up to about mid-June for an Earth formed on January 1st), change was driven primarily by physical processes working to establish chemical and thermal equilibrium: thus we have the differentiation into core, mantle and crust; the cooling of the outer Earth to form rigid plates; the segregation of oceanic and continental crust.
But since then, the single most fundamental agent of planetary change has always been life.
Although primitive microbes have been around since the Eoarchean (that’s maybe early March), it was the advent of photosynthetic organisms that created the greatest change the globe has ever seen, generating free oxygen in its atmosphere about 2.25 billion years ago (roughly the first of July). This is the first and most compelling example of an irreversible transformation wrought upon the Earth by its inhabitants. And ever since this Great Oxidation Event, as it’s called, biologically-mediated processes have driven the great changes that our Earth “hast seen.”
One quick example from my own field, mineralogy, courtesy of Robert Hazen and his co-authors :
- During the era of planetary accretion, Earth (and all the solar system) was comprised of only a few dozen minerals, maybe 60 in total.
- The era of physically-mediated change brought elemental segregation and concentration that increased the number of mineral species, but only up to perhaps 1,500.
- It wasn’t until we entered the biologically-mediated era that we saw an explosion to the more than 4,300 mineral species we count today, all created as increasingly diverse lifeforms modified the planet, putting their environment to use for their own ‘purpose’ of propagating themselves into the future.
But these bio-mediated changes, immense as they are, have — until now — proceeded at a geologic pace, slow enough that life on Earth was able to evolve, adapting to the irreversible changes it induced.
But Man is different.
Man is very different.
It’s mind-blowing to contrast the astoundingly slow and gradual changes seen by the earth before the advent of humankind with the blindingly rapid modifications to the earth system brought about by our actions. Remember, modern man only showed up a few minutes before midnight on the last day of December. From the end of Stone Age to now — the interval of man’s manipulation of the earth system for his own ends — is only an eyeblink in earth history. But look what’s happened in that time…
All of Earth’s systems — land, water, air, ice, and certainly its ecosystems — are now more heavily impacted by human activity than by any other agent of geologic change.
- Through construction and agricultural activities, humans now displace enough sediment and rock to lower all ice-free continental surfaces by a few hundred meters per million years — that’s greater by a factor of ten than the sum of all other natural processes operating on the surface of the planet .
- More nitrogen fertilizer is applied in agriculture than is fixed naturally in the sum of all terrestrial ecosystems, and nitric oxide produced by the burning of fossil fuel and biomass also overrides all natural emissions .
- More than half of all accessible fresh water is already used by humankind .
- Our energy use has grown 16-fold during the twentieth century, producing emissions of sulfur dioxide that are twice the sum of natural emissions .
- And our impact on the rest of the biosphere is nearly incalculable: current estimates put the rate of extinction of species at 100 to 1000 times the natural background level, and that rate is projected to increase by yet another factor of ten in the coming century .
At the root of it all, of course, is the exponential growth of our global population: a tenfold increase to 6.5 billion people has occurred in the last 3 centuries, and the number is projected to reach nearly 10 billion in the lifetime of today’s graduates . And this is compounded by an ever-increasing per capita demand: each newcomer exploits substantially more of Earth’s resources than those who came before.
There’s no escaping it: Man is now the most powerful agent of geologic change on the planet, bringing modifications — some likely to be irreversible — at a pace that far outstrips any possible chance of adaptation by natural evolution.
This global explosion of humanity’s impact, in a geological instant, has shoved us over the brink, into what Zalasiewicz and others  describe as “a new phase in the history of both humankind and the Earth, when natural forces and human forces [are] intertwined, so that the fate of one determines the fate of the other.”
Graduates: a grasp of this extraordinary connection between humanity and the Earth system — which defines “man’s singular place in the vastness of nature,” to use Colin Fletcher’s words  — is the great gift of your study of the geosciences.Your comprehension of it sets you apart from everyone else.
For most folks, today seems not much different from yesterday; this year not so unlike the last; my generation not altogether different from yours. But for geoscientists, who uniquely combine the perspective of deep time with a sense of the immediacy of humanity’s need for resources, there’s a greater appreciation of the urgency of our situation: we realize that for Homo sapiens, tomorrow will indeed be importantly different from today; next year will be fundamentally different from this one; and the generation after yours will live in a worldunforeseeably unlike the one that hosted the generation before mine.
So your degree in the geosciences comes with special responsibilities. Some of you will discover the resources we need to expand civilization; others will find the energy needed to power it. Some of you will protect the soils in which our food is grown and the oceans from which it is drawn. Some of you will safeguard the water we drink and the air we breathe.
But all of you now possess something vitally needed by the rest of mankind: the sure knowledge that Earth and Man are now intimately and inextricably interlinked; its fate is now ours.
Share that great truth with all you meet.
So I’ll wrap up with a quick recap:
AIM HIGH! WORK HARD! BE GRATEFUL! [Did I say to WEAR SUNSCREEN?]
and remember …
YOU HAVE A BRIGHT FUTURE AHEAD, BUT YOU ALSO HAVE A RESPONSIBILITY THAT COMES ALONG WITH THIS DEGREE IN GEOSCIENCES FROM ONE OF THE GREAT UNIVERSITIES OF THE WESTERN WORLD.
So follow your passion for all the Earth’s glories and wonders, but always keep in mind the meaning behind the majesty.
Congratulations again, and thank you.
 Fletcher, C. , 1967, The Man Who Walked Through Time; Random House, New York. Back to text.
 McPhee, J. , 1981, Basin and Range; Farrar, Straus and Giroux, New York.Back to text.
 Tennyson, A. , 1849, In Memoriam A.H.H., CXXIII, st. 1. Back to text.
 Hazen et al., 2008, American Mineralogist, v. 93, p. 1693. Back to text.
 Wilkinson, B. H., 2005, Geology, v. 33, p. 161. Back to text.
 Crutzen, P. J., 2002, Nature, v. 415, p. 23. Back to text.
 Zalasiewicz et al., 2010, Environmental Science and Technology, v. 44, p. 2228. Back to text.