GLOBAL CHANGE

Global change

Global change

Introduction

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 (Leichenko, 2008).

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. 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.

Land Cover and Land Use

Every organism changes its immediate environment to suit its habitat needs. However, humans change Earth as no other species in the geologic record has done. Throughout history, deforestation has been driven by the local civilization's land use intensity, as the demand for timber products has often intersected with the demand for agricultural land to dramatically alter landscapes. These impacts are exacerbated by climate, fire, and insect disturbances. Human impacts on land cover have a variety of climatic, ecological, and socioeconomic drivers, and landscape fragmentation often results. Biological impacts such as changes in the assemblage of species, local extinctions, dispersal, and relocation also result from local changes in habitat parameters. Land use changes transform the land's productivity and biochemical/hydrologic cycling. The most profound alteration has been the conversion of various land types to agricultural uses, so that now, over one half of Earth's potential agricultural land is already in use (Brookfield, 2001).

Soil Degradation

Soil quality is the inherent capability of soil to perform environmental functions, and degradation may result in the partial or complete loss of soil's productive capacity. Global soil degradation includes erosion, compaction, acidification, soil organic matter and fertility losses, and salinization. Mismanagement of soils for agriculture, timber activity, and by livestock owners is the major cause of soil ...