Based on the present growth rate of 1.
Page 48 Share Cite Suggested Citation: Atmosphere, Oceans, Land, and Humans. One Earth, One Future: Our Changing Global Environment.
The National Academies Press. A change in one part of the earth system has repercussions for other parts often Human atmosphere and earth ways that are neither obvious nor immediately apparent.
It is beyond the human ken, however, to study the whole, multicli- mensional system at once. As the following sections attest, the effort to understand the dynamics driving change in the global environment is clesigned along the academic lines that essen- tially define classical disciplines.
In fact, though, researchers are ever-aware that the various sciences of the atmosphere, ocean, land, and water are connected in countless ways. The intrica- cies of the earth system range from the obvious links between currents in the ocean and atmosphere, to the all-encompassing global cycles of carbon and water, to the subtle, distant effect of clearing a tract of tropical forest on the amount of carbon in the atmosphere.
But the atmosphere touches each of us. The atmosphere, a gaseous envelope that surrounds the earth, is the engine of the physical climate system.
When ra- diation from the sun enters the atmosphere, some is reflected back upward by clouds and dust, and some continues on to the land surface.
Of that radiation that strikes the surface, some is absorbed by the earth, but some is reflected back to space by ice, snow, water, and other reflective surfaces. In addition, infrared radiation is emitted by the earth.
A portion of this en- ergy gets trapped by certain atmospheric gases whose particular chemistries do not allow the outgoing, longer-wave infrared ra- diation to escape. Insteacl, this bounces back to the earth, raising the surface temperature.
Water vapor, present in variable concentrations up to a few percent, is the major gas responsible for the greenhouse effect on earth. Other greenhouse gases are present in trace amounts, usually measured in parts per billion ppb.
The trace gas that has recently received the most attention is carbon dioxide, which currently constitutes 0. They are of special interest now because their concentrations in the atmosphere are rising.
Carbon dioxide poses the single greatest threat because it is the most abundant of these gases. It occurs naturally in the atmosphere and is cy- cled through nearly all living organisms.
Animals, including humans, exhale it as a waste product, whereas plants "breathe" it, using the carbon to make the carbohydrates they require in the processes known as photosynthesis.
Analysis of air bubbles trapped in glacial ice and contem- porary measurements reveal that carbon dioxide concentrations have increased by nearly 25 percent since the eighteenth century, when industrialization began.
The main cause is the combustion of fossil fuels, which produces compounds that also contribute to problems such as local air pollution and acid deposition. During combustion, carbon is oxidized to carbon dioxide and released to the atmosphere. The destruction of forests for settIe- ments or cultivation contributes to this rise also.Fossil fuel combustion for heat, electricity and transportation remains the single most significant factor in the human impact on the Earth's atmosphere.
The significant scale of human impact on our planet has changed the course of Earth history, an international team of scientists led by the University of Leicester has suggested.
The researchers. Atmosphere: Atmosphere, the gas and aerosol envelope that extends from the ocean, land, and ice-covered surface of a planet outward into space. The density of the atmosphere decreases outward, because the gravitational attraction of the planet, which pulls .
Written for nonscientists, One Earth, One Future can help individuals understand the basic science behind changes in the global environment and the resulting policy implications that the population of the entire planet must face. The volume describes the earth as a unified system--exploring the interactions between the atmosphere, land, and water .
The Earth's climate has changed throughout history. Just in the last , years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7, years ago marking the beginning of the modern climate era — and of human civilization.
Nitrogen, oxygen and argon make up the chief of these gases at approximately 78, 21, and 1 percent by volume. Small amounts of water vapor, carbon dioxide, methane, nitrogen dioxide and sulfur dioxide are also part of our air.