« Glossary Index
An increase in the earth’s average atmospheric temperature that causes corresponding changes in climate that result from the greenhouse effect (The effect of significant increases in warming greenhouse gases) Greenhouse gases include water vapour, carbon dioxide, methane, nitrous oxide, ozone and some artificial chemicals such as chlorofluorocarbons (CFCs).
Human activities – particularly burning fossil fuels (coal, oil and natural gas), agriculture and land clearing – are increasing the concentrations of greenhouse gases. This is the enhanced greenhouse effect, which is contributing to warming of the Earth.
The impacts of climate change are only beginning to be felt. Atmospheric levels of carbon dioxide are at their highest in 650,000 years. Oceans are becoming warmer and more acidic, and the population of zooplankton, the basis of the marine food chain, has dropped 73 percent since 1960. Natural habitats everywhere are under threat, the cloud forests of the Andes, the grasslands of the Asian steppe, ‘the lowland rain-forests of the Amazon, and the entire arid belt of the sub-Sahara from the Horn of Africa to the Atlantic shores of Mauritania. Half the coral reefs of the world either have died or are on the edge of collapse. The largest known insect infestation in the history of North America has destroyed millions of ‘ hectares of forest in the western United States, more than 130,000 square kilometers of lodgepole pine in British Columbia alone, and has now spread to Alberta to threaten the arboreal forests of the Subarctic. In the Pacific and Indian oceans, island nations such as the Maldives, faced with the possibility of dramatic increases in sea level, have made contingency plans for the evacuation of their entire populations.
But arguably the greatest immediate threat is to be found in the mountain ice-fields that are the birthplaces of all the world’s great rivers.
“On the Tibetan plateau, source of the Yellow River, the Mekong and Yangtze, the Brahmaputra, Salween, Sutlej, Indus, and Ganges, there has been no net accumulation of snow since at least 1950; These glaciers are not just retreating at the margins, they 1 are melting from the surface down. Conservative estimates predict that 60 percent of China’s glaciers will be gone by the end of this century. Half of humanity . depends on these rivers. Five hundred million people in the Indian subcontinent. alone turn to the Ganges for water; for 800 million Hindus it is the sacred Ganga Ma, holiest of rivers. During the dry season, fully 70 percent of the river’s flow originates in the Gangotri glacier, which is receding at a rate of nearly 40 meters a year. If, as currently anticipated, the glacier’completely disappears, the Ganges will become a seasonal river within our lifetimes. One shudders to anticipate the economic, political, and psychological consequences for India. In 2007 riots occurred when a few hundred pilgrims to the Amarnath Cave in Kashmir, located at 3,800 meters and one of the holiest of Hindu shrines, found that the phallus-shaped stalagmite of ice, for generations considered the sacred image of Lord Shiva, had melted.”
Full Glossary Index
This past year for the first time
in human history we became a predominantly urban species. In the year 1820 only London had a population of more than a million. Today there are 414 cities of such size or larger, and within 35 years demographers predict there will be more than 1,000, many following the pattern of places like Lagos, capital of Nigeria, which in 1955 had a population of 470,000 and by 2015 is projected to be home to over 16 million.