Chapter 01

Author: Lee Hannah

FIGURE 1.1 Earth ’ s Atmosphere. The atmosphere of the Earth is an amazingly thin layer of gases. At its thickest, the atmosphere is approximately 100 km deep, which is less than 1/100th of the Earth ’ s diameter (12,700 km). Viewed in this perspective, the atmosphere appears as a thin, vulnerable shroud around the Earth. Alterations to this gossamer protective layer may have major consequences for life. Reproduced with permission from NASA.

FIGURE 1.2 The Greenhouse Effect.Solar radiation reaches the Earth, warming the surface. The surface then radiates long-wave radiation back toward space. Greenhouse gases absorb and re-emit some of this long-wave radiation. The net effect is that some radiation that would have escaped to space is re-radiated within the atmosphere, causing warming. From Climate Change 2001: The Scientifi c Basis . Intergovernmental Panel on Climate Change, 2001.

FIGURE 1.3 O cean Chemistry and Marine Life. Marine organisms such as these Pacifi c white-sided dolphin ( Lagenorhynchus obliquidens ) are already experiencing ocean acidifi cation. The pH of seawater varies signifi cantly by region and by depth, and it is increasing due to human CO 2 emissions. CO 2 from human fossil fuel combustion enters theatmosphere and then dissolves in seawater, making it more acidic. Surface waters already contain about 30% more hydrogen ions than they did in pre-industrial times. Courtesy of NOAA.