Posted on by Robin Delaloye

We’ve got a great post today by George Stephens, Professor of Geology and Geography and Deputy Director, University Honors Program. Dr. Stephens has both a BS and MS in Geology from GW and a PhD in Geology from Lehigh University. He’s been teaching GW students about Geology since 1978!



Geology is the study of the Earth, its history and the processes that shape its future. Thus geology is a four-dimensional science, three spatial and one temporal. It is from this viewpoint that I am reading Flat, Hot and Crowded. I am not an expert on climate change; my research interests lie elsewhere. But, as a geologist, my understanding of contemporary global climate change (“Hot”) and the increasing world population (“Crowded”) is informed by four billion years of Earth history.

My initial premise is that human behavior is, unquestionably, affecting our planet. It is disingenuous to argue that deforestation and fossil fuel consumption do not affect atmospheric CO2 levels and atmospheric temperatures. Long-term records from deep Antarctic and Greenland ice cores as well as short-term direct measurements confirm human-induced CO2 increases. But it is also true that the surface of our planet has been significantly warmer in the geologic past. Melting of modern-day glaciers and ice sheets is taken as a reliable indicator of global warming. But for most of its history our planet has been entirely ice-free. Glacial epochs through geologic time are very few and reasonably brief. The last great ice age began just three million years ago and during this time there have been approximately 30 major ice advances and retreats. A mere 20,000 years ago we reached the apex of the latest ice advance. At this time virtually all of New England, New York, northern New Jersey, parts of Pennsylvania and much of the mid-west were covered by an ice sheet two miles in thickness. For the past 10,000 years we have been in a warming post-glacial period. Whether this truly marks the end of Cenozoic glaciation or in simply yet another inter-glacial remains an open question. If another major ice advance is headed our way 80,000 years from now, maybe a little global warming is not a bad idea. In any case, the Earth doesn’t care. Surface temperatures have been significantly warmer throughout Earth history, climatic belts have shifted dramatically and some biological species have thrived while others have been driven to extinction.

An examination of the fossil record confirms that extinction is the ultimate fate of virtually all biological species. Paradoxically, simple life forms seem to be longer lived than more complex organisms. Cyanobacteria (think slime mats) have been around for two or three billion years whereas humans began their evolutionary trek only three million years ago or so. To put this in perspective, three million years is but a geological blink of an eye. True, we humans have developed a hitherto unknown capacity to alter our world environment. Still, biologically, we are just another species. If we are unwise enough to use our opposable thumbs and advanced reasoning ability to drive ourselves to extinction, the Earth doesn’t care. Life will likely continue and another, less presumptuous species will rise to dominance in “our” ecological niche.

Over-population is another non-problem for Mother Earth. Human population growth will ultimately be limited by the carrying capacity of individual geographic regions and the present exponential population growth will ultimately obey a “logistic curve”. That is, the present growth curve will flatten dramatically and approach zero as the carrying capacity of our resource base is reached.

I conclude that “hot, flat and crowded” are real problems of planetary magnitude but they are ultimately only human problems. Our planet will survive and perhaps even thrive with us or without us. I am relatively pessimistic about the ability of the human race to come together as an international community to alter our current trajectories before it is too late. But I am comforted by the history of cataclysmic changes recorded by our planet and by the robustness of plant and animal life in successfully adapting to these changes.

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