Global Change

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Global change came into use in the late 1980s as humans became as a planetary force affecting the basic functioning of the overall Earth system. Previously, the change wrought by human activity had been local or regional in extent. While this term has a history in other fields, in the context of the global environment, it refers to linked planetary-scale changes in environment and human society described in the 1990 report A Study of Global Change [1] that marked the beginning of the International Geosphere-Biosphere Programme.

The more familiar term climate change is but one symptom of modern civilization’s new and problematic relationship with Earth. Global change is a far more extensive and complex phenomenon, stemming from disruption not only of the atmosphere and climate, but of many other interacting processes and components of the Earth’s metabolism that keep the planet hospitable for humans and the rest of life.

Human transformation of nature

Since living things inevitably alter their environment in the process of living, human transformation of nature is not itself new. But with the advent of the modern industrial economy propelled by abundant, cheap, concentrated energy in fossil fuels, the human enterprise over the past two centuries has been transforming Earth on a scale and at a speed that is mind-boggling and unprecedented.

In this time, the human population has increased by more than sixfold from 1 billion to approaching 7 billion, energy use has escalated more than eightyfold, and the world’s economy has grown roughly sixty-eightfold. After World War II, this transformation accelerated explosively, altering the planet as much in a single lifetime as our ancestors had since the move to agriculture and complex civilization some 10,000 years ago. It took all of human history for the global economy to reach the 1950 level of $5 trillion; in this decade, it expanded that much in a single year. This explosive, exponential growth in the scale of the world economy made humans a planetary force and agent of global change.

Humanity confronted the first life-threatening breakdown of a planetary system in the mid-1980s when a yawning hole suddenly appeared in the ozone layer over Antarctica caused by man-made chemicals, a close call we survived thanks not to scientific prowess, but rather, according to Nobel chemistry laureate Paul Crutzen, to mere luck.

The growing concentration of greenhouse gases that trap heat poses a different danger. What is immediately at risk is the stable climate necessary for complex civilization. The world as we know it with agriculture, civilization, and dense human numbers emerged during an exceptional, long, tranquil period of climatic stability over the past 11,700 years. Because of humanity’s planetary impact, this benign period, known to scientists as the Holocene and described as “the long summer”, is now ending.

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Author: Dianne Dumanoski