Definition

Global Warming refers to the rise in the average temperature of the climate system of the earth.

Causes

The naturally occurring gases in the earth’s atmosphere like CO2, CH4 and N2O help to keep the temperature of earth’s surface above freezing point. These gases have “internal vibration modes” which absorb and reradiate infrared radiation or heat back to the earth surface .This process is known as the Greenhouse effect and the gases are thus referred to as Greenhouse gases. However over the past century the level of these gases has risen due to large scale cutting down of forests in North Eastern America and other parts of the world since 1800. The industrial revolution and other human activities have added to this increase. Annually some 22 billion tons of carbon dioxide is added to the atmosphere, a third of this from electricity generation and another third from transportation.

Indicators

Media worldwide has reported the unusually high temperatures in different parts of the world in the past few years. Instrumental records tracking global temperature have provided evidence of temperature rise indicative of global warming. This was supported by observations by groups of scientist worldwide. There has been significant melting of old glaciers in the Polar Regions. Sea water is gradually moving into some coastal cities and fresh water marshlands in Indonesia, Philippines, Bangladesh and the Oceanic Islands all of which indicate rise in sea level. The weather conditions are showing extreme behavior like massive decrease or increase in the amount of rainfall, floods in new areas, hurricanes and forest fires. Certain diseases like Malaria are beginning to appear in new areas which are also experiencing rising temperatures. In the Oceans coral reefs are getting bleached while there has been alarming reduction in Plankton both of which are due to acidification and warming of the seas.

Acid Rain

The term “Acid rain” is used in reference to any form of rain or precipitation including snow, sleet, fog, cloud water and dew that has a very high content of hydrogen ions or low pH.

It is caused when sulfur dioxide and nitrogen oxide react with water molecules present in the atmosphere to produce acids. When precipitation occurs it removes the acids from the atmosphere and reaches it to the earth’s surface. It flows across the surface in runoff water, enters the water system and sinks into the soil. It removes essential nutrients from the soil, releases aluminum into the soil making it hard for trees to take up water. The particles can also stick to the ground, plants or other surfaces.

Acid rain results from the presence in large scale of sulfur and nitrogen compounds released by human sources. The amount of Sulfur dioxide and nitrogen oxides in the atmosphere has increased since the start of the Industrial revolution due to the presence of sulfur in coal used in electricity generation and in the smoke released by factories and motor vehicles. All of these emissions enter the atmosphere. The use of tall smokestacks to reduce local pollution ends up in release of the gases into regional atmospheric circulation contributing to the spread of acid rain over larger areas.

These acids have a harmful effect on plants and trees leaving them less able to withstand cold temperatures and the attack of insects and diseases apart from inhibiting their  ability to reproduce. Acid rains have a corrosive effect on infrastructure particularly those made of marble and limestone. They damage freshwaters and soils besides killing insects and aquatic life-forms including dissolving coral reefs.

Conclusion

Mankind today faces a massive challenge. Not only do we have to clean up the already polluted environment but change our lifestyle to prevent more pollution.

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