Rise of Human Influence on the World's Biota

Abstract

The earliest appreciable human impacts on the world's biota probably came near the end of the Pleistocene, when human hunting pressures may have driven some species of megafauna to extinction in Australia and the Americas. Early Holocene land clearance and rice cultivation may have begun the process of anthropogenic greenhouse enhancement, possibly warming the planet by up to 2°C before the Industrial Revolution. Human population growth reached exponential rates in the twentieth century, as humans converted increasing proportions of temperate and tropical landscapes to agriculture and animal husbandry. Today, 40% of all terrestrial landscapes have been converted for human use. In addition, specific threats to the world's oceanic ecosystems include habitat loss, global climate change, overexploitation and other effects of fishing, pollution, species introductions/invasive species, the physical alteration of coasts and watersheds, and marine litter. Combined with the human ecological footprint. The IPCC (2013) estimate that global mean temperatures will rise another 4°C and 5°C by the year 2100, assuming that anthropogenic greenhouse gas emissions continue to influence the climate. This level of warming will bring considerable disruption to the world's ecosystems, but not in a uniform manner. The introduction of invasive species to non-native regions has wrought havoc in most ecosystems, both terrestrial and aquatic. The natural world is in jeopardy. It remains to be seen where the world's governments will exert the political will to make ecosystem conservation a top priority.