Global Environmental Change

Throughout geologic history, Earth has experienced dramatic environmental changes from forces such as plate tectonics and glaciation. However, recent human activities have accelerated the rate and scale of global changes immensely—so much so that many authorities now suggest that the Holocene is ended and a new geologic epoch has been entered: the Anthropocene. Human impacts on Earth have multiplied as technology develops and populations grow. The rate of change has increased much faster than just the population growth rate, as humans have moved from merely procuring food and shelter to exploiting Earth for myriad products to add comfort to their lives and to using increasingly advanced technology that creates a variety of waste products. Global environmental change encompasses the study of all these anthropogenic impacts on Earth. Global environmental change includes global climate change and more regional changes such as urbanization, ozone depletion, soil erosion and land degradation, desertification, habitat alterations, deforestation, hydrologic perturbations, and other changes that directly affect ecological systems.

Institutions and governance of local societies often dictate the rate and regional impacts of global environmental change. These changes manifest themselves at multiple spatial, temporal, and sociopolitical scales, and it is this complexity that makes examining the entire phenomenon so difficult. Current research in global environmental change is concerned both with documenting change and the interactions of forcing mechanisms as well as with mitigating their impacts. Environmental change mitigation is accomplished by reducing societal and ecological vulnerability to disruption by maximizing the resilience and adaptive capacity of the systems.

Human activities affect the majority of natural global environmental systems, and often these impacts interact to create ramifications far larger than their sums. Specific manifestations of global environmental change in regions of the Earth differ depending on an area's society and its economic capabilities, but ultimately, they always have biodiversity impacts. For example, when discussing agricultural impacts on water quality, Guatemala must cope with primarily sediment erosion, while the United States also has to address agricultural pesticides and fertilizers, and each of these pollution types affects aquatic ecosystems in different ways. A century or more ago, Earth's biogeochemical cycling could accommodate human waste products and extraction. But the exponential growth of human populations has depleted or exceeded the resilience of natural systems, and thus today, global environmental change impacts are growing exponentially. While technology accelerates the rate and severity of impacts, it also offers the potential to remediate much of the damage, if society demands and is willing to pay for such remediation.

Global climate change is the overriding factor that affects all other anthropogenic alterations. To avoid duplication, this discussion focuses on the other regional forces that interact with climate change to create global environmental changes and biodiversity impacts. These forcing mechanisms include land-cover changes, soil degradation, hydrologic perturbations, and both ocean and atmospheric changes. No part of the Earth is untouched—from the stratosphere and its new gases to the deepest ocean trenches with warmer, more carbon dioxide-rich waters and trash disposal—even the moon and other planets have space vehicle wreckage. The physical impacts on the landscape in turn have major social impacts—especially for food security and human health.

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