In 1979 James Lovelock, a British atmospheric chemist, published a book that proposes that the Earth is a single living entity. This is known as the G Hypothesis and it suggests that Gaia, or Mother Earth, is alive. He developed this hypothesis in the 1960s and it gained enormous interest due to the space flights when astronauts brought back with them pictures that allowed us to view Earth for the first time from outer space. Practically glowing blue and white, the Earth really did look alive compared to other planets such as its dark and lifele looking neighbor, Mars
According to his hypothesis the various components that make up the planet such as the atmosphere, the seas etc., are in balance. This is much like the homeostatic condition within the human body where a constant temperature and blood PH is maintained through various processes controlled by the liver,kidneys etc.
The idea of the Earth being alive has brought new awareness to the impact that man has on global processes. Everything that happens on the planet from the deforestation of trees, the increase of emissions of carbon dioxide to the removal of croplands all have an effect on our planet. We can no longer think of pollution in one part of the planet as being distinct from another part; it is all related. No longer can governments sit back and happily state that their pollution levels are lower than other countries because what goes on in say India, the United States or even Timbuktu will affect what goes on anywhere else on the planet.
Lovelock stated that the planet regulates itself just like the human body. If our body temperature rises above a desirable level then the body sweats to cool itself down. Lovelock suggested that this can be compared to the fact that the heat of the sun has increased a lot since life began on Earth but the planet has maintained the same temperature. So how does it do this? A good example is the carbon dioxide cycle. Volcanoes constantly produce massive quantities of carbon dioxide. Carbon dioxide is a greenhouse gas and so naturally warms the Earth. If we don't sweat to cool ourselves down, then our temperatures will continue to increase with a disastrous effect. Just like our bodies, if the Earth's temperature is not regulated then soon enough it would not be able to support life. While plants and animals absorb and release carbon dioxide through life processes such as photosynthesis, respiration and decay, these processes don't have any effect upon total amount of the gas.
Rock weathering is a process by which carbon dioxide is removed from the atmosphere. Rainwater and carbon dioxide combine with rocks and form carbonates, which are washed away into the ocean, where microscopic algae make tiny shells by using them. When the algae are dead, their shells sink to the bottom of the occan and form limestone sediments. Limestone has comparatively great physical weight, so it gradually sinks underneath the Earth's mantle and melts there. The carbon dioxide within the limestone in turn will be returned to the atmosphere through a bout of volcanic activity. Since soil bacteria are more active in high temperatures, the removal of carbon dioxide acts faster when the planet is hot. This has the effect of cooling the planet, completing the cycle.
But if it is true as Lovelock suggests that the Earth self regulates, we can assume that it does not respond to environmental stresses in a simple way. The amount of solar energy the Earth has received over thousands of years has fluctuated and these fluctuations have produced complex climatic changes between cold Ice Age episodes and warmer interglacial periods during the last 2million years.
Since the Industrial Revolution in the 19th Century, man has released huge amounts of pollutants into the atmosphere in a relatively short period of time.Evidence from carbon dioxide in air bubbles trapped in ice shows that the amount of CO2 in the air has increased by about a quarter since. As the Earth experiences more and more stresses in the form of increased pollution from natural and man made activities, just how the Earth will react could yield abrupt and dramatic climatic change. What took thousands of years to bring about the Ice Age could take a far lesser time today.
There is no proof yet, however, to support Lovelock's Gaia hypothesis and while it has attracted a lot of interest, it also received a lot of criticism. But despite this, Lovelock's hypothesis has changed the way we view our planet. Through his theories, we are far more aware of the damage we are doing to the Earth and we now see the Earth as a living entity.
What is the main idea of the passage?
A When man realized how beautiful Earth is from outer space, it changed our attitude toward our life.
B The Earth is like any other living organism and has an inbuilt survival mechanism.
C Man-made pollution is pushing the Earth to its absolute limits.
D If man does not halt all poisonous emissions immediately then the Earth will enter another Ice Age.
What is the main idea of paragraph 1?
A All other planets look lifeless compared to Earth.
B No one realized that Earth looks alive from outer space.
A new concept of Earth as a living being was introduced.
D If the Earth is alive then it will struggle to survive.
What is the main idea of paragraph 2?
A The Earth maintains condition necessary for its survival.
B By figuring out human physiology we can understand our planet better.
C Plants and animals act as Earth's senses.
D Increased pollution interferes with Earth's climatic rhythms
What is the main idea of paragraph 3?
A Timbuktu's pollution levels will affect anywhere else on the planet.
B Lovelock's hypothesis has brought governments together in our global fight gainst pollution.
C Governments don't care about pollution levels in other countries and refuse to dis-cuss a global environmental strategy.
D Deforestation is adversely affecting the croplands of the planet and this might reduce their annual yield.
What is the main idea of paragraph 4?
A The sun is emitting very dangerous levels of radiation.
B Volcanoes emit the highest amount of carbon dioxide.
C The Earth self-regulates and maintains a balance.
D Carbon dioxide warms the planet.
What is the main idea of paragraph 5?
A Limestone is so heavy that it melts but sometimes it escapes into the air.
B Carbon dioxide is removed from the atmosphere by natural processes.
C Volcanoes emit carbon dioxide from limestone by natural processes.
D When the planet is hot, bacteria will produce more carbon dioxide.
What is the main idea of paragraph 6?
A There have been many ice ages during the last 2 million years.
B Scientists are expecting another Ice Age very soon
Interglacial periods are caused by solar fluctuations.
D The Earth does not respond well to environmental stress.
What is the main idea of paragraph 7?
A We cannot predict how the Earth will respond to increased pollution.
B The Industrial Revolution sparked mass pollution
Carbon dioxide levels have increased dramatically since the 18th century.
D We can measure pollution levels by air bubbles trapped in ice.
What is the main idea of paragraph 8?
A Not many scientists believe Lovelock's hypothesis.
B Lovelock's hypothesis has changed the way we look at the Earth.
C Lovelock's hypothesis will help us survive environmental disaster.
D Lovelock's hypothesis will help reduce harmful emissions of pollutants.