The use of the term global change results from the fact that the Earth now, more than ever, appears to us as one entity. What happens in one part of the Earth affects the other. The concept of plate tectonics and the coupling of the history of continents and oceans. The anthropogenic release of certain gases, with possible environmental consequences, to the atmosphere in which we live and move and have our being. Most discussions of global change have been focusing on global warming or the ozone hole growth above the polar regions or other forms of global pollution.
Global change is more than that it is the essence of the history of the planet.
Even larger changes in atmospheric composition, earth surface temperature and sea levels have occurred in the past than are projected for the immediate future based on current trends of human actions. Through studies made by geologists, solid-earth geophysicists, paleontologists, oceanographers and atmospheric scientists we are capable of assessing the nature of global change over the Earth s history. Through these studies we can know the changes that have occurred in the past over timescales of tens, hundreds, thousands, tens of thousands and millions of years based on the record in rocks, ice and historical and archaeological sources. We can also discover the fundamental scientific processes responsible for determining the state of the environment. We do not, however, know all the feedbacks that affect climate change such as the role of cloud formation on the Earth s heat balance and the variability of the sun s energy output.