Under the influence of the greenhouse, there can be large scale changes in the atmosphere conditions. Twenty years ago nobody believed that the earth was warming up. Scientists warn that if this heating continues for the next few decades, snow at the poles will melt, especially in Greenland, and shrink it to half its size. Similarly, many places in Antarctica will submerge under large tracts of water. This melting snow is raising the levels of the sea, submerging small islands and costal areas. Many coastal cities may be lost too.
The plants have always witnessed a rise in sea level. N fact there has been a rise four to six meters in the sea level since the ice ages. This rise came about in 1, 29, 000 years! Presently, similar rise in sea level is predicted in just a few decades. With sea levels rising, disasters in the sea have become common now. Jonathan Park, director, study of planet earth and Betty Butto- Blisnek of the national research centre for temperature, Colorado, have shown us how the oceans have risen as icebergs have melted, and the seacoast has been taken in by the sea. Some scientists also tell us that if we don’t change our habits, more natural disasters will occur. The situation is so grim that if the sea level rises by just about one meter Maldives and a few islands in Bangladesh will disappear from the face of the earth!
The effects of depletion of ozone layer
The ozone layer protects us from the ultraviolet rays of the sun. However, this layer is being destroyed by the Chloro Fluoro [CFC] that is being released into the atmosphere. The ozone layer is formed in the stratosphere about 16-50 km above earth’s surface. In some parts of the world, especially around the Antarctic, Australia, New Zealand, South Africa and over parts of the of south America, the ozone layer has thinned considerably. The main reason is the release of ozone depleting substances like CFCs which are used in appliance like refrigerators, air-conditioners sprays and fire –extinguishers.
The chances of the ozone layer getting thinned are more in other seasons than in winter. CFC does not occur in nature. It gets released into the atmosphere from the appliances we have been using for the last 20 years or so. The CFC problem did not exist earlier and is thus related to our changing lifestyle. Along with CFCs, the other naturally occurring gases that destroy the ozone layer are halons [like bromo Chloro Fluoro carbons] used in fire extinguishers and in nitrogenous fertilizers. As the ozone layer weakens, the UV-B rays from the sun freely reach the earth. An effect of this is seen in the growing incidence of skin cancer in countries like Australia.
Ultraviolet rays weaken human resistance to disease. They cause cataracts in the eye. If one percent of the ozone layer is destroyed, scientists say, skin cancer can increase by two percent. The UV B rays can also affect marine like aquatic plants, fishes and birds. They affect production of food grains and fishers too. The Montreal protocol is aimed at preserving the ozone layer.
The inter connection
As the planet heats up, the use of air –conditioners increases leading to the release of more CFCs which destroy the ozone layer. CFCs, even when released in small quantities, are ten thousand times more harmful than the greenhouse gasses like carbon dioxide and methane as they trap large amount of heat. It is thus clear that the greenhouse effect and the destruction of the ozone layer depend on each other.