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close this bookDiversity, Globalization, and the Ways of Nature (IDRC, 1995, 234 p.)
View the document(introduction...)
View the documentAcknowledgments
View the documentForeword
close this folder1. Introduction
View the documentGlobalization and the ways of nature
View the documentThe new globalization processes
close this folder2. Global trends and their effects on the environment
View the documentThe information revolution
View the documentDevelopment of global financial markets
View the documentDevelopment of more effective transportation networks
View the documentMovement of people
View the documentGlobalization and the unequal distribution of wealth
View the documentInternational migration
View the documentThe development of free markets
close this folder3. Planet-wide deterioration
View the document(introduction...)
View the documentOur sister planet
View the documentThe unusual, oxygenated planet
View the documentThe paradox of ozone
View the documentOceans can be degraded too
View the documentThe rivers are becoming muddy
View the documentOvershooting
close this folder4. Forests under attack
View the document(introduction...)
View the documentDeforestation in the 20th century
View the documentRain-forest environments
View the documentTemperate forests
close this folder5. Grasslands
View the documentSavannas
View the documentThe temperate grasslands
View the documentModifying grassland ecosystems
View the documentEnvironmental balance in grassland ecosystems
close this folder6. Aquatic ecosystems
View the documentExtractive exploitation
View the documentThe future of fish production
close this folder7. Managing planetary thirst
View the documentSome basic facts
View the documentWater supply and options
View the documentThe demand side of the issue
View the documentWater issues throughout the world
close this folder8. Protecting air quality
View the document(introduction...)
View the documentAir and its principal contaminants
View the documentProcesses of contamination in industrial and urban areas
View the documentCurrent and future trends
close this folder9. Clean energy for planetary survival
View the document(introduction...)
View the documentThe industrial revolution
View the documentThe use of hydroelectricity
View the documentThe age of petroleum
View the documentNuclear power
View the documentThe clean options
close this folder10. Africa in the 21st Century: Sunrise or sunset?
View the document(introduction...)
View the documentThe causes of poverty
View the documentHistorical causes of the current situation
View the documentWars are environmentally unfriendly
View the documentEvolution of environmental management in Africa
View the documentOld and new development models
close this folder11. Latin America and the Caribbean: A history of environmental degradation
View the document(introduction...)
View the documentIndigenous cultures
View the documentThe colonial period
View the documentExploitation of natural resources after independence
View the documentEffects of globalization on the environment
View the documentThe maquiladora phenomenon
close this folder12. The urban environmental challenge
View the documentThe development of modern cities
View the documentLarge cities in the Third World
View the documentThe megacities of today
close this folder13. Diversity and human survival
View the document(introduction...)
View the documentDocumenting diversity
View the documentResources for the future
View the documentDiversity of living systems
View the documentCauses and effects of the loss of natural diversity
View the documentDiversity and culture
View the documentRestoring what is lost
View the documentBiodiversity and research
close this folder14. Strategies for the future
View the document(introduction...)
View the documentDecentralize decision-making
View the documentPeople value their environment
View the documentProblems and responsibilities are global
View the documentBibliography

The unusual, oxygenated planet

Among the planets of the solar system, the Earth is an oddity. Although several bodies are similar in volume and mass (Venus, Mars, Mercury, Ganymede, and Titan), several features of the Earth make it unique. The Earth is the only known planet with a large oceanic area; its atmosphere contains very little CO2 (about 0.3%) and a large amount of free oxygen (21%).

The level of oxygen seems particularly high when we consider that it is a very active gas and combines with many other elements. It is found on many other planets, but usually combined with carbon or hydrogen as CO2 and water (in gaseous or solid forms) or with silicon, aluminium, and other elements to form the crystal lattices of minerals. Free oxygen does not exist in significant quantities on any other planet.

On Earth, oxygen occurs in water, ice, and rocks. In fact, oxygen represents 45% of the total mass of the Earth’s crust and 90% of the total volume. However, the huge amount of free oxygen in the atmosphere is unique in the solar system, and this oxygen has existed for many hundred million years. There is every indication that its proportion has increased during geological time, as a result of a long period of photosynthetic activity by algae and green plants.

Originally, Earth was probably more like Venus and Mars. Venus’ atmosphere is composed mainly of CO2 (95%) and nitrogen (4%); the Martian atmosphere is 94% CO2 and 5% nitrogen. Three billion years ago, the amount of CO2 in the Earth’s atmosphere was also high (perhaps over 90%); however, photosynthetic activity released the oxygen from CO2 to form organic matter. It is believed that noticeable volumes of free oxygen first appeared about 2 billion years ago. One billion years later, it probably made up I to 3% of the atmosphere and ozone started filtering out ultraviolet radiation. The 5% level was probably reached about 750 million years ago, and the current oxygen concentration was not reached until about 100 million years ago (Cloud and Gibor 1970). A large proportion of the carbon was buried in sediments as limestone, coal, petroleum, and gas. A small amount remained in the atmosphere or dissolved in ocean waters.

While the level of CO: decreased and carbon was trapped in geological layers, oxygen molecules were being released into the atmosphere, increasing slowly to a concentration of about 20%. The upper limit for oxygen concentration is related to the probability of natural fires occurring; the more free oxygen there is, the more likely spontaneous fires will break out. Fires oxidize the carbon in the organic matter, such as wood, to produce CO2, thus reducing the amount of oxygen in the air relative to CO2.

The decrease in CO2 concentration during geological times brought about important climatic changes, the main one likely being a decrease in average temperature. Carbon dioxide in the atmosphere produces a strong greenhouse effect, and its elimination promotes a general cooling of the atmosphere. The decrease in CO2 was not continuous. It occurred in leaps, and qualitative changes were determined by the development of new, more sophisticated biological systems to use it.

According to Lovelock (1988, p. 164), the decrease in CO2 was also a way for the planet to cool in spite of increasing solar heat. In other words, life seems to possess a “thermostat” that has ensured a relatively constant temperature throughout geological times, a temperature that allows survival of life. Every time the solar heat increased to a certain level, new biological systems developed to use smaller proportions of CO2, causing the concentration of this gas to decrease further, cooling the biosphere.

Through successive adaptations of photosynthetic processes, biosystems were able to reduce the CO2 content in the air to 0.3%, the current level. If solar radiation continues to increase, there is little room for additional cooling (that is, for continued lowering of CO2 levels). In that respect, biological systems are “living on the edge.” If additional CO2 is released into the air, and if the volume and activity of CO2 users (algae and plants) are reduced because of deforestation and water pollution by pesticides and oil, there is a risk that the thermostat may break down (Cloud and Gibor 1970). When that happens, it may be too late to change course.

We must seriously consider a rapid, drastic reduction in systems that burn fossil fuels and produce large quantities of CO2 and other greenhouse gases. Postponing action will put at risk not only the survival of humankind, but that of “Gala” itself.