Physical Evidence For Global Change
Humans have always altered their environment. The advent of agriculture around 10000 years ago led to a radical change in land use that still continues. But, the relatively small human population had little impact on a global scale until the start of the industrial revolution in 1750. This event, followed by the invention of the Haber-Bosch process in 1909, which allowed large-scale manufacture of fertilizers, led directly to rapid changes to many of the planet’s most important physical, chemical and biological processes.
The 1950s marked a shift in gear: global change began accelerating. Between 1950 and 2010, the population more than doubled. In that time, rapid expansion of international trade coupled with upsurges in capital flows and new technologies, particularly information and communication technologies, led to national economies becoming more fully integrated. There was a tenfold increase in economic activity and the world’s human population became more tightly connected than ever before. The period saw sixfold increases in water use and river damming. About 70 percent of the world’s freshwater resource is now used for agriculture. This rises to 90 percent in India and China. Half of the Earth’s land surface had now been domesticated. By 2010, urban population, for the first time, exceeded rural population. And there has been a fivefold increase in fertilzser use. Indeed, manufactured reactive nitrogen from fertilizer production and industry now exceeds global terrestrial production of reactive nitrogen. Without artificial fertilizers there would not be enough food to sustain a population of seven billion people.
These changes to the human sub-system have a direct influence on all components of the Earth system. The chemical composition of the atmosphere has changed significantly. Concentrations of important greenhouse gases, carbon dioxide, methane and nitrous oxide are rising fast. Over Antarctica a large hole in the ozone layer appeared. Fisheries collapsed: most of the world’s fisheries are now fully or over-exploited. Thirty percent of tropical rainforests disappeared.
In 2000, Nobel prize-winning scientist Paul Crutzen announced the scale of change is so great that in just 250 years, human society has pushed the planet into a new geological era: the Anthropocene. This name has stuck and there are calls for the Anthropocene to be adopted officially. If it is, it may be the shortest of all geological eras. Evidence suggests that if human activities continue to change components of the Earth system, which are all interlinked, this could heave the Earth system out of a one state and into a new state.
Read more about this topic: Global Change
Famous quotes containing the words physical, evidence, global and/or change:
“I have no purpose to introduce political and social equality between the white and black races. There is a physical difference between the two, which, in my judgement, will probably for ever forbid their living together upon the footing of perfect equality; and inasmuch as it becomes a necessity that there must be a difference, I ... am in favour of the race to which I belong having the superior position.”
—Abraham Lincoln (1809–1865)
“In fact, there is clear evidence of black intellectual superiority: in 1984, 92 percent of blacks voted to retire Ronald Reagan, compared to only 36 percent of whites.”
—Barbara Ehrenreich (b. 1941)
“However global I strove to become in my thinking over the past twenty years, my sons kept me rooted to an utterly pedestrian view, intimately involved with the most inspiring and fractious passages in human development. However unconsciously by now, motherhood informs every thought I have, influencing everything I do. More than any other part of my life, being a mother taught me what it means to be human.”
—Mary Kay Blakely (20th century)
“Change your opinions, keep to your principles; change your leaves, keep intact your roots.”
—Victor Hugo (1802–1885)