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Global change results when large global and regional systems are altered at a rate that is much faster than those systems are accustomed to experiencing. These alterations are not all human induced. Natural1 events such as volcanic eruptions or meteorite impacts have the capacity to create sudden, massive changes in global systems that can legitimately be classed as global change. The cool, wet summer experienced across eastern Canada in 1992 was attributed in part to the immense volume of ash and sulphur dioxide spewed into the stratosphere by Mount Pinatubo in the Philippines in June of 1991. Figure 6 shows how ash from previous eruptions has affected the amount of solar light transmitted through the atmosphere. For the most part however, these disturbances are catastrophic, infrequent events of short duration.
[Figure 6]: In contrast, while human induced disturbances with global consequences can be catastrophic (such as the Chernobyl nuclear accident) they are more commonly progressive and of long duration. If anything, a catastrophic event such as nuclear war is more easily averted since the potential for environmental devastation would be immediate, obvious and relatively certain. Instead, the vast majority of global change is caused by society's slow, steady, persistent and unspectacular consumption of resources and by the creation of unwanted by products during the course of that consumption. Put simply, global systems are mostly being changed by the overconsumption of the one billion wealthy members of the globe's 5.3 billion people.
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PREFACE | WHAT IS GLOBAL CHANGE? | THE IMPORTANCE OF GLOBAL CHANGE TO CANADA | CAUSES OF GLOBAL CHANGE | CONSEQUENCES OF GLOBAL CHANGE FOR THE BIOSPHERE AND GEOSPHERE | HOW WILL GLOBAL CHANGE AFFECT SOCIETY? | CANADIAN RESPONSES TO GLOBAL CHANGE | A FINAL WORD
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