September 23: Earth is the only planet with an atmosphere congenial to life forms as we know of. If a blanket of air didn’t surround us…our planet would have been a frozen wasteland – much too cold for human habitation. We have a lot to be thankful for. But we humans have been taking things for granted. As a result, this protective blanket is now slowly suffocating us.
According to a worldwide study carried out by the World Wildlife Fund. (WWF), concentrations of carbon dioxide (CO2) in the atmosphere have doubled in the last 50 years.
Scientists say there might be a three-fold increase in concentrations, by 2100, unless immediate action is taken. Research show that the USA is the world’s biggest emitter of CO2 and advanced countries account for 52 percent of the world’s CO2 emission.
The emission of carbon dioxide and other gases (like methane and chlorofluorocarbons), has resulted in what is known as global warming (or the increase in the average global temperature).
According to the report, the North Pole is melting at a steady pace. For the first time, scientists have noticed a 16 km long (and 5 km wide) ice-free patch of water in the Arctic – a sure sign of a meltdown. Yes, global warming is causing the sea ice to melt. This in turn will slowly cause sea levels to rise, leading to the submergence of low-lying coastal areas, the world over.
WWF’s report points out that if we continue to maintain the same levels of emissions, then more than 60 per cent of the habitat would be lost by the end of the century.
The researchers predict that by the turn of the century, the rise in global temperatures will result in the extinction of many animal and plant species. And the combined effect of global warming and the depletion of ozone could affect more than one-third of world habitats in this century.
All this sounds serious indeed, but it also leads to some questions — for instance what causes global warming? No, you don’t have to study tomes of books to understand this, instead just walk down to a greenhouse.
If you have been inside a greenhouse, you will know that it can get very warm within. This is because the glass panels overhead trap the heat emitted by the plants. The blanket of air surrounding the Earth behaves exactly like the glass of a greenhouse. It allows solar radiations to pass through and traps the radiation emitted by the Earth. This is known as the Greenhouse effect and helps to maintain the Earth’s temperature.
The rays from the Sun cause the Earth to heat up and release heat radiation or infra-red radiation. Some of the radiation escapes, but large amounts get reflected back. Certain gases in the atmosphere (such as carbon dioxide, methane, chlorofluorocarbons or CFCs and ozone) reflect back the heat radiations, further adding to the heating process. These gases are known as greenhouse gases.
Certain quantities of these gases are helpful. However due to excessive usage of fossil fuels, aerosols and air conditioners (which contain CFCs) not to mention the indiscriminate cutting down of trees, the quantity of the gases has reached alarming proportions. This is what is causing the average temperatures to shoot up.
Now there’s more evidence that the earth is warming up like never before. This evidence comes from ice cores in a glacier on the “roof” of the world, the Himalayas.
Holes were drilled in ice, each about 150 metres, at the Dasuopu glacier by an international team of scientists. The glacier is located on the flank of Xixabangma, a peak that rises to 26,293 ft. on the southern rim of the Tibetan plateau.
According to a report in the ‘Times of India’, the scientists analysed the cores to estimate air temperatures. They were able to identify layers in the ice cores that corresponded to the passing years and the estimates of in air temperatures and dryness.
The amount of dust trapped in the ice cores increased by four times in the 20th century, with concentrations of chloride doubling for the same period. That suggests an increase in the dryness of air and the rate at the land is becoming desert, the scientists said. They added that at least part of the warming is driven by human activity.