Global Warming and Its Impact

Looking at the fact from the evidences available, we can certainly arrive at a conclusion of human impact on climate. From prehistoric times until relatively recent past, all people had at least one thing in common. Irrespective of which part of the world they lived, they could not affect the climate, on the contrary the climate was the prime force behind their lively hood. But today, something fundamental has changed. Through their actions, - particularly due to burning of fossil fuels - human beings are now influencing the world's climate.
The human induced climate change began in the late eighteenth century, around the time of James Watt's invention of steam engine and the beginning of industrial revolution. Over the period of last 200 to 225 years, with accelerating advances in technology and rapidly increasing population, people are now causing changes in regional climate with global consequences. The Earth has been growing warmer at an accelerating pace, yet the changes are complex and vary from place to place where some regions are growing warmer, others cooler, some direr and others wetter.
 
The global population around pre-industrial era was less than a billion, which increased to 2.5 billion in 1950 and today we are over 6 billion people on earth. It is projected that, by 2025 there would be around 8.5 billion of us and by 2050 it would cross 10 billion count. As compared to world, India's population was nearly 350 million in 1950, today we alone stand over a billion. 
Cities are called 'heat islands' as their temperatures are a few degrees higher than the surrounding region. One of the easily understood examples apart from carbon emissions from vehicles and industries is the concentration of tar roads, which not only traps more heat than less 'developed' outlying areas but also reduces the amount of water that the ground absorbs. The best example is Mumbai, where there is no open land left, as it is either covered by roads, buildings, footpaths and the newer addition being pavers blocks which is covering whatever balance open land was visible. The result is even with a moderate rainfall the water logs in the low lying areas which barely have any place to penetrate land, on the other hand the temperature which used to be 35°Cto 36°C is exceeding 40°C today.
It is estimated that carbon dioxide in earth's atmosphere has increased by 31% since pre industrial period. Other green house gases like methane and nitrous oxide are also at their highest recorded levels. This is measured through air bubbles trapped in ice cores taken from glaciers, which provide a continuous record of atmospheric carbon dioxide levels stretching back to 1000 years. Fossil fuels viz.: coal, oil and natural gas which are formed from the fossilized remains of prehistoric plants and animals are the primary cause of the rise of these greenhouse gases (GHG). These fossil fuels provide 90% of the world's commercial energy.
Agriculture and urbanization are another major cause of rise in GHG. Forests are natural storage areas for carbon which they absorb to convert it with the help of sunlight into wood, leaves and other organic matter which is termed as biomass. Especially during last two centuries the forest cover has been cut mercilessly for timber and to make way for towns as well as for agriculture to cater increasing demand of food. Adding to this, nitrous oxide, a GHG which is 300 times more powerful than carbon dioxide, is released through the nitrogen based chemical fertilizer which is used by farmers. Another GHG, Methane is released by rice fields and cattles which is a major food source to the world.

To arrive at these conclusions scientists world over use sophisticated technology and gadgets, where they deploy specialized instruments on land, under the sea, suspended balloons in air and finally satellites in space. These instruments record the data about temperature, humidity, precipitation, wind speed, energy entering and leaving the atmosphere, changes in oceans, changing extent of polar ice caps and so on. For reliable evidence of past weather, scientists gather information from sea floor sediments, ice cores, tree rings, fossils etc. All these data is then complied, processed to arrive at the conclusion of climate fluctuations.
In year 2005 from the recorded data of past 150 years the World Meteorological Organization announced that 1998, 2002, 2003 and 2004 were four hottest years during that period. The IPCC reported in 2001 that average global surface temperature has increased by 0.6°C during the last 100 years. Though it may seem to be very insignificant, some parts of the globe has recorded major shift in temperature. Even this marginal shift in average global surface temperature make a considerable rise (almost upto 8 inches) in the sea level, thereby endangering the costal areas. IPCC continues further and predicts that if the carbon dioxide concentration continues to increase, the average surface temperature will rise to the extent of 5.8°C by year 2100. Even the present rise in the temperature has warmed up the oceans by at least ten times than other parts of the earth within last fifty years. As we all know, that oceans constitutes more than 70% of our planet, it can be imagined the extent of impact it can cause to the climatic conditions around the globe.
 
The floating ice is diminishing faster, this includes perennial ice (ice that remains year-round) even after seasonal ice has melted in the summer. Studies show that the ice thickness has decreased by 40% over past 50 years. Ice at higher altitude from Mount Kilimanjaro in Africa to the Himalayas in Asia is also disappearing. Mountain glaciers world wide have melted significantly since 1960's. The estimated loss is 4 lakh cubic Km of water, more than the annual discharge of water from world's four major rivers combined. All this water ultimately ends up in the oceans making a dual loss - the loss in the fresh water stock as well as rise in ocean levels.
Changing climates have also caused numerous alterations in living things. Many birds are reproducing earlier and flowers are blooming earlier than they have in the past. In some cases, the changes can be deadly; Coral reefs have been destroyed as the water became too warm, polar bears are threatened by the loss of sea ice on which they hunt. Other elements have also changed significantly. Rainfall has increased by 5 to 10% over northern hemisphere.
Let us now understand other effects of changing climate. Rise in temperature is one of the prime effects of changing climate. It in turn also has a direct effect on many aspects of life on earth, from agriculture to forestry, from the health of human beings to the welfare of other living beings.
Rising temperatures have direct impact on living things of all kinds, from bacterias to plants to animals. It affects individual growth rates, availability of food and water, and another biological events such as flowering, spawning and birth. Even after an organism dies, heat is still important as the decomposition process is also temperature dependent.
Biologists have found that 84% of the 334 species they studied showed significant changes in their overall biological cycle. Increasing warmth can have positive as well as negative effects on human physiology. Where as the colder regions may some what benefit temporarily by rise in temperature, the hotter places can produce heat related injuries which can disturb body cycle and even could be fatal. Warmer weather may also lead to increase in occurrence of diseases. Allergies will probably increase and even simple act of breathing may become harder. The heat waves in our country are taking more death toll as the summer temperature is nearing to almost 50°C at some places. Europe experienced a series of extraordinary heat waves in the summer of 2003 killing thousands of people. The World Meteorological Organization has projected that heat related deaths will double in next twenty years. Forest fires are another consequence of extreme heat, which is already on a rise in Europe, Australia and North America, threatening various species. In a vicious circle, fires further contribute to climate change as burning releases more carbon dioxide and diminish the possibility of in taking the ever increasing carbon emissions. All this will carry large economic costs.
 
Coral reefs - a hard limestone structure built by tiny animals - is a habitat for about 25% of marine species, support more biodiversity than any other marine ecosystems. The rising ocean temperatures are destroying them across the globe. They also act as natural break waters that protect shorelines from storms and also benefit humanity through fisheries and tourism of scuba diving. It will affect the tourism industry in a significant way as the popular tourist destinations will loose their balance of nature for which they are better known for. Due to rise in temperature a phenomenon of coral bleaching occurs, thereby disrupting the habitat for marine life. It also affects it other way as the rise in temperature lowers the concentration of carbonate which is used by marine organisms to build their skeletons.

It is believed by most scholars across the globe that an average rise of 2° to 3°C will cause severe problems in terms of many species becoming extinct. Rise in sea level to the extent of around 20 to 23 feet within this century will affect the sea ports, 100's of billion dollars will be required to maintain current functioning and stability of sea ports across the world, impact of loosing land to sea would be unparalleled. Insurance and risk management companies will have to spend double to pay for the risks covered against natural calamities and so on.
Around the world, a major ecological change is underway, the animals and other living species are shifting towards the poles or to higher altitudes. The study reveals that many animals, butterflies, birds, fishes and even plant species are moving to higher altitudes, varying from 6 km up to 97 km, either northward or southward, per decade. All of these animals and plants are reacting in their own ways to the steady temperature increase. The ecological effect of this migration depends on the ability to adapt to new environment of these species. Some may adapt quickly others may vanish completely. The species which better adapt to new climate might make it harder for existing species persisting in a region.
 
The known example is Red fox which migrated north wards, now competes with the Arctic Fox, which now may not survive. Human civilization often becomes barriers to migration with cities, roads and farms, the best known example is of the Leopards which are seen in vicinities of towns and cities. Even the plant species such as mosses and planktons which were alien to some habitats are now colonizing at newer places. Such transitions can seriously disrupt a region's native species on which the food chain depends.
 
There is also other school of thought which does not agree the human factor behind global warming. Some critics disagree the basis on which the climate models are derived, though all of them agree that the temperature is indeed on rise. Whatever way the scholars interpret the change, it is for sure the global warming will affect socio-economic development, technological change and the population as a whole. Therefore even though it is sometimes said that population is our asset, it is a partial truth, looking only from an angle of becoming super power. But what super power it would be, if by the time we achieve that status, there would hardly be any resources left on earth to really celebrate and show our supremacy.

Ironically it is up to us to decide how much and how fast we would like to make the earth warmer and thus make it inhabitable. To sum up in words of St. Lucia's Ambassador, Charles Fleming "If we wait for the proof, the proof will kill us."

Comments

Popular posts from this blog

विष्ठेचे विश्वरूपदर्शन 

विकासाचा प्रलय

Climate: The fundamental force that shapes the life on Earth